Functional properties of single crystals and optical ceramics based on AgCl – AgI and AgCl – AgBr0.7I0.3 as isothermal sections of the AgCl – AgBr – AgI system

Emission Kinetics of Yb3+ Upper Laser Level in Optical Ceramics of Different Thicknesses Based on Y2O3

Optimization of synthesis techniques and characterization of AgBr0.7I0.3 – TlBr0.46I0.54 optical ceramics and single crystals

Abstract Modern advances in the technology of materials based on the Al2O3-Y2O3 system compounds allowed for the development of turbomachinery, scintillation materials science, as well as lighting and laser systems. Growing single crystals and ceramic composites from melt using methods characterized by weak convective mixing (e.g., horizontally directed crystallization) presents a number of difficulties that can be avoided during the feedstock preparation stage. The lack of information in the existing literature on the process of preparing monophasic, homogeneous, and high-density raw material for single-crystal growth prompted this paper. It addresses a wide range of issues: raw material selection (the possibility of using highly active nano-powders synthesized by wet chemistry methods is considered), factors influencing the solid-state synthesis process and ways to intensify the solid-state reaction of YAG formation, the choice of green body molding method, and potential ways to increase the relative density of the feedstock. This review is devoted to the assessment of the applicability and efficiency of some technological operations from ceramic technology, including the production of optical ceramics, in the production of monophasic YAG from commercial micro-sized oxide powders by solid-state synthesis.

NIR-emitting scintillation of YAG optical ceramics as a testing platform for radio-bioimaging

Abstract The pursuit of eco-friendly, high-performance energy storage materials has intensified interest in lead-free ceramics, especially K0.5Na0.5NbO3 (KNN), known for its exceptional ferroelectric and piezoelectric properties. This study delves into the comparative potential of eco-friendly, lead-free ceramics, specifically K0.5Na0.5NbO3 (KNN) and its modified forms with 3% Bi0.5Na0.5TiO3 additives (KNN-BNT) and 3% Bi0.5K0.5TiO3 additives (KNN-BKT), synthesized via the solid-state reaction technique. These novel multiferroic compositions were systematically investigated using Powder X-ray Diffraction (PXRD) and Field-Emission Scanning Electron Microscopy (FESEM), which revealed distinct variations in crystal structure, morphology, and composition. The addition of bismuth-based additives induced a crystal transformation from orthorhombic to tetragonal, accompanied by particle size reduction, particularly in KNN-BKT. UV-vis spectroscopy highlighted a reduced energy band gap in KNN-BKT, with superior optical transmission ~ 75% and a lower refractive index in the visible spectrum. A thorough analysis of the material’s ferroelectric characteristics using the P-E loop reveals information on their improved energy density, high efficiency, and polarization properties. The study also examines the dielectric properties of all three compositions, elucidating the impact of composition and temperature on the dielectric constant and dielectric loss. These tailored structural, optical, and dielectric properties position KNN-BKT and KNN-BNT ceramics as promising candidates for next-generation transparent energy harvesting devices, such as smart windows, wearable electronics, and self-powered sensors, advancing the field of sustainable energy storage and multifunctional device applications.

Hot Pressing Conditions of CVD ZnSe Powder Influence the Properties of Optical Ceramics

Investigating the impact of Y/Lu ratio on the optical, luminescent, and thermal properties of YLuAG:Yb,Er optical ceramics

Laser material Y3Al5O12 (YAG), originally known in the form of a single-crystal, has been distributed and widely commercialized in the form of optical ceramics. The desire to expand the functionality of materials made of nanocrystals due to the size effect actualizes the study of the influence of their structure on the optical (vibrational and electronic) and other properties of new promising materials with the YAG base including glass ceramics. In this work, models of crystalline alumina-iodine garnet fragments have been calculated by DFT/uPBEPBE/SDD, DFT/uPBEPBE/lanl2DZ, and DFT/uB3PW91/SDD methods. The IR spectra were calculated by DFT/uPBEPBE/lanl2DZ method and the absorption bands of the calculated wave numbers were correlated with the measured ones. The electronic absorption spectrum and energy levels were calculated by the DFT/RB3PW91/SDD method.

For the first time, inductively coupled plasma mass spectrometry (ICP-MS) was developed for determining the target elemental composition of gadolinium–aluminum garnets with the varying composition Gd3–xCexScyAl5–yO12, where x = 0.01–0.16 and y = 0.25–1.75. This fact has a fundamental importance for obtaining optical ceramics with predictable properties. Using the proposed acid mixture and temperature-time program, microwave digestion of these materials and complete transfer of the sample’s components into solution were possible. Moreover, we estimated the influence of the matrix composition, sample introduction system and collision cell on the limits of determination (LOD) of impurity elements by ICP-MS (Mg, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, La, Pr, Nd, Sm, Eu, Tb, Er, Ho, Tm, Yb, and Lu). It has been shown that the conditions of mass spectral analysis proposed in this work provide LOD of target analytes in the range of 1∙10−6–4.15∙10−3 wt.%. The accuracy of the obtained results has been confirmed by the added-found method and by analyzing samples with known chemical composition. The standard deviation of repeatability (Sr) of the developed technique lies in the range from 1 to 6%. The developed analysis method is characterized by sensitivity, robustness and multi-elementality. It has application potential for other optical and ceramic materials of similar composition.

Optical MgO Ceramics Fabricated by Hot Pressing with LiF

Investigation of Luminescent Properties of Optical Ceramics Based on YAG and Luag Co-Activated by Yb3+ and Er3+

Abstract Using the method of non‐reactive sintering of nanocrystalline powders, highly transparent samples of optical ceramics based on solid solutions of yttrium‐scandium aluminum garnets containing 50 at.% scandium in the dodecahedral position and doped with erbium (1 at.%) and ytterbium (0–49 at.%) cations (YSAG:Yb:Er) were produced. The influence of Yb3+ concentration on the crystal lattice parameter, density, refractive index, stability of YSAG:Yb:Er solid solutions during high‐temperature sintering, thermal conductivity, optical transmittance and absorption coefficients in the wavelength range from 200 to 1100 nm, as well as Stokes and anti‐Stokes luminescence, was determined. The revealed patterns make it possible to fine‐tune the physical and chemical characteristics of ceramics for the design of composite laser materials.

The influence of mechanical grinding conditions of high-purity CVD zinc selenide (ZnSe) powders on their particle size distribution, their sintering process, and the transparency of optical ceramics has been studied. Powders with an optimal granulometric composition were obtained, having an average particle size of 0.3 μm with a maximum of not more than 1 μm. These parameters were achieved by grinding the powders in a planetary ball mill for 20 hours at a grinding bowl rotation speed of 150 rpm. ZnSe optical ceramics are fabricated by a combination of hot pressing and subsequent hot isostatic pressing of CVD powders. The maximum transmission for 2 mm thick samples was 69% (close to theoretically achievable) at a wavelength of 14 μm. The combination of characteristics of CVD ZnSe powders subjected to additional grinding shows their promise for use in optical ceramic technology.

Abstract In this study, the dense and fine‐grained zirconia toughened alumina (ZTA) composite ceramics were efficiently prepared by 3D gel printing technology. Zirconia powder, zirconium oxychloride, and zirconium sol were introduced into boehmite gel as zirconium sources, and their effects on rheological properties, drying characteristics, microstructure, and mechanical properties of ceramics were discussed. The results showed that all gels exhibit reversible shear thinning properties. The gel with zirconia powder has a relaxation phenomenon; zirconium sol forms another gel network in the boehmite gel network, and two linear viscoelastic regions are observed. The gel with zirconia powder has the highest solid loading, small drying shrinkage, and fewer drying defects. The grain growth of ZTA ceramics with zirconium sol was inhibited, and the zirconia grains were evenly distributed, with the highest bending strength of 518 ± 103 MPa. The new gel preparation method and gel drying process offer great possibilities for manufacturing optical glasses and functional ceramics with high‐performance geometric structures, which cannot be achieved by traditional manufacturing methods.

Comparison of the thermophysical and optical properties of ceramics based on YSAG: Yb,Er solid solutions with different forms of crystal lattice disorder

Optical Ceramics Obtained by Hot Pressing of CVD-ZnSe Powder

Our objective is to achieve a new good-quality and mechanically durable high-transparency material that, when activated by rare earth ions, can be used as laser sources, scintillators, or phosphors. The best functional transparent ceramics are formed from high-symmetry systems, mainly cubic. Considering hexagonal hydroxyapatite, which shows anisotropy, the particle size of the initial powder is extremely important and should be of the order of several tens of nanometers. In this work, transparent micro-crystalline ceramics of non-cubic Ca10(PO4)6(OH)2 calcium phosphate were fabricated via Spark Plasma Sintering (SPS) from two types of nanopowders i.e., commercially available (COM. HA) and laboratory-made (LAB. HA) via the hydrothermal (HT) protocol. Our study centered on examining how the quality of sintered bodies is affected by the following parameters: the addition of LiF sintering agent, the temperature during the SPS process, and the quality of the starting nanopowders. The phase purity, microstructure, and optical transmittance of the ceramics were investigated to determine suitable sintering conditions. The best optical ceramics were obtained from LAB. HA nanopowder with the addition of 0.25 wt.% of LiF sintered at 1000 °C and 1050 °C.

Modulation of photoluminescence properties by poling and quenching strategy in rare earth ions doped Na1/2Bi1/2TiO3-based ceramics

Optical glass ceramics based on oxyfluoride glasses activated by rare earth ions have attractive properties for development of lasers and near-infrared amplifiers, since they combine properties of fluoride crystals with low phonon frequencies and chemical and mechanical properties of oxide matrices. Spectroscopic properties of activator ions in crystalline and glass phases of glass-ceramics can differ significantly. Thus, it is possible to determine impurity ions’ distribution between these phases by means of absorption or luminescence spectra analysis. The main goal of this work was to develop a method for determining the concentration of Tm3+ and Ho3+ ions in the crystalline, PbF2 and glassy phases of glass ceramics after secondary thermal treatment of thulium-doped and thulium-holmium co-doped oxyfluoride glasses. Spectroscopic characteristics of oxyfluoride glasses activated by Tm3+ ions and co-activated by Tm3+ and Ho3+ ions, as well as glass ceramics obtained from the original glasses as a result of secondary heat treatment were studied. It was established by X-ray phase analysis method that under certain heat treatment conditions crystalline β-PbF2 phase is formed in those glasses. Absorption and luminescence spectra of Tm3+ and Ho3+ impurity ions in the original glass and in β-PbF2 crystals were compared with their ones in glass ceramics. A method for determining the concentration of ions in the crystalline and glass phases of glass ceramics was proposed on the basis of this comparison. Dependence of Tm3+ and Ho3+ ions distribution between the glass and crystalline phases on different regime of glasses' secondary heat treatment was studied.