Crystal Research and Technology最新文献

Tellurite glass and anti-glass samples of two systems: 12.5Bi₂O₃–12.5Nb₂O₅–(75-x)TeO₂–xNd₂O₃ and 7.5Bi₂O₃–7.5Nb₂O₅–(85-x)TeO₂–xNd₂O₃; x = 0 and 1 mol% are prepared by melt–quenching. Transparent glass-ceramics (TGCs) containing anti-glass inclusions co-existing with the glass are prepared by heat–treatment 26 °C above their respective glass transition temperatures. Heating at a higher temperature of 510 °C formed opaque crystalline samples. The effects of Nd³⁺ doping and heat treatment on the samples are studied by X–ray diffraction (XRD), density measurements, Differential scanning calorimetry (DSC), micro-Raman, and UV–visible spectroscopy. The growth of inclusions of anti-glass phases in the TGCs is confirmed by optical microscopy. XRD studies showed sharp peaks of orthorhombic BiNbTe₂O₈ and TeO₂ phases in TGC samples. DSC studies found that the addition of Nd³⁺ enhances the glass transition temperature. Micro-Raman studies found very similar spectra in both anti-glass inclusions and glass matrix confirming that the anti-glass inclusions have vibrational disorder. The size of inclusions is found to be higher in Nd³⁺ doped sample containing lower concentration of Bi₂O₃ and Nb₂O₅ (7.5 mol%). The Nd³⁺ doped samples exhibit broad near-infrared emission bands on excitation with 785 nm laser light.

The bonding features of sesquioxides have been thoroughly investigated by precise experimental charge density distribution using the Maximum Entropy Method (MEM) and multipole models of charge density. The topology of the charge density is investigated and the atoms enacting different bonding characteristics and vibrations at different symmetries are well documented by studying (3,-1) bond critical points. The intermediate nature of interactions are visibly evident in the systems and are mapped. In the course of study, evidences of an increase in closed-shell interaction characteristics of bonding with the increase in the oxidation state of the metal cations in binary oxides are also witnessed. Thermal vibration parameters and charge density at the mid-bond regions, observed in the compound Y₂O₃, shows that its lattice is more rigid and has more covalent character than Al₂O₃ and In₂O₃. The charge integration studies explored the high ionic conductivity nature of In₂O₃.

In this study, an organic nonlinear optical single crystal, creatininium p-toluene sulphonate (CPTS), is synthesized and grown using slow solvent evaporation in an aqueous medium at ambient conditions. Single-crystal X-ray diffraction demonstrates an orthorhombic structure with non-centrosymmetric space group P2₁2₁2₁. Phase purity and specific (hkl) planes are verified by powder X-ray diffraction, while Fourier-transform infrared spectroscopy identifies functional groups within CPTS. Crystalline integrity of the harvested single crystal is assessed through high-resolution X-ray diffraction techniques. High-resolution X-ray diffraction assessed crystal integrity, and microhardness testing categorized CPTS as a soft material. Growth patterns are investigated using surface etching analysis. UV–vis–NIR absorbance and photoluminescence studies provide optical properties. Third-order nonlinearity studies are performed on a thin, well-cut, and polished single crystal using the Z-scan technique, revealing a nonlinear refractive index of $��-�6.87�\times �{10}^{�-�14��}�m^2�/�W�$ and a nonlinear absorption coefficient of $��6.08�\times �{10}^{�-�7�}�m�/�W�$.

In this work, the effects of Ti content on the electrochromic properties of TiWO₃ films are investigated. These films with a nanorod structure are prepared by oblique angle deposition (OAD) in the sputtering process. Sputtered films with a thickness of 100 nm of W and W: Ti for ratios of 5:95 and 50:50 wt.% are thermally oxidized at 500 °C for 1 h. The WO₃ nanorod films exhibit a clear crystalline structure, whereas the TiWO₃ nanorod films show decreased crystallinity, retaining the crystalline structure of WO₃. Moreover, the TiO₂ phase appeared in the presence of W: Ti is 50:50 wt.%. The thermally oxidized films show a clear grain cluster-forming surface. The WO₃ nanorod films exhibit the highest optical contrast of 0.485 with a coloration efficiency of 10.129% and superior electrochromic performance compared to TiWO₃ nanorod films. Meanwhile, the TW5 films reveal a significant increase in the CV loop, demonstrating the most effective test cycle for electrochromic applications.

The Terahertz generation is reported from novel single crystals of 2-amino-5-nitropyridinium L(+) tartrate (ANPT), grown by slow evaporation solution growth technique (SEST), using formic acid as the solvent. The preliminary analysis is conducted for the crystal to understand their structural, chemical, thermal, electrical, and optical behavior. Terahertz time domain spectroscopy (THz-TDS) is used to extract complex refractive index, dielectric constant, and conductivity of the crystal in Terahertz (THz) frequency. The Terahertz emission studies of the grown crystal is conducted and reported for the first time. ANPT crystal is found to generate THz radiation by optical rectification, with emission amplitude comparable to that of commercially used ZnTe crystals. Thus, these crystals could be a prominent candidate in designing Terahertz devices for future applications.

In recent years, Copper(I)-based inorganic halides have garnered significant interest for their exceptional optical properties. In this paper, Cs₃Cu₂Br₅ single crystals are grown by the vertical Bridgman method, resulting in large transparent single crystals ≈40 mm in length. The crystals are characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). Transmission spectra, photoluminescence (PL), temperature-dependent fluorescence spectra, X-ray excitation spectra, and photoluminescence decay time are also measured. The results indicate that the Cs₃Cu₂Br₅ single crystal exhibits good optical transmittance of 85% in the wavelength range of 250–800 nm and a large direct bandgap of 3.85 eV. The Cs₃Cu₂Br₅ single crystal displays intense broadband blue luminescence, featuring significant Stokes shifts, a microsecond-long fluorescence lifetime decay, and higher quantum yield, all attributed to self-trapped exciton emission. The temperature-dependent fluorescence spectra of the crystals are measured to analyze the luminescence mechanism. In summary, the research indicates that the Cs₃Cu₂Br₅ single crystal has certain potential applications in the field of photodetectors, light-emitting diodes, scintillators, etc.

Blue phosphorescence is confronted with significant challenges due to its need to populate and stabilize the relatively high-energy excited states. Herein, blue room temperature phosphorescence is achieved by introducing a chlorine atom with three p-orbitals to restrict the free rotation of triphenylmethane. Theoretical calculations indicate that the p-orbital of the chlorine atom promotes the spatial conjugation of three benzene rings, thereby limiting their free rotation.

In isotropic solid-state lasers, polarization control remains a challenging yet crucial aspect, especially in the absence of intrinsic birefringence. Recent studies have revealed that linearly polarized output can be realized through mechanisms such as pump polarization influence, stress- and symmetry-induced anisotropies, and frequency locking between polarization eigenmodes. This review summarizes key experimental findings and theoretical interpretations, including polarization self-selection originating from dopant site symmetry and the emergence of coherent eigenmode superposition under specific cavity conditions. While significant progress is made, most models remain confined to low-power or single-mode regimes and overlook complex behaviors in multimode, high-power scenarios. Future research should emphasize multi-physics coupling, spatiotemporal polarization diagnostics, and full-field simulation methods to bridge the gap between theoretical mechanisms and practical implementations.

Calcium phosphate-based bioceramic materials have shown tremendous potential in biomedical applications, particularly in bone repair and replacement, due to their excellent biocompatibility and osteoconductivity. However, since nucleation events occur at the atomic scale, traditional experimental methods face significant limitations in exploring the nucleation and growth mechanisms of calcium phosphate. The introduction of multi-scale computational simulation techniques can provide comprehensive understanding the nucleation mechanism and properties of calcium phosphate. This review systematically summarizes recent progress in the computational simulation of calcium phosphate nucleation and analyzes the current challenges in the field. Finally, this study further proposes that the integration of advanced computational methods, machine learning techniques, and experimental validation will enable a comprehensive understanding of the nucleation process of calcium phosphate, bridging the gap between microscopic mechanisms and macroscopic properties.