Electrical and structural characterization of PTCR pure BaTiO3 nanopowders synthesized by sol–gel emulsion technique

BaTiO3 ceramics have been widely studied for its application as multilayer ceramic capacitors. However, they have been reported to deviate from their insulating to semiconducting behavior upon doping, and are used as positive temperature coefficient (PTC) thermistors and transducers. In this work, sol–gel emulsion technique was used for synthesis of BaTiO3 powders of various shapes and sizes. The synthesized powders were calcined at two different temperatures i.e. 750°C, and 1000°C. XRD revealed the powders to be primarily cubic in structure. Presence of tetragonality was noted in the powders calcined at 1000°C. Crystallite size was calculated for the powders calcined at 750°C and 1000°C. Average particle size of the prepared powders varied from 42 to 94 nm. The shape and size of the particles were dependent on the type and concentration of the surfactant used. The synthesized material showed positive temperature coefficient of resistivity (PTCR) behavior. From the recorded resistivity values a maximum of 1010 Ωcm was achieved. The ferroelectric to paraelectric transition temperature, Curie point, (Tc) was found to be at 75°C from the impedance spectroscopy analysis for the prepared material.