Barium orthotitanate

Structure

The solid has two known phases: a low-temperature (β) phase with P21/n symmetry and a high-temperature (α) phase with P21nb symmetry. 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.

Production

It forms as white crystals from a melt of BaCl2, BaCO3 and TiO2 or from just sintering BaCO3 and TiO2. Another method of preparation is heating pellets of Ba(OH)2 and TiO2. Additionally, there are polymer precursor, sol-gel and reverse micellar routes to Ba2TiO4 synthesis. Ba2TiO4 has also been successfully grown as a thin film with chemical vapor deposition.

Properties

• Room temperature entropy – 47.0 cal/deg. mol
• Dielectric constant – 20 (at 100 kHz)
• It is hygroscopic and decomposes with swelling in moist air.

Barium orthotitanate can remove up to 99.9% of from a high-temperature gas stream by the reaction: : + → +

References

References

1. (10 April 1973). "The Crystal Structure of β-Barium Orthotitanate, β-Ba₂TiO₄, and the Bond Strength-Bond Length Curve of Ti-O". Acta Crystallographica.
2. (14 September 1983). "Orthorhombic Barium Orthotitanate, α{{prime}}-Ba₂TiO₄". Acta Crystallographica.
3. (October 2004). "Investigation of Ba_2–xSr_xTiO₄: Structural aspects and dielectric properties". Bulletin of Materials Science.
4. Bland, J. A.. (August 1961). "The Crystal Structure of Barium Orthotitanate, Ba₂TiO₄". Acta Crystallographica.
5. Bobovich, Ya. S.. "The Raman Scattering of Barium Orthotitanate". Optics and Spectroscopy.
6. Todd, S. S.. (August 1952). "Heat Capacities at Low Temperatures and Entropies at 298.16K. of Orthotitanates of Barium and Strontium". Journal of the American Chemical Society.
7. Guo, Dongyun. (2012). "High-speed growth of (103)-oriented Ba₂TiO₄ film by laser chemical vapor deposition". Materials Letters.
8. Ahmad, Tokeer. (1 October 2004). "Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties". Journal of Materials Research.
9. Jaffe, Bernard. (1971). "Piezoelectric Ceramics". Academic Press.
10. (20 May 2008). "CO₂ Recovery at High Temperatures Using Ba₂TiO₄". Journal of Chemical Engineering of Japan.