Tdk Corporation

Junji Terauchi

Masakazu Hirose

Hitoshi Oka

Yasuo Watanabe

Takeo Tsukada

Piezoelectric ceramics include a bismuth layer compound containing M , Bi, Ti, Ln and O, wherein M represents at least one element selected from the group consisting of Sr, Ba and Ca, and Ln represents at least one element selected from the group consisting of lanthanoids. The piezoelectric ceramics include M Bi Ti O typed crystals, and a mole ratio of Ln/(Ln&plus;M ) is 0<Ln/(Ln&plus;M )<0.5. In the case where M is Sr, a mole ratio of 4Bi/Ti is 4.000<4Bi/Ti&lE;4.030. Preferably, piezoelectric ceramics further include Y oxide.

Piezoelectric ceramics

A piezoelectric ceramic material comprising a bismuth layer compound containing M , Bi, Ti and O wherein M is selected from Sr, Ba and Ca, and containing M Bi Ti O type crystals, wherein M , is represented by Sr Ba Ca wherein x&plus;y&plus;z&equals;1, utilizes thickness shear vibration when 0&lE;x&lE; 1, 0&lE;y&lE;0.9, and 0&lE;z&lE;1, and thickness extensional vibration when 0&lE;x<0.9, 0&lE;y&lE;0.9, and 0&lE;z<1. Also provided is a piezoelectric ceramic material comprising a bismuth layer compound containing Ca, Bi, Ti, Ln and 0 wherein Ln is a lanthanoid, and containing CaBi Ti O type crystals, wherein the atomic ratio Ln/(Ln&plus;Ca) is in the range: 0<Ln/(Ln&plus;Ca)<0.5. These piezoelectric ceramic materials are free of lead, and have a high Curie point and improved piezoelectric characteristics.

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Tokyo, Japan

Junji Terauchi