Bulk growth, structure, and characterization of the new monoclinic TbCa4O(BO3)3 crystal

Abstract

Bulk TbCa₄O(BO₃)₃ single crystals with diameter of 25 mm and length of 70 mm were successfully grown by the Czochralski (Cz) method for the first time to the best of our knowledge. The main problems of crystal growth were discussed and solved resulting in a high quality crystal. The crystalline perfection of the as-grown crystal was evaluated with full-width at half-maximum (FWHM) of the rocking curve being 35.05′′, and the optical homogeneity being 7.76 × 10⁻⁵. TbCa₄O(BO₃)₃ crystallizes in the monoclinic space group Cm with unit cell parameters of a = 8.0715(7) Å, b = 16.0000(15) Å, c = 3.5454(3) Å, and β = 101.2550(10)°. Several interesting phenomena of atom occupancy and structure distortion were observed and analysed. Furthermore, the hardness, density, absorption and transmission spectra were measured. The TbCOB crystal has a Mohs hardness value of 5.58, and it exhibits a high transparency ranging from 490 nm to 1500 nm.