This work investigates the luminescent properties of fluorapatite doped with Tb 3+ ions (HAp–F:Tb) to determine the nature of the luminescent centers and the excitation features. Biohydroxyapatite was obtained from cattle bone raw material by rapid pyrolysis followed by annealing at 750 ◦C ; doping was carried out by the solvation–precipitation method. The samples were characterized by X-ray diffraction analysis, IR spectroscopy, and photoluminescence spectroscopy in the 200–700 nm range. It was established that the main active center is Tb 3+ : intense emission bands corresponding to the 5 D4 → 7 F5 , 5 D4 → 7 F4 , and 5 D4 → 7 F3 transitions were recorded in the 490–620 nm region. The maximum intensity was observed under excitation at 220–260 nm and 355–377 nm, indicating direct excitation of Tb 3+ and/or energy transfer from the matrix and defect levels. The obtained results demonstrate the promise of HAp–F-Tb as a luminescent material and the possibility of targeted modification of its optical properties through doping with rare-earth ions.
The photocatalytic degradation of paracetamol, a widely detected harmaceutical contaminant, was investigated using WO3 nanopowders synthesized via a hydrothermal method. The obtained materials exhibited a hierarchical micro/nanostructured morphology composed of interconnected grains and well-defined nanoplate-like particles. Optical characterization revealed an indirect band gap of approximately 2.9 eV. The photocatalytic performance of WO3 was evaluated under light irradiation, demonstrating a gradual decrease in paracetamol concentration with increasing irradiation time. The degradation process followed pseudo-first-order kinetics, with an apparent rate constant ( kapp ) of 2.54 × 10−2 min −1 . The enhanced photocatalytic activity is attributed to the developed surface morphology and improved charge transport within the interconnected structure. These results highlight the potential of WO3 nanopowders as effective photocatalysts for the removal of pharmaceutical pollutants from aqueous environments.
A process for the purification and growth of alkali halide crystals (AHCs) has been demonstrated using the KCl:Li crystal as a representative example. The experiments were performed on an experimental crystal growth setup manufactured by Across International (USA). The procedure comprised the following sequential stages: (i) establishment of a deep static vacuum ( 10−3 Pa or 10−6 Torr) within a quartz reactor containing a quartz ampoule with a raw material; (ii) introduction of high-purity argon at room temperature to a pressure of 0.3–0.5 bar, calculated to reach 1.1–1.3 bar at the melt temperature of the material (770–800 ◦ C), in order to suppress the evaporation of aggressive halogen vapors. Crystal growth was conducted in strict accordance with the protocol of the Eurotherm system and the MCGS (Monitor and Control Generated System) human–machine interface (HMI) platform. Owing to this integrated control architecture, a controlled slow-cooling regime of the “superheated” crystal at a rate of 20–30 ◦ C/h was implemented, a capability not previously attainable in comparable crystal growth systems. The newly developed integrated crystal growth system differs fundamentally from conventional designs and does not require: (i) quartz-sealing laboratory facilities for ampoule sealing, since the raw material within the quartz ampoule is maintained under vacuum inside the quartz reactor; (ii) additional water cooling of the installation, as the crystallization center is formed close to the thermal block and ends of the quartz tube are positioned outside the high-temperature zone. In a test regime, X-ray luminescence (XRL) spectra of freshly grown KCl:Li crystals were recorded as a function of lithium ion concentration. The anticipated enhancement of the luminescence light yield was observed, attributed to the recombination assembly of electron–hole pairs within the field of lithium ions. The result constitutes an important parameter for the development of the scientific basis of scintillation detectors.
In experiments performed at GELINA (IRMM, Belgium) and IREN (FLNP JINR, Dubna, Russia) facilities, variations in the total kinetic energy (TKE) of fission fragments as a function of incident neutron energy were experimentally observed in the resonance region of 235 U fission. These observations provided a basis to assume a correlation between the number of prompt fission neutrons and the TKE. To further investigate this dependence, the ENGREN setup was developed. It consists of a twin Frisch-gridded ionization chamber (GIC) with a target at its center, surrounded by 32 detectors based on EJ-309 liquid scintillator arranged in a spherical configuration around the GIC. The setup is designed for simultaneous measurement of the TKE and angular distributions of fission fragments, as well as for registration of prompt fission neutrons. We present its comprehensive calibration and performance validation. Energy calibration was performed by comparing measured gamma-ray spectra ( 22 Na, 137 Cs, 60 Co) with Monte Carlo simulations, establishing a linear response ( R2 = 0.9977 ) and an energy resolution of ∆E/E = 7.7% at 1.333 MeV. The resolution parameters are consistent with the characteristics of organic liquid scintillators. Optimal neutron-gamma pulse shape discrimination (PSD) was achieved, with Figure of Merit (FoM) values matching standard specifications. The system’s readiness is demonstrated by a geometric efficiency of 4.55% and successful test measurements with a 235 U target at the JINR IREN facility, confirming its capability for high-statistics fission studies.
Thermoelectric materials, an important class within the semiconductor family for energy conversion, have been extensively studied in bulk form. However, growing interest in nanoscale materials driven by the quantum confinement effect has made it increasingly important to investigate how their properties change at reduced dimensions. In this work, we demonstrate the successful fabrication of nanosized ternary van der Waals (vdW) compounds SnSb2Te4 and GeBi2Te4 from their high-quality single crystals using High Energy Ball Milling (HEBM) for the first time. Here we discuss the effect of milling variables, i.e., materials of the milling container or grinding vessel and balls, milling medium (wet vs. dry), milling time, etc. The scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analysis of the fabricated nanopowders reveals a strong sensitivity of the samples to the grinding vessel and ball materials, which introduces significant contamination during the milling process. Upon the milling time, this contamination can significantly impact the final composition of the powder, which is undesirable for functional semiconductor materials, where electronic properties are highly sensitive to impurities. Using different types of milling equipment, we demonstrate that nanoscale refinement with minimal impurity can be achieved simply by selecting appropriate milling materials, without modifying the target material or using protective agents. This result is particularly valuable for the preparation of high-purity nanoscale thermoelectric materials based on single-crystalline layered vdW compounds by the top-down method.
