Doping of ferroelectric solid solution of (Ba, Sr) TiO_ to increase the RC time constant
Jain, G. C.
Master of Science
Solid solutions of various percentages of SrTiO3 in BaTiO3 were prepared and their dielectric properties and electrical resistivities were studied. It is observed that SrTiO3 increases the Curie constant of BaTiO3. Whereas the Curie temperature of the solid solutions linearly decreases with increasing amount of SrTiO3, an oscillatory behavior was observed for both the reciprocal of the permittivity at Curie temperature and the Curie constant, with the maxima of both occurring at the same concentration. A solid solution of (Ba0.77, Sro23) TiO3 was doped with In203. It was observed that In203 increased the resistivity of the material, there being an optimum doping level for the highest resistivity. This is attributed to P-type behavior of indium in the BaTiO3 lattice. At low doping levels In203 does not affect the Curie temperature, permittivity at Curie temperature or the Curie constant of the material. It is proposed that BaTiO3 can be treated analogously to the semiconductor elements of the IVth group like silicon or germanium in so far as its impurity doping behavior is concerned. The advantages of a capacitor made of In203 doped (Ba0.77, Sr0.23) TiO3 solid solution in the conversion of solar energy to electrical energy on spinning satellites are discussed.