Size Effects in Fine Barium Titanate Particles

Abstract

¹³⁷Ba NMR spectroscopy is very suitable to study size effects in very fine particles of barium titanate. The particle sizes varied between 155 and 15 nm. The NMR measurements were carried out within a temperature range of 295 to 420 K covering also the cubic to tetragonal phase transition at T_C . Below T_C the NMR line shape was explained by a superposition of two contributions the relative fractions of which were analyzed over a wider temperature range. Assuming the core-shell model the thickness of the outer shell was estimated. The shell thickness strongly decreased with decreasing particle size. The applicability of other structural models was also discussed.

Keywords:

• Barium titanate
• nanoparticles
• NMR
• ferroelectric phase transition
• core-shell mode

Dedicated to Dr. George W. Taylor with gratitude.