Compositions: ceramic – Ceramic compositions – Titanate – zirconate – stannate – niobate – or tantalate or...
Patent
1998-12-01
2000-02-15
Brunsman, David
Compositions: ceramic
Ceramic compositions
Titanate, zirconate, stannate, niobate, or tantalate or...
3332191, 3613215, C04B 3546, C04B 3550, H01B 312
Patent
active
06025291&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a dielectric ceramic composition having a high Q value in high frequency ranges of microwaves and millimeter waves.
BACKGROUND OF THE INVENTION
Dielectric ceramics has been widely used as dielectric resonators, MIC-use dielectric substrates and waveguides in high frequency ranges of microwaves, millimeter waves and the like. For such uses, the ceramics is required to have the following characteristics;
1) A high dielectric constant .di-elect cons..sub.r to meet the needs for miniaturization of devices as a wavelength in a dielectric material having a dielectric constant .di-elect cons..sub.r is shortened to 1/.di-elect cons..sub.r.sup.1/2 times that in vacuum;
2) A low dielectric loss at high frequencies, that is, high Q value; and,
3) A small change .DELTA.f/.DELTA.T (=.tau..sub.f) in resonance frequency f with respect to temperature T, that is, low dependence and high stability of the dielectric constant with respect to temperature.
Oxide ceramic materials, such as BaO--TiO.sub.2 based materials, BaO--REO--TiO.sub.2 based materials (REO stands for a rare-earth metal oxide) and MgTiO.sub.3 --CaTiO.sub.3 based materials, have been known as this kind of dielectric ceramics (refer to Japanese Patent Publication JP-61-10806A, Japanese Patent Publication JP-63-100058A and Japanese Patent Publication JP-60-19603A, for example).
Although the BaO--TiO.sub.2 based materials have a dielectric constant .di-elect cons..sub.r in the range of 37 to 40 and a high Q value of about 40000, it has been impossible to obtain a single-phase material having a very nearly zero temperature dependence .tau..sub.f of resonance frequency. Furthermore, the dielectric constant of such a single-phase material changes significantly with a change in composition, and also the dielectric constant thereof also changes significantly with temperature. Therefore, it has been difficult to control the composition to obtain a low temperature coefficient .tau..sub.f of resonance frequency in the state where the dielectric constant is maintained high and where the dielectric loss is maintained low.
In addition, regarding the BaO--REO--TiO.sub.2 -based materials, BaO--Nd.sub.2 O.sub.3 --TiO.sub.2 -based and BaO--Sm.sub.2 O.sub.3 --TiO.sub.2 -based materials have been known, and it has been possible to obtain materials having a very high dielectric constant .di-elect cons..sub.r in the range of 40 to 60, and a temperature coefficient .tau..sub.f of resonance frequency of 0 (zero). However, these materials have a small Q value of 5000 or less.
Furthermore, in the case of the MgTiO.sub.3 --CaTiO.sub.3 -based materials, it has been possible to obtain materials having a high Q value of 30000, and a temperature coefficient .tau..sub.f of resonance frequency of 0 (zero). However, these materials have a small dielectric constant in the range of 16 to 25.
As described above, any of the above-mentioned materials dose not sufficiently satisfy the above-mentioned three characteristics required for high-frequency dielectric materials.
DISCLOSURE OF THE INVENTION
In view of the above-mentioned disadvantages, an object of the present invention is to provide a dielectric ceramic composition having a high dielectric constant, a high Q value and a small and stable temperature dependence of dielectric constant.
Another object of the present invention is to provide a dielectric ceramic resonator having a high Q value, a small and stable temperature dependence of dielectric constant and high frequency stability.
In order to attain the objects, the dielectric ceramic composition of the present invention contains at least lanthanide element Ln, Al, Sr and Ti as metal elements and is formed of a Ln.sub.2 O.sub.x --Al.sub.2 O.sub.3 --SrO--TiO.sub.2 based ceramics. In the present invention, the dielectric ceramics of the present invention has a two-phased structure comprising a Ln.sub.2 O.sub.x --Al.sub.2 O.sub.3 phase and a SrO--TiO.sub.2 phase, and may probably include perovskite type crystals. By adjusting the
REFERENCES:
patent: 4309295 (1982-01-01), McSweeny
patent: 4547314 (1985-10-01), Masuyama et al.
patent: 5356844 (1994-10-01), Hirahara et al.
Brunsman David
Kyocera Corporation
LandOfFree
Dielectric ceramic composition and dielectric resonator using th does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dielectric ceramic composition and dielectric resonator using th, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric ceramic composition and dielectric resonator using th will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1905711