Crystal Growth and Basic Characterisation of the Bismuth Borate Bi2B8O15

Bi3TeBO9: A Promising Mid-Infrared Nonlinear Optical Crystal with a Large Laser Damage Threshold

Mid-infrared (mid-IR) nonlinear optical (NLO) crystals are key materials in the field of laser technology. Nevertheless, the applications of these significant optical materials are always limited by their low laser damage threshold (LDT). Here, an oxide mid-IR NLO crystal, Bi₃TeBO₉, with a large LDT was discovered. The centimeter-sized Bi₃TeBO₉ single crystal was successfully grown by the top-seeded solution growth (TSSG) method. The Bi₃TeBO₉ features a high LDT of 450 MW/cm² (∼15 × AgGaS₂) and the widest transparent range (0.35-7.10 μm) among known borate crystals. The second-harmonic generation (SHG) effect is about 1.6 times that of KDP. First-principles calculations and structural analysis show that the optical characteristics of Bi₃TeBO₉ are mainly affected by distorted [BiO₆] groups. Furthermore, its thermal characteristics including specific heat, thermal diffusivity, thermal conductivity, and thermal expansion were also measured.

Kyropoulos growth and characterization of monoclinic α-Bi2B8O15 single crystal with a noncentrosymmetric structure

A high-quality crystalline α-Bi2B8O15 crystal is grown by the Kyropoulos method that might have potential for opto-electric applications.

The activity of lone pair contributing to SHG response in bismuth borates: a combination investigation from experiment and DFT calculation

A theoretical estimation for the intensity of the Bi-6s stereochemically active lone pair (SCALP) is built, quantified by the R_SCA factor, which indicates that a larger R_SCA factor is beneficial for a larger SHG response.

Influence of the Bi 6s 2 lone electron pair on elastic properties of monoclinic Bi4B2O9

The coefficients of thermal expansion and the complete set of elastic stiffness coefficients of monoclinic Bi4B2O9 were determined as functions of temperature employing dilatometry and, respectively, a combination of resonant ultrasound spectroscopy and the plate resonance technique. Thermal expansion as well as elasticity of Bi4B2O9 exhibit a pronounced anisotropy, with the directions of the maximum longitudinal elastic stiffness and of the minimal longitudinal thermal expansion running almost parallel to [1̅02]. Further, between 100 K and 535 K the principal axes system of the linear thermal expansion rotates by more than 30° around the 2-fold symmetry axis. The deviations from Cauchy-relations show a similar behavior. Both, the anisotropy and the temperature induced changes of the investigated properties are mainly controlled by the stereochemically active Bi 6s 2 lone electron pairs. At room temperature their Wang–Liebau vectors possess preferred components within a plane that runs almost perpendicular to [1̅02]. A systematic analysis of the elastic behavior of bismuth oxides using the quasi-additivity rule for elastic S-factor reveals a general trend: With decreasing relative amount of Bi2O3 the Bi3+ cations tend to align their stereochemically active lone electron pairs in planes or eventually in one direction. With respect to the elastic behavior of the compound the alignment of the easliy deformable lone electron pairs is unfavorable and causes an elastic softening.

Crystallization of bismuth borate glasses

Bismuth borate glasses with Bi(2)O(3) concentration of 20-66 mol% were prepared by melt quenching and devitrified by heat treatment above their glass transition temperatures. All glasses show a strong tendency towards crystallization on annealing that increases with Bi(2)O(3) concentration. The crystalline phases formed on devitrification were characterized by FTIR absorption spectroscopy and DSC measurements. Our studies reveal that phases produced in glasses are strongly determined by initial glass composition and the two most stable crystalline phases are: Bi(3)B(5)O(12) and Bi(4)B(2)O(9). The metastable BiBO(3) phase can also be formed by devitrification of glass with 50 mol% of Bi(2)O(3). This phase is, however, unstable and decomposes into Bi(3)B(5)O(12) and Bi(4)B(2)O(9) on prolonged heat treatment.