Ngk Spark Plug Company, Limited

Kyohei Hayashi

Masaki Iwaya

Hiroshi Matsuzaki

Yoshirou Suematsu

A ceramic composition for thermistor exhibiting stable resistance values over a wide temperature range and capable of being used for a prolonged time. The composition is represented by (M.sup.1 M.sup.2 O.sub.3).sub.1-x .multidot.(M.sup.1 AlO.sub.3).sub.x, wherein M.sup.1 is an element selected from the elements of the group 3A excluding La and M.sup.2 is an element of the groups 4A, 5A, 6A, 7A and 8, and wherein the mixing ratio between an electrically conductive substance stable at elevated temperatures and an insulating substance stable at elevated temperatures, may be adjusted. A thermistor formed of the composition is superior in high-temperature stability and can be used over a broad temperature range because its resistance value can be selected to an optimum value.

Ceramic composition for thermistor, thermistor element, and process for

Ceramic composition for thermistor for detecting elevated temperatures which exhibits stable properties at elevated temperatures for permitting use in both oxidizing and reducing atmospheres. In a YCrO.sub.3 based material, Sr or Sm is partly or completely substituted for Y, and Fe and Ti are substituted for part of Cr. Such material enables the production of a thermistor element exhibiting practical, low resistance values at 300.degree. to 1100.degree. C. and also exhibiting stability against changes in the environmental conditions or thermal hysteresis. Generally AMO.sub.3 perovskite structure (A=2A,3A,3B subgroup elements, M=4A,5A,6A,8 subgroup elements) having a combination of n-type and p-type components provides the same property, the subgroup being of IUPAC international periodic table. La-free is preferred and sintering aid may be used.

Ceramic composition for thermistor

A ceramic composition for a thermistor of the formula (M.sup.1.sub.1-x.N.sup.1.sub.x)(P.sup.2.sub.1-y-z.N.sup.2.sub.y.Al.sub.z)O .sub.3 where M.sup.1 is one or more elements selected from the group 3A elements of the Periodic Table excluding La, N.sup.1 is one or more selected from the group 2A elements of the Periodic Table, P.sup.2 is one or more selected from the elements of the groups 4A, 5A, 6A, 7A and 8 of the Periodic Table whose oxides exhibit p-type characteristics, and N.sup.2 is one or more selected from the elements of the groups 4A, 5A, 6A, 7A and 8 whose oxides exhibit n-type characteristics, wherein x, y and z are larger than 0 and smaller than 1 and 0.001.ltoreq.x/(1-y-z)&lt;0.20, 0.05.ltoreq.y/(1-y-z).ltoreq.0.80 and 0&lt;z/(1-y-z).ltoreq.0.90. Thermistor elements are usable within a broad temperature range of 300.degree.-1100.degree. C., have a stable resistance in oxidizing and reducing atmospheres, can prevent deterioration of lead wires, and have superior stability at high temperatures.

Ceramic composition for thermistor and thermistor element

A ceramic composition for thermistor exhibiting stable resistance values over a wide temperature range and capable of being used for a prolonged time. The composition is represented by (M.sup.1 M.sup.2 O.sub.3).sub.1-x .multidot.(M.sup.1 AlO.sub.3).sub.x, wherein M.sup.1 is an element selected from the elements of the group 3A of the International Periodic Table excluding La and M.sup.2 is an element of the groups 4A, 5A, 6A, 7A and 8 of the International Periodic Table, and wherein the mixing ratio between an electrically conductive substance stable at elevated temperatures and an insulating substance stable at elevated temperatures, may be adjusted. A thermistor formed of the composition is superior in high-temperature stability and can be used over a broad temperature range because its resistance value can be selected to an optimum value.

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Aichi, Japan

Kyohei Hayashi