Search

The bulk of the LiNa5Mo9O30 (LNM) crystals were successfully grown in the [010] and [001] directions without internal inclusions and cracks, using the Czochralski method with a low temperature gradient. The crystal grown in the [010] direction showed a tendency to twinning. The crystal grown in the [001] direction demonstrated high structural perfection (FWHM = 13″) for the (001) plane and high optical quality Δn ≈ 2 × 10−5. The laser-induced damage threshold was measured along a, b and c axes and was 12.2, 27.0 and 27.5 J/cm2, respectively. The thermo-optical coefficient dn/dT was measured for the main crystallographic axes, which was −5.75 × 10−6, −20.2 × 10−6 and 3.65 × 10−6 K−1 along the a, b and c axes, respectively. The second harmonic generation (SHG) was conducted in the crystalline LNM sample. The maximum efficiency value of 3.5% at a pump power of 12 W was achieved. [ABSTRACT FROM AUTHOR]

Bismuth-germanate glasses, which are well known as a promising active medium for broadband near-infrared spectral range fiber lasers and as an initial matrix for nonlinear optical glass ceramics, have been synthesized in a 5–50 mol% Bi2O3 wide concentration range. Their structural and physical characteristics were studied by Raman and FT-IR spectroscopy, differential scanning calorimetry, X-ray diffraction, optical, and luminescence methods. It has been found that the main structural units of glasses are [BiO6] and [GeO4]. The growth in bismuth oxide content resulted in an increase in density and refractive index. The spectral and luminescent properties of glasses strongly depended on the amount of bismuth active centers. The maximum intensity of IR luminescence has been achieved for the 5Bi2O3-95GeO2 sample. The heat treatment of glasses resulted in the formation of several crystalline phases, the structure and amount of which depended on the initial glass composition. The main phases were non-linear Bi2GeO5 and scintillating Bi4Ge3O12. Comparing with the previous papers dealing with bismuth and germanium oxide-based glasses, we enlarge the range of Bi2O3 concentration up to 50 mol% and decrease the synthesis temperature from 1300 to 1100 °C. [ABSTRACT FROM AUTHOR]

In the present research, an individual Bi2GeO5 crystalline phase is successfully synthesized on air from Bi2O3‐Bi‐GeO2 batch in which some part of bismuth oxide is replaced by metallic bismuth to create an oxygen deficiency. The crystallization process is carried out by three methods: heterophase synthesis, melt cooling, and glass crystallization. The structure of the formed crystalline phases as well as the influence of the bismuth metal quantity and synthesis temperature on crystallization results have been investigated by X‐ray diffraction (XRD). It is found that both the melt temperature rising, and an increase of metallic bismuth amount led to the formation of an individual Bi2GeO5 phase. The optimal initial batch compositions and crystallization conditions to produce an individual Bi2GeO5 or Bi4Ge3O12 phase have also been found. [ABSTRACT FROM AUTHOR]

The method of synthesis of a monophase boron phosphate (BPO4) powder has been refined. Single crystals of BPO4 free from solvent inclusions and cracks have been obtained by the top‐seeded solution growth technique with the seed orientation [010]. The growth is carried out under conditions of a low axial temperature gradient in the melt‐solution, which is varied in the range of 1–4°C cm−1. The value of the temperature gradient that promotes the growth of defective crystals is determined. The absorption spectra and optical homogeneity of crystals are studied. The chemical composition of polycrystalline BPO4 is studied using inductively coupled plasma mass spectrometry. The purity of the synthesized powder is better than 4 N. [ABSTRACT FROM AUTHOR]

The theoretical and experimental analysis of the ternary system Zn‐Se‐Fe for obtaining new fundamental information on phase using X‐ray analysis and inductively coupled plasma mass‐spectrometry is carried out. New experimental data of isothermal annealing in the Zn‐Se‐Fe system at the temperatures 730, 814, 1073 K by X‐ray studies confirms the reliability of theoretical isothermal sections. The information on Fe solubility and concentrations of native point defects of atomic scale at bi‐ and monovariant conditions at 1073 and 1273 K have been carried out. Taking into account the new data on phase equilibria, it is possible to fabricate active ZnSe:Fe2+ elements to create an effective laser operating at the temperature of 300 K with 1.52 Joule emission energy with efficiency of ≈50% relative to the absorbed energy. [ABSTRACT FROM AUTHOR]

Hybrid materials were synthesized using a high temperature reaction. We used 80PbF2-20B2O3 glass as an inorganic matrix and various phenanthroline complexes europium(III) - as organic phosphors. The photoluminescence spectra of hybrid materials were measured just after synthesis and after heat treatment. We suggested that an exchange reaction between a Eu-complex and a glass matrix had occurred. [ABSTRACT FROM AUTHOR]

Tris(8-hydroxyquinoline)boron (Bq3) was synthesized by means of a high-temperature substitution reaction. Mixtures of different Bq3 polymorphs were obtained and their spectral and structural properties were investigated. A comparison of organic light-emitting diode (OLED) structures with Bq3 and Alq3 as emitting materials showed the prospective application of Bq3 as a blue-light emitter. Thin-film hybrid materials (HM) were made by vacuum thermal deposition. HM films were produced by layer-by-layer thermal vacuum sputtering of B2O3/Alq3/B2O3/MoO3/Al on a glass substrate with an indium tin oxide (ITO) conducting layer. The HM films were locally heated by a diode laser (785 nm). The pumping of 150 W cm-2 energy for one second resulted in an irreversible change in the HM film. Chromaticity coordinates for the as-prepared and laser-induced HM films showed a significant difference in their photoluminescent properties. [ABSTRACT FROM AUTHOR]

Homogeneity regions of ZnTe, CdTe, CdSe, and CdS were determined by the direct physic-chemical 'extraction' technique combined with the high temperature equilibrium freezing technique. The general scheme of homogeneity range for all studied compounds has been constructed according to which 'wurtzite-zincblende' transition occurred by peritectic reactions from both Metal and Chalcogen rich sides. The analysis of nonstoichiometry as a solid solution of an over-stoichiometric component in the above compounds has been fulfilled. The thermodynamic parameters of stability of 'wurtzite-zincblende' transition were estimated. [ABSTRACT FROM AUTHOR]

We synthesized and investigated a new series of Sm 3+ 1,3-diketonate complexes with C n F 2 n +1 -homologous thiophene-containing ligands. A clear correlation was found between the number of fluorine atoms in the 1,3-diketone's carbon chain and the luminescent properties of the samarium(III) complexes. The ligand modification method employed facilitates targeted and significant enhancements in the photoluminescence quantum yield (PLQY). Notably, the PLQY value peaked at 5.2% for the complex with n = 4 before decreasing with longer chains, a trend contrasting with that observed for Eu and Nd complexes. Temperature-dependent shifts in the CIE coordinates were observed, making these compounds suitable as luminescent thermometers with a sensitivity of 2.2% K -1 and resolution of 0.2 K at 120 K.