# US 2019/0378970 A1 · Piezoelectric ceramics, piezoelectric element, and electronic apparatus

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- Number: US 2019/0378970 A1
- Document ID: US20190378970A1
- Status: Published application
- Kind: A1
- Application number: 16/425,139
- Filed: 2019-05-29
- Published: 2019-12-12
- Earliest claimed: 2018-06-08
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Akira Uebayashi; Kanako Oshima; Makoto Kubota; Tatsuo Furuta; Yasushi Shimizu; Mikio Shimada; Chiaki Arii
- Web page: https://patentgrep.com/patent/US20190378970A1

## CPC

- C04B 35/26: based on ferrites
- H10N 30/8536: {Alkaline earth metal based oxides, e.g. barium titanates}
- C04B 35/462: based on titanates
- C04B 35/465: based on alkaline earth metal titanates
- C04B 35/4682: {based on BaTiO3 perovskite phase}
- C04B 35/475: based on bismuth titanates
- C04B 35/49: containing also titanium oxides or titanates
- C04B 35/491: based on lead zirconates and lead titanates {, e.g. PZT}
- C04B 35/495: based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
- C04B 35/6261: {Milling}
- C04B 35/62655: {Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying}
- C04B 35/62695: {Granulation or pelletising (devices for shaping artificial aggregates from ceramic mixtures B28B1/004)}
- C04B 35/63416: {Polyvinylalcohols [PVA]; Polyvinylacetates}
- C04B 35/64: Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F})
- H04R 17/02: Microphones
- H10N 30/50: having a stacked or multilayer structure
- H10N 30/871: {Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes}
- H10N 30/872: {Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices}
- C04B 2235/3201: Alkali metal oxides or oxide-forming salts thereof
- C04B 2235/3203: Lithium oxide or oxide-forming salts thereof
- C04B 2235/3215: Barium oxides or oxide-forming salts thereof
- C04B 2235/3236: Alkaline earth titanates
- C04B 2235/3244: Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
- C04B 2235/3262: Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
- C04B 2235/3298: Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate
- C04B 2235/604: Pressing at temperatures other than sintering temperatures
- C04B 2235/6567: Treatment time
- C04B 2235/76: Crystal structural characteristics, e.g. symmetry
- C04B 2235/762: Cubic symmetry, e.g. beta-SiC
- C04B 2235/768: Perovskite structure ABO3
- C04B 2235/77: Density
- C04B 2235/786: Micrometer sized grains, i.e. from 1 to 100 micron
- C04B 2235/79: Non-stoichiometric products, e.g. perovskites (ABO3) with an A/B-ratio other than 1
- C04B 2235/87: Grain boundary phases intentionally being absent
- C04B 2235/96: Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
- 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
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

Provided is a piezoelectric ceramics including crystal grains each including: a first region that is formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at an asymmetrical position; and a second region that is formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at a symmetrical position, and that is present inside the first region, wherein a ratio of a cross-sectional area of the second region to a cross-sectional area of the piezoelectric ceramics is 0.1% or less.

## Claims

### Claim 1

A piezoelectric ceramics comprising crystal grains each including:
a first region formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at an asymmetrical position; and
a second region formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at a symmetrical position, and is present inside the first region,
wherein a ratio of a cross-sectional area of the second region to a cross-sectional area of the piezoelectric ceramics is 0.1% or less.

### Claim 2 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein a ratio of a cross-sectional area of the first region to the cross-sectional area of the piezoelectric ceramics is 99% or more.

### Claim 3 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein a peripheral portion of each of the crystal grains is occupied by the first region.

### Claim 4 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the piezoelectric ceramics has a Curie temperature of 100° C. or more.

### Claim 5 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the piezoelectric ceramics has an absolute value |d31| of a piezoelectric constant at 25° C. of 80 pm/V or more.

### Claim 6 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the crystal grains have an average equivalent circular diameter of 1.0 μm or more and 10 μm or less.

### Claim 7 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the piezoelectric ceramics has a relative density of 93% or more and 100% or less.

### Claim 8 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the second region has a cubic or GdFeO3-type crystal structure.

### Claim 9 (depends on 8)

The piezoelectric ceramics according to claim 8, wherein the crystal structure of the second region is represented by a space group Pnma.

### Claim 10 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the crystal structure of the first region is represented by a space group P4mm.

### Claim 11 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the metal oxide forming the second region comprises Ca and Ti.

### Claim 12 (depends on 1)

The piezoelectric ceramics according to claim 1, wherein the metal oxide forming the first region comprises Ba and Ti.

### Claim 13 (depends on 1)

The piezoelectric ceramics according to claim 1,
wherein the metal oxide forming the second region comprises Ca and Ti, and
wherein the metal oxide forming the first region comprises Ba and Ti.

### Claim 14 (depends on 13)

The piezoelectric ceramics according to claim 13, wherein the piezoelectric ceramics has an absolute density of 5.5 g/cm3 or more and 5.8 g/cm3 or less.

### Claim 15

A piezoelectric element comprising:
electrodes; and
at least one piezoelectric ceramics portion,
wherein a piezoelectric ceramics forming the at least one piezoelectric ceramics portion comprises the piezoelectric ceramics comprising crystal grains each including:
a first region formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at an asymmetrical position; and
a second region formed of a perovskite-type metal oxide having a crystal structure in which a central element of a unit cell is located at a symmetrical position, and is present inside the first region,
wherein a ratio of a cross-sectional area of the second region to a cross-sectional area of the piezoelectric ceramics is 0.1% or less.

### Claim 16 (depends on 15)

The piezoelectric element according to claim 15,
wherein the electrodes and the at least one piezoelectric ceramics portion are alternately stacked.

### Claim 17 (depends on 15)

An electronic apparatus comprising the piezoelectric element of claim 15.