The grain-size effect on phase transition temperatures orthorhombic→ tetragonal, Tot, and tetragonal → cubic (ferroelectric → paraelectric), Tc, of barium titanate samples (BaTiO3) was studied by using differential scanning calorimetric technique (DSC). This last temperature was also measured by using impedance spectroscopic technique (IS). The results indicate that the obtained values of Tc (for each grain size sample) when the sample forms and it does not forms part of an external electric circuit, by using IS and DSC techniques, respectively, are equal. On the other hand, it was observed that while the grain size increases the temperatures and enthalpies transitions as well as their thermal hysteresis increases. These results are in agreement with the Arlt et al. [G. Arlt, D. Hennings, and G. of With, J. Appl. Phys. 58, 1619 (1985)] hypothesis that systems with greater grain size exhibit greater internal tensions, thus requiring greater thermal energy to produce the ferroelectric paraelectric transformation. This hypothesis could also be applied to the other structural phase transition: the orthorhombic→ tetragonal one.
