Search Results (16)

A novel series of Gd₂O₃-doped Pb₃O₄–Sb₂O₃–B₂O₃–Bi₂O₃ glasses was synthesized via the conventional melt-quenching technique to explore their structural, thermal, and optical properties for potential photonic and medical phototherapy applications. X-ray diffraction and SEM analyses confirmed the amorphous and homogeneous nature of the samples, while their FTIR spectra revealed characteristic Pb–O, Sb–O, Bi–O, and B–O vibrational bands indicative of a stable glass network. Differential scanning calorimetry (DSC) demonstrated good thermal stability, suitable for high-temperature optical applications. Optical absorption and emission studies indicated the presence of prominent Gd³⁺ ion transitions, with a strong and sharp ultraviolet emission at 311 nm (⁶P_7/2→⁸S_7/2) when excited at 274 nm. The emission intensity and lifetime increased with Gd₂O₃ concentrations of up to 1.0 mol%, beyond which concentration quenching was observed. The optimized composition exhibited a reduced optical band gap and enhanced NB-UVB emission efficiency, suggesting efficient energy transfer with minimal non-radiative losses. These results establish the designed glass system as a promising multifunctional material for NB-UVB-based phototherapy, UV-laser generation, scintillation, and other next-generation photonic devices. Full article

The investigation of environmentally friendly, Pb-free ceramic dielectric materials with excellent energy storage capability represents a fundamental yet challenging research direction for the development of next-generation high-power capacitors. In this study, linear dielectric Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ was added into [0.65BaTiO₃–0.35(Na_0.5Bi_0.5)TiO₃] to form a solid solution. The introduction of Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ modified the crystal structure, enhanced insulation performance and breakdown strength, and reduced hysteresis loss. These improvements collectively contributed to higher energy storage density and efficiency (η). The ceramic pellet with the optimal 10 mol% Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ demonstrated a higher retrievable energy density (~3.40 J cm⁻³) and efficiency (~81%) at a breakdown strength of 340 kV cm⁻¹ compared to BaTiO₃-based ferroelectric ceramics. The sample also exhibited good stability across a temperature range of 30–90 °C and a frequency range of 0.5–300 Hz. Thus, the as-prepared ceramics sample exhibited significant potential for pulsed power device applications. Full article

Molybdenite Re–Os and zircon U–Pb isotopic data are first obtained from the stockwork and disseminated-style gold-bearing ores and the fine-grained granite hosting these ores in the Xiawolong gold mine, respectively, which is located within the Muping–Rushan gold metallogenic belt, eastern Jiaodong Peninsula, so as to illustrate the genesis of gold mineralization and its implication for exploration. Four molybdenite samples yield a well-defined Re–Os isochron age of 118.4 ± 2.5 Ma (2σ), which is identical to the weighted average Re–Os model age of 118 ± 1.7 Ma (2σ). Integration of the new geochronologic data with those reported recently from the other gold mines in the Muping–Rushan gold metallogenic belt suggests that a discrete gold event occurred in Xiawolong ca. 4 m.y. older than that for the other gold mineralization at ca. 114 Ma in eastern Jiaodong. In addition, two fine-grained granite samples, measured using the LA-ICP-MS zircon U–Pb method, produce the first precise ages of 118 ± 2 to 117 ± 2 Ma (2σ), identical to the molybdenite Re–Os ages, within the margin of error and obtained in this study. The fine-grained granite has a similar lithology and emplacement age as those of the medium-grained monzogranite consisting of the marginal facies of the Sanfoshan batholith, and is considered to be the crystallization products of Sanfoshan granitic magma in the late stage. Combined with the previous S-Pb-D-O isotope, fluid inclusion and geological studies, which suggest that the ore-forming fluid of Xiawolong gold mineralization is from magmatic water, and the identification that the magnetite coexists with the gold-bearing pyrite and molybdenite in the gold ores, which indicates a high oxygen fugacity (fO₂) of both the magma and resultant hydrothermal fluids, it is logical to infer that the Xiawolong gold deposit is genetically in relation to the Sanfoshan granitic magmatism, which is high in fO₂ and rich in Au at the magmatic–hydrothermal transition stage, and the change in fO₂ mostly likely makes a significant contribution to the precipitation of Au. This result reveals that the late-stage granitic magma with high fO₂, which is crystallized into the fine-grained granite, probably is also rich in Au, except the W–Mo–Cu–Zn–U–Be–Li–Nb–Ta–Sn–Bi-elements. Therefore, based on the extensional tectonic regime for the early Cretaceous Jiaodong gold deposits, we propose that gold exploration in the Jiaodong should not only focus on the fault-hosted Au but also on the fine-grained granite-hosted Au around the apical portions of the late Early Cretaceous small-granitic intrusions with high fO₂. This model could also be important for prospecting in other gold ore districts, which have a similar tectonic setting. Full article

Unlike municipal solid waste bottom ash (MSWBA), fly ash (MSWFA) is landfilled due to its toxicity. However, MSWFA may also be a source of elements. Ash samples collected from a Portuguese MSW incinerator from different locations and over six months were analyzed. Their geochemical composition was normalized to the upper continental crust (UCC) and compared since metal enrichment may be used as an indicator for potential recovery. The potential recovery economic viability was also assessed for metals K, Sb, Cu, Pb, and Zn, considering the ore cut-off grade and minimum industrial grade (MIG) from Chinese geological and mineral industry standards. Compared to the global samples, only the Baghouse 1 FA size fraction’s coarse fraction showed a slight enrichment (1- to 5-fold) in Bi, Nb, and Zr. After wet sieving, most trace elements were enriched in all fractions, but Sb, Bi, Pb, Zn, Ag, As, Cd, Sn, Se, and Hg were depleted in the coarse fractions and enriched in the fine ones. For Baghouse 1 samples collected over 6 months, the normalization to the UCC showed enrichment of Zn and Pb between 10× and 50×, Zr, Cu, In, and Se between 50× and 100×, and Ag, Mn, Cd, Sb, and Bi at more than 100×. Over six months, the Baghouse 1 FA soluble fraction ranged between 21 wt.% and 30 wt.%, and its precipitates comprised 27% CaO, 6% Na₂O, and 9% K₂O. The K concentration in the MSWFA was above the cut-off and the MIG, and K could be concentrated in precipitates via simple washing. Full article

In this study, an Integrated Electronics Piezoelectric (IEPE)-type accelerometer based on an environmentally friendly lead-free piezoceramic was fabricated, and its field applicability was verified using a cooling pump owned by the Korea Atomic Energy Research Institute (KAERI). As an environmentally friendly piezoelectric material, 0.96(K,Na)NbO₃-0.03(Bi,Na,K,Li)ZrO₃-0.01BiScO₃ (0.96KNN-0.03BNKLZ-0.01BS) piezoceramic with an optimized piezoelectric charge constant (d₃₃) was introduced. It was manufactured in a ring shape using a solid-state reaction method for application to a compression mode accelerometer. The fabricated ceramic ring has a high piezoelectric constant d₃₃ of ~373 pC/N and a Curie temperature T_C of ~330 °C. It was found that the electrical and physical characteristics of the 0.96KNN-0.03BNKLZ-0.01BS piezoceramic were comparable to those of a Pb(Zr,Ti)O₃ (PZT) ring ceramic. As a result of a vibration test of the IEPE accelerometer fabricated using the lead-free piezoelectric ceramic, the resonant frequency f_r = 20.0 kHz and voltage sensitivity S_v = 101.1 mV/g were confirmed. The fabricated IEPE accelerometer sensor showed an excellent performance equivalent to or superior to that of a commercial IEPE accelerometer sensor based on PZT for general industrial use. A field test was carried out to verify the applicability of the fabricated sensor in an actual industrial environment. The test was conducted by simultaneously installing the developed sensor and a commercial PZT-based sensor in the ball bearing housing location of a centrifugal pump. The centrifugal pump was operated at 1180 RPM, and the generated vibration signals were collected and analyzed. The test results confirmed that the developed eco-friendly lead-free sensor has comparable vibration measurement capability to that of commercial PZT-based sensors. Full article

This paper studies the structural parameters and electrophysical properties (dielectric and piezo electric, as well as currents of thermostimulated depolarization) of samples of composition 0.20BiScO₃·0.45PbTiO₃·0.35PbMg_1/3Nb_2/3O₃ (or in short 0.20BS·0.45PT·0.35PMN) obtained by ceramic and melt-hardening methods of synthesis. In the ceramic method, the samples were obtained from the starting oxides by two-stage firing. In the melt method, amorphous precursors were first obtained from heat-treated and non-heat-treated starting oxide mixtures by melting and subsequent quenching under sharply gradient temperature conditions. Samples were obtained after grinding, pressing, and thermal annealing of the synthesized precursors, and four types of samples differing in size and shape of the intermediate precursor particles (crystallites) were obtained. The X-ray phase analysis showed that the predominant phase in the studied samples is the perovskite phase; in both types of samples, up to 5 wt.% of impurity phase with pyrochlore structure was also present. The samples of 0.20BS·0.45PT·0.35PMN exhibit dielectric properties characteristic of relaxor ferroelectrics, and the polarized samples exhibit a pronounced piezo effect with a piezo modulus value of d₃₃~200 pC/N. A comparative analysis of the properties of the samples obtained by different methods has been carried out. The essential advantage of the melt method is that its use allows obtaining varieties of four kinds of ferroelectric relaxors and reduces the time of synthesis of samples by 2–3 times. Full article

The Shuangjianzishan silver polymetallic deposit is located in the copper–tin–lead–zinc–silver polymetallic metallogenic belt in the Southern Great Xing’an Range, with silver resources of more than 18,000 t, which is the largest silver polymetallic deposit in Asia. Early studies concluded that the Shuangjianzishan deposit is typically an epithermal Ag-Pb-Zn deposit that lacks a high-temperature mineralization stage. In recent years, with the deepening of research, a large amount of Cu-Sn mineralization has been found in the deep part of the Shuangjianzishan deposit, but it is less studied. The laser-ablation inductively coupled mass spectroscopy (LA-ICP-MS) technique is used to investigate the distribution and substitution of trace elements in chalcopyrite and cassiterite. In this paper, the trace element study of chalcopyrite and cassiterite from the Shuangjianzishan deposit reveals that Sn, In, As, Se, Sb, and Tl mainly exist in chalcopyrite in isomorphic form, while Pb, Bi, and Ni mainly exist in chalcopyrite in the form of mineral inclusions. The enrichment of the high-temperature elements Sn and Se in chalcopyrite, and the deficit of the middle- and low-temperature elements Ga, Sb, etc., reflect that the chalcopyrite in the Shuangjianzishan deposit was formed in a middle- and high-temperature environment, and it also indicates that the early ore-forming hydrothermal solution may be rich in Sn. Fe, In, Co, and Ni mainly exist in cassiterite in isomorphic form, and the content of W in cassiterite is high. There are two main forms, one is isomorphic and the other is wolframite inclusion. Cassiterite has Fe-rich and W-U-poor characteristics, indicating that cassiterite from the Shuangjianzishan deposit was formed under relatively oxidized conditions, and the relative enrichment of elements such as Fe, W, Zr, and Hf indicates that the temperature of cassiterite formation was high. The elemental content and inter-ionic coupling relationships suggest that the cassiterite from the Shuangjianzishan deposit may have an elemental replacement mechanism of W⁶⁺ + Fe²⁺ ↔ 2Sn⁴⁺ or Fe³⁺ + OH⁻ ↔ Sn⁴⁺ + O²⁻. The trace elements in cassiterite of the Shuangjianzishan deposit are rich in Fe and Mn and depleted in Nb and Ta, according to the Fe-W diagram, and the tin mineralization of the Shuangjianzishan deposit belongs to cassiterite–sulfide-type tin mineralization. Chalcopyrite Co/Ni ratios >1 are consistent with the characteristics of chalcopyrite genesis in hydrothermal deposits. Full article

Piezoelectric ceramics with excellent piezoelectric properties and a high Curie temperature are important for numerous electromechanical devices in a broad range of temperature environments. In this work, the relaxor ferroelectric Pb(Yb_1/2Nb_1/2)O₃ end member was selected to be introduced into a BiScO₃-PbTiO₃ high-temperature piezoelectric ceramic to reduce the dielectric loss and improve the piezoelectric properties while slightly reducing the Curie temperature. The phase structure and dielectric, ferroelectric and piezoelectric properties of 0.025Pb(Yb_1/2Nb_1/2)O₃-(0.975$-$x)BiScO₃-xPbTiO₃ (0.60 ≤ x ≤ 0.63) ceramics were systematically analyzed, and the best electrical properties were observed in the morphotropic phase boundary region x = 0.61 with d₃₃ = 370 pC/N, k_p = 44%, P_r = 33.9 μC/cm². Importantly, no significant depolarization was observed in the x = 0.61 ceramic from room temperature to 290 °C, demonstrating its good thermal stability and potential applications in a wide range of temperature environments. Full article

Ceramics of the quasi-binary concentration section (0.1 ≤ x ≤ 0.2, Δx = 0.025) of the ternary solid solution system (0.5 − x)BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-xPbTiO₃ were prepared by the conventional solid-phase reaction method. An X-ray study at different temperatures revealed that (0.5 − x)BF-0.5PFN-xPT ceramics have a cluster morphology. Clusters have different modulation, crystal lattice symmetry, and chemical composition. The presence of a cluster structure in a solid solution with heterovalent substitution, consisting of regions rich in Ti⁺⁴, Nb⁺⁵, or Fe³⁺, has led to the appearance of Maxwell–Wagner polarization in the studied ceramics. The study of the dielectric characteristics revealed the relaxor-like behavior of the studied ceramics. The grain morphology, dielectric, pyroelectric, and piezoelectric properties of the selected solid solutions were investigated. The highest piezoelectric coefficient, d₃₃ = 280 pC/N, was obtained in the 0.3BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-0.2PbTiO₃ ceramics. Study of the dielectric characteristics of all samples revealed relaxor ferroelectric behavior and a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 140–170 °C. Full article

A simple solid-state reaction was applied to synthesize Fe-doped perovskite-type PBFNO catalysts, and methylene blue decomposition studies were performed in the form of visible light according to the changes in the Fe doping content (0.4 to 1.9 mol ratio compared with Bi mol) and the amount of catalyst used (0.05 to 0.2 g used). As the Fe doping content increases, the absorbance and bang gap energy of the PBFNOs sample rapidly increase and decrease, respectively, because the Fe dopant in the PBNO lattice acts as an intermediate band between the valence and conduction bands of the PBNO and reduces the band gap energy. As a result, it showed a performance degradation of approximately 42% compared to the maximum performance. In addition, the presence of Fe dopants in the PBNO lattice greatly reduces the intensity of the photoluminescent lines. This is because the Fe dopant can play an important role in light-induced electron transfer and as a hole trap, reducing the recombination rate. Additionally, when too much photocatalyst was used (>0.1 g used), the Fe dopant played an important role as a light-induced electron transfer and hole trap, reducing the recombination rate and lowering the overall photocatalytic activity by 51%. In particular, 0.1 g of PBNO-0.2-F showed continuous catalytic activity, even when the photocatalytic reaction proceeded for 180 min. Therefore, this study demonstrates that the Fe-doped aurivillius-phase PBFNO photocatalyst is very promising for the dye manufacturing industry. Full article

Geochemical baselines are crucial to explore mineral resources and monitor environmental changes. This study presents the first Laos geochemical baseline values of 69 elements. The National-scale Geochemical Mapping Project of Lao People’s Democratic Republic conducted comprehensive stream sediment sampling across Laos, yielding 2079 samples collected at 1 sample/100 km², and 69 elements were analyzed. Based on the results of LGB value, R-mode factor analysis, and scatter plot analysis, this paper analyzes the relationship between the 69 elements and the geological background, mineralization, hypergene processes and human activities in the study area. The median values of element contents related to the average crustal values were: As, B, Br, Cs, Hf, Li, N, Pb, Sb, Zr, and SiO₂, >1.3 times; Ba, Be, Cl, Co, Cr, Cu, F, Ga, Mn, Mo, Ni, S, Sc, Sr, Ti, Tl, V, Zn, Eu, Al₂O₃, Tot.Fe₂O_3, MgO, CaO, and Na₂O, <0.7 times; and Ag, Au, Bi, Cd, Ge, Hg, I, In, Nb, P, Rb, Se, Sn, Ta, Th, U, W, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and K₂O, 0.7–1.3 times. R-mode factor analysis based on principal component analysis and varimax rotation showed that they fall into 12 factors related to bedrock, (rare earth, ferrum-group, and major Al₂O₃ and K₂O elements; mineralization–Au, Sb, and As) and farming activities–N, Br, S, and C). This study provides basic geochemical data for many fields, including basic geology, mineral exploration, environmental protection and agricultural production in Laos. Full article

Cobalt-modified 0.40Bi(Sc_3/4In_1/4)O₃–0.58PbTiO₃–0.02Pb(Mg_1/3Nb_2/3)O₃ ceramics (abbreviated as BSI–PT–PMN–xCo) were produced by conventional two-step solid-state processing. The phase structure, micro structure morphology, and electrical properties of BSI–PT–PMN–xCo were systematically studied. The introduction of Co ions exerted a significant influence on the structure and electrical properties. The experiment results demonstrated that Co ions entered the B-sites of the lattice, resulting in slight lattice distortion and a smaller lattice constant. The average grain size increased from ~1.94 μm to ~2.68 μm with the increasing Co content. The optimized comprehensive electrical properties were obtained with proper Co-modified content 0.2 wt.%. The Curie temperature (T_c) was 412 °C, the piezoelectric constant (d₃₃) was 370 pC/N, the remnant polarization (P_r) was 29.2 μC/cm², the relatively dielectric constant (ε_r) was 1450, the planar electromechanical coupling coefficient (k_p) was 46.5, and the dielectric loss (tanδ) was 0.051. Together with the enhanced DC resistivity of 10⁹ Ω cm under 300 °C and good thermal stability, BSI–PT–PMN–0.2Co ceramic is a promising candidate material for high-temperature piezoelectric applications. Full article

In this paper, ferroelectric–ferrimagnetic ceramic composites based on multicomponent PZT-type (PbZr_1−xTi_xO₃-type) material and ferrite material with different percentages in composite compositions were obtained and studied. The ferroelectric component of the composite was a perovskite ceramic material with the chemical formula Pb_0.97Bi_0.02(Zr_0.51Ti_0.49)_0.98(Nb_2/3Mn_1/3)_0.02O₃ (P), whereas the magnetic component was nickel-zinc ferrite with the chemical formula Ni_0.5Zn_0.5Fe₂O₄ (F). The process of sintering the composite compounds was carried out by the free sintering method. Six ferroelectric-ferrimagnetic ceramic P-F composite compounds were designed and obtained with different percentages of its components, i.e., 90/10 (P90-F10), 85/15 (P85-F15), 80/20 (P80-F20), 60/40 (P60-F40), 40/60 (P40-F60), and 20/80 (P20-F80). X-ray diffraction patterns, microstructural, ferroelectric, dielectric, magnetic properties, and DC electrical conductivity of the composite materials were investigated. In this study, two techniques were used to image the microstructure of P-F composite samples: SB (detection of the signals from the secondary and backscattered electron detectors) and BSE (detection of backscattered electrons), which allowed accurate visualization of the presence and distribution of the magnetic and ferroelectric component in the volume of the composite samples. The studies have shown that at room temperature, the ceramic composite samples exhibit good magnetic and electrical properties. The best set of physical properties and performance of composite compositions have ceramic samples with a dominant phase of ferroelectric component and a small amount of the ferrite component (P90-F10). Such a composition retains the high ferroelectric properties of the ferroelectric component in the composite while also acquiring magnetic properties. These properties can be prospectively used in new types of memory and electromagnetic converters. Full article

In this paper, for the application to multi-layer piezoelectric devices capable of being used in piezoelectric speakers, Pb(Ni_1/3Nb_2/3)O₃-Pb(Zr,Ti)O₃-BiFeO₃ ceramics substituted with Pb(Mg_1/2W_1/2)O₃ were manufactured according to MnO₂ addition, and their physical properties were studied. At non-doped MnO₂ added specimen, the maximum values of piezoelectric properties were shown, respectively: the ε_r of 2182, d₃₃ of 513 pC/N, and k_p of 0.634. When taking into consideration the low dielectric constant and high d₃₃ in case of increasing the numbers of multilayer in ceramics, the x = 0.2 composition ceramics was suitable for the device application such as speaker using low-temperature sintering multilayer piezoelectric actuators. Full article

A series of mixed-metal oxide structures based on the stacking of α-U₃O₈ type pentagonal bipyramid layers have been investigated for symmetry lowering distortions and photocatalytic activity. The family of structures contains the general composition A^m+_((n+1)/m)B_(3n+1)O_(8n+3) (e.g., A = Ag, Bi, Ca, Cu, Ce, Dy, Eu, Gd K, La, Nd, Pb, Pr, Sr, Y; B = Nb, Ta; m = 1–3; n = 1, 1.5, 2), and the edge-shared BO₇ pentagonal pyramid single, double, and/or triple layers are differentiated by the average thickness, (i.e., 1 ≤ n ≤ 2), of the BO₇ layers and the local coordination environment of the “A” site cations. Temperature dependent polymorphism has been investigated for structures containing single layered (n = 1) monovalent (m = 1) “A” site cations (e.g., Ag₂Nb₄O₁₁, Na₂Nb₄O₁₁, and Cu₂Ta₄O₁₁). Furthermore, symmetry lowering distortions were observed for the Pb ion-exchange synthesis of Ag₂Ta₄O₁₁ to yield PbTa₄O₁₁. Several members within the subset of the family have been constructed with optical and electronic properties that are suitable for the conversion of solar energy to chemical fuels via water splitting. Full article