AbstractsChemistry

"The lead titanate-bismuth chromate system was studied employing x-ray diffraction techniques at both room and high temperatures. Samples were prepared by sintering stoichiometric mixtures of the corresponding oxides followed by air quenching. Bismuth chromate was prepared by resintering and air quenching for four times. The results of the analyses show the structure of BiCrO₃ to be tetragonal with 8 molecules per unit cell. Solid solutions exist over the range 100 to 35 mole percent PbTiO₃ of the binary system, although small amounts of other phases are present in some regions. X-ray data at room temperature indicate the tetragonal perovskite structure exists over the range of 100 to 65 mole percent PbTiO₃. From 60 to 35 mole percent PbTiO₃ the structure is cubic. Dielectric measurements show that the specimen containing 95 mold percent PbTiO₃ is ferroelectric with a Curie point of 475ʻC, slightly lower than that of pure PbTiO₃. From 90 to 50 mole percent PbTiO₃ the samples are too conductive for meaningful dielectric measurements. High temperature x-ray results show that the Curie point drops almost linearly from 100 to 65 mole percent PbTiO₃. The phenomenon is exhibited by ferroelectric binary systems containing PbTiO₃ with the exception of the PbTiO₃-BiFeO₃ system" – Abstract, p. ii.