New insights into the positive temperature coefficient of resistance model of BaTiO3-based ceramics

The speculation concerning the presence of interfacial states in the BaTiO3-based positive temperature coefficient of resistance (PTCR) model originating from the formation of the grain boundary barrier in semiconductor is argued to be unsuitable. This communication provides new insights into the formation of the grain boundary barrier without the grain boundary phase of the BaTiO3-based PTCR model. New insights into the temperature and voltage dependences of the resistance or resistivity with and without grain boundary phase of the BaTiO3-based PTCR model are proposed. Concerning the absence of the grain boundary phase, two new plausible models are proposed: the net dipolar polarization field due to the applied voltage and effective permittivity owing to the net dipole charges accumulated near the grain boundary. As for the presence of the grain boundary phase, a new thinking concerning the field emission tunneling with the conduction band conduction mechanism for the occurrence of low resistance at low applied voltage is posited.