[en] A convenient method for preparation of pure and doped yttrium oxide was developed, which is based on irradiation of solutions containing yttrium nitrate and ammonium formate with UV light or accelerated electrons. Solid phase formed under irradiation was consequently calcined at 500 °C or higher temperatures to obtain nanocrystalline yttrium oxide. Addition of small amount of cerium(III) or europium(III) nitrates to irradiated solutions resulted in doping of yttrium oxide with Ce(III) or Eu(III) ions. Under both types of irradiation, the method yields material with high specific surface area, consisting of spherical nanoparticles 25–100 nm in diameter depending on preparative conditions and post-radiation treatment and with narrow size distribution. In the doped oxides (Y₂O₃:Ce or Y₂O₃:Eu), radioluminescence spectra typical for Ce³⁺ or Eu³⁺ doped oxide structures were observed.

[en] A method of the chemical generation of atomic iodine for a chemical oxygen-iodine laser (COIL) using atomic fluorine as a reaction intermediate was studied experimentally. This method is based on the reaction between F₂ and NO providing F atoms, and the reaction of F with HI resulting in iodine atoms generation. Atomic iodine was produced with efficiency exceeding 40% relative to initial F₂ flow rate. This efficiency was nearly independent on pressure and total gas flow rate. The F atoms were stable in the reactor up to 2 ms. An optimum ratio of the reactants flow rates was F₂:NO:HI = 1:1:1. A rate constant of the reaction of F₂ with HI was determined. The numerical modelling showed that remaining HI and IF were probably consumed in their mutual reaction. The reaction system was found suitable for employing in a generator of atomic iodine with its subsequent injection into a supersonic nozzle of a COIL

[en] Preparation of zinc oxide nanoparticles from aqueous solutions containing zinc nitrate or formate using UV irradiation was investigated. Analysis of solid phase formed during irradiation confirmed the presence of zinc oxide or zinc peroxide nanoparticles ranging in size from 1 to 70 nm, depending on initial precursors. Annealing at temperatures 650–1000 °C results in forming of rice-like zinc oxide particles, up to hundreds of nm in size. Photochemical method yields material with high chemical purity and uniform particle size distribution. In addition, photo-induced doping of zinc oxide with lanthanum was studied. Presence of lanthanum in zinc oxide crystal lattice and post-preparation treatment in reduction atmosphere significantly increase the UV excitonic luminescence at 395 nm in radioluminescence spectra.

[en] A chemical method of atomic iodine generation followed by iodine injection into the supersonic nozzle of Chemical Oxygen-Iodine Laser (COIL) was studied experimentally. This method is based on the reaction of gaseous hydrogen iodide (or deuterium iodide) with fluorine atoms formed in a preceding reaction between molecular fluorine and nitrogen oxide. Iodine atoms are generated in specially designed reactors and then injected into the primary gas flow in the COIL cavity. Concentration profiles of atomic iodine along the primary gas flow or perpendicularly to it were measured in dependence on the flow rates of reaction gases. Very high concentrations of atomic iodine (up to 3.2 x 10¹⁵ cm^-3) were measured in the laser cavity when the primary gas contained no singlet oxygen, O₂(¹Δ_g). Yields of atomic iodine related to either F₂ or HI were rather high (I/F₂ ≤ 100%, I/HI ≤ 60%). A small signal gain on the I*-I laser transition was measured when atomic iodine was injected into the primary gas containing singlet oxygen. The measured gain was lower than the gain estimated from the determined concentration of atomic iodine, temperature, and O₂(¹Δ_g) yield measured upstream the iodine admixing. This difference was ascribed to the O₂(¹Δ_g) quenching by some product of DI oxidation (probably the radical DO₂^·)

[en] The preparation of solid precursors to Zn_1−xCd_xO and (Lu,Y)₃Al₅O₁₂:Ce induced by ⁶⁰Co gamma-ray irradiation of aqueous solutions containing soluble metal salts and ammonium formate is presented. Due to the irradiation, crystalline zinc carbonate hydroxide Zn₄(CO₃)(OH)₆·H₂O or amorphous carbonates of Lu, Y and Al were formed in the solutions. After calcination at 500 °C, the agglomerated phase-pure Zn_1−xCd_xO with crystallite size about 50 nm was obtained if the Cd concentration in solutions remained below 16 M% (with respect to Zn) with x being up to 0.035. The solid precursors to garnets contained the intended concentration of all elements, according to X-ray fluorescence analysis. After calcination at 1200 °C in mild vacuum, the respective phase-pure garnets with crystallite size 100 nm or their solid solution were produced when the Ce dopation was kept below 2 M% (with respect to rare-earth metals). The Ce solubility in the garnet lattice was estimated as 1–2 M% at the calcination conditions used. - Highlights: • Precursors to Zn_1−xCd_xO and (Lu,Y)₃Al₅O₁₂ oxides were formed under γ-radiation. • Heat treatment was required for wurtzite (ZnO) or garnet (YAG) modification forming. • Phase-pure Zn_0.97Cd_0.03O solid solution with the maximum Cd content was prepared. • Phase-pure (Lu,Y)₃Al₅O₁₂:Ce garnets up to 2 M% of Ce were produced. • Crystallite size amounts 50 nm for Zn_1−xCd_xO and 100 nm for (Lu,Y)₃Al₅O₁₂.

[en] CeO₂, Eu₂O₃ and mixed oxides of CeO₂–UO₂, Eu₂O₃–UO₂ were fabricated. The preparative method was based on the irradiation of aqueous solutions containing cerium/europium (and uranyl) nitrates and ammonium formate. In the course of irradiation, the solid phase (precursor) was precipitated. The composition of irradiated solutions significantly affected the properties of precursor formed in the course of the irradiation. However, subsequent heat treatment of (amorphous) precursors at temperatures ≤650 °C invariably resulted in the formation of powder oxides with well-developed nanocrystals with linear crystallite size 13–27 nm and specific surface area 10–46 m² g⁻¹. The applicability of both ionizing (e-beam) and non-ionizing (UV) radiation was studied. - Highlights: • Cerium, europium and their mixed oxides with uranium were prepared in powder form. • Radiation-induced precipitation and heat treatment of the precipitate were used. • E-beam or UV irradiation were used in the process and compared. • Prepared materials are prospective for pelletizing.

[en] Zinc oxide nanoparticles were prepared by irradiation of aqueous solutions containing zinc(II) ions, propan-2-ol, polyvinyl alcohol, and hydrogen peroxide. Zinc oxide was found in solid phase either directly after irradiation, or after additional heat treatment. Various physicochemical parameters, including scintillation properties of prepared materials, were studied. After decomposition of impurities and annealing of oxygen vacancies, the samples showed intensive emission in visible spectral range and well-shaped exciton luminescence at 390-400 nm. The best scintillating properties had zinc oxide prepared from aqueous solutions containing zinc formate as initial precursor and hydrogen peroxide. Size of the crystalline particles ranged from tens to hundreds nm, depending on type of irradiated solution and post-irradiation thermal treatment.

[en] Yttrium-aluminium garnet powders were prepared from aqueous solutions containing yttrium nitrate and aluminium chloride or nitrate via irradiation with accelerated electrons or UV light and via consequent calcination of formed solid phase. UV light seems to be more convenient for yttrium-aluminium garnet preparation; both types of irradiation yield crystalline Y₃Al₅O₁₂ phase after 1 h calcination at 1000 deg. C in air, but some amounts of yttrium oxide and aluminium oxide were also detected in calcinated solid phase formed under accelerated electrons irradiation. Preliminary radioluminescence and thermoluminescence measurements were performed to further evaluate prepared materials. Intensive radioluminescence typical for Ce³⁺ doped structure was observed; thermoluminescence glow curves show distinctive peaks at 135-140 and 240-250 deg. C. - Highlights: → YAG and YAG:Ce were synthesized via irradiation of aqueous solutions of precursors. → Ionizing and/or non-ionizing radiation were used for the synthesis. → Calcination for 1 h at 1000 deg. C leads to well developed crystalline YAG phase. → Synthesized powder YAG consists of 50 nm nanocrystals. → The best prepared materials have very intensive radioluminescence.