Hitachi Metals, Ltd.

Sumitomo Special Metals Co., Ltd.

Kazuhiro Kura

Takeshi Shimada

Kazuhiro Nishikawa

Kazuya Toji

Tomoyuki Tada

Shugo Ohtsuki

The invention intends to provide a dielectric porcelain composition for use in electronic devices, in which the relative dielectric constant &#x2208;r is high, the Qf value is high and, the temperature coefficient &#x3c4;f can be controlled while maintaining the temperature coefficient &#x3c4;f at the resonant frequency small and the Qf value high. According to the invention, when, in an LnAlO&#x2014;CaTiO-based dielectric porcelain composition, a molar ratio of LnAlOand CaTiOis optimized and Al is substituted by a slight amount of Ga, a structure that has an LnAlO&#x2014;CaTiOsolid solution as a main phase and a solid solution of Al&#x2014;Ga-based oxide as a secondary phase and does not substantially contain &#x3b1;-AlOin the structure can be obtained, and the temperature coefficient &#x3c4;f can be controlled while maintaining the temperature coefficient &#x3c4;f at the resonant frequency small and the Qf value high.

Dielectric porcelain composition for use in electronic devices

The invention intends to provide a dielectric porcelain composition for use in electronic devices, which has the dielectric characteristics such that the Qf value is high, the temperature coefficient &#x3c4;f of a resonant frequency is small and a value thereof can be controlled in a wide range in positive and negative directions in the vicinity where the relative dielectric constant &#x2208;r is 39. According to the invention, when, in La&#x2014;Pr&#x2014;Al&#x2014;Ga&#x2014;Sr&#x2014;Ti-based oxide dielectric porcelain, contents of the respective elements are limited to be within particular ranges and Sr is partially substituted by Ca, a structure having a (1-x)(LaLn)(AlGa)O-x(SrCa)TiOsolid solution as a main phase, in which a solid solution of Al&#x2014;Ga&#x2014;Sr-based oxide and/or a solid solution of Al&#x2014;Ga-based oxide and a Sr oxide is/are precipitated in a grain boundary thereof, can be obtained, whereby the above-mentioned object can be achieved.

A dielectric ceramic composition for microwave use having a relative permittivity &egr;r of 35 to 45, Qf value of more than 50,000 GHz (at 7 GHz), and dielectric characteristic of &tgr;f&equals;0&plusmn;10 ppm/&deg; C includes an La O .Al O .SrO.TiO based ceramic composition and a specific quantity of Ga O to increase the Qf value and a specific amount of Pr O to control the &tgr;f value.

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Osaka, Japan

Kazuhiro Kura