Dielectric material and process for producing the same

Details Dielectric material and process for producing the same Dielectric material and process for producing the same

1999-06-16

2002-04-30

Brunsman, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Titanate, zirconate, stannate, niobate, or tantalate or...

Reexamination Certificate

active

06380117

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a dielectric material and a process for producing the same. More particularly, it relates to a dielectric material having excellent dielectric characteristics, such as a relatively high specific dielectric constant (hereinafter represented by &egr;
r
) in a high frequency region, a small absolute value of a temperature coefficient (hereinafter represented by &tgr;
f
) of resonance frequency (hereinafter represented by f
0
), and a large unloaded quality value (hereinafter represented by Q
u
), and a process for producing the same. The dielectric material of the invention is particularly useful as a resonator and a filter for a high frequency region, a matching element for various microwave circuits, and the like.
BACKGROUND OF THE INVENTION
With the recent increase of communication information, various communication systems using the microwave region, such as mobile telecommunication systems, satellite communication systems, positioning systems using communication data, and satellite broadcasting, have been advancing rapidly. Many dielectric materials for microwave have been developed accordingly. The dielectric materials for microwave are required to have (1) a high specific dielectric constant &egr;
r
, (2) a small absolute value of a temperature coefficient &tgr;
f
of resonance frequency f
0
(i.e., small temperature dependence of f
0
), and (3) a large unloaded Q-value Q
u
(i.e., small dielectric loss 1/Q
u
).
Known dielectric materials with a small dielectric loss, i.e., with a large Q
u
, include Ba (Mg
1/3
Ta
2/3
) O
3
and Ba (Zn
1/3
Ta
2/3
) O
3
, and known dielectric materials with a high &egr;
r
include BaO—RE
2
O
3
—TiO
2
-based ceramics (wherein RE represents a rare earth element)
JP-A-6-275126 discloses a dielectric ceramic composition comprising Ba, Bi, Ti and O as essential components and Nd and Sm as optional components. JP-A-6-309926 and JP-A-6-325620 teach addition of an alkali metal, e.g., Na, Kor Li, to the above-described ceramic composition to further improve the dielectric characteristics, explaining that Q
u
, can be improved without changing &egr;
r
. On the other hand, it is mentioned that an increase in Bi content increases &egr;
r
and decreases the absolute value of &tgr;
f
but diminishes Q
u
. In fact, the ceramic compositions disclosed in the above publications have a considerable Bi content and cannot be necessarily said to have a high Q
u
,. Besides, the &tgr;
f
varies widely among the compositions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a dielectric material having a high &egr;
r
a small absolute value of &tgr;
f
, or with the &tgr;
f
adjusted to the negative side, and a large Q
u
and a process for producing the same.
Another object of the invention is to provide a dielectric material that meets the demands for communication equipment having reduced size and height and is also applicable to new uses in, for example, a duplexer while exhibiting improved dielectric characteristics and a process for producing the same. A Q
u
is a relatively important characteristic for use in a duplexer, etc., and it is required that Q
u
×f
0
be 5000 GHz or more, particularly 6000 GHz or more. The present invention provides a dielectric material satisfying this requirement.


REFERENCES:
patent: 4330631 (1982-05-01), Kawashima et al.
patent: 4643984 (1987-02-01), Abe et al.
patent: 10029863 (1998-02-01), None
patent: 0 873 979 (1998-10-01), None
patent: 59-37526 (1984-09-01), None
patent: 59-37527 (1984-09-01), None
patent: 59-48484 (1984-11-01), None
patent: 60-54899 (1985-12-01), None
patent: 002115343 (1988-03-01), None
patent: 63-222064 (1988-09-01), None
patent: 6-44406 (1994-06-01), None
patent: 002115344 (1994-11-01), None
patent: 6-309926 (1994-11-01), None
patent: 6-325620 (1994-11-01), None
patent: 8-15012 (1996-02-01), None

Affiliated with

Also associated with

Rating

Dielectric material and process for producing the same 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 material and process for producing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric material and process for producing the same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2817067