Dielectric Ceramic Material
View Patent ↗A ceramic material includes at least two different components. Each of the components is present in separate phases. Each of the components has a perovskite structure which contains silver in A positions and niobium or tantalum in B positions. A composition of a first component and a composition of a second component has respective permittivities TKε A and TKε B . In the ceramic material, temperature components of the permittivities TKε A and TKε B have different signs within a temperature interval.
1. A ceramic material comprising:
at least two different components, each of the components being present in separate phases, each of the components having a perovskite structure which contains silver in A positions and niobium or tantalum in B positions, a composition of a first component and a composition of a second component having respective permittivities TKε A and TKε B , wherein temperature components of the permittivities TKε A and TKε B have different signs within a temperature interval.
2. The ceramic material according to claim 1 , wherein a volume share of the first component in a total volume of the first and second components deviates by less than 25% from a volume share V calculated using the following formula:
V×S A +(1 −V )× S B =0,
wherein S A and S B , respectively, represent slopes of straight lines that approximate respective temperature-dependent progression of a relative change in the permittivities of the first and second components in the temperature interval.
3. The ceramic material according to claim 1 , wherein at least one of the components is doped with one or more doping substances at a concentration of no more than 20% for each substance.
4. The ceramic material according to claim 1 , wherein at least one of the components has a composition of Ag(Nb 1-x Ta x )O 3 , with 0.30≦1-x≦0.70.
5. The ceramic material according to claim 1 , wherein one of the components contains, in the A positions, a metal M I as a doping substance, wherein M I is lithium, sodium or potassium and has a composition of (Ag 1-y M I y )(Nb 1-x Ta x )O 3 , with 0.45≦1-x≦0.55 and 0≦y <0.15.
6. The ceramic material according to claim 5 , wherein the one of the components contains, in the A positions, as an additional doping substance, a metal M II that differs from M I , wherein M II is selected from among the metals lithium, sodium and potassium, and has a composition (Ag 1-y-z M I y M II z )(Nb 1-x Ta x )O 3 , with 0.45≦1-x≦0.55,0≦y≦0.15 and 0<z≦0.1.
7. The ceramic material according to claim 1 , wherein one of the components contains, in the A positions, as a doping substance, a metal M III and, in the B positions, a metal M IV , wherein M III is bismuth or a metal of the rare earth elements, and M IV is indium, scandium or gallium, and wherein the components have a composition (Ag 1-y M III y )(Nb 1-x Ta x ) 1-y M IV y )O 3 , with 0<y ≦0.10 and 0.35≦x≦0.5.
8. The ceramic material according to claim 1 , wherein one of the components contains, in the A positions, a metal Milt and, in the B positions, a metal M IV , wherein M III is barium, calcium, lead or strontium, and MIV is tin or zirconium, and wherein the components have a composition (Ag 1-y M III y )(Nb 1-x Ta x )O 3 , with 0<y≦0.10 and 0.35≦x≦0.5.
9. The ceramic material according to claim 1 , wherein the first component has a composition Ag(Nb 1-x Ta x )O 3 and the second component has a composition (Ag 1-x Sm y )(Nb 1-x Ta x ) 1-y Ga y )O 3 , with 0.38≦x≦0.42 and 0.04≦y≦0.06, and wherein a volume-specific mixing ratio of first/second components is between 45/55 and 40/60.
10. The ceramic material according to claim 1 , wherein the first and second components have a composition Ag(Nb 1-x Ta x )O 3 , wherein for the first component 0.50<1-x0.70 , and wherein for the second component 0.30≦l -x ≦0.50.
11. The ceramic material according to claim 10 , wherein the first and second components have a composition Ag(Nb 1-x Ta x )O 3 , wherein for the first component 0.64 ≦1-x≦0.66 and for the second component 0.34 ≦1-x≦0.36, and wherein a volume-specific mixing ratio of first/second components is between 40/60 and 50/50.
12. The ceramic material according to claim 1 , wherein the first and second components comprise particles with dimensions between 5 and 500 μm, the particles of the first component being mixed with the particles of the second component.
13. The ceramic material according to claim 12 , which is produced by sintering a mixture of particles of the first component with particles of the second component.
14. The ceramic material according to claim 13 , which contains H 3 Bo 3 or V 2 O 5 as a sintering process material.