The growth and optical properties of Bi12SiO20 single crystals

Abstract

Single crystals of Bi12SiO20 were grown from the melt by the Czochralski technique. The critical crystal diameter dc=10 mm and the critical rate of rotation ωc=20 rpm were calculated by equations from the hydrodynamics of a melt. The rate of crystal growth was experimentally obtained to be 5 mm/h. The crystal growth was in the [111] direction. The lattice parameter a=1.0096nm was determined by X-ray powder diffraction. The reflectance spectra were recorded in the wave numbers range 20–5000 cm-1 at different temperatures. For all the recorded spectra the values of the vibrational TO and LO modes were found using the Kramers-Kronig analysis (KKA). Twentyfive TO and LO modes were found at 70 K, and eighteen at 295 K. The obtained results are discussed and compared with published data.

Keywords

• bismuth silicon oxide single crystals
• czochralski technique
• critical diameter
• critical rate of rotation
• optical properties.