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Article

Green Mechanochemical Synthesis of Binary and Ternary Cadmium Chalcogenides with Tunable Band Gaps

by
Matjaž Kristl
1,*,
Neža Zanjkovič
1,
Jona Kunej
1,
Sašo Gyergyek
1,2 and
Janja Stergar
1
1
Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia
2
Department of Materials Synthesis, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
*
Author to whom correspondence should be addressed.
J. Manuf. Mater. Process. 2025, 9(11), 375; https://doi.org/10.3390/jmmp9110375
Submission received: 29 September 2025 / Revised: 11 November 2025 / Accepted: 13 November 2025 / Published: 15 November 2025
(This article belongs to the Special Issue Recent Developments in Materials Processing for Modern Applications: Advancements and Challenges)
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Versions Notes

Abstract

In this work, we report on the mechanochemical preparation and characterization of binary (CdS, CdSe, and CdTe) and ternary (CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5) cadmium chalcogenides. The compounds were synthesized in a planetary micro mill using a zirconia grinding bowl and zirconia grinding balls. The products were examined by powder X-ray diffraction (pXRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), UV–Vis spectroscopy, and differential scanning calorimetry (DSC). Interestingly, CdO formed as a by-product only during milling of Cd+S and Cd+Se in air, while it was absent in the Cd+Te and all ternary systems. The materials were obtained in the form of irregularly shaped aggregates measuring up to several hundred nanometers, composed of nearly spherical primary nanoparticles with diameters in the 10–20 nm range. The band gap energies calculated using Tauc plots for CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5 were 2.01 eV, 1.72 eV, and 1.53 eV, respectively. These results demonstrate the expected tunability of band gaps in ternary cadmium chalcogenides and attest to the potential of such materials for semiconducting applications, particularly in solar cells. The mechanochemical approach is once again shown to be a simple and effective method for the preparation of both binary and ternary chalcogenides, avoiding the use of solvents, toxic precursors, and energy-consuming reaction conditions.

1. Introduction

Cadmium chalcogenides, namely cadmium sulfide (CdS), cadmium selenide (CdSe), and cadmium telluride (CdTe), represent an important class of II–VI semiconductor materials with wide-ranging applications in optoelectronics, photovoltaics, and luminescent devices. Cadmium sulfide with a direct band gap of 2.42 eV was reported to possess immense potential applications in LED diodes and solar cells already two decades ago [1] and has recently been under intense investigation due to its outstanding catalytic, optical, and electronic properties, enabling its use in photocatalytic water splitting [2,3,4]. Cadmium selenide has served as the subject of many studies due to its good application prospects in optoelectronic devices [5]. The insertion of alkali metals and group 12 metals has led to the synthesis of a large group of chalcogenides with desirable electrical and optical properties [6,7].
Beyond these binary compounds, their ternary and quaternary solid solutions allow fine-tuning of band gaps and optical properties, thereby expanding their technological potential [8]. In particular, Cd-based ternary and quaternary (CdSeTe and CdSSeTe) compounds have shown superior properties that can be controlled by managing the composition, even without changing the particles’ size [9]. As an instance, the CdS: CdSe ternary system has been reported to exhibit a perfect choice for photodetectors due to its wide adjustable band gap range [10]. CdSSe/ZnS nanocomposites were reported for their applications in quantum-dot light-emission diodes (qLEDs) [11] while CdSeS ‘magic-size’ clusters have shown potential for applications for light scavenging and bioimaging [12].
Among the cadmium chalcogenides, cadmium telluride CdTe holds a prominent position as a II–VI semiconductor that has been widely investigated for its favorable optoelectronic properties [13]. With a direct band gap of ~1.5 eV, close to the Shockley–Queisser optimum for single-junction solar cells, and a high absorption coefficient, CdTe efficiently absorbs sunlight even in very thin layers [14,15]. These properties make it particularly attractive for thin-film photovoltaics, where CdTe-based devices have achieved competitive conversion efficiencies while maintaining lower production costs compared to crystalline silicon [16]. Today, CdTe solar cells represent one of the most commercially mature thin-film technologies and continue to play a key role in the development of scalable, high-efficiency, and cost-effective renewable energy systems [16,17,18].
While conventional methods for the synthesis of transition metal chalcogenides have long been known and established, they have key shortcomings that make them incompatible with the principles of green chemistry: they often require high temperatures, toxic precursors, or complex processing steps [19,20,21]. Among alternative preparation methods, which have been gaining popularity over the last decades, the single-source precursor method has emerged as an attractive approach for synthesizing metal chalcogenides, as both the metal and chalcogen are incorporated within one molecule, enabling better stoichiometric control [20,21,22]. While this method was also successfully applied during our previous research [23], it has a serious impediment due to the limited number of potential ligands containing sulfur, selenium and especially tellurium. The sonochemical method, using the effects of ultrasound, was successfully applied during our previous research for the synthesis of binary CdS, CdSe, and CdTe nanoparticles in aqueous solutions [24,25] and was also successfully utilized for producing hexagonal CdS nanoplatelets in a continuous reactor [26]. Nevertheless, the aforementioned method obviously encounters its limitations when it comes to the synthesis of ternary compounds [27].
In contrast, the mechanochemical synthesis has emerged as a simple, energy-efficient, and environmentally benign alternative, enabling direct solid-state reactions at room temperature, in most cases without the need for solvents [19]. Mechanochemical reactions are the result of chemical transformations, occurring from grinding, milling, and alloying solid precursors. The method is carried out at relatively low temperatures (i.e., without external energy input), is reported to be reproducible, simple, and easy to operate, ensuring a high yield and control of the particle size by changing the milling conditions [20,28,29]. This approach offers several advantages, including reduced reaction times, scalability, and access to metastable phases, making it a promising and environmentally friendly method for the synthesis of a wide range of materials [30,31]. While traditionally limited to niche applications, mechanochemistry has recently evolved from a laboratory curiosity to a powerful tool for the synthesis of nanosized materials [32], especially when combined with other energy sources like light irradiation, sound agitation, or electrical impulses [33]. Among other possible applications, the mechanochemical synthesis of nanoparticles for potential antimicrobial applications was reported recently [34].
Mechanochemical syntheses of binary transition metal chalcogenides have been extensively reported in the literature. One of the earliest studies, published more than four decades ago, described the synthesis of a series of binary chalcogenides, including CdS, CdSe, and CdTe, via an explosive-like mechanochemical process [35]. Since then, the explosive (also referred to as self-sustaining) character of mechanochemical synthesis has evolved into an important subarea within mechanochemistry [36]. Among the earlier studies in this field, the mechanochemical synthesis of CdS quantum dots [37] and the preparation of CdTe nanocrystals by ball milling [38] should be mentioned.
Nevertheless, this topic remains an active area of research. For instance, CdS/ZnS nanocomposites prepared via a two-step mechanochemical approach have demonstrated good potential for theranostic applications [39]. An excellent review summarizing recent developments in chalcogenide mechanochemistry, including examples of their application in materials engineering, was published recently [40].
The mechanochemical method is undoubtedly well suited for the synthesis of binary chalcogenides [40,41,42], including Cu, Cd, Al, Ga, and Ni chalcogenides, as reported in our previous studies [43,44,45]. However, its extension to ternary systems has been less explored. Most research has focused on ternary chalcogenides of the I–III–VI2 type, such as CuInS2 and CuInSe2, owing to their potential applications in thin-film solar cells [40,46,47]. Among cadmium-based ternary chalcogenides, the mechanochemical preparation of CdIn2S4, regarded as a promising photocatalytic material candidate due to its narrow band gap, from elemental precursors in a one-step ball-milling method, has been reported recently [48]. In contrast, the mechanochemical synthesis of mixed ternary cadmium chalcogenides such as CdSxSe1−x, CdSxTe1−x, and CdSxTe1−x has, to the best of our knowledge, not yet been described, and therefore represents the novel contribution of the present study.

2. Materials and Methods

2.1. Ball Milling

All reagents used were commercially available and employed without additional purification. Cadmium (powder, ~100 mesh, 99.5% trace metal basis) and tellurium (powder, 200 mesh, 99.8% trace metal basis) were obtained from Sigma-Aldrich, St. Louis, MO, USA. Selenium powder (p. a., >99%) was acquired from Kemika d.d., Zagreb, Croatia, while sulfur (powder, 99.98%) was obtained from Merck KGaA, Darmstadt, Germany. The treatment of the mixtures was performed in a Fritsch premium line PULVERISETTE 7 Planetary Micro Mill (Fritsch, Idar-Oberstein, Germany) equipped with two 20 mL zirconia griding bowls and 10 mm diameter zirconia grinding balls. During all experiments, we used 10 milling balls (with a total mass of ≈30 g), a 15:1 ball-to-powder mass ratio, and a rotational speed of 600 rpm. For practical reasons, only one of the bowls was used for the synthesis, while the other one was counterbalanced by inert silica powder. As an example: for the synthesis of CdS0.5Se0.5, we weighed 1.3388 g (=11.91 mmol) of Cd, 0.1909 g (=5.95 mmol) of S, and 0.4703 g (=5.96 mmol) of Se, to satisfy both the conditions: n(S) + n(Se) = n(Cd) and m(S) + m(Se) + m(Cd) ≈ 2 g. The masses of precursors during other experiments were calculated based on the same assumptions. To prevent overheating, the milling was conducted in 15 min intervals, followed by 15 min breaks. While initial experiments were performed in air atmosphere, we used argon atmosphere during some of the subsequent experiments to prevent oxidation, as explained further on.

2.2. Characterization

Powder X-ray diffraction (pXRD) data were collected on a PANalytical X’pert PRO diffractometer (Malvern Panalytical Ltd., Malvern, UK) using CuKα1 radiation (λ = 1.5406 Å), scanning range from 10° to 70°, step size 0.02° and time/step = 1 s. Transmission electron microscopy (TEM) measurements were performed using a JEOL 2100 microscope (JEOL Inc., Peabody, MA, USA) using the accelerating voltage of 200 kV. The obtained powders were dispersed in isopropanol using an ultrasonic bath and placed on a carbon-coated copper grid. The elemental composition of the particles was analyzed in the TEM mode using a Jeol JED 2300 EDXS system, (JEOL Inc., Peabody, MA, USA). The hydrodynamic particle size was measured by dynamic light scattering (DLS) with Zetasizer Nano-S equipment (Malvern Instruments, Malvern, UK) using disposable 1 cm polystyrene cuvettes. A UV-VIS spectrometer Varian Cary 50 Bio (Varian Inc., Palo Alto, CA, USA) was used to study the optical properties of the prepared cadmium chalcogenides. The samples were dispersed in ethanol in an ultrasonic bath prior to the measurement. The cadmium content was measured on a Varian SpectrAA-10 flame atomic spectrometer (AAS) (Varian Inc., Palo Alto, CA, USA) after digestion of the samples [49] with concentrated HNO3 in PTFE vessels in a microwave oven (MDS-2000, CEM Corporation, Matthews, NC, USA). Thermal analysis of the samples was carried out by Mettler DSC 3 (Mettler Toledo, Greifensee, Switzerland) in 40 µL aluminum crucibles sealed with a pierced aluminum lid, using a heating rate of 10 K/min and a temperature range from 30 to 600 °C.

3. Results and Disussion

3.1. Binary Mixtures

The detailed structural analysis of cadmium chalcogenides appears to be challenging, with the most interesting aspect being the possibility of polymorphous transformations. All three binary cadmium chalcogenides are known to exist in both cubic and hexagonal modifications, as summarized in Table 1.
Both hexagonal and cubic forms of CdS and CdSe can be obtained by mechanochemical synthesis. Tsuzuki & McCormick reported that experimental details like milling ball diameters can influence the structure of the synthesized CdS, with a mixture of both the cubic and hexagonal structures obtained when milling with 12.6 mm balls, while only the cubic phase was evident when milling with 4.8 mm balls, in both cases using a SPEX 8000 mill ad 1 h milling time [37]. The Baláž group reported the synthesis of hexagonal CdS and CdSe from elemental precursors in a Fritsch 7 Pulverisette ball mill after very short (8 min and 3.5 min, respectively) reaction times [42], while during a previous study utilizing different reaction conditions (cadmium acetate and sodium sulfide precursors, 30 min milling time), cubic CdS was obtained [39]. Tan et al. prepared CdSe from elemental powders in a SPEX 8000 mill, reporting hexagonal product after 2–3 h milling time, changing to a cubic polymorph after prolonged (up to 40 h) milling [56]. The situation seems to be the clearest with CdTe, for which the literature states that the cubic structure is generally more stable, although the hexagonal structure is occasionally found in special modifications such as thin films. Previous reports by Tan et al. and Campos et al. report only the presence of the cubic form by mechanical alloying [38,57].
Powder X-ray diffraction (pXRD) patterns of products obtained during our research by ball milling equimolar Cd:S, Cd:Se, and Cd:Te mixtures for 15 min are shown in Figure 1, Figure 2 and Figure 3. In the case of the Cd:S system (Figure 1), the diffraction pattern indicates the presence of both hexagonal and cubic CdS phases. The reflections were identified as hexagonal CdS (ICDD PDF-4, file No. 00-006-0314), while the contribution of the cubic modification is suggested by the mismatch in peak intensity at 26.5°, where the (111) reflection of the cubic phase overlaps with the (002) peak of the hexagonal polymorph. According to previously published results, the reaction may be nearly complete before 15 min of milling. When milling was carried out in air, additional peaks attributable to CdO (ICDD file No. 00-005-0640) were observed. This oxidation was effectively suppressed when the milling was performed under an argon atmosphere, yielding phase-pure CdS. In the Cd:Se system, the main product was identified as cubic CdSe (ICDD file No. 00-019-0191), while minor CdO reflections appeared in samples prepared in air (Figure 2). The shoulder peak at approximately 24° can be assigned to an unknown phase. As in the case of CdS, performing the reaction under argon completely prevented CdO formation. In contrast, the mechanochemical reaction of Cd and Te consistently yielded single-phase cubic CdTe (ICDD file No. 00-015-0770), even when milling was conducted in air (Figure 3), with no CdO impurities detected.
Differential scanning calorimetry (DSC) was used as an alternative approach to XRD to gain insight into the reaction progress at various milling times. The DSC curves for all precursors and ball-milled binary products are presented in Figure 4a–c. For the Cd:S system (Figure 4a), the DSC curves of both elemental precursors display pronounced endothermic peaks corresponding to the melting points of Cd (Tm = 321 °C) and S (Tm = 119 °C). The minor endothermic peaks on the DSC curve of sulfur correspond to Sα → Sβ and Sβ → Sγ transitions [58] and the endotherm occurring at T ≈ 400 °C indicates the boiling point of sulfur; however, the changes beyond the melting point can be considered to be irrelevant to the discussion. A minor deviation in the DSC curve at approximately 143 °C is observed for the sample obtained by 15 min milling. While the possibility of residual unreacted reagents cannot be entirely excluded, the observed deviation is too subtle to allow a definitive conclusion in this regard. Anyway, no detectable precursor melting endotherms remain after 15 min of milling, suggesting complete conversion into CdS. This is consistent with the high melting point of CdS (≈1750 °C), which lies well beyond the accessible range of conventional DSC. The DSC curve of the product obtained after 60 min of milling is comparable to that after 15 min, with the above-mentioned minor endothermal deviation at approximately 143 °C missing altogether, thus further indicating the complete formation of CdS. For comparison, a sample prepared by simple mortar-and-pestle grinding for ~5 min was also analyzed. Its DSC curve still shows both precursor melting peaks, albeit with significantly reduced intensity, suggesting that the reaction is initiated even under such mild mechanical treatment. A similar phenomenon was previously reported for the mechanochemical synthesis of CuS [43].
For the Cd:Se system (Figure 4b), the DSC curve of elemental selenium shows a sharp endothermic peak at ~221 °C, corresponding to its melting point. After 15 min of milling, the melting endotherms of both precursors are undetectable, indicating complete conversion to CdSe. Extending the milling time to 60 min produces no further changes, confirming the rapidity of the reaction. Analogous behavior was observed for the Cd:Te system (Figure 4c). The DSC curve of tellurium exhibits a sharp endothermic peak at ~449 °C, corresponding to its melting point. After 15 min of milling, this peak disappears, consistent with complete reaction to CdTe. As CdTe has a melting point close to 1100 °C [59], no product-related endotherms can be detected within the accessible DSC temperature range.
The binary systems thus demonstrate that mechanochemical synthesis enables the rapid and complete formation of CdS, CdSe, and CdTe within 15 min of milling, with phase purity dependent only on the milling atmosphere in the cases of CdS and CdSe. Having established the efficiency and reliability of the method for binary cadmium chalcogenides, attention was next directed to ternary Cd–S–Se–Te systems. These compounds are of particular interest because their tunable compositions enable adjustment of structural and electronic properties, making them attractive for optoelectronic and photovoltaic applications.

3.2. Ternary Mixtures

Powder diffraction patterns of CdSxSe1−x samples, prepared using two different S:Se ratios, are presented in Figure 5a,b. Figure 5a shows the diffraction pattern of the sample synthesized with an S:Se ratio of 0.5:0.5, alongside those of the binary compounds CdS and CdSe. As the binaries adopt different structures, i.e., predominantly hexagonal (wurtzite) for CdS and mainly cubic (zincblende) for CdSe, and no ICDD reference exists for CdS0.5Se0.5, a simple visual comparison only confirms the formation of a mixed cadmium chalcogenide phase without any detectable CdO impurity. Another ternary compound with a S:Se ratio of 0.8:0.2 ratio was prepared due to the fact that this composition is reported in the ICDD/JPCDS database. The sample prepared by using the 0.8:0.2 ratio (Figure 5b), matches perfectly with the pattern of ICDD file No. 00-040-0837, reported therein as hexagonal ‘Cd10S8.13Se1.87’. However, comparison of the reported and measured peak intensities indicates the possible presence of an additional cubic phase. Despite minor discrepancies, the observed trends are consistent with those published recently by Bibiano-Salas et al. [60], who studied the variation of lattice parameters and band gap tuning in the CdSxSe1−x (0 ≤ x ≤ 1) system as a function of composition. Notably, in contrast to the binary CdS and CdSe systems, no peaks of CdO were detected, even when milling was conducted in air.
A similar outcome was obtained for the CdSxTe1−x system. The diffraction pattern of the sample with S:Te = 0.5:0.5 (Figure 6) displays reflections located between those of CdS and CdTe. No ICDD reference exists for CdS0.5Te0.5; however, the absence of CdO peaks indicate that no oxidation of cadmium could be detected even when milling was performed in air. The formation of CdO in the Cd+S and Cd+Se systems, but not in Cd+Te or ternary mixtures, likely reflects differences in reaction kinetics. Cd appears to react more rapidly with Te than with S or Se, so CdTe formation may outcompete surface oxidation of Cd by atmospheric O2 during milling.
Finally, diffraction patterns for the CdSexTe1−x system are depicted in Figure 7. The peaks of CdSe0.5Te0.5 are located almost exactly midway between those of both binary chalcogenides, which in this particular case indicates the formation of a solid solution between two end members sharing the same (i.e., zincblende) structure type. The lattice parameters of CdSe0.5Te0.5 were calculated using TOPAS software and the as-obtained value of a = 6.25 ± 0.02 Å falls almost exactly between those of both binaries, in accordance with Vegard’s law. Those findings are consistent with results obtained by Ouendadji et al. by density functional studies [61]. Although no ICDD reference exists for CdS0.5Te0.5, the measured peaks correspond closely to the reported pattern of CdSe0.6Te0.4 (ICDD file No. 00-041-1325).
As with the binary systems, the pXRD findings were complemented by DSC measurements performed on all precursors and products, as presented in Figure 8a–c. In all three ternary systems, no precursor melting endotherms were observed after 15 min of milling, indicating complete conversion. Minor deviations observed in the Cd:Se:Te system are within the experimental uncertainty of the measurements. Prolonged milling up to 60 min produced no significant changes in the DSC curves, demonstrating that the reactions are already complete within the initial 15 min.
The crystallite sizes of all products were estimated using the Scherrer equation:
d x = 0.94 ⋅ λ ⋅ 57.3 β ⋅ cos θ
where λ is the wavelength of the X-ray radiation (nm), β the full-width at half-maximum (FWHM) of the corresponding peak (°) and θ is the diffraction angle (°). The results, presented in Table 2, were obtained by calculating the average value of 2–3 most prominent peaks.
The morphology of the binary products obtained after 15 min of milling was examined by TEM (Figure 9a–c). All samples consist of irregularly shaped aggregates with dimensions extending up to several hundred nanometers. The formation of aggregates and agglomerates during mechanochemical synthesis, resulting from the intense forces involved, is a well-known phenomenon, frequently reported in the literature (see, for example, [40] and the references cited therein). A similar behavior was observed in our previous experiments [45]. Although controlling agglomeration was not the focus of the present study, we assume that it could be mitigated through the use of suitable capping agents, as demonstrated by Tan et al. [38].
Similar conclusions can be drawn from TEM images of selected ternary products (CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5), as presented in Figure 10a–c. At higher magnifications, the presence of spherical primary nanoparticles with diameters in the 10–20 nm range is visible, as depicted in Figure 11a–c. These dimensions are broadly consistent with crystallite sizes estimated from pXRD data using the Scherrer equation, although the clustered nature of the samples limits a more precise assessment. Results of the EDX analysis correspond well to the results obtained by pXRD and to Cd content, determined by AAS, as shown in Table 3 for binary and ternary products.
Particle size measurements and hydrodynamic size distribution were additionally corroborated by DLS measurements in water suspensions after applying an ultrasonic bath. For each of the samples, three independent measurements were performed and the average value calculated. The results are presented in Table 4. As expected, the hydrodynamic diameters obtained by DLS are significantly larger than crystallite sizes estimated from pXRD or the primary nanoparticle dimensions suggested by TEM. This discrepancy is well known and arises because DLS measures the apparent size of particles as they diffuse in suspension, which includes contributions from solvation layers and possible particle agglomeration in liquid media [45,62,63]. Within this general trend, the CdTe and CdSe0.5Te0.5 samples appear to exhibit comparatively smaller hydrodynamic sizes, although the origin of this behavior is not yet clear and would require more systematic investigation.
As already outlined in the Introduction, a key motivation for investigating ternary cadmium chalcogenides lies in the possibility of tailoring their band gaps by varying the composition [9,10]. Generally, the band gap width of bulk CdS is reported to be 2.42 eV, while that of CdSe is 1.74 eV, although variations exist in the literature due to size effects and sample morphology. As expected, there are variations in values reported throughout the literature, with the band gap increasing with decreasing nanoparticles size due to the quantum confinement effect [64]. On the other hand, CdS thin films have been reported with slightly reduced band gap values in the 2.27–2.33 eV range [65].
In ternary systems, the band gap typically falls between those of the two binary end members, but the relationship is often nonlinear due to the so-called bowing effect [66]. For the CdSxSe1−x system, the deviation from linearity is relatively small, since CdS and CdSe are miscible with almost zero enthalpy change due to small lattice mismatch [67]. By contrast, the CdSxTe1−x system exhibits a more complex dependence, with some of the ternary compositions reported to display either broader or narrower band gaps than any of the binaries [68,69]. Similar behavior was reported for the CdSexTe1−x system, which has gained considerable attention in photovoltaic research, as partial incorporation of CdSe into CdTe thin film solar cells has been shown to improve cell performance [70,71]. At first glance, using a 1.74 eV band gap CdSe to increase the optical absorption of CdTe (Eg = 1.45 eV) seems counterintuitive, however alloying of CdSe into CdTe can effectively reduce the band gap below the values of either of the binary compounds due to the large bowing effect [72].
In the present work, the optical band gap energies of ternary cadmium chalcogenides were determined from UV–Vis absorption spectra using Tauc plots, according to the relation:
(αhν)n = A(hν − Eg)
here, α is the absorption coefficient (cm−1), hν the photon energy (eV), A is a constant, and n = 2 for a direct transition. By plotting (αhν)2 vs. (hν) and extrapolating the linear portion of the curve to the x-axis, the band gap value Eg (eV) can be obtained as the intercept [45,64,65,67].
The optical band gap energies, calculated for CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5, were 2.01 eV, 1.72 eV, and 1.53 eV, respectively, as presented in Figure 12. The value obtained for CdS0.5Se0.5 fits perfectly between the values of the binaries, while being slightly higher when compared to the values of 1.8–1.95 eV reported in literature [66,67]. In contrast, the measured band gap value of CdS0.5Te0.5 is slightly lower than the values of 1.88–1.94 eV previously reported [68,73], though still in reasonable agreement. Finally, the result measured for CdSe0.5Te0.5 (=1.53 eV) matches perfectly with ≈1.55 eV, reported in [74]. The ternary compounds exhibit band gaps intermediate between those of the corresponding binaries, as expected for solid solutions. Nevertheless, CdSe0.5Te0.5 shows a band gap (1.53 eV) much closer to CdTe (1.45 eV) than to CdSe (1.74 eV), suggesting a stronger influence of Te on the band structure. These findings support the expected tunability of band gaps in ternary cadmium chalcogenides and further confirm the successful synthesis of the targeted compositions.

4. Conclusions

Binary and ternary cadmium chalcogenides were successfully synthesized from elemental precursors using a mechanochemical approach. Powder XRD and DSC analyses confirmed the complete formation of CdS, CdSe, and CdTe within 15 min of milling, with phase purity for CdS and CdSe achievable under an inert atmosphere to prevent oxidation. Ternary alloys, namely CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5, were successfully synthesized and their compositions confirmed by pXRD and AAS measurements, while their diffraction patterns indicate the formation of homogeneous solid solutions, free from detectable oxide impurities.
TEM imaging revealed that the products consist of irregular aggregates of several hundred nanometers, composed of smaller spherical primary nanoparticles in the 10–20 nm range, consistent with crystallite sizes estimated from XRD. DLS measurements in aqueous suspensions indicated larger hydrodynamic diameters, as expected due to particle solvation and aggregation. UV–Vis spectroscopy demonstrated tunable optical band gaps in the ternary systems, with measured values in good agreement with literature reports and consistent with expected bowing effects.
Overall, mechanochemical synthesis proves to be a simple, rapid, and environmentally friendly method for preparing binary and ternary cadmium chalcogenides, avoiding solvents, toxic precursors, and high-temperature treatments. The tendency of the products to form aggregates may be mitigated in future work through the use of surfactants or optimized milling protocols, enabling improved control over particle size and dispersion for potential applications in optoelectronic devices.

Author Contributions

Conceptualization, M.K. and J.S.; Methodology, M.K., S.G. and J.S.; Investigation, M.K.; N.Z.; J.K.; and S.G.; Supervision, M.K. and J.S.; Writing—original draft preparation, M.K.; Writing—review and editing, M.K. and J.S. All authors have read and agreed to the published version of the manuscript.

Funding

The authors acknowledge the financial support from the grant number P2-0006 of the Slovenian Research Agency (ARIS).

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Acknowledgments

The first author would like to thank Janja Kristl for performing UV-Vis and AAS analysis, and Sabina Vohl for DLS measurements and evaluation as well as for coordinating the work of N.Z. and J.K. in the laboratory.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
pXRDPowder X-ray Diffraction
DSCDifferential Scanning Calorimetry
TEMTransmission Electron Microscopy
EDXEnergy-Dispersive X-ray Spectroscopy
DLSDynamic Light Scattering
AASAtomic Absorption Spectroscopy

References

  1. Maity, R.; Kundoo, S.; Chattopadhyay, K.K. Synthesis and Optical Characterization of CdS Nanowires by Chemical Route. Mater. Manuf. Process. 2006, 21, 644–647. [Google Scholar] [CrossRef]
  2. Isa, A.T.; Hafeez, H.Y.; Mohammed, J.; Kafadi, A.D.G.; Ndikilar, C.E.; Suleiman, A.B. A review on the progress and prospect of CdS-based photocatalysts for hydrogen generation via photocatalytic water splitting. J. Alloy. Comp. Comm. 2024, 4, 100043. [Google Scholar] [CrossRef]
  3. Suhaimi, N.H.S.; Syed, J.A.S.; Azhar, R.; Adzis, N.S.; Halim, O.M.A.; Chang, Y.H.R.; Taylor, S.H.; Bailey, L.A.; Ab Rahim, M.H.; Ramli, M.Z.; et al. Perspective on CdS-based S-scheme photocatalysts for efficient photocatalytic applications: Characterisation techniques and optimal semiconductor coupling. Int. J. Hydrogen Energy 2025, 165, 150929. [Google Scholar] [CrossRef]
  4. Mamiyev, Z.; Balayeva, N.O. Metal Sulfide Photocatalysts for Hydrogen Generation: A Review of Recent Advances. Catalysts 2022, 12, 1316. [Google Scholar] [CrossRef]
  5. Li, J.; Zheng, H.; Zheng, Z.; Rong, H.; Zeng, Z.; Zeng, H. Synthesis of CdSe and CdSe/ZnS Quantum Dots with Tunable Crystal Structure and Photoluminescent Properties. Nanomaterials 2022, 12, 2969. [Google Scholar] [CrossRef]
  6. Khan, I.; Ali, A.; Ul Haq, I.; Abdul Aziz, S.; Ali, Z.; Ahmad, I. The effect of potassium insertion on optoelectronic properties of cadmium chalcogenides. Mater. Sci. Semicond. Process. 2021, 122, 105466. [Google Scholar] [CrossRef]
  7. Rojas, J.A.; Oliva, A.I. A Double Energy Transition of Nanocrystalline CdxZn1-xS Films Deposited by Chemical Bath. Mater. Manuf. Process. 2015, 30, 785–792. [Google Scholar] [CrossRef]
  8. Aldakov, D.; Lefrançois, A.; Reiss, P. Ternary and quaternary metal chalcogenide nanocrystals: Synthesis, properties and applications. J. Mater. Chem. C 2013, 1, 3756–3776. [Google Scholar] [CrossRef]
  9. Ebrahim, F.; Al-Hartomy, O.; Wageh, S. Cadmium-Based Quantum Dots Alloyed Structures: Synthesis, Properties, and Applications. Materials 2023, 16, 5877. [Google Scholar] [CrossRef]
  10. Moger, S.N.; Mahesha, M.G. Colour tunable co-evaporated CdSxSe1-x (0 ≤ x ≤ 1) ternary chalcogenide thin films for photodetector applications. Mater. Sci. Semicond. Process. 2020, 120, 105288. [Google Scholar] [CrossRef]
  11. Diker, H.; Unluturk, S.S.; Ozcelik, S.; Varlikli, C. Improving the Stability of Ink-Jet Printed Red QLEDs By Optimizing The Device Fabrication Process. Nanofabrication 2024, 9, 1–13. [Google Scholar] [CrossRef]
  12. Jiang, Y.; Wang, Z.; Wang, S.; Zhang, C.; Luan, C.; Chen, X.; Yu, K. Development of aqueous-phase CdSeS magic-size clusters at room temperature and quantum dots at elevated temperatures. Nano Res. 2024, 17, 10529–10535. [Google Scholar] [CrossRef]
  13. Abu-Farsakh, H.; Gul, B.; Khan, M.S. Investigating the Optoelectronic and Thermoelectric Properties of CdTe Systems in Different Phases: A First-Principles Study. ACS Omega 2023, 8, 14742–14751. [Google Scholar] [CrossRef]
  14. Romeo, A.; Artegiani, E. CdTe-Based Thin Film Solar Cells: Past, Present and Future. Energies 2021, 14, 1684. [Google Scholar] [CrossRef]
  15. Bosio, A.; Rosa, G.; Romeo, N. Past, present and future of the thin film CdTe/CdS solar cells. Sol. Energy 2018, 175, 31–43. [Google Scholar] [CrossRef]
  16. Scarpulla, M.A.; McCandless, B.; Phillips, A.B.; Yan, Y.; Heben, M.J.; Wolden, C.; Xiong, G.; Metzger, W.K.; Mao, D.; Krasikov, D.; et al. CdTe-based thin film photovoltaics: Recent advances, current challenges and future prospects. Sol. Energy Mater. Sol. Cells 2023, 255, 112289. [Google Scholar] [CrossRef]
  17. Sivasankar, S.M.; Amorim, C.d.O.; Cunha, A.F.d. Progress in Thin-Film Photovoltaics: A Review of Key Strategies to Enhance the Efficiency of CIGS, CdTe, and CZTSSe Solar Cells. J. Compos. Sci. 2025, 9, 143. [Google Scholar] [CrossRef]
  18. Jamaatisomarin, F.; Chen, R.; Hosseini-Zavareh, S.; Lei, S. Laser Scribing of Photovoltaic Solar Thin Films: A Review. J. Manuf. Mater. Process. 2023, 7, 94. [Google Scholar] [CrossRef]
  19. Pinto, A.H.; Cho, D.Y.; Oliynyk, A.O.; Silverman, J.R. Green Chemistry Applied to Transition Metal Chalcogenides through Synthesis, Design of Experiments, Life Cycle Assessment, and Machine Learning. In Green Chemistry—New Perspectives; IntechOpen: London, UK, 2022; Volume 139. [Google Scholar] [CrossRef]
  20. Ghasempour, A.; Dehghan, H.; Ataee, M.; Chen, B.; Zhao, Z.; Sedighi, M.; Guo, X.; Shahbazi, M.-A. Cadmium Sulfide Nanoparticles: Preparation, Characterization, and Biomedical Applications. Molecules 2023, 28, 3857. [Google Scholar] [CrossRef] [PubMed]
  21. Buckingham, M.A.; Norton, K.; McNaughter, P.D.; Whitehead, G.; Vitorica-Yrezabal, I.; Alam, F.; Laws, K.; Lewis, D.J. Investigating the Effect of Steric Hindrance within CdS Single-Source Precursors on the Material Properties of AACVD and Spin-Coat-Deposited CdS Thin Films. Inorg. Chem. 2022, 61, 8206–8216. [Google Scholar] [CrossRef] [PubMed]
  22. Karmakar, G.; Tyagi, A.; Shah, A.Y. A comprehensive review on single source molecular precursors for nanometric group IV metal chalcogenides: Technologically important class of compound semiconductors. Coord. Chem. Rev. 2024, 504, 215665. [Google Scholar] [CrossRef]
  23. Dojer, B.; Pevec, A.; Breznik, K.; Jagličić, Z.; Gyergyek, S.; Kristl, M. Structural and thermal properties of new copper and nickel single-source precursors. J. Mol. Struct. 2019, 1194, 171–177. [Google Scholar] [CrossRef]
  24. Kristl, M.; Ban, I.; Danč, A.; Danč, V.; Drofenik, M. A sonochemical method for the preparation of cadmium sulfide and cadmium selenide nanoparticles in aqueous solutions. Ultrason. Sonochem. 2010, 17, 916–922. [Google Scholar] [CrossRef] [PubMed]
  25. Ban, I.; Kristl, M.; Danč, V.; Danč, A.; Drofenik, M. Preparation of cadmium telluride nanoparticles from aqueous solutions by sonochemical method. Mater. Lett. 2012, 67, 56–59. [Google Scholar] [CrossRef]
  26. Palanisamy, B.; Paul, B.; Chang, C.-H. The synthesis of cadmium sulfide nanoplatelets using a novel continuous flow sonochemical reactor. Ultrason. Sonochem. 2015, 26, 452–460. [Google Scholar] [CrossRef]
  27. Denac, B.; Kristl, M.; Gyergyek, S.; Drofenik, M. Preparation and characterization of ternary cadmium chalcogenides. Chalcogenide Lett. 2013, 10, 87–98. [Google Scholar]
  28. Shalabayev, Z.; Baláž, M.; Khan, N.; Nurlan, Y.; Augustyniak, A.; Daneu, N.; Tatykayev, B.; Dutková, E.; Burashev, G.; Casas-Luna, M.; et al. Sustainable Synthesis of Cadmium Sulfide, with Applicability in Photocatalysis, Hydrogen Production, and as an Antibacterial Agent, Using Two Mechanochemical Protocols. Nanomaterials 2022, 12, 1250. [Google Scholar] [CrossRef]
  29. Gancheva, M.; Iordanova, R.; Ivanov, P.; Yordanova, A. Effect of Ball Milling Speeds on the Phase Formation and Optical Properties of α-ZnMoO4 and ß-ZnMoO4 Nanoparticles. J. Manuf. Mater. Process. 2025, 9, 118. [Google Scholar] [CrossRef]
  30. Pagola, S. Outstanding Advantages, Current Drawbacks, and Significant Recent Developments in Mechanochemistry: A Perspective View. Crystals 2023, 13, 124. [Google Scholar] [CrossRef]
  31. Fantozzi, N.; Volle, J.-N.; Porcheddu, A.; Virieux, D.; Garcia, F.; Colacino, E. Green metrics in mechanochemistry. Chem. Soc. Rev. 2023, 52, 6680–6714. [Google Scholar] [CrossRef]
  32. Mukherjee, N. Mechanochemistry: A Resurgent Force in Chemical Synthesis. Synlett 2024, 35, 2331–2345. [Google Scholar] [CrossRef]
  33. Martinez, V.; Stolar, T.; Karadeniz, B.; Brekalo, I.; Užarević, K. Advancing mechanochemical synthesis by combining milling with different energy sources. Nat. Rev. Chem. 2023, 7, 51–65. [Google Scholar] [CrossRef]
  34. Dubadi, R.; Huang, S.D.; Jaroniec, M. Mechanochemical Synthesis of Nanoparticles for Potential Antimicrobial Applications. Materials 2023, 16, 1460. [Google Scholar] [CrossRef]
  35. Tschakarov, C.G.; Gospodinov, G.G.; Bontschev, Z. Über den Mechanismus der mechanochemischen Synthese anorganischer Verbindungen. J. Solid. State Chem. 1982, 41, 244–252. [Google Scholar] [CrossRef]
  36. Takacs, L. Self-sustaining reactions as a tool to study mechanochemical activation. Faraday Dicuss. 2014, 170, 251–265. [Google Scholar] [CrossRef] [PubMed]
  37. Tsuzuki, T.; McCormick, P. Synthesis of CdS quantum dots by mechanochemical reaction. Appl. Phys. A 1997, 65, 607–609. [Google Scholar] [CrossRef]
  38. Tan, G.L.; Hömmerich, U.; Temple, D.; Wu, N.Q.; Zheng, J.G.; Loutts, G. Synthesis and optical characterization of CdTe nanocrystals prepared by ball milling process. Scr. Mater. 2003, 48, 1469–1474. [Google Scholar] [CrossRef]
  39. Baláž, P.; Baláž, M.; Dutková, E.; Zorkovská, A.; Kováč, J.; Hronec, P.; Kováč, J., Jr.; Čaplovičová, M.; Mojžiš, J.; Mojžišová, G.; et al. CdS/ZnS nanocomposites: From mechanochemical synthesis to cytotoxicity issues. Mater. Sci. Eng. C 2016, 58, 1016–1023. [Google Scholar] [CrossRef] [PubMed]
  40. Baláž, P.; Baláž, M.; Achimovičová, M.; Bujňáková, Z.; Dutková, E. Chalcogenide mechanochemistry in materials science: Insight into synthesis and applications (a review). J. Mater. Sci. 2017, 52, 11851–11890. [Google Scholar] [CrossRef]
  41. Campos, C.E.M. Solid State Synthesis and Characterization of NiTe Nanocrystals. J. Nano Res. 2014, 29, 35–39. [Google Scholar] [CrossRef]
  42. Baláž, M.; Džunda, R.; Bureš, R.; Sopčák, T.; Csanádi, T. Mechanically induced self-propagating reactions (MSRs) to instantly prepare binary metal chalcogenides: Assessing the influence of particle size, bulk modulus, reagents melting temperature difference and thermodynamic constants on the ignition time. RSC Mechanochem. 2024, 1, 94–105. [Google Scholar] [CrossRef]
  43. Kristl, M.; Ban, I.; Gyergyek, S. Preparation of Nanosized Copper and Cadmium Chalcogenides by Mechanochemical Synthesis. Mater. Manuf. Process. 2013, 28, 1009–1013. [Google Scholar] [CrossRef]
  44. Kristl, M.; Gyergyek, S.; Srt, N.; Ban, I. Mechanochemical Route for the Preparation of Nanosized Aluminum and Gallium Sulfide and Selenide. Mater. Manuf. Process. 2016, 31, 1608–1612. [Google Scholar] [CrossRef]
  45. Kristl, M.; Gyergyek, S.; Škapin, S.D.; Kristl, J. Solvent-Free Mechanochemical Synthesis and Characterization of Nickel Tellurides with Various Stoichiometries: NiTe, NiTe2 and Ni2Te3. Nanomaterials 2021, 11, 1959. [Google Scholar] [CrossRef]
  46. Dutková, E.; Sayagués, M.J.; Briančin, J.; Zorkovská, A.; Bujňáková, Z.; Kováč, J.; Kováč, J., Jr.; Baláž, P.; Ficeriová, J. Synthesis and characterization of CuInS2 nanocrystalline semiconductor prepared by high-energy milling. J. Mater. Sci. 2016, 51, 1978–1984. [Google Scholar] [CrossRef]
  47. Dutková, E.; Sayagués, M.J.; Kováč, J.; Kováč, J., Jr.; Bujňáková, Z.; Briančin, J.; Zorkovská, A.; Baláž, P.; Ficeriová, J. Mechanochemically synthesized nanocrystalline ternary CuInSe2 chalcogenide semiconductor. Mater. Lett. 2016, 173, 182–186. [Google Scholar] [CrossRef]
  48. Sun, M.; Liu, Y.; Na, Y.; Li, Z.; Chen, M.; Dai, S.; Guo, X.; Li, P.; Zhao, T.; Zheng, R. Mechanochemical preparation of Z-scheme CdIn2S4/Zn-Al LDH heterojunction with enhanced photocatalytic performance for SIPX degradation. J. Alloys Compd. 2025, 1010, 177247. [Google Scholar] [CrossRef]
  49. Salvador, A.; Pascual-Martí, M.C.; Aragó, E.; Chisvert, A.; March, J.G. Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion. Talanta 2000, 51, 1171–1177. [Google Scholar] [CrossRef] [PubMed]
  50. Al-Bassam, A.A.I.; Al-Juffali, A.A.; Al-Dhafiri, A.M. Structure and lattice parameters of cadmium sulphide selenide (CdSxSe1−x) mixed crystals. J. Cryst. Growth 1994, 135, 476–480. [Google Scholar] [CrossRef]
  51. Isik, M.; Gullu, H.H.; Delice, S.; Parlak, M.; Gasanly, N.M. Structural and temperature-dependent optical properties of thermally evaporated CdS thin films. Mater. Sci. Semicond. Process. 2019, 93, 148–152. [Google Scholar] [CrossRef]
  52. Wu, J.; Li, K.; Xu, X.; Yu, J.; Li, X.; Tian, J. In situ synthesis of spherical CdS1-xSex red pigment used for ceramic ink-jet printing. Mater. Chem. Phys. 2018, 203, 193–201. [Google Scholar] [CrossRef]
  53. Abbassi, A.; Zarhri, Z.; Azahaf, C.; Ez-Zahaouy, H.; Benyoussef, A. Boltzmann equations and ab initio calculations: Comparative study of cubic and wurtzite CdSe. SpringerPlus 2015, 4, 543. [Google Scholar] [CrossRef]
  54. Xi, L.F.; Lam, Y.M. Synthesis and characterization of CdSe nanorods using a novel microemulsion method at moderate temperature. J. Colloid Interface Sci. 2007, 316, 771–778. [Google Scholar] [CrossRef]
  55. Freik, D.; Parashchuk, T.; Volochanska, B. Thermodynamic parameters of CdTe crystals in the cubic phase. J. Cryst. Growth 2014, 402, 90–93. [Google Scholar] [CrossRef]
  56. Tan, G.L.; Liu, R.H. Preparation of pure CdSe nanocrystals through mechanical alloying. J. Nanopart. Res. 2010, 12, 605–614. [Google Scholar] [CrossRef]
  57. Campos, C.E.M.; Ersching, K.; De Lima, J.C.; Grandi, T.A.; Höhn, H.; Pizani, P.S. Influence of minor oxidation of the precursor powders to form nanocrystalline CdTe by mechanical alloying. J. Alloys Compd. 2008, 466, 80–86. [Google Scholar] [CrossRef]
  58. Souaya, E.R.; Elkholy, S.A.; Abd El-Rahman, A.M.M.; El-Shafie, M.; Ibrahim, I.M.; Abo-Shanab, Z.L. Partial substitution of asphalt pavement with modified sulfur. Egypt. J. Pet. 2015, 24, 483–491. [Google Scholar] [CrossRef]
  59. Triboulet, R. Fundamentals of the CdTe synthesis. J. Alloys Compd. 2004, 371, 67–71. [Google Scholar] [CrossRef]
  60. Bibiano-Salas, L.A.; Martínez-Ara, L.A.; Maldonado-Altamirano, P.; Hernández-Pérez, M.A.; Sastré-Hernández, J.; Santoyo-Salazar, J. High-quality CdSxSe1−x thin films with tunable bandgap for optoelectronic applications: Growth by pulsed laser deposition and characterization. Mater. Res. Express 2025, 12, 055902. [Google Scholar] [CrossRef]
  61. Ouendadji, S.; Ghemid, S.; Meradji, H.; El Haj Hassan, F. Density functional study of CdS1−xSex and CdS1−xTex alloys. Comput. Mater. Sci. 2010, 48, 206–211. [Google Scholar] [CrossRef]
  62. Ban, I.; Markuš, S.; Gyergyek, S.; Drofenik, M.; Korenak, J.; Helix-Nielsen, C.; Petrinić, I. Synthesis of Poly-Sodium-Acrylate (PSA)-Coated Magnetic Nanoparticles for Use in Forward Osmosis Draw Solutions. Nanomaterials 2019, 9, 1238. [Google Scholar] [CrossRef] [PubMed]
  63. Larichev, Y.V. Application of DLS for metal nanoparticle size determination in supported catalysts. Chem. Pap. 2021, 75, 2059–2066. [Google Scholar] [CrossRef]
  64. Praus, P.; Kozák, O.; Kočí, K.; Panáček, A.; Dvorský, R. CdS nanoparticles deposited on montmorillonite: Preparation, characterization and application for photoreduction of carbon dioxide. J. Colloid Interface Sci. 2011, 360, 574–579. [Google Scholar] [CrossRef] [PubMed]
  65. Sinha, T.; Verma, L.; Khare, A. Variations in photovoltaic parameters of CdTe/CdS thin film solar cells by changing the substrate for the deposition of CdS window layer. Appl. Phys. A 2020, 126, 867. [Google Scholar] [CrossRef]
  66. Shoaib, M.; Wang, X.; Zhang, X.; Zhang, Q.; Pan, A. Controllable Vapor Growth of Large-Area Aligned CdSxSe1−x Nanowires for Visible Range Integratable Photodetectors. Nano-Micro Lett. 2018, 10, 58. [Google Scholar] [CrossRef]
  67. Tyagi, J.; Gupta, H.; Purohit, L.P. Ternary alloyed CdS1−xSex quantum dots on TiO2/ZnS electrodes for quantum dots-sensitized solar cells. J. Alloys Compd. 2021, 880, 160480. [Google Scholar] [CrossRef]
  68. Mezrag, F.; Bouarissa, N.; El-Houda Fares, N. The band gap bowing of CdSxTe1−x alloys beyond the virtual crystal approximation. Emerg. Mater. Res. 2020, 9, 1056–1059. [Google Scholar] [CrossRef]
  69. Lane, D.W. A review of the optical band gap of thin film CdSxTe1−x. Sol. Energy Mater. Sol. Cells 2006, 90, 1169–1175. [Google Scholar] [CrossRef]
  70. Baines, T.; Zoppi, G.; Bowen, L.; Shalvey, T.P.; Mariotti, S.; Durose, K.; Major, J.D. Incorporation of CdSe layers into CdTe thin film solar cells. Sol. Energy Mater. Sol. Cells 2018, 180, 196–204. [Google Scholar] [CrossRef]
  71. Song, X.; Ma, Z.; Li, L.; Tian, T.; Yan, Y.; Su, J.; Deng, J.; Xia, C. Aqueous synthesis of alloyed CdSexTe1-x colloidal quantum dots and their In-situ assembly within mesoporous TiO2 for solar cells. Sol. Energy 2020, 196, 513–520. [Google Scholar] [CrossRef]
  72. Yang, X.; Wei, S.-H. First-principles study of the band gap tuning and doping control in CdSexTe1−x alloy for high efficiency solar cell. Chin. Phys. B 2019, 28, 086106. [Google Scholar] [CrossRef]
  73. Hoa, N.M.; Thi, L.A.; Hung, L.X.; Toan, L.D. Tunable excitonic dynamics and photoluminescence modulation in graded CdSe/CdSeS quantum dots for optoelectronic applications. J. Mater. Sci. Mater. Electron. 2025, 36, 1539. [Google Scholar] [CrossRef]
  74. Kashuba, A.I.; Andriyevsky, B. Growth and crystal structure of CdTe1−xSex (x ≥ 0.75) thin films prepared by the method of high-frequency magnetron sputtering. Low Temp. Phys. 2024, 50, 29–33. [Google Scholar] [CrossRef]
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Figure 1. XRD patterns of CdS, prepared mechanochemically after 15 min milling time. Red and purple vertical bars represent the hexagonal and cubic phases of CdS while the blue bars correspond to CdO.
Figure 1. XRD patterns of CdS, prepared mechanochemically after 15 min milling time. Red and purple vertical bars represent the hexagonal and cubic phases of CdS while the blue bars correspond to CdO.
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Figure 2. XRD patterns of CdSe, prepared mechanochemically after 15 min milling time. Red and blue vertical bars represent CdSe and CdO, respectively.
Figure 2. XRD patterns of CdSe, prepared mechanochemically after 15 min milling time. Red and blue vertical bars represent CdSe and CdO, respectively.
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Figure 3. XRD patterns of CdTe, prepared mechanochemically after 15 min milling time. Red vertical bars represent CdTe, as reported in the ICDD database.
Figure 3. XRD patterns of CdTe, prepared mechanochemically after 15 min milling time. Red vertical bars represent CdTe, as reported in the ICDD database.
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Figure 4. DSC curves of corresponding elemental precursors and binary chalcogenides, obtained by 15 min and 60 min ball milling for the Cd:S system (a), Cd:Se system (b), and Cd:Te system (c).
Figure 4. DSC curves of corresponding elemental precursors and binary chalcogenides, obtained by 15 min and 60 min ball milling for the Cd:S system (a), Cd:Se system (b), and Cd:Te system (c).
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Figure 5. (a). XRD patterns of ternary CdS0.5Se0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdS and CdSe, are shown for comparison. (b). XRD patterns of ternary CdS0.8Se0.2, prepared mechanochemically after 15 min milling time. The red vertical bars represent ‘Cd10S8.13Se1.87’, as reported in the ICDD database.
Figure 5. (a). XRD patterns of ternary CdS0.5Se0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdS and CdSe, are shown for comparison. (b). XRD patterns of ternary CdS0.8Se0.2, prepared mechanochemically after 15 min milling time. The red vertical bars represent ‘Cd10S8.13Se1.87’, as reported in the ICDD database.
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Figure 6. XRD patterns of ternary CdS0.5Te0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdS and CdTe, are shown for comparison.
Figure 6. XRD patterns of ternary CdS0.5Te0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdS and CdTe, are shown for comparison.
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Figure 7. XRD patterns of ternary CdSe0.5Te0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdSe and CdTe, are shown for comparison. The red vertical bars represent CdSe0.6Te0.4, as reported in the ICDD database.
Figure 7. XRD patterns of ternary CdSe0.5Te0.5, prepared mechanochemically after 15 min milling time. The patterns of the binary compounds, CdSe and CdTe, are shown for comparison. The red vertical bars represent CdSe0.6Te0.4, as reported in the ICDD database.
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Figure 8. DSC curves of corresponding elemental precursors and ternary chalcogenides, obtained by 15 min and 60 min ball milling for the Cd:S:Se system (a), Cd:S:Te system (b), and Cd:Se:Te system (c).
Figure 8. DSC curves of corresponding elemental precursors and ternary chalcogenides, obtained by 15 min and 60 min ball milling for the Cd:S:Se system (a), Cd:S:Te system (b), and Cd:Se:Te system (c).
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Figure 9. TEM images of binary chalcogenides CdS (a), CdSe (b), and CdTe (c) after 15 min milling times.
Figure 9. TEM images of binary chalcogenides CdS (a), CdSe (b), and CdTe (c) after 15 min milling times.
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Figure 10. TEM images of ternary chalcogenides CdS0.5Se0.5 (a), CdS0.5Te0.5 (b), and CdSe0.5Te0.5 (c) after 15 min milling times.
Figure 10. TEM images of ternary chalcogenides CdS0.5Se0.5 (a), CdS0.5Te0.5 (b), and CdSe0.5Te0.5 (c) after 15 min milling times.
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Figure 11. TEM images of ternary chalcogenides CdS0.5Se0.5 (a,b), and CdSe0.5Te0.5 (c) after 15 min milling times, showing primary spherical nanoparticles under higher magnifications.
Figure 11. TEM images of ternary chalcogenides CdS0.5Se0.5 (a,b), and CdSe0.5Te0.5 (c) after 15 min milling times, showing primary spherical nanoparticles under higher magnifications.
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Figure 12. Tauc plots used for the determination of band gaps for CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5.
Figure 12. Tauc plots used for the determination of band gaps for CdS0.5Se0.5, CdS0.5Te0.5, and CdSe0.5Te0.5.
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Table 1. Crystal structures and reported unit cell parameters for CdS, CdSe, and CdTe.
Table 1. Crystal structures and reported unit cell parameters for CdS, CdSe, and CdTe.
Cubic (Zincblende) StructureHexagonal (Wurtzite) StructureReferences
CdSa = 5.81 Åa = 4.14 Å; c = 6.71 Å[50,51,52]
CdSea = 6.05 Åa = 4.30 Å; c = 7.01 Å[53,54]
CdTea = 6.48 Åa = 4.57 Å; c = 7.48 Å[55]
Table 2. Crystallite sizes of binary and ternary cadmium chalcogenides after 15 min milling time, estimated from the pXRD data using Scherrer equation.
Table 2. Crystallite sizes of binary and ternary cadmium chalcogenides after 15 min milling time, estimated from the pXRD data using Scherrer equation.
SampleCdSCdSeCdTeCdS0.8Se0.2CdS0.5Se0.5CdS0.5Te0.5CdSe0.5Te0.5
d [nm]11.111.216.913.711.610.410.3
Table 3. Results obtained by EDX measurements and AAS analysis for binary and ternary cadmium chalcogenides.
Table 3. Results obtained by EDX measurements and AAS analysis for binary and ternary cadmium chalcogenides.
SampleMeasured by EDXMeasured by AASCalculated
Cd (at %)S (at %)Se (at %)Te (at %)Cd (wt. %)Cd (wt. %)
CdS4951−−77.477.8
CdSe48−51−58.558.7
CdTe47−−5246.346.8
CdS0.5Se0.5492624−66.566.9
CdS0.5Te0.54827−2558.558.5
CdSe0.5Te0.549−232751.952.1
Table 4. Hydrodynamic diameter of binary and ternary cadmium chalcogenides after 15 min milling time, obtained from DSL measurements.
Table 4. Hydrodynamic diameter of binary and ternary cadmium chalcogenides after 15 min milling time, obtained from DSL measurements.
SampleCdSCdSeCdTeCdS0.8Se0.2CdS0.5Se0.5CdS0.5Te0.5CdSe0.5Te0.5
d(H) [nm]325.8202.7124.4271.0207.7347.1126.2
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Kristl, M.; Zanjkovič, N.; Kunej, J.; Gyergyek, S.; Stergar, J. Green Mechanochemical Synthesis of Binary and Ternary Cadmium Chalcogenides with Tunable Band Gaps. J. Manuf. Mater. Process. 2025, 9, 375. https://doi.org/10.3390/jmmp9110375

AMA Style

Kristl M, Zanjkovič N, Kunej J, Gyergyek S, Stergar J. Green Mechanochemical Synthesis of Binary and Ternary Cadmium Chalcogenides with Tunable Band Gaps. Journal of Manufacturing and Materials Processing. 2025; 9(11):375. https://doi.org/10.3390/jmmp9110375

Chicago/Turabian Style

Kristl, Matjaž, Neža Zanjkovič, Jona Kunej, Sašo Gyergyek, and Janja Stergar. 2025. "Green Mechanochemical Synthesis of Binary and Ternary Cadmium Chalcogenides with Tunable Band Gaps" Journal of Manufacturing and Materials Processing 9, no. 11: 375. https://doi.org/10.3390/jmmp9110375

APA Style

Kristl, M., Zanjkovič, N., Kunej, J., Gyergyek, S., & Stergar, J. (2025). Green Mechanochemical Synthesis of Binary and Ternary Cadmium Chalcogenides with Tunable Band Gaps. Journal of Manufacturing and Materials Processing, 9(11), 375. https://doi.org/10.3390/jmmp9110375

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