Investigation of Grain-Size Influence on the Ferroelectric-to-Paraelectric Phase Transition in BaTiO3 Ceramics by Means of AC Calorimetry

Barium titanate ceramic samples of four different average grain sizes from 0.5 µm to 20 µm were studied by means of the ac calorimetric method. The ferroelectric-to-paraelectric transition temperature decreased with decreasing grain size. The temperature dependence of heat capacity showed hysteresis during a heating/cooling cycle. The thermal hysteresis was found to be grain-size dependent, with a possible maximum for grain sizes between 0.5 µm and 2.5 µm. The small shift of the Curie temperature detected in these ac calorimetry experiments suggests that internal stresses are the main cause of the observed grain-size effects.