Low-loss microwave dielectric ceramic
There is provided a low-loss microwave dielectric ceramic having a composition represented by xCaO.yLn 2 O 3 .zAl 2 O 3 .mTiO 2 wherein Ln is Nd or Sm, 25.0 mole %≦x≦75.0 mole %, 10.0 mole %≦y≦30.0 mole %, 10.0 mole %≦z≦30.0 mole %, 0.8 mole %≦m≦20.0 mole %, x+y+z+m=100 mole %. It has a dielectric constant in the range from 18 to 25, an extremely large Qf value ranging from 80,000 to 200,000 GHz, and a temperature coefficient of resonant frequency tunable in the vicinity of 0. It can make the applications of dielectric resonators, filters, and antennas extended to higher frequency and larger power; it can also be applied to microwave capacitors, temperature-compensated capacitors, microwave substrates, et al.
1. A low-loss microwave dielectric ceramic consisting essentially of a composition represented by xCaO.yLn 2 O 3 .zAl 2 O 3 .mTiO 2 , wherein Ln is selected from a group consisting of Nd and Sm, and the following relations are satisfied: 25.0 mole %≦x≦75.0 mole %, 10.0 mole %≦y≦30.0 mole %, 10.0 mole %≦z≦30.0 mole %, 0.8 mole %≦m≦20.0 mole %, x+y+z+m=100 mole %.
2. The low-loss microwave dielectric ceramic according to claim 1 , wherein x, y, z and m satisfy the following relations: 45.0 mole %≦x≦60.0 mole %, 15.0 mole %≦y≦25.0 mole %, 15.0 mole %≦z≦25.0 mole %, 4.0 mole %≦m≦20.0 mole %, x+y+z+m=100 mole %.
3. The low-loss microwave dielectric ceramic according to claim 2 , wherein Ln is Sm, x=54.55 mole %, y=18.18 mole %, z=18.18 mole %, and m=9.09 mole %.