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X‐ray detection has drawn great attention in industrial examination, medical imaging, scientific research, and beyond. Herein, the anisotropic X‐ray detection performances are investigated based on a novel oxide crystal KCsMoP2O9 (KCMP). The large dielectric screening effect and 1D infinite chain structure consisting of MoO6 octahedron and two PO4 tetrahedrons are conducive to efficient carrier transport along the X‐direction, leading to a higher µτ (4.77 × 10−3 cm2 V−1) of X direction than that of Z direction (1.05 × 10−4 cm2 V−1). Additionally, the KCMP‐based X‐ray detector along the X direction shows weaker ion migration than that of the Z direction due to the large migration barrier of O2− (8.0 eV) and high ion active energy (784.9 meV) along the X direction. Owing to the high resistivity (2.29 × 1013 Ω cm), high µτ, high ion activation energy, suppressed ion migration, and ultralow dark current, the X‐ray detection performance of the KCMP detector along the X direction is superior to that of the Z direction. Specifically, the high sensitivity (131.2 µC Gy−1 cm−2) and ultralow detection limit (8.9 nGys−1) are achieved in the KCMP detector along the X direction. This work clarifies anisotropic engineering to enhance the X‐ray detection performance of oxide crystals and proposes a novel X‐ray detection crystal with an ultralow detection limit. [ABSTRACT FROM AUTHOR]

Large size and high quality single crystals are the prerequisite to fully evaluate their physical properties and potential technical applications. Herein, centimeter-sized KCsMoP2O9 (KCMP) crystals were successfully grown using the Kyropoulos method. The value of the full width at half maximum (36′′) indicated that the grown KCMP crystals were of high quality. The type of phase transition for KCMP crystals was found to be incommensurate to prototypic transition by in situ X-ray diffraction, and the phase transition mechanism was studied using a rigid unit mode approach. In addition, the linear and nonlinear optical properties of KCMP crystals were studied, and an efficient 515 nm second harmonic laser was successfully achieved in nonbirefringent-matched KCMP crystals using the emerging additional periodic phase technology. [ABSTRACT FROM AUTHOR]

Monoclinic bismuth-based borate crystal α-Bi2B8O15 was grown by the Kyropoulos method. High-resolution X-ray diffraction analysis showed that the full width at half maximum of the Y plate was about 0.04° for the α-Bi2B8O15 crystal. The ideal morphology of the α-Bi2B8O15 crystal was analyzed based on the refined structure obtained by the Rietveld method and it was found that the α-Bi2B8O15 crystal had a layered structure along the b axis. X-Ray photoelectron spectroscopy and transmission spectroscropy were performed together with analysis of the density, mechanical, and thermal properties and the electrical resistivity of the α-Bi2B8O15 crystal. Furthermore, the opto-electric properties were evaluated from the perspective of structural distortion. The results supported that the α-Bi2B8O15 crystal possessed good chemical and thermal stability. The specific heat (0.61 J g−1 K−1) was larger than that of the α-BiB3O6 crystal (0.48 J g−1 K−1) at room temperature. In addition, the α-Bi2B8O15 crystal had a relatively large band gap (4.41 eV) and a wide transmission range (260 nm–4.43 μm). The infrared cut-off edge was 4.43 μm, larger than other borate crystals, such as β-BaB2O4, CsB3O5, and LiB3O5 crystals. Besides, a high electrical resistivity was observed for the α-Bi2B8O15 crystal, reaching as high as 1.5 × 1010 Ω cm at 300 °C along the Y axis, nearly two orders of magnitude higher than that of the La3Ga5SiO14 crystal (∼8 × 108 Ω cm). The multifunctional α-Bi2B8O15 crystal may have potential for opto-electric applications. [ABSTRACT FROM AUTHOR]

Nd-doped YAl3(BO3)4 (NYAB) is a multifunctional crystal material with laser, nonlinear optical, and piezoelectric performances. In this study, the dielectric, elastic, and piezoelectric properties of an 11.8 mol% doped NYAB crystal were evaluated using impedance and ultrasonic pulse-echo methods. The NYAB crystal exhibited electro-elastic properties comparable to those of α-SiO2, GaPO4, and AlPO4 crystals. In addition, the structural distortions and dipole moment of the NYAB crystal were studied, where the AlO6 octahedron exhibited a relatively larger polarization and contributed to the piezoelectric properties of the NYAB crystal. Moreover, the temperature-dependent behaviors of the NYAB crystal were investigated. The NYAB crystal exhibited a high mechanical quality factor, Qm, (12 000 at 25 °C and 4400 at 450 °C), low dielectric loss (0.3% at 25 °C and 0.5% at 450 °C), and good temperature stability of electro-elastic properties (Ts111 = 6.9 ppm °C−1; Td141 = 1.7 ppm °C−1) in the temperature range of 25–450 °C. [ABSTRACT FROM AUTHOR]