Gallium solubility in the Bi12TiO20 (BTO) matrix was investigated by solid state reaction synthesis and Bi12Ti(1-x)Ga xO20 (BTGaO) single crystals were grown by Top Seeded Solution Growth (TSSG). We determined that it is possible to obtain a continuous solid solution from (x)Bi12TiO20: (1-x)Bi12[Ga0.7Bi0.3]O20 and that Ga replaces Ti in the BTO matrix giving Bi12Ti(1-x)Ga(x)O20 up to x < 0.2. BTGaO single crystals grown with an excess of Bi2O3 were transparent, a bleaching effect was observed due to the presence of gallium in the crystalline sillenite structure and their lattice parameter was higher than for pure BTO. The results for BTGaO single crystals showed an increase in the optical activity from rho0 = 6.4° ± 0.3°/mm, for BTO, to rho0 = 9.7° ± 0.3°/mm, for BTGaO grown with x = 0.30 in the melt. The BTGaO crystal presented an activation energy value of 0.48 ± 0.02 eV for 100 °C <= T <= 300 °C.
crystal growth; bismuth titanium oxide; optical material
