New ferroelectric BaTi2O5

A needle-shaped BaTi2O5 crystal was grown from a Ti-rich solution. The chemical composition of the crystal was analyzed by an electron probe micro-analyzer (EPMA). X-ray Weissenberg photographs were taken at room temperature (RT): the crystal is monoclinic with a = 16.91 Angstrom, b = 3.94 Angstrom, c = 9.49 Angstrom, beta = 103.0degrees and Z = 6. A broad and large dielectric anomaly reaching 30,000 was observed at 430degreesC for the dielectric constant along the b-axis. Also, spontaneous polarization was estimated to be approximately 7 muC/cm(2) from the D-E loops at RT. Thus the crystal is a new ferroelectric substance with a high Curie temperature of 430degreesC and the space group C-2 at RT.