Sensing properties of barium titanate nanoceramics tailored by doping and microstructure control

BaTiO3 nanopowders doped with La and co-doped with La/Mn were prepared by auto-combustion and Pechini methods, respectively. The influence of the synthesis methods, dopants and sintering temperature on the BaTiO3 structure and its potential to be used as humidity and/or H-2 gas sensor were studied. The optimization of all process parameters was performed to obtain adequate microstructure for the development of good sensor properties. The difference in the grain size between the La-doped and La/Mn co-doped samples and the formation of different types of defect structures in these ceramics were found to be significant for the desired electrical and ferroelectric properties. The La-doped ceramics with a pseudo-cubic structure showed the highest potential for gas sensors. The materials obtained by the Pechini method had a tetragonal structure and showed the best response, i.e., the change in electrical resistivity by four orders of magnitude in the humid atmosphere.