Glass and Ceramics最新文献

The influence of the content and ratio of MgO and CaO sintering additives on the optical properties of YAG:Cr³⁺ and YAG:Cr⁴⁺ ceramic materials was investigated. All samples showed high transparency at 1100 nm (more than 80%). However, in the approx. 340 nm region, the light transmittance values of the samples decreased with increasing amounts of Ca²⁺ or Mg²⁺ ions. The most intense absorption in the range of 750 – 1100 nm after annealing in air was observed in the samples containing the highest value of sintering additives. The absorption of Cr⁴⁺ cations increased with the increase of Ca/Mg content. The optimum CaO content among the investigated samples was 0.12 wt.%. Above this value, additional absorption was observed due to the formation of microdefects. The data obtained by scanning electron microscopy showed that the ceramic samples had a granular structure with grain size ranging from 1 to 10 μm. There were no significant differences in the microstructure depending on the content and type of sintering additives.

The PbO–Ga₂O₃ glass-forming system with a lead oxide content of more than 50 mol.% was studied. The glass structure was found to be significantly affected by the introduction of lead oxide. Vibrational spectroscopy results showed that PbO significantly reduces the number of Ga–O–Ga bridging bonds, leading to a weakening of the glass network and the dominance of PbO₄ pyramids in it. Structural changes lead to a significant change in the physicochemical properties of glasses. The spectral and optical properties of the PbO–Ga₂O₃ glass system are discussed in detail. The glasses have a wide transparency window (from 0.5 to 7.1 μm), a high refractive index (approximately 2.2), and a small Abbe number (approximately 12). The developed materials show promise for optics and photonics applications in devices operating in the infrared range of the spectrum.

The structure of ZrO₂–Sc₂O₃ powders in the composition range from 1 to 15 mol.% of Sc₂O₃ with the addition of 0.1 mol.% Eu₂O₃ as a spectroscopic probe was studied. The powders were obtained by the coprecipitation method and subsequent heat treatment at temperatures ranging from 500 to 1200°C. The crystal structure was identified through x-ray diffraction analysis (XRD) and Raman spectroscopy. The local structure was evaluated based on the spectral and luminescent properties of the Eu³⁺ ion in the powder samples.

The results of the synthesis of complex YErYbNbO₇ paraniobate using different methods are presented. The chemical composition of the final synthesis products was determined. The peculiarities of the thermal behavior of the precursors are revealed. Crystallographic parameters of single phase samples were calculated and crystallite sizes were determined.

Influence of the specific surface area and filler concentration on the coefficient of linear thermal expansion (CLTE) of sintered composites based on high lead fused glass and lead titanate was investigated in order to obtain solder materials offering unusually low CLTE values. The microstructure of compositions was investigated by optical microscopy methods in combination with birefringence testing with a localization of about 1 μm. In samples containing up to 55% PbTiO₃ powder having a specific surface area of less than 560 cm²/g, near-zero and even negative values have been achieved.

Phosphate glasses with a high concentration of Nd³⁺ ions are key components for the development of efficient near-infrared (NIR) laser systems. The sensitization of Nd³⁺ ion luminescence in BaO–P₂O₅ glass using Ag nanoaggregates is investigated in this study. The results show that the thermally stimulated formation of ({text{Ag}}_{m}^{n+}) molecular clusters allow a 15-fold enhancement of the photoluminescence intensity of Nd³⁺ ions, whereas the formation of plasmonic nanoparticles (NPs) did not achieve such an enhancement. These results open new perspectives for controlling the properties of phosphate glasses and improving the efficiency of laser systems.

The main types of defects in ceramic blanks and the causes of their occurrence are considered in this article. Comparative analysis of two materials—duralumin alloy and caprolon—used in the manufacture of cores is presented. The influence of passive forming surface materials of the core on the quality characteristics of quartz ceramic products is estimated. The possibility of using of caprolon, which has water-absorbing properties and does not require the use of lubricants for the production of quartz ceramic products by the slip-casting method, to reduce the occurrence of technological defects of ceramic blanks to 25%, is demonstrated.

Chemical elements capable of contaminating high-purity crystalline, ceramic and glass materials used in the production and research of photonic and electronic devices have been identified. Sources of pollution included street air during the spring and summer seasons, as well as airborne particles resulting from construction activities, various personal care products, protective gloves, and cleaning materials. Possible measures for reducing uncontrolled pollution are proposed.

LuAG-based optical ceramics co-doped with Yb³⁺ and Er³⁺ ions was successfully synthesized for the first time. The optical, spectral-luminescent, and kinetic characteristics of ceramics based on Y_2.82Yb_0.15Er_0.03Al₅O₁₂ (YAG 5-Yb, 1-Er) and Lu_2.82Yb_0.15Er_0.03Al₅O₁₂ (LuAG 5-Yb, 1-Er) compositions were investigated. It is demonstrated that excitation of luminescence at a wavelength of 940 nm in YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics results in the effective transfer of excitation radiation energy from Yb³⁺ ions to Er³⁺ ions. The energy transitions that play a pivotal role in the processes of Stokes and anti-Stokes luminescence of ceramics based on YAG 5-Yb, 1-Er and LuAG 5-Yb compositions was identified, and a schematic representation of these transitions is presented. The mutual variation of the intensity of anti-Stokes luminescence bands resulting from the transitions ²H_11/2 → ⁴I_15/2 (525 nm) and ⁴S_3/2 →⁴I_15/2 (546 nm) was observed, with regard to the power of the excitation radiation. This study demonstrates the potential of YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics as materials for optical thermometry.

By means of vibrational spectroscopy, the study examines the structure of matrix materials synthesized through the quenching of sodium-rubidium aluminoborosilicate melts with the addition of zirconium. Zirconium was found to have a significant effect on the ratio of the main structural units and the distribution of modifier cations among them in the glass structure. The obtained results were used to explain changes in the glass-melt transition temperature and synthesized material density; they can be useful in adjusting the composition and synthesis parameters of matrix materials for the immobilization of high-level radioactive waste containing significant amounts of zirconium.