BaTiO₃ nanoparticles of orthorhombic structure following a polymer precursor. Part II. A thermodynamic analysis

Abstract

The growth of BaTiO₃ (BT) nanoparticles, via support of a polymer template of PVA molecules, in a new polymorph with Pnma orthorhombic crystal structure (o-BT-II) is proposed. A metal ion–polymer complex forms of small templates with selective degrees of the cationic loading and regeneration of small PVA molecules of reaction in solution. The species is a derived skeleton of Ba²⁺, Ti⁴⁺ and O²⁻ after burning off the polymer in air and grows in a specific lattice structure, which shares a minimal value of the surface (or energy) per unit mass, . The o-BT-II polymorph has a value of as small as 1782.28 m² g⁻¹, compared with 2004.2 m² g⁻¹ for the known polymorph (o-BT-I) or 2490.9 m² g⁻¹ for t-BT (tetragonal). As a high-energy polymorph with crystallite size ≤15 nm, it converts slowly to t-BT via a composite structure at temperatures as low as 650°C in air.

Acknowledgements

This work has been supported by a research grant from the Nanoscience and Technology Initiative of the Department of Science and Technology, Government of India.