Bismuth titanate or bismuth titanium oxide is a solid inorganic compound of bismuth, titanium and oxygen with the chemical formula of Bi<sub>12</sub>TiO<sub>20</sub>, Bi <sub>4</sub>Ti<sub>3</sub>O<sub>12</sub> or Bi<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>.
Bismuth titanate ceramics can be produced by heating a mixture of bismuth and titanium oxides. Bi<sub>12</sub>TiO<sub>20</sub> forms at 730âÂÂ850 ðC, and melts when the temperature is raised above 875 ðC, decomposing in the melt to Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub> and Bi<sub>2</sub>O<sub>3</sub>. Millimeter-sized single crystals of Bi<sub>12</sub>TiO<sub>20</sub> can be grown by the Czochralski process, from the molten phase at 880âÂÂ900 ðC.
Bismuth titanates exhibit electrooptical effect and photorefractive effect, that is, a reversible change in the refractive index under applied electric field or illumination, respectively. Consequently, they have potential applications in reversible recording media for real-time holography or image processing applications.