Lead-free piezoceramic material based on bismuth sodium titanate (BST)

• US 10,246,376 B2
• Filed: 06/23/2014
• Issued: 04/02/2019
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: PI Ceramic Gmbh
• Original Assignee: PI Ceramic Gmbh
• Inventors: Hennig, Eberhard, Kynast, Antje, Topfer, Michael, Hofmann, Michael
• Primary Examiner(s): Dougherty, Thomas
• Application Number:
  US14/909,821
• Publication Number:
  US 20160194249A1
• Time in Patent Office: 1,744 Days
• Field of Search: 310358, 501132, 252 629 PZ, 252 629 R
• CPC Class Codes: C04B 2235/3201 Alkali metal oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/3298 Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate
• CPC Class Codes: C04B 2235/42 Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
• CPC Class Codes: C04B 2235/447 Phosphates or phosphites calcium phosphates C04B2235/3212, e.g. orthophosphate, hypophosphite
• CPC Class Codes: C04B 2235/727 Phosphorus or phosphorus compound content
• CPC Class Codes: C04B 2235/768 Perovskite structure ABO3
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 35/462 based on titanates
• CPC Class Codes: C04B 35/4682 based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/475 based on bismuth titanates
• CPC Class Codes: C04B 35/6261 Milling
• CPC Class Codes: C04B 35/62645 Thermal treatment of powders or mixtures thereof other than sintering
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/62695 : Granulation or pelletising devices for shaping artificial aggregates from ceramic mixtures B28B1/004
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: H10N 30/097 : by sintering
• CPC Class Codes: H10N 30/50 : having a stacked or multilayer structure
• CPC Class Codes: H10N 30/853 : Ceramic compositions

Abstract

The invention relates to a lead-free piezoceramic material based on bismuth sodium titanate (BST) having the following parent composition: x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ where x+y+z=1 and 0<x<1, 0<y<1, 0≤z≤0.07 or x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zCaTiO₃ where x+y+z=1 and 0<x<1, 0<y<1, 0<z≤0.05 or x(Bi_0.5Na_0.5)TiO₃-y(Bi_0.5K_0.5)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

1. A lead-free piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ with x+y+z=1 and 0<

x<

1, 0<

y<

1, 0≤

z≤

0.07 or

x(Bi_0.5Na_0.5)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.

2. The lead-free piezoceramic material based on bismuth sodium titanate (BST) according to claim 1, wherein the fundamental composition is

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ with y≥

0.1 and x+y+z=1 or

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zCaTiO₃ with y≥

0.1 and x+y+z=1.

3. The lead-free piezoceramic material according to claim 1,

in that the phosphoric compound is an inorganic phosphate, hydrogen phosphate, or dihydrogen phosphate.

4. 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.

5. 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.

6. 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.

7. 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.

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

9. 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.

10. A use of a phosphoric material in a piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ with x+y+z=1 and 0<

x<

1, 0<

y<

1, 0≤

z≤

0.07 or

x(Bi_0.5Na_0.5)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.

11. The use according to claim 10, wherein the fundamental composition is

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ with y≥

0.1 and x+y+z=1 or

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zCaTiO₃ with y≥

0.1 and x+y+z=1.

12. The use according to claim 10,

characterized in that the phosphoric compound is an inorganic phosphate, hydrogen phosphate, or dihydrogen phosphate.

13. The use according to claim 10,

characterized in that the phosphoric compound is selected from the group which consists of KH₂PO₄, (NH₄)H₂PO₄.

14. A use of a phosphoric material in a piezoceramic material based on bismuth sodium titanate (BST) of the fundamental composition

x(Bi_0.5Na_0.5)TiO₃-yBaTiO₃-zSrTiO₃ with x+y+z=1 and 0<

x<

1, 0<

y<

1, 0<

z<

0.07

or

x(Bi_0.5Na_0.5)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.