Growth and dielectric properties of congruently melting Ba1-xCaxTiO3 crystals

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–CaTiO₃ is investigated with regard to a congruently melting composition. The liquidus curve is determined from x=0.0 to 0.3, where x is the mole fraction of CaTiO₃. It shows a minimum melting point near x=0.23. Ba_1-xCa_xTiO₃ crystals are grown by the Czochralski technique from melts close to this composition. X-ray fluorescence analyses of the crystals indicate a congruently melting composition at x=0.227, corresponding to the observed minimum melting point. At the growth temperature the crystals possess a cubic perovskite-type structure. They undergo a structure change to the ferroelectric tetragonal phase at 98±3 °C, indicated by a sharp peak of the dielectric constant. Down to -120 °C no further phase transition is observed.