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Mg3Sb2‐based Zintl compounds have been paid much attention in recent years because of their high peak figure of merit (zT), however, there is room for the improvement of the average zT. In this work, the thermoelectric performance of Mg3(Sb,Bi)2 single crystal by using density functional theory is investigated. The optimal carrier concentration (n) of Mg3SbBi is 2 × 1019 to 3 × 1020 cm–3 at 100−700 K. At the n of 3 × 1019 cm–3, it can exhibit a high average zT of ≈1.27 at cold‐side temperature (Tc) of 300 K and hot‐side temperature (Th) of 700 K, and the electrical transport performance can be further improved by increasing the n. When the optimal n is reached, the maximum average zT of Mg3SbBi at Tc of 100 K and Th of 300 K can be up to 0.54, which is comparable to that of state‐of‐the‐art Bi2(Te,Se)3. Because the decreasing trend of the optimal n with temperature, the maximum low‐temperature thermoelectric performance is easier to be achieved by less extrinsic doping. This work reveals the great potential of Mg3(Sb,Bi)2 single crystal for thermoelectric cooling or power generation, which is expected to provide useful guidance for thermoelectric devices. [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]

Centimeter-sized Bi2ZnB2O7 (BZBO) and Nd:Bi2ZnB2O7 (Nd:BZBO) single crystals are grown using the Kyropoulos method. The thermal properties and continuous wave (CW) laser performance are investigated. Results show that the BZBO crystal possesses moderate specific heat (0.62 J g−1 K−1 at 20 °C), small thermal expansion (α11 = 6.9 × 10−6 K−1, α22 = 11.2 × 10−6 K−1 and α33 = 1.9 × 10−6 K−1 at 20 °C) and large thermal conductivities (4.3, 3.2 and 4.0 W m−1 K−1 along the crystallographic a-, b- and c-axes at 25 °C, respectively). Moreover, the CW laser tests are realized at a wavelength of 1.06 μm for the Nd:BZBO crystal (0.5 mol% Nd3+), and the output powers are found to be around 256 mW, 235 mW and 312 mW along the optical X-, Y- and Z-orientations, respectively. Nd:BZBO might be another kind of important laser and nonlinear optical crystal in the oxyborate family. [ABSTRACT FROM AUTHOR]

The self-frequency-doubling crystal is an important kind of multi-functional crystal materials. In this work, Nd 3+ doped Sr 3 TaGa 3 Si 2 O 14 (Nd:STGS) single crystals were successfully grown by using Czochralski pulling method, in addition, the nonlinear and laser-frequency-doubling properties of Nd:STGS crystals were studied. The continuous-wave laser at 1064 nm was demonstrated along different physical axes, where the maximum output power was obtained to be 295 mW for the Z-cut samples, much higher than the Y-cut (242 mW) and X-cut (217 mW) samples. Based on the measured refractive indexes, the phase matching directions were discussed and determined for type I (42.5°, 30°) and type II (69.5°, 0°) crystal cuts. As expected, self-frequency-doubling green laser at 529 nm was achieved with output powers being around 16 mW and 12 mW for type I and type II configurations, respectively. [ABSTRACT FROM AUTHOR]