Conductive atomic force microscopy characterization of PTCR-BaTiO3 laser-sintered ceramics

Thermistor ceramics based on BaTiO3 (BT) with a positive temperature coefficient of resistivity (PTCR) are widely used for sensor applications in the semiconductor industry. The distinct properties of the ceramics depend on the conditions used to process them. In this work, a laser sintering technique was employed to produce BaTiO3:La,Mn ceramics for the first time. In this technique, a CO2 laser was used as the main heating source and no atmosphere control was employed. The ceramics sintered at a power density of 5.5 W/mm2 for 1 s presented high relative density, homogeneous microstructures, and a PTCR jump of three orders of magnitude. From simultaneous electrical and topographical images obtained via conductive atomic force microscopy (C-AFM), it was possible to estimate the depletion layer in PTCR-BT ceramics to be at about 600 nm. The results presented here support the core-shell model employed to explain the electrical microstructure in PTCR-BT ceramics.