Murata Manufacturing Co., Ltd.

Kohichi Hayashi

Akira Ando

Hiroshi Takagi

Kosuke Shiratsuyu

Akira Nagai

Kiyoshi Hase

Kenichi Nada

The present invention provides a piezoelectric ceramic having a low mechanical quality coefficient Qm and excellent heat resistance, for example, a piezoelectric ceramic for a filter element which can be applied to surface mounting. The piezoelectric ceramic contains at least a composite oxide of lead, zirconium and titanium, and oxides of manganese, silicon and boron, the concentration of the manganese oxide present in the crystal gain boundary being higher than that in crystal grains of the piezoelectric ceramic.

Piezoelectric ceramic

A piezoelectric ceramic which maintains a high piezoelectric property in a composition having MPB structure and has an excellent ability for stabilizing the resonant frequency is provided. The piezoelectric ceramic has a solid solution expressed by the general expression xPbTiO.sub.3 --(1-x) PbZrO.sub.3 as its main component. The value of x in the above general expression causes the piezoelectric ceramic to have a composition having the morphotropic phase boundary structure. A ceramic having a spinel type structure is dispersed within the structure of the piezoelectric ceramic. The amount of the ceramic having the spinel type structure existing in the structure is set at about 5 volume % or less. Co.sub.2 TiO.sub.4, Mn.sub.3 O.sub.4, Fe.sub.3 O.sub.4, Mg.sub.2 TiO.sub.4 and a ceramic having a compound spinel type structure which is a solid solution of them can be used as the ceramic having the spinel type structure.

Piezoelectric ceramics

Growing community of inventors

Shiga-ken, Japan

Kohichi Hayashi