Ceramic material
A ceramic material includes first and second ceramic materials. The first ceramic material has a perovskite structure and defines a host lattice. The first ceramic material contains lead, zirconium and titanium, e.g., lead zirconate titanate. The second ceramic material has a cryolite structure. The ceramic material may be part of a piezo-actuator containing ceramic layers formed of the ceramic material.
1. A material comprising:
a ceramic material having the empirical formula A′ 1−b−c B′ b C′ c where: 0<b≦0.5 and 0<c≦0.01;
wherein A′ represents the composition Pb(Zr a Ti 1−a )O 3 and 0.5≦a≦0.6 and A′ serves as host lattice for B′ and C′,
B′ is an additive component of the perovskite lattice type and is selected from the following components:
KNbO 3 ,
Pb(M II 1/2 M VI 1/2 )O 3 ) where M II is Zn, Co, Ni, Mn or Cu and where M VI is W,
Pb(M III 1/2 M V 1/2 )O 3 where M III is Fe, Mn, Cr, or Ga and M V is Nb, Ta, or Sb,
Pb(M III 1/2 M VI 1/3 )O 3 where M III is Fe, Mn, Cr, or Ga and M VI is W,
Pb(Li I 1/4 M V 3/4 )O 3 where M V is Nb, Ta or Sb,
C′ is a ceramic material of the cryolite lattice type which has the general formula
A 4 (B 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x , where A comprises barium or strontium, where B comprises strontium, magnesium, or calcium, where V comprises an oxygen vacancy having a phase range and the parameter x is such that: 0≦x<1.
2. The ceramic material of claim 1 , wherein C′ comprises
Sr 4 (Sr 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where 0≦x<1.
3. The ceramic material of claim 1 , wherein C′ comprises
Sr 4 (Ca 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where: 0≦x<1.
4. The ceramic material of claim 1 , wherein C′ comprises
Sr 4 (Mg 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where 0≦x<1.
5. The ceramic material of claim 1 , wherein C′ comprises
Ba 4 (Sr 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where 0≦x<1.
6. The ceramic material of claim 1 , wherein C′ comprises
Ba 4 (Ca 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where 0≦x<1.
7. The ceramic material of claim 1 , wherein C′ comprises
Ba 4 (Mg 2−2x/3 Nb 2+2x/3 )O 11+x V 1−x ,
where V comprises an oxygen vacancy, and where 0≦x<1.
8. A piezo-actuator comprising:
a stack comprised of piezoelectric ceramic layers and electrode layers interspersed among the piezoelectric ceramic layers;
wherein at least one of the piezoelectric ceramic layers comprises a ceramic material according to claim 1 .
9. The ceramic material of claim 1 which is substantially free of KNbO 3 .