The corresponding inverse permittiv

The corresponding inverse permittivity shows a linear relationship with the temperature (Figure 3(c)). It is clear that the phase transitions obey the Curie-Weiss law (1/εr =(T θC)/ C’: θC is Curie-Weiss temperature and C’ is constant). The parameters obtained are listed in Table 1. The Curie-Weiss constant, C’ for BT-150nm and BT-75nm, are reasonable values for the reported values in the BaTiO3[44,45]. A number of the theoretical and experimental studies showed that the transition temperatures of TO-T and TC have a grain (crystalline size) dependence[33,36,38–42,46,47]. Namely, the phase transition becomes the diffused character and then a slight increase of TO-T and decrease of TC are expected. As shown in Figure 3(d), the TO-T and TC in this study are good agreement with the reported intrinsic size dependences. Finally, the values of θC in the present study are also in the range of the reported values of BaTiO3 sintered by SPS and Hot-Press Sintering methods. Overall, dielectric properties and phase transition behaviors of the cold-sintered BaTiO3 nanocrystalline ceramics are well-explained by the size effect. It is noteworthy that these cold sintered BaTiO3 dielectrics are densified under the lowest sintering temperatures with high permittivity values, earlier it was thought that only high permittivities could be obtained only with higher thermal treatments[48].