# US 7,608,215 B2 · Method of manufacturing a piezoelectric ceramic composition

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- Number: US 7,608,215 B2
- Document ID: US7608215B2
- Status: Granted
- Kind: B2
- Application number: 10/949,742
- Filed: 2004-09-24
- Published: 2005-04-07
- Granted: 2009-10-27
- Earliest claimed: 2003-09-24
- Assignees: TDK Corporation
- Inventors: Tomohisa Azuma; Masakazu Hirose
- Web page: https://patentgrep.com/patent/US7608215B2

## CPC

- H03H 9/02031: {consisting of ceramic}
- C04B 35/493: containing also other lead compounds
- C04B 35/6262: {of calcined, sintered clinker or ceramics}
- C04B 35/6268: {characterised by the applied pressure or type of atmosphere, e.g. in vacuum, hydrogen or a specific oxygen pressure}
- C04B 35/64: Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F})
- H10N 30/04: Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
- H10N 30/045: by polarising
- H10N 30/097: by sintering
- H10N 30/8554: {Lead-zirconium titanate [PZT] based}
- C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
- C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B 2235/3241: Chromium oxides, chromates, or oxide-forming salts thereof
- C04B 2235/3251: Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
- C04B 2235/3262: Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
- C04B 2235/3418: Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
- C04B 2235/5445: submicron sized, i.e. from 0,1 to 1 micron
- C04B 2235/604: Pressing at temperatures other than sintering temperatures
- C04B 2235/658: Atmosphere during thermal treatment
- C04B 2235/662: Annealing after sintering
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

There are provided steps of polarizing a ceramic composition including a perovskite compound containing Pb, Zr, Ti and Mn as main components and a heat treatment step for keeping the polarized ceramic composition within a temperature range lower than Tc (Tc denoting the Curie temperature of the ceramic composition) for 1 to 100 minutes.

## Claims

### Claim 1

A manufacturing method for a piezoelectric ceramic composition comprising steps of:
polarizing a ceramic composition comprising a perovskite compound containing Pb, Zr, Ti, Mn and Nb; and
heat-treating said polarized ceramic composition within a temperature range higher than 0.80 Tc and lower than Tc (Tc denoting the Curie temperature of said ceramic composition) for 1 to 40 minutes,
wherein the Curie temperature Tc of said ceramic composition is 340° C. or higher;
wherein said ceramic composition is represented by a formula, Pbα[(Mn1/3Nb2/3)xTiyZrz]O3, in which α, x , y and z fall within the ranges of 0.95≦α≦1.02, 0.02≦x≦0.15, 0.48≦y≦0.62, and 0.30≦z≦0.42, respectively; and wherein said ceramic composition comprises as an additive Mn in 0.65 wt % or less (not inclusive of 0) in terms of MnCO3 and/or Cr in 0.65 wt % or less (not inclusive of 0) in terms of Cr2O3.

### Claim 2 (depends on 1)

The manufacturing method for a piezoelectric ceramic composition according to claim 1, wherein:
in said polarizing step, an electric field of 1.0 to 2.0 Ec (Ec denoting a coercive electric field) is applied to said ceramic composition within a temperature range from 50 to 300° C. for 0.5 to 30 minutes.

### Claim 3 (depends on 1)

The manufacturing method for a piezoelectric ceramic composition according to claim 1, wherein:
said ceramic composition comprises as an additive Al in 5.0 wt % or less (not inclusive of 0) in terms of Al2O3 and/or Sc in 5.0 wt % or less (not inclusive of 0) in terms of Sc2O3.

### Claim 4 (depends on 1)

The manufacturing method for a piezoelectric ceramic composition according to claim 1, wherein:
in said heat treatment step, the product between the heat treatment temperature and the heat treatment time is 500 (° C. hour) or less.

### Claim 5 (depends on 1)

The manufacturing method for a piezoelectric ceramic composition according to claim 1, wherein:
the vibrational mode of said piezoelectric ceramic composition is a thickness-shear mode.