Thermistor element

Abstract

An element portion of a thermistor element is composed of a mixed sintered body (MM′)O 3 ·AO x of a composition of a complex perovskite oxide presented as (MM′)O 3 , and a metallic oxide presented as AO x . In said complex perovskite oxide (MM′)O 3 , 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 AO x is a heat-resistant, metallic oxide having a melting point of 1300° C. and more, and a resistivity of AO x itself at 100° C. in the form of a thermistor element is 1000Ω or more. The thermistor element can realize a resistivity of 100Ω-100 kΩ, within the temperature range from room temperature to 1000° C., and small change in resistivity.

1 . A thermistor element comprising a mixed sintered body (MM′)O 3 ·AO x  of a composition of a complex perovskite oxide presented as (MM′)O 3 , and a metallic oxide presented as AO x , 
 wherein in said complex perovskite oxide (MM′)O 2 , 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,  
 wherein a and b satisfy the relations 0≦a<1.0, 0.05<b≦0.95 and a+b=1, where said a is a molar fraction of said complex perovskite oxide (MM′)O 3  of a mixed sintered body and said b is a molar fraction of said metallic oxide AO x ,  
 wherein said M in said complex perovskite oxide (MM′)O 3  is at least one or element selected from Mg, Ca, Sr, Ba, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb and Sc, and M′ is at least one element selected from Al, Ga, Ti,Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt,  
 and wherein a metal A in said metallic oxide AO x  is at least one element selected from B, Mg, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Ga, Ge, Sr, Zr, Nb, Sn, Ce, Pr, Nd, Sn, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf and Ta.  
 
     
     
         2 . A thermistor element according to  claim 1 , wherein said metallic oxide AO x  is at least one metallic oxide selected from MgO, SiO 2 , Sc 2 O 3 , TiO 2 , Cr 2 O 3 , MnO, Mn 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , NiO, ZnO, Ga 2 O 3 , ZrO 2 , Nb 2 O 5 , SnO 2 , CeO 2 , Pr 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , Lu 2 O 2 , HfO 2 , Ta 2 O 5 , MgAl 2 O 4 , Y 2 SiO 5 , 3Al 2 O 3 ·2SiO 2 , YAlO 3 , Y 3 Al 5 O 12 , 2MgO·SiO 2 , CaSiO 3  and MgCr 2 O 4 .  
     
     
         3 . A thermistor element according to  claim 1 , wherein said metallic oxide AO x  is at least one metallic oxide selected from MgO, Sc 2 O 2 , ZrO 2 , Lu 2 O 3 , HfO 2 , Cr 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , CeO 2  and MgCr 2 O 4 .  
     
     
         4 . A thermistor element according to  claim 4 , wherein said metallic oxide AO x  is at least one metallic oxide selected from SiO 2 , TiO 2 , MnO, Mn 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , NiO, ZnO, Ga 2 O 3 , Nb 2 O 5 , SnO 2 , Ta 2 O 5 , 2MgO·SiO 2 , MgAl 2 O 4 , CaSiO 3 , Y 2 SiO 5 , 3Al 2 O 3 ·2SiO 2 , YAlO 3  and Y 3 Al 5 O 12 .  
     
     
         5 . A thermistor element according to one of claims  1 - 4 , further comprising a sintering aid composed of at least one of CaO, CaCO 2 , SiO 2  and CaSiO 3 .  
     
     
         6 . A temperature sensor comprising a thermistor element according to any one of claims  1 - 5 .  
     
     
         7 . A method of producing a thermistor element according to any one of claims  1 - 5 , which comprises mixing said complex perovskite oxide (MM′)O 3  with said metallic oxide AO x ; grinding the mixture to adjust an average particle diameter of the mixture after grinding to an average particle diameter which is not more than that of said metallic oxide before grinding; molding the mixture into an article having a predetermined shape; and sintering the article.  
     
     
         8 . A method of producing a thermistor element according to any one of claims  1 - 5 , which comprises mixing a raw material of said M with a raw material of said M′ in said complex perovskite oxide (MM′)O 3 ; grinding the mixture to adjust an average particle diameter of the mixture after grinding to an average particle diameter which is not more than that of the raw material of said M before mixing and is not more than 0.5 μm; calcining the ground mixture to obtain said complex perovskite oxide (MM′)O 3 ; mixing said (MM′)O 3  with said metallic oxide AO x ; molding the mixture into an article having a predetermined shape; and sintering the article.  
     
     
         9 . A method of producing a thermistor element according to any one of claims  1 - 5 , which comprises mixing a raw material of said M with a raw material of said M′ in said complex perovskite oxide (MM′)O 3 ; grinding the mixture to adjust an average particle diameter of the mixture after grinding to an average particle diameter which is not more than that of a raw material of said M before mixing and is not more than 0.5 μm; calcining the ground mixture to obtain said complex perovskite oxide (MM′)O 3 ; mixing said (MM′)O 3  with said metallic oxide AO x ; grinding the mixture to adjust an average particle diameter of the mixture after grinding to an average particle diameter which is not more than that of said metallic oxide AO x  before mixing; molding the mixture into an article having a predetermined shape; and sintering the article.