Abstract: A temperature sensor includes a metal tube having an opening tip portion, a temperature sensing element for measuring a temperature, a pair of lead wires contacting with a surface of the temperature sensing element, an insulating support material for insulating the pair of lead wires from the metal tube, and a coating material for covering the temperature sensing element, lead tip portions of the pair of lead wires, and a tip surface of the insulating support material at the opening tip portion of the metal tube. The coating material has a property of not allowing measurement target gas to pass through and contains oxide and at least one of platinum, platinum alloy, and platinum-containing oxide that are dispersed in the oxide.

Abstract: An alumina sintered body comprises alumina crystals as a main phase and a grain boundary phase made up of crystalline Y2Si2O7 and amorphous SiO2 at grain boundaries of the alumina crystals wherein when the alumina sintered body is taken as 100 wt %, the high melting phase is present in the range of from 0.1 wt % to 15 wt %. There is also provided a method for preparing the alumina sintered body, which method comprising a first mixing step P1 of mixing, at least, a yttria powder having an average particle size of 60 to 100 nm and a silica powder having a given average particle size to provide a mixed slurry and a second mixing step of further mixing an alumina powder having an average particle size of 0.5 to 1.0 ?m in the mixed slurry.

Abstract: An alumina sintered body of the present invention has alumina crystals as a main phase and an amorphous grain boundary glass phase. The amorphous grain boundary glass phase is a grain-boundary glass phase having an amorphous glass component in which at least one of either CaO or MgO is added to SiO2, and at least one type of oxide selected from rare-earth elements and elements in Group IV of the periodic table included in the amorphous glass component as a specific component. When a composition ratio of the main phase and the amorphous grain boundary glass phase is alumina:amorphous glass component:specific component=a:b:c (a+b+c=100% by weight), in a triangular coordinate of which peaks are alumina, the amorphous glass component, and the specific component, a point (a,b,c) is within a range surrounded by four points, A(98.0,1.0,1.0), B(90.0,5.0,5.0), C(93.5,5.0,1.5), and D(97.8,2.0,0.2).

Abstract: An alumina sintered body comprises alumina crystals as a main phase and a grain boundary phase made up of crystalline Y2Si2O7 and amorphous SiO2 at grain boundaries of the alumina crystals wherein when the alumina sintered body is taken as 100 wt %, the high melting phase is present in the range of from 0.1 wt % to 15 wt %. There is also provided a method for preparing the alumina sintered body, which method comprising a first mixing step P1 of mixing, at least, a yttria powder having an average particle size of 60 to 100 nm and a silica powder having a given average particle size to provide a mixed slurry and a second mixing step of further mixing an alumina powder having an average particle size of 0.5 to 1.0 ?m in the mixed slurry.

Abstract: There is described a gas sensor element 1 including a solid electrolyte body 11, insulators 15, 141, 142, 197, 161, 162, 163, 164, 165, and a pair of electrodes 121, 131 formed such that the solid electrolyte body 11 is held therebetween. The gas sensor element 1 satisfies the following requirement (a) and/or the requirement (b). (a) The solid electrolyte body 11 is made of ion-conductive composite material in which nanoparticles with specific particle diameters are dispersed in ion-conductive ceramics. (b) The insulators 15, 141, 197, 161, 162, 163, 164, 165 are made of insulative composite material in which nanoparticles with specific particle diameters are dispersed in insulative ceramics. Further, there is described a manufacturing method of a gas sensor element in which the particle diameter and dispersion quantity of the nanoparticles dispersed in the solid electrolyte body 11 and/or insulative ceramics 11 are controlled.

Abstract: An alumina compound sintered compact, having a principal component of alumina, a method of manufacturing the same, and a spark plug employing such an alumina compound sintered compact are disclosed. The alumina compound sintered compact contains alumina, mullite, zircon, zirconia and a specified metal oxide composed of an oxide of at least one element selected from Group III elements excepting Mg, Ca, Sr, Ba and actinoid, wherein the alumina compound sintered compact contains 0.5 to 10 total parts by weight of mullite, zircon and zirconia, 0.5 to 10 parts by weight of the specified metal oxide and a balance of substantially alumina based on 100 parts by weight in total. The spark plug for an internal combustion engine includes a porcelain insulator made of the alumina compound sintered compact.

Abstract: An alumina composite sintered body 1 in which fine particles 2 are dispersed in the crystal grains 4 and/or at the crystal grain boundaries 3 of an alumina sintered body obtained by sintering alumina crystal grains 4; an evaluation method thereof; and a spark plug using the alumina composite sintered body 1. Arbitrary regions in the cross-section of the alumina composite sintered body 1 are taken as analysis surfaces, and when the cross-sectional areas of the fine particles 2 contained in each analysis surface are measured, the ratio of the cross-sectional areas occupying in the area of the analysis surface is from 1 to 20%; when the cross-sectional areas of the fine particles 2 contained in each of analysis surfaces adjacent to each other are measured, and the cross-sectional area is converted into a circle having the same area, the diameter of the circle is from 0.

Abstract: An alumina-based ceramic composition comprising a composite sintered body of alumina as a main component and a composition of at least one element selected from Al, Si, Mg and rare earth elements, wherein an amount of the composition of at least one element selected from Al, Si, Mg and the rare earth elements is not greater than 5 parts by weight on the basis of 100 parts by weight of alumina as the main component, and a spark plug using this alumina-based ceramic composition for an insulator.

Abstract: The thermistor portion of a thermistor device consists of a mixed sintered body of aY(Cr0.5Mn0.5)O3.bAl2O3 made of the perovskite-type compound Y(Cr0.5Mn0.5)O3 and Al2O3, or a mixed sintered body of aY(Cr0.5Mn0.5)O3.b(Al2O3+Y2O3) made of Y(Cr0.5Mn0.5)O3, Al2O3 and Y2O3. The mole fractions a and b have the relationships 0.05?a<1.0, 0<b?0.95 and a+b=1. This is required to obtain a thermistor device that has stable characteristics and exhibits a small change in its resistance value, even in a heat history from room temperature to 1000° C. or the like, and also has a resistance value of 50? to 100 k? in the temperature range from room temperature to 1000° C. The precursor compounds triethoxy yttrium, diethoxy manganese and tris (2,4-pentadiono) chromium are mixed in a mixed solvent of ethanol and isopropyl alcohol, and refluxing is performed to obtain a composite metal alkoxide solution.

Abstract: A highly accurate reduction resistant thermistor exhibiting stable resistance characteristics even under conditions where the inside of a metal case of a temperature sensor becomes a reducing atmosphere, wherein when producing the thermistor comprised of a mixed sintered body (M1 M2)O3.AOx, the mean particle size of the thermistor material containing the metal oxide, obtained by heat treating, mixing, and pulverizing the starting materials, is made smaller than 1.0 ?m and the sintered particle size of the mixed sintered body, obtained by shaping and firing this thermistor material, is made 3 ?m to 20 ?m so as to reduce the grain boundaries where migration of oxygen occurs, suppress migration of oxygen, and improve the reduction resistance.

Abstract: Thermistor elements composed mainly of a metal oxide sintered body are prepared by mixing a metal oxide precursor in a liquid phase to prepare a solution or slurry of the precursor. The precursor solution or slurry is sprayed to form droplet particles which are heat treated to form a thermistor raw material powder which powder is then molded and sintered into a shape to provide a metal oxide sintered body.

Abstract: The thermistor element of the present invention is composed of a mixed sintered body aM1M2O3bY2O3 of a composition M1M2O3 (wherein M1 is Y, and M2 is at least one element selected from the elements such as Cr, Mn, Ti, etc.) as a perovskite compound and Y2O3, wherein molar fractions a and b satisfy the relations 0.05≦a<1.0, 0<b≦0.95 and a+b=1. Another wide-range type thermistor element of the present invention is composed of a perovskite compound M1 (M2M3)O3, wherein M1 is at least one element selected from the elements of the groups II and IIIA excluding La in the Periodic Table, and each of M2 and M3 is at least one element selected from the elements of the groups IIB, IIIB, IVA, VA, VIA, VIIA and VIII. a and b satisfy the relations a+b=1 and 0<b<0.1, where a is a molar fraction of M2 and b is a molar fraction of M3 in M1(M2M3)O3.

Abstract: This invention provides a reducing-atmosphere-resistant thermistor element, the resistance of which does not greatly change even when the element is exposed to a reducing atmosphere, and which has high accuracy and exhibits excellent resistance value stability. The thermistor element has a construction in which an oxygen occlusion-release composition, having oxygen occlusion-release characteristics, such as CeO2 is dispersed in a composition containing a mixed sintered body (M1 M2)O3.AOx as a principal component. The oxygen occlusion-release composition emits absorbed oxygen in a reducing atmosphere and suppresses migration of oxygen from the composition constituting the element. Therefore, the resistance value does not greatly change even when the element is exposed to a reducing atmosphere, and the element can accurately detect the temperature for a long time. The present invention can thus provide a temperature sensor having high reliability.

Abstract: The thermistor portion of a thermistor device consists of a mixed sintered body of aY(Cr0.5Mn0.5)O3.bAl2O3 made of the perovskite-type compound Y(Cr0.5Mn0.5)O3 and Al2O3, or a mixed sintered body of aY(Cr0.5Mn0.5)O3.b(Al2O3+Y2O3) made of Y(Cr0.5Mn0.5)O3, Al2O3 and Y2O3. The mole fractions a and b have the relationships 0.05≦a<1.0, 0<b≦0.95 and a+b=1. This is required to obtain a thermistor device that has stable characteristics and exhibits a small change in its resistance value, even in a heat history from room temperature to 1000° C. or the like, and also has a resistance value of 50 &OHgr; to 100 k&OHgr; in the temperature range from room temperature to 1000° C.

Abstract: When producing a ceramic element formed of a metal oxide sintered body as a principal component thereof, this invention contemplates to make further uniform a composition of a ceramic raw material and to reduce the variance of a resistance value of the ceramic element. A production method of the invention comprises a step of preparing a precursor solution by mixing a precursor of a metal oxide in a liquid phase, a step of spraying the precursor solution and obtaining droplet particles, a step of heat-treating the droplet particles and obtaining thermistor raw material powder, and a step of molding and sintering the thermistor raw material powder into a predetermined shape and obtaining a metal oxide sintered body.

Abstract: This invention provides a reducing-atmosphere-resistant thermistor element, the resistance of which does not greatly change even when the element is exposed to a reducing atmosphere, and which has high accuracy and exhibits excellent resistance value stability. The thermistor element has a construction in which an oxygen occlusion-release composition, having oxygen occlusion-release characteristics, such as CeO2 is dispersed in a composition containing a mixed sintered body (M1 M2)O3.AOx as a principal component. The oxygen occlusion-release composition emits absorbed oxygen in a reducing atmosphere and suppresses migration of oxygen from the composition constituting the element. Therefore, the resistance value does not greatly change even when the element is exposed to a reducing atmosphere, and the element can accurately detect the temperature for a long time. The present invention can thus provide a temperature sensor having high reliability.

Abstract: A highly accurate reduction resistant thermistor exhibiting stable resistance characteristics even under conditions where the inside of a metal case of a temperature sensor becomes a reducing atmosphere, wherein when producing the thermistor comprised of a mixed sintered body (M1 M2)O3·AOx, the mean particle size of the thermistor material containing the metal oxide, obtained by heat treating, mixing, and pulverizing the starting materials, is made smaller than 1.0 &mgr;m and the sintered particle size of the mixed sintered body, obtained by shaping and firing this thermistor material, is made 3 &mgr;m to 20 &mgr;m so as to reduce the grain boundaries where migration of oxygen occurs, suppress migration of oxygen, and improve the reduction resistance.

Abstract: An element portion of a thermistor element is composed of a mixed sintered body (MM′)O3·AOx of a composition of a complex perovskite oxide presented as (MM′)O3, and a metallic oxide presented as AOx. In said complex perovskite oxide (MM′)O3, M is at least one element selected from the elements of the groups 2A and 3A excluding La in the Periodic Table, and M′ is at least one element selected from the elements of the groups 3B, 4A, 5A, 6A, 7A and 8 in the Periodic Table. Said metallic oxide AOx is a heat-resistant, metallic oxide having a melting point of 1300° C. and more, and a resistivity of AOx itself at 100° C. in the form of a thermistor element is 1000&OHgr; or more.

Abstract: The thermistor portion of a thermistor device consists of a mixed sintered body of aY(Cr0.5Mn0.5)O3.bAl2O3 made of the perovskite-type compound Y(Cr0.5Mn0.5)O3 and Al2O3, or a mixed sintered body of aY(Cr0.5Mn0.5)O3.b(Al2O3+Y2O3) made of Y(Cr0.5Mn0.5)O3, Al2O3 and Y2O3. The mole fractions a and b have the relationships 0.05≦a>1.0, 0<b≦0.95 and a+b=1. This is required to obtain a thermistor device that has stable characteristics and exhibits a small change in its resistance value, even in a heat history from room temperature to 1000° C. or the like, and also has a resistance value of 50&OHgr; to 100 k&OHgr; in the temperature range from room temperature to 1000° C.

Abstract: The thermistor element of the present invention is composed of a mixed sintered body aM1M2O3.bY2O3 of a composition M1M2O3 (wherein M1 is Y, and M2 is at least one element selected from the elements such as Cr, Mn, Ti, etc.) as a perovskite compound and Y2O3, wherein molar fractions a and b satisfy the relations 0.05≦a<1.0, 0<b≦0.95 and a+b=1. Another wide-range type thermistor element of the present invention is composed of a perovskite compound M1(M2M3)O3, wherein M1 is at least one element selected from the elements of the groups II and IIIA excluding La in the Periodic Table, and each of M2 and M3 is at least one element selected from the elements of the groups IIB, IIIB, IVA, VA, VIA, VIIA and VIII. a and b satisfy the relations a+b=1 and 0<b<0.1, where a is a molar fraction of M2 and b is a molar fraction of M3 in M1(M2M3)O3.