Pyrochlore based oxides with high dielectric constant and low temperature coefficient

• US 5,658,485 A
• Filed: 10/03/1995
• Issued: 08/19/1997
• Est. Priority Date: 10/03/1995
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Peck, William Frederick, Cava, Robert Joseph, Krajewski, James Joseph
• Primary Examiner(s): JONES, DEBORAH D
• Application Number:
  US08/538,318
• Time in Patent Office: 686 Days
• Field of Search: 252/62.9, 501/136
• US Class Current: 252/62.9PZ
• CPC Class Codes: C04B 35/499 containing also titanates

Abstract

The temperature dependent dielectric constants in the vicinity of room temperature have been measured for bulk ceramics which are phase-mixtures of Pb₂ (Nb,Mg,Ti)₂ O_6+x pyrochlores and Pb(Nb,Mg,Ti)O₃ perovskites. A band of compositions has been found in which the negative temperature coefficient of dielectric constant for the pyrochlore is very closely compensated by the positive temperature coefficient of dielectric constant of the perovskite. These compositions have dielectric constants near 200, with Q'"'"'s near 200 at 1 MHz, making them an intermediate family of dielectrics between the much studied high dielectric constant low Q Barium-Strontium Titanates and low dielectric constant high Q Barium-Lanthanide Titanates.

Claims

1. A dielectric material having a high dielectric constant and a small temperature dependence of the dielectric constant comprising a quaternary system PbO--MgO--Nb₂ O₅ --TiO₂ in a plane of a phase diagram shown in FIG. 1 where perovskites and pyrochlores are in substantial equilibrium.

2. A dielectric material according to claim 1, wherein 1PbO:

Σ

(Mg+Ti+Nb) is about 1;

1.

3. A dielectric material according to claim 1, in a Pb₂ Mg_1/3 Nb_2/3 O₆.5 -PbTiO₃ -PbMg_1/3 Nb_2/3 O₃ triangle of the phase diagram of FIG. 1.

4. A dielectric material according to claim 1 comprising PbTiO₃ and PbMg_1/3 Nb_2/3 O₃ perovskites and Pb₂ Nb₂ O₇ and Pb₂ Mg_1/3 Nb_2/3 O₆.5 pyrochlores in amounts that fall within the phase diagram shown in FIG. 1.

5. A dielectric material according to claim 1 comprising Pb_x Nb_y Mg_z Ti_t oxide where 0.9≦

x≦

1.1, 0.6≦

y≦

0.8, 0.05≦

z≦

0.15, and 0.10≦

t0.30.