Barium orthotitanate
Barium orthotitanate is the inorganic compound with the chemical formula Ba2TiO4. It is a colourless solid that is of interest because of its relationship to barium titanate, a useful electroceramic.
Contents
Structure
The solid has two known phases: a low-temperature (β) phase with P21/n symmetry[1] and a high-temperature (α′) phase with P21nb symmetry.[2] The structure of Ba2TiO4 is unusual among the titanates because its titanium atoms sit in a four-oxygen tetrahedron rather than a six-oxygen octahedron.[1][3]
Production
It forms as white crystals from a melt of BaCl2, BaCO3 and TiO2[4] or from just sintering BaCO3 and TiO2.[5] Another method of preparation is heating pellets of Ba(OH)2 and TiO2.[6] Additionally, there are polymer precursor, sol-gel and reverse micellar routes to Ba2TiO4 synthesis.[3] Ba2TiO4 has also been successfully grown as a thin film with chemical vapor deposition.[7]
Properties
- Room temperature entropy - 47.0 cal/deg. mol[6]
- Dielectric constant - 20 (at 100 kHz)[8]
- It is hygroscopic and decomposes with swelling in moist air.[9]
Barium orthotitanate can remove up to 99.9% of CO
2 from a high-temperature gas stream[10] by the reaction:
- Ba
2TiO
4 + CO
2 → BaTiO
3 + BaCO
3
References
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