Search Results (23)

The spectroscopic properties of Pr³⁺ ions in the aluminosilicate matrix were investigated for the first time. Synthesis of CaAl₂SiO₆ (CASO) polycrystals doped with Pr³⁺ ions was carried out using the sol–gel method. The crystalline structures have been confirmed with XRD measurement. The absorption, excitation, emission spectra, and time decay profiles of the praseodymium (III) ions were measured and analyzed. It was found that upon excitation with visible light, this material exhibits emission mainly in the UVC region, via an upconversion emission process. The Stokes emission in the visible range is observed mainly from the ³P₀ and ¹D₂ energy levels. The ¹D₂→³H₄ emission is very stable even at very high temperatures. The studied aluminosilicate phosphors possess characteristics that confirm their potential in upconversion emission applications. Full article

Rare earth metals (REMs) are vital for high-tech industries, but their extraction from secondary sources is challenging due to environmental and technical constraints. This study investigates the ion-exchange extraction of light REMs (neodymium, praseodymium, and samarium) from sulfuric and phosphoric acid solutions, modeling industrial leachates from apatite concentrates and phosphogypsum. The study considers the use of anion- and cation-exchange resins with different functional groups for efficient and environmentally safe REM separation. Experimental sorption isotherms were obtained under static conditions at 298 K and analyzed using a thermodynamic model based on the linearization of the mass action equation. Equilibrium constants and Gibbs energy were calculated, which reveals the spontaneity of the processes. Cation-exchange resins demonstrated high selectivity towards individual REMs, while anion-exchange resins were suitable for group extraction. Infrared spectral analysis confirmed the presence of sulfate and phosphate complexes in the resin matrix, clarifying the ion-exchange mechanisms. Thermal effect measurements indicated exothermic sorption on anion-exchange resins with negative entropy and endothermic sorption on cation-exchange resins with positive entropy. The findings highlight the potential of ion-exchange resins for selective and sustainable REM recovery, offering a safer alternative to liquid extraction and enabling the valorization of industrial wastes like phosphogypsum for resource recovery. Full article

This study focused on the nature of rare earth metal complex compounds that can form during the carbonate–alkaline processing of industrial waste materials, such as phosphogypsum and red mud, at 70–100 °C and 1–10 atm. Experimental findings revealed that the dissolution of synthetic carbonates of rare earth elements (REEs) in a concentrated carbonate-ion medium (3 mol/L) leads to the formation of ion-associates of varying strengths. Light (lanthanum, praseodymium, and neodymium) and medium (samarium) REE groups exhibited a tendency to form loose ion-associates, whereas heavy REEs (terbium, dysprosium, holmium, erbium, thulium, lutetium, and yttrium) formed close ion-associates. To confirm the existence of these ion-associates, the specific conductivity of solutions was measured after dissolving thulium (III) and samarium (III) carbonates at phase ratios ranging from 1:2000 g/mL to 1:40 g/mL in a potassium carbonate medium. The decay of ion-associates, leading to the precipitation of rare earth metal (III) carbonates, was tested in an ammonium carbonate medium. Thermal decomposition of ammonium carbonate at 70–75 °C during 1–4 h was accompanied by full rare earth carbonates’ sedimentation and its in-the-way separation into groups because of the varied strength of ion-associates. The results of this study provide a basis for developing processes to separate rare earth metals into groups during their carbonate–alkaline extraction into solution. Full article

This work presents a comparative study of five rare earth compounds—Erbium nitrate pentahydrate lll (Er), Neodymium nitrate pentahydrate (Nd), Samarium III Nitrate Hexahydrate (Sm), Yterbium III Chloride Hexahydrate (Yb) and Praseodymium nitrate hexahydrate lll (Pr)—protecting API 5L X70 steel from corrosion in saline medium that uses electrochemical impedance spectroscopy (EIS) and polarization curves (CPs) at different concentrations and in static mode. The results show that Erbium is the best corrosion inhibitor, containing 50 ppm and reaching an inhibition efficiency of about 89%, and similar result was shown by Sm with an IE~87.9%, while the other rare earths (Nd, Yb and Pr) showed a decrease in corrosion protection at the same concentration, since they were below an IE~80%. On the other hand, with the Langmuir model it was possible to describe that the adsorption process of the three rare earths follows a combined physisorption–chemisorption process to protect the metal’s surface. The observed adsorption free energy, ΔG°ads, reaches −38.7 kJ/mol for Er, −34.4 kJ/mol for Nd, and −33.6 kJ/mol for Pr; whereas Sm and Yb have adsorption free energies of −33.9 and −35.0 kJ/mol, respectively. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) further confirmed the formation of a protective film. Their characterization using density functional theory showed the transference of charge from the iron cluster towards the rare earth metal compounds. The adsorption process produced a slightly polarized region of interaction with the metal surface. Also, it was found that the adsorption of the rare earths affected the magnetic properties of the surface of the iron cluster. Quantum chemical descriptors, such as Pearson’s HSAB (Hard and Soft Acids and Bases) descriptors, were useful in predicting the behavior of the flow of electrons between the metal surface and the interacting rare earth ions. Full article

In this study, the possibilities of selective sorption of neodymium and praseodymium ions from a mixture of their solution using interpolymer systems composed of two industrial sorbents, cation exchangers KU-2-8 (Na⁺) and AB-17-8 (Cl⁻), at different molar ratios were investigated. The processes of sorption and desorption were carried out in two modes: dynamic (with active stirring) and static (without stirring the working solution from which REEs were extracted). According to the obtained results, sorption in the dynamic mode in the ratios of 4:2 and 3:3 does not lead to any selectivity. However, a high degree of extraction was noted for both ions: Pr³⁺ = 99.36%, Nd³⁺ = 95.67% for the 4:2 system and Pr³⁺ = 81.33%, Nd³⁺ = 79% for the 3:3 system. In the static mode, the degree of extraction of both metals was significantly lower: for the 4:2 system Pr³⁺ = 19.33%, Nd³⁺ = 24%, but greater selectivity with respect to neodymium was observed. With a ratio of 4:2, neodymium was sorbed better than praseodymium by 24.16%, and in the 3:3 system by 39.83%. When desorption from the cationite was carried out with nitric acid, a similar tendency was preserved. Thus, it was shown that interpolymer systems can be used in industry by varying the conditions of sorption and desorption for the successful extraction of neodymium and praseodymium from industrial solutions. Full article

The praseodymium-doped indium zinc oxide (PrIZO) thin-film transistor (TFT) is promising for applications in flat-panel displays, due to its high carrier mobility and stability. Nevertheless, there are few studies on the mechanism of annealing on PrIZO films and the fabrication of flexible devices. In this work, we first optimized the annealing-process parameters on the glass substrate. As the annealing temperature rises, the film tends to be denser and obtains a lower surface roughness, a narrower optical-band gap and less oxygen-vacancy content. However, the μ-PCD test shows the 250 °C-annealed film obtains the least defects. And the PrIZO TFT annealed at 250 °C exhibited a desired performance with a saturation mobility (μ_sat) of 14.26 cm²·V⁻¹·s⁻¹, a subthreshold swing (SS) of 0.14 V·dec⁻¹, an interface trap density (D_it) of 3.17 × 10¹¹, an I_on/I_off ratio of 1.83 × 10⁸ and a threshold voltage (Vth) of −1.15 V. The flexible devices were prepared using the optimized parameters on the Polyimide (PI) substrate and subjected to static bending tests. After bending at a radius of 5 mm, the mobility of devices decreases slightly from 12.48 to 10.87 cm²·V⁻¹·s⁻¹, demonstrating the great potential of PrIZO for flexible displays. Full article

The thermal stability of oxyfluorotellurite glass systems, (65-x)TeO₂-20ZnF₂-12PbO-3Nb₂O₅-xPr₂O₃, doped with praseodymium was examined. The different concentrations of praseodymium oxide (x = 0.5 and 2 mol%) were applied to verify the thermal, optical and luminescence properties of the materials under study. The relatively high values of the Dietzel (ΔT) and Saad–Poulain (S or H′) thermal stability factors determined using a differential thermal analysis (DTA) indicate the good thermal stability of the glass matrix, which gradually improves with the content of the active dopant. The temperature dependence of optical spectra in the temperature range 300–675 K for the VIS–NIR region was investigated. The involved Pr³⁺ optical transition intensities and relaxation dynamic of the praseodymium luminescent level were determined. The ultrashort femtosecond pulses were utilized to examine a dynamic relaxation of the praseodymium luminescent levels. Although the measured emission of the Pr³⁺ active ions in the studied glass encompasses the quite broad spectral region, the observed luminescence may only be attributed to ³P_J excited states. As a result, the observed decrease in the experimental lifetime for the ³P₀ level along with the increasing activator content was identified as an intensification of the Pr–Pr interplay and the associated self-quenching process. The maximum relative sensitivities (S_r) estimated over a relatively wide temperature range are ~0.46% K⁻¹ (at 300 K) for FIR (I₅₃₀/I₄₉₇) and 0.20% K⁻¹ (at 600 K) for FIR (I₆₃₀/I₄₉₇), which seems to confirm the possibility of using investigated glasses in optical temperature sensors. Full article

The recent COVID-19 pandemic has made everyone aware of the threat of viruses and the growing number of antibiotic-resistant bacteria. It has become necessary to find new methods to combat these hazards. One tool that could be used is UVC radiation, i.e., 100–280 nm. Currently, the available sources of this light are mercury vapor lamps. However, the modern world requires more compact, mercury-free, and less energy-consuming light sources. This work presents the results of our research on a new material in which efficient UVC radiation was obtained. Here, we present the results of research on Ca₉Y(PO₄)₇ polycrystals doped with Pr³⁺ ions prepared using the solid-state method. The absorption, excitation, emission, and emission decay profiles of praseodymium(III) ions were measured and analyzed. The upconversion emission in the UVC region excited by blue light was observed. Parameters such as energy bandgap, refractive index, and thermal stability of luminescence were determined. The studied phosphate-based phosphor possesses promising characteristics that show its potential in luminescent applications in future use in medicine or for surface disinfection. Full article

A comprehensive study of the thermoelectric properties of CuCr_0.99Ln_0.01S₂ (Ln = La…Lu) disulfides was carried out in a temperature range of 300 to 740 K. The temperature dependencies of the Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed. It was found that the cationic substitution of chromium with lanthanides in the crystal structure of layered copper–chromium disulfide, CuCrS₂ resulted in notable changes in the thermoelectric performance of CuCr_0.99Ln_0.01S₂. The cationic substitution led to an increase in the Seebeck coefficient and electrical resistivity and a thermal conductivity decrease. The highest values of the thermoelectric figure of merit and power factor corresponded to the praseodymium-doped sample and an initial CuCrS₂-matrix at 700–740 K. The cationic substitution with lanthanum, cerium, praseodymium, samarium, and terbium allowed for an enhancement of the thermoelectric performance of the initial matrix at a temperature range below 600 K. The cationic substitution of CuCrS₂ with lanthanum and praseodymium ions appeared to be the most promising approach for increasing the thermoelectric performance of the initial matrix. Full article

Fluorides have a wide bandgap and therefore, when doped with the appropriate ions, exhibit emissions in the ultraviolet C (UVC) region. Some of them can emit two photons in the visible region for one excitation photon, having a quantum efficiency greater than 100%. In a novel exploration, praseodymium (Pr³⁺) ions were introduced into KLaF₄ crystals for the first time. The samples were obtained according to a high-temperature solid-state reaction. They exhibited an orthorhombic crystal structure, which has not been observed for this lattice yet. The optical properties of the material were investigated in the ultraviolet (UV) and visible ranges. The spectroscopic results were used to analyze the Pr³⁺ electronic-level structure, including the 4f5d configuration. It has been found that KLaF₄:Pr³⁺ crystals exhibit intense luminescence in the UVC range, corresponding to multiple 4f → 4f transitions. Additionally, under vacuum ultraviolet (VUV) excitation, distinct transitions, specifically ¹S₀ → ¹I₆ and ³P₀ → ³H₄, were observed, which signifies the occurrence of photon cascade emission (PCE). The thermal behavior of the luminescence and the thermometric performance of the material were also analyzed. This study not only sheds light on the optical behavior of Pr³⁺ ions within a KLaF₄ lattice but also highlights its potential for efficient photon management and quantum-based technologies. Full article

In this work, were synthesized (Pb_0.91La_0.09)(Zr_0.65Ti_0.35)_0.9775O₃ ceramic materials with different concentrations of praseodymium (0, 0.1, 0.3, 0.5, 1 wt.%) via gel-combustion route and sintered by the hot uniaxial pressing method. Measurements were conducted on the obtained ceramics using X-ray powder diffraction (XRD), scanning electron microscope (SEM), EDS analysis, and examination of dielectric and ferroelectric optical properties. Results give us a detailed account of the influences of the praseodymium ions on the structural, microstructural, and dielectric properties. 3D fluorescence maps and excitation and emission spectra measurements show how a small admixture changes the ferroelectric relaxor behavior to an optically active ferroelectric luminophore. Full article

Nanotherapeutics have attracted tremendous research interest in the modern pharmaceutical and biomedical industries due to their potential for drug development, targeted delivery, and therapeutic applications. Therefore, the current study underpins the synthesis of praseodymium ion (Pr³⁺)-substituted Ni_0.5Co_0.5Fe₂O₄ nano-spinel ferrites, (Co_0.5Ni_0.5Pr_xFe_2−xO₄ (0.0 ≤ x ≤ 0.10) NSFs, CoNiPr (x ≤ 0.10) NSFs) via the sonochemical route for its application as a nanotherapeutic treatment option. The synthesized nanomaterial was characterized using various analytical techniques, including scanning/transmission electron microscopy (SEM) and X-ray powder diffractometry (XRD). After substitution with Pr (x = 0.08), the particle size, polydispersity index, and zeta potential analysis indicated an increase in hydrodynamic diameter, with an average zeta potential value of −10.2 mV. The investigation of CoNiPr (x ≤ 0.10) NSFs on colorectal cancer (HCT-116) cells demonstrated a significant effect on cancer cell viability. The inhibitory concentration (IC₅₀) of CoNiPr (x ≤ 0.10) NSFs was between 46 ± 0.91 and 288 ± 8.21 for HCT-116 cells. The effect of CoNiPr (x ≤ 0.10) NSFs on normal human embryonic kidney (HEK-293) cells showed a reduction in the HEK-293 cell viability; however, the cell viability was better than HCT-116. The NSFs treatment also showed morphological changes in cancer cell nuclei, as revealed by DAPI (4′,6-diamidino-2-phenylindole), nuclear disintegration, and chromatic fragmentation, which are signs of apoptosis or programmed cell death. To examine the potential antifungal effects of CoNiPr NSFs on Candida albicans, known to cause candidemia among cancer patients, the viability of the cells was assessed post treatment with CoNiPr (x ≤ 0.10) NSFs. The increasing ratio of dopant had a moderate impact on the percentage of cell viability loss of 42, 44, and 43% with x = 0.06, 0.08, and 0.10, respectively. These results reinforce that increased dopant significantly impacts the antifungal properties of the synthesized nanomaterial. These findings support the idea that NSFs might be useful in pharmaceuticals. Full article

The coordination of rare-earth metal ions (Ln³⁺) to polyoxometalates (POM) is regarded as a way of modifying and controlling their properties, such as single-molecular magnetism or luminescent behavior. The half-sandwich complexes of Ln³⁺ with monolacunary Keggin POMs (Ln³⁺/POM = 1:1) are of particular interest, since the Ln³⁺ retains its ability to coordinate extra ligands. Thus, the knowledge of the exact structures of 1:1 Ln/POM complexes is important for the development of reliable synthetic protocols for hybrid complexes. In this work, we isolated three 1:1 Gd³⁺/POM complexes of the general formula Cat₄Gd(PW₁₁O₃₉)·xH₂O (Cat = K⁺ or Me₄N⁺). Complex (Me₄N)₂K₂[Gd(H₂O)₂PW₁₁O₃₉]·5H₂O (1) is polymeric, revealing a layered structural motif via bridging Gd³⁺ and K⁺ ions. Complexes (Me₄N)₆K₂[Gd(H₂O)₃PW₁₁O₃₉]₂·20H₂O (2) and (Me₄N)₇K[Gd(H₂O)₃PW₁₁O₃₉]₂·12H₂O (3) are classified as dimeric; the difference between them consists of the different crystal packing of the polyoxometalates, which is induced by a variation in the cationic composition. Isostructural complexes have also been characterized for praseodymium, europium, terbium and dysprosium. The coordination number of Ln³⁺ (8) persists in all the compounds, while the binding mode of the POM varies, giving rise to different architectures with two or three H₂O co-ligands per Ln³⁺. However, whatever the particular structure and exact composition, the {Ln(PW₁₁O₃₉)} moieties are always involved in bonding with each other with the formation either of polymeric chains or dimeric units. In water, these aggregates can dissociate with the formation of [Ln(H₂O)₄PW₁₁O₃₉]^4-. This behavior must be taken into account when choosing L for the design of hybrid {Ln(L)POM} complexes. Full article

Aurivillius BaBi₂Nb₂O₉ and Ba_1-xPr_xBi₂Nb₂O₉ ceramics were successfully synthesized by a simple solid state reaction method. Ceramics were prepared from reactants: Nb₂O₅, Bi₂O₃, BaCO₃ and Pr₂O₃. The microstructure, structure, chemical composition, and dielectric properties of the obtained materials were examined. Dielectric properties were investigated in a wide range of temperatures (T = 20–500 °C) and frequencies (f = 0.1 kHz–1 MHz). The obtained ceramic materials belong to the group of layered perovskites, crystallizing in a tetragonal structure with the space group I4/mmm. Modification of the barium niobate compound with praseodymium ions influenced its dielectric properties and introducing a small concentration of the dopant ion causes a slight increase in the value of electric permittivity and shifts its maximum towards higher temperatures. Full article

We studied the spectral-luminescent properties of (ZrO₂)_0.805(Y₂O₃)_0.188(Pr₂O₃)_0.007 and (ZrO₂)_0.802(Y₂O₃)_0.195(Pr₂O₃)_0.003 crystals grown by directional melt crystallization in a cold skull. Analysis of the absorption spectra of the crystals suggested the presence of Pr³⁺ and Pr⁴⁺ ions. Measurement of the relative intensities of the luminescence bands corresponding to the ³P₀ → ³H_4,5, ³P₀ → ³F_2,3,4, ³P₁ → ³H₅ and ¹D₂ → ³H₄ optical transitions of the Pr³⁺ ions, and analysis of luminescence extinction kinetics for the ³P₀ and ¹D₂ levels of the Pr³⁺ ions, suggests the presence of cross-relaxation (¹D₂ → ¹G₄) → (³H₄ → ³F₄) of the Pr³⁺ ions in the ZrO₂-Y₂O₃-Pr₂O₃ crystals. Full article