Size Effects in BaTiO₃ Nanopowders Studied by EPR and NMR

Abstract

To study the effect of the particle size on the material properties, Mn ^{2 +} EPR and ¹³⁷ Ba NMR measurements were performed on BaTiO ₃ particles with average diameters between 15 nm and 255 nm. Typical changes in the fine structure tensor and the quadrupole coupling tensor, respectively, are observed which allow us to make conclusions about the structure model for the nanograins in the ferroelectric tetragonal phase.

Keywords:

• Size effects
• perovskites
• nanoparticles
• ferroelectricity
• EPR
• NMR

PACS numbers:

• 61.46.+w
• 77.80.−e
• 76.60.−k

Acknowledgment

The authors are indebted to Prof. Voelkel for his comments and suggestions and to Dr. Mulla-Osman for his help in the NMR measurements. The support of the Deutsche Forschungsgemeinschaft is gratefully acknowledged.