Tdk Corporation

Tdk Electronics Company, Limited

Other

Masatada Yodogawa

Dai Matsuoka

Hisayoshi Ueoka

Susumu Miyabayashi

Makoto Takahashi

Takashi Yamamoto

Etsuo Mitsuhashi

Kentaro Sawamura

Yoshinari Yamashita

Munemitsu Hamada

Nobuyuki Miki

Hiraku Harada

Akira Takeishi

Masahiro Kitajima

Kohji Hayashi

Shinichi Sato

Masahito Furukawa

Masaru Nanao

Ryoichi Kondo

Minoru Ogasawara

Masuo Okada

Nobuo Kaihara

Takahiro Sawaguchi

Akio Okamura

Hitomi Naitou

Toshiyuki Yamazaki

Matsuo Morisawa

Katsunobu Okutani

An electron-emitting electrode for discharge lamps etc. uses an electron-emitting material which contains a first metal component selected from Ba, Sr and Ca and a second metal component selected from Ta, Zr, Nb, Ti and Hf and also contains oxynitride perovskite. The electron-emitting material has restrained evaporation during electric discharge and a high resistance to ion sputtering.

Electrode

An electron-emitting material contains a first metal component selected from Ba, Sr and Ca and a second metal component selected from Ta, Zr, Nb, Ti and Hf and also contains oxynitride perovskite. The electron-emitting material has improved electron emission characteristics, restrained evaporation at elevated temperatures, and minimized consumption by ion sputtering. The electron-emitting material is prepared by firing a metal component-containing raw material disposed in proximity to carbon in a nitrogen gas-containing atmosphere to thereby create oxynitride perovskite.

Electron-emitting material and preparing process

The PTC thermistor material of the invention comprises a matrix phase and electrically conductive phases substantially uniformly dispersed in the matrix phase, said conductive phases having a resistivity lower than that of the matrix phase, and has a resistivity changing sharply in the vicinity of the melting point of the conductive phases. The matrix phase is made up of any one of a polycrystalline ceramic material, a glass-polycrystalline ceramic composite material, a glass, a crystallized glass, and a polymer material, and the conductive phases are made up of a metal containing bismuth as a main component. It is thus possible to achieve a PTC thermistor material which can be controlled in terms of various properties such as the temperature at which PTCR property becomes available and the rate of resistivity change and so can be applied to circuit parts through which large currents pass in a normal operation state. Further, the PTC thermistor material can be easily manufactured with the stable PTCR property maintained. Furthermore, the PTC thermistor material can be operated with an increased rated current albeit being of small size, and has a high degree of shape freedom.

PTC thermistor material

A resistive temperature sensor is constituted by an insulating body mainly composed of alumina; and a temperature sensing resistor mainly composed of a conductive material containing a metal silicide. The insulating body and the temperature sensing resistor are laminated and sintered to form a lamination sintered body in which a resistance circuit is formed.

Resistive temperature sensor and manufacturing method therefor

The invention provides a rapid temperature rise heater element comprising an exothermic section (1) and a lead section (2), the exothermic section (1) comprising an exothermic section conductor of ceramic material which includes at least four stacked exothermic section conductive layers (1a) with an exothermic section insulating layer (1c) of ceramic material interposed therebetween and connections (1b) each for connecting adjacent exothermic section conductive layers (1a). The lead section (2) includes first and second lead section conductive layers (2a and 2b) electrically connected to the uppermost and lowermost exothermic section conductive layers (1a), respectively, the first and second lead section conductive layers (2a and 2b) being stacked with a lead section insulating layer (2c) of ceramic material interposed therebetween. A durable rapid temperature rise heater element can be efficiently fabricated at low cost while maintaining heater performance.

Rapid temperature rise heater element

A rectangular plate shaped rapid temperature rise heater element includes a sintered insulating ceramic layer, an exothermic section, and first and second lead layers for applying voltage across the exothermic section to develop heat. Typically the sintered insulating ceramic layer, exothermic section, and lead layers are formed of ceramic compositions composed mainly of an identical insulating component in the form of a metal oxide, typically Al.sub.2 O.sub.3 and an identical conductive component in the form of a metal silicide and/or carbide, typically MoSi.sub.2, blended in different ratios for the respective layers. The heater element is easy and inexpensive to manufacture, capable of rapid heating, and durable.

Ceramic heater

In preparing a zinc oxide base varistor in the form of a sintered body which itself has a voltage-dependent nonlinear resistance, firing is done in an atmosphere containing at least 60% of oxygen at or above the temperature at which additives form a liquid phase, and thereafter the sintered body is heat treated in an atmosphere containing at least 10% of oxygen at a temperature of 600.degree. to 1,000.degree. C. There is obtained a zinc oxide base varistor having a high energy handling capability, a high nonlinearity index .alpha., and satisfactory load life characteristics such as a humid load life.

Method for preparing the zinc oxide base varistor

Voltage-dependent nonlinear resistor

A voltage non-linear resistor comprises a sintered body of a ceramic composition comprising zinc oxide at a ratio of 99.88 to 84.88 mol % as ZnO; a praseodymium oxide component at a ratio of 0.01 to 0.035 mol % as Pr.sub.2 O.sub.3 and a lanthanum oxide component at a ratio of 0.01 to 0.035 mol % as La.sub.2 O.sub.3 and a cobalt oxide component at a ratio of 0.1 to 15 mol % as CoO and a specific additional component selected from chromium oxide, boron oxide, silicon oxide, titanium oxide, tin oxide, zirconium oxide, niobium oxide, tantalum oxide, tungsten oxide and germanium oxide at a ratio of 0.0001 to 0.05 mol %.

Voltage non-linear resistor

A novel non-linear resistance element or a varistor element is proposed which is a sintered body composed of a ternary oxide mixture comprising titanium dioxide as the base component, bismuth oxide and a third oxide component selected from the group consisting of oxides of tantalum, niobium and antimony admixed in limited proportions. The sintered body is prepared by subjecting the powder mixture obtained by admixing a solution containing tantalum, niobium or antimony with titanium dioxide and bismuth oxide to sintering following drying and calcination. The varistor element of the invention is stable in its performance and has a sufficiently high non-linearity index so that excellent noise suppressors are prepared with the varistor element to be useful in absorbing the noise voltages generated in various rotatory machines such as miniature motors. Further improvement in the above varistor element is proposed by adding a small amount of silicon dioxide to the ternary oxide mixtures.

Non-linear resistance element, method for preparing same and noise

A sintered body of a ceramic composition for voltage non-linear resistor is produced by sintering an oxide semiconductor composition comprising a main component of zinc oxide and a minor component at 1100.degree. to 1400.degree. C.; then maintaining the sintered body in an inert gas such as N.sub.2, Ar and so on having an oxygen content of 0.1 to 21 vol. % at the temperature lower than the sintering temperature for a specific time; changing the atmosphere into an inert gas having an oxygen content of lower than 0.02 vol. % at 800.degree. to 1200.degree. C.; and cooling it.

Process for producing sintered body of ceramic composition for voltage

A non-linear resistor comprises a sintered body of a ceramic composition which comprises 99.93 to 50 mole % of zinc oxide as ZnO; 0.01 to 10 mole % of a specific rare earth oxide as R.sub.2 O.sub.3 (R represents lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium) 0.01 to 10 mole % of an alkaline earth oxide as MO (M represents calcium, strontium or barium) and 0.05 to 30 mole % of cobalt oxide as CoO.

Non-linear resistor

A non-linear resistor comprises a sintered body of a ceramic composition which comprises 99.94 to 80.0 mole % of zinc oxide as ZnO, 0.02 to 10.0 mole % of the specific rare earth oxide selected from the group consisting of oxides of cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium as R.sub.2 O.sub.3, and 0.04 to 10 mole % of manganese oxide as MnO.

Semiconducting ceramics are produced by firing a semiconducting composition of the barium titanate type containing vanadium oxide in the amount of 0.001 to 0.5 wt%. A change in the specific resistance over the range of the temperature at which the positive temperature coefficient characteristic of resistivity (PTCR) is exhibited can be increased by as much as 10.sup.5 times and the specific resistance value at room temperature can be controlled at a desired value. By further adding silicon dioxide to the above composition in the amount of 0.05 to 1.5 wt% the above effects can be enhanced, especially the specific resistance at ambient temperature.

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Tokyo, Japan

Masatada Yodogawa