Microwave dielectric ceramic
View Patent ↗A dielectric ceramic material consisting essentially of a composition of Formula 1 x ATiO 3 (1 −x )Nd z Re (1−z) AlO 3 (1) doped with 0.005% to 5% of a dopant selected from the group consisting of: cerium oxide, manganese oxide and mixtures thereof; wherein A may be selected from the group consisting of: Ca, Sr, Mg and mixtures thereof; Re may be selected from a group consisting of La, Sm, Pr, Dy, Er, Gd, Y and mixtures thereof; wherein z is from 0.95 to 0.995; and wherein x is a positive number less than 1.
1. A dielectric ceramic material consisting essentially of a composition of formula 1:
x ATiO 3 +(1 −x )Nd z Re (1−z) AlO 3 (1)
doped with about 0.005% to about 5% of a dopant selected from the group consisting of:
CeO 2 , MnO y and mixtures thereof;
wherein A is selected from the group consisting of: Ca, Sr, Mg and mixtures thereof;
Re is selected from a group consisting of La, Sm, Pr, Dy, Gd, Y, Er and mixtures thereof;
wherein z is from 0.95 to 0.995;
wherein x is a positive number less than 1 and 1≦y≦2.
2. A dielectric ceramic material as claimed in claim 1 with a composition of formula 2:
x Ca d Sr (1−d) TiO 3 +(1 −x )Nd z Re (1− z )AlO 3 (2)
doped with about 0.005% to about 5% of a dopant selected from the group consisting of:
CeO 2 , MnO y and mixtures thereof;
wherein 0.5≦x≦0.9
0.25≦d≦1.0
0.95≦z≦0.995
1≦y≦2
Re is selected from a group consisting of La, Sm, Pr, Dy, Gd, Y, Er and
mixtures hereof and wherein
CeO 2 is added as a dopant in the range about 50 ppm to about 2.5 wt %.
MnO y is added as a dopant in the range about 50 ppm to about 2.5 wt %.
3. A dielectric ceramic material as claimed in claim 1 with a composition of formula 3:
x CaTi 1.03 O 3 +(1 −x )Nd 0.95 Re 0.05 AlO 3 (3)
wherein 0.60≦x≦0.72 and y are as stated above and Re is Sm or Pr and wherein
CeO 2 is added as a dopant in the range about 50 ppm to about 2.5 wt %, and
MnO y is added as a dopant in the range about 50 ppm to about 2.5 wt %.
4. A dielectric ceramic material as claimed in claim 3 ,
wherein 0.65≦x≦0.72, Re is Sm
and CeO 2 is added as an excess dopant in an amount of 0.2 wt %.
5. A dielectric ceramic material as claimed in claim 1 with a composition of formula 4:
x CaTi 1.03 O 3 +(1 −x )Nd 0.05 Re 0.95 AlO 3 (4)
wherein 0.60≦x≦0.72 and y are as stated above and Re is Sm or Pr and wherein
CeO 2 is added as a dopant in the range about 50 ppm to about 2.5 wt %, and
MnO y is added as a dopant in the range about 50 ppm to about 2.5 wt %.
6. A dielectric ceramic material as claimed in claim 5 ,
wherein 0.60≦x≦0.72, Re is Sm
and CeO 2 is added as an excess dopant in an amount of from 0.01 wt % to 1.0 wt %.
7. A dielectric ceramic material as claimed in claim 5 ,
wherein 0.60≦x≦0.72: Re is Pr
and CeO 2 is added as an excess dopant in an amount of from 0.01 wt % to 1.0 wt %.
8. A dielectric ceramic material as claimed in claim 3 wherein Sr, Mg or a mixture thereof are substituted for Ca in an amount of 0 to 20 mol % and wherein 0.85≦x≦1.0.
9. A dielectric ceramic material as claimed in claim 1 , further comprising an additional dopant in an amount of 20 to 5000 ppm, wherein the additional dopant is selected from the group consisting of: Fe 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Ga 2 O 3 and mixtures thereof.
10. A dielectric ceramic material as claimed in any preceding claim 2 , including further comprising an additional dopant in an amount of 20 to 5000 ppm, wherein the additional dopant is selected from the group consisting of: Fe 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Ga 2 O 3 and mixture thereof.
11. A dielectric ceramic material as claimed in any preceding claim 3 , including further comprising an additional dopant in an amount of 20 to 5000 ppm, wherein the additional dopant is selected from the group consisting of: Fe 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Ga 2 O 3 and mixture thereof.
12. A dielectric ceramic material as claimed in claim 9 , wherein the additional dopant is Ga 2 O 3 .
13. A dielectric ceramic material as claimed in claim 12 , wherein the amount of Ga 2 O 3 is from 20 to 2000 ppm.
14. A dielectric ceramic material as claimed in claim 3 , wherein the cation site occupancy of Ca, Ti, Nd and Al is varied by ±10%.
15. A dielectric ceramic material as claimed in claim 1 , wherein the material has electrical properties summarised as follows:
ε r 42−48
Q (2 GHz)>10,000
TCf (variable through composition)−10 to +10 MK −1 .
16. A dielectric ceramic material as claimed in claim 1 , wherein the material has electrical properties summarised as follows:
ε r 42−48
Q (2.7 GHz)>14,000
TCf (variable through composition)−10 to +10 MK −1 .
17. A dielectric resonator comprising a dielectric ceramic material as claimed in claim 1 .
18. A dielectric resonator as claimed in claim 17 with a composition of formula 2.
19. A dielectric resonator as claimed in claim 17 with a composition of formula 3.
20. A dialectic resonator as claimed in claim 17 , wherein the dielectric ceramic material has electrical properties summarised as follows:
ε r 42−48
Q (2 GHz)>10,000
TCf (variable through composition)−10 to +10 MK −1 .