# US 10,246,376 B2 · Lead-free piezoceramic material based on bismuth sodium titanate (BST)

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- Number: US 10,246,376 B2
- Document ID: US10246376B2
- Status: Granted
- Kind: B2
- Application number: 14/909,821
- Filed: 2014-06-23
- Published: 2016-07-07
- Granted: 2019-04-02
- Earliest claimed: 2013-08-07
- Assignees: PI Ceramic GmbH
- Applicants: Pi Ceramic GmbH Keramische Technologien Und Bauelemente
- Inventors: Eberhard Hennig; Antje Kynast; Michael Töpfer; Michael Hofmann
- Web page: https://patentgrep.com/patent/US10246376B2

## CPC

- C04B 35/475: based on bismuth titanates
- C04B 35/462: based on titanates
- C04B 35/4682: {based on BaTiO3 perovskite phase}
- C04B 35/6261: {Milling}
- C04B 35/62645: {Thermal treatment of powders or mixtures thereof other than sintering}
- 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 35/64: Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F})
- H10N 30/097: by sintering
- H10N 30/50: having a stacked or multilayer structure
- H10N 30/853: Ceramic compositions
- C04B 2235/3201: Alkali metal oxides or oxide-forming salts thereof
- C04B 2235/3208: Calcium oxide or oxide-forming salts thereof, e.g. lime
- C04B 2235/3213: Strontium oxides or oxide-forming salts thereof
- C04B 2235/3215: Barium oxides or oxide-forming salts thereof
- C04B 2235/3232: Titanium oxides or titanates, e.g. rutile or anatase
- C04B 2235/3236: Alkaline earth titanates
- C04B 2235/3298: Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate
- C04B 2235/42: Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
- C04B 2235/447: Phosphates or phosphites, e.g. orthophosphate or hypophosphite
- C04B 2235/727: Phosphorus or phosphorus compound content
- C04B 2235/768: Perovskite structure ABO3
- C04B 2235/77: Density
- C04B 2235/80: Phases present in the sintered or melt-cast ceramic products other than the main phase
- 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

## Abstract

The invention relates to a lead-free piezoceramic material based on bismuth sodium titanate (BST) having the following parent composition: x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 where x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.07 or x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 where x+y+z=1 and 0<x<1, 0<y<1, 0<z≤0.05 or x(Bi0.5Na0.5)TiO3-y(Bi0.5K0.5)TiO3-zBaTiO3 where x+y+z=1 and 0<x<1, 0<y<1, 0≤z<1, characterized by addition of a phosphorus-containing material in a quantity that gives a phosphorus concentration of from 100 to 2000 ppm in the piezoceramic material.

## Claims

### Claim 1

A lead-free piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition
x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.07 or
x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.05
characterized by the addition of a phosphoric material in a quantity such that the concentration of phosphorus in the piezoceramic material is 250 to 2000 ppm, wherein the specification ppm (parts per million) relates to the mass of phosphorus in relation to the total mass of the piezoceramic composition.

### Claim 2 (depends on 1)

The lead-free piezoceramic material based on bismuth sodium titanate (BST) according to claim 1, wherein the fundamental composition is
x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 with y≥0.1 and x+y+z=1 or
x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 with y≥0.1 and x+y+z=1.

### Claim 3 (depends on 1)

The lead-free piezoceramic material according to claim 1,
in that the phosphoric compound is an inorganic phosphate, hydrogen phosphate, or dihydrogen phosphate.

### Claim 4 (depends on 1)

The lead-free piezoceramic material according to claim 1,
characterized in that the phosphoric compound is selected from the group which consists of KH2PO4, (NH4)H2PO4.

### Claim 5 (depends on 1)

The lead-free piezoceramic material according to claim 1,
characterized in that the phosphoric material is added in a quantity such that the concentration of phosphorus in the lead-free piezoceramic material is 270 to 1800 ppm.

### Claim 6 (depends on 1)

The lead-free piezoceramic material according to claim 1,
characterized in that the fundamental composition contains additives in the form of oxides or complex perovskites.

### Claim 7 (depends on 1)

A method for producing a lead-free piezoceramic material according to claim 1,
characterized by the following steps:
producing a raw material mixture of the fundamental composition,
producing a calcinate of the fundamental composition,
finely grinding the calcinate,
producing a granulate in particular by spray granulation or producing a casting slurry for the multilayer or “co-firing” process,
further processing in a known manner including sintering in normal atmosphere,
wherein phosphoric additives are added during the fine grinding or the spray granulation and/or during the preparation of casting slurries.

### Claim 8 (depends on 1)

A piezoceramic multilayer actuator based on a lead-free piezoceramic material according to claim 1.

### Claim 9 (depends on 1)

A piezoceramic component, preferably having at least one piezoceramic body having at least two electrodes, more preferably in the form of a piezoelectric ultrasonic transducer, based on a lead-free piezoceramic material according to claim 1.

### Claim 10

A use of a phosphoric material in a piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition
x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.07 or
x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.05
to reduce the giant grain growth, wherein the phosphoric material is used in a quantity such that the concentration of phosphorus in the piezoceramic material is 250 to 2000 ppm,
wherein the specification ppm (parts per million) relates to the mass of phosphorus in relation to the total mass of the piezoceramic composition.

### Claim 11 (depends on 10)

The use according to claim 10, wherein the fundamental composition is
x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 with y≥0.1 and x+y+z=1 or
x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 with y≥0.1 and x+y+z=1.

### Claim 12 (depends on 10)

The use according to claim 10,
characterized in that the phosphoric compound is an inorganic phosphate, hydrogen phosphate, or dihydrogen phosphate.

### Claim 13 (depends on 10)

The use according to claim 10,
characterized in that the phosphoric compound is selected from the group which consists of KH2PO4, (NH4)H2PO4.

### Claim 14

A use of a phosphoric material in a piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition
x(Bi0.5Na0.5)TiO3-yBaTiO3-zSrTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0<z<0.07
or
x(Bi0.5Na0.5)TiO3-yBaTiO3-zCaTiO3 with x+y+z=1 and 0<x<1, 0<y<1, 0<z<0.05
to reduce the giant grain growth, wherein the phosphoric material is used in a quantity such that the concentration of phosphorus in the piezoceramic material is 270 to 1800 ppm,
wherein the specification ppm (parts per million) relates to the mass of phosphorus in relation to the total mass of the piezoceramic composition.