# US 10,501,367 B2 · Ceramics and glass ceramics exhibiting low or negative thermal expansion

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- Number: US 10,501,367 B2
- Document ID: US10501367B2
- Status: Granted
- Kind: B2
- Application number: 15/742,236
- Filed: 2016-07-05
- Published: 2018-07-19
- Granted: 2019-12-10
- Earliest claimed: 2015-07-06
- Assignees: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
- Applicants: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
- Inventors: Christian Thieme; Christian Ruessel
- Web page: https://patentgrep.com/patent/US10501367B2

## CPC

- C03C 10/0054: {containing PbO, SnO2, B2O3}
- C03B 19/063: {by hot-pressing powders}
- C03C 3/06: with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)}
- C03C 3/062: with less than 40% silica by weight
- C03C 3/066: containing zinc
- C03C 3/068: containing rare earths
- C03C 8/04: containing zinc
- C03C 10/0009: {containing silica as main constituent}
- C03C 10/0027: {containing SiO2, Al2O3, Li2O as main constituents}
- C04B 35/01: based on oxide ceramics
- C04B 35/16: based on silicates other than clay {(zircon C04B35/48)}
- C04B 35/453: based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
- C04B 35/6261: {Milling}
- C04B 35/6455: {Hot isostatic pressing}
- C03C 2204/00: Glasses, glazes or enamels with special properties
- C03C 2209/00: Compositions specially applicable for the manufacture of vitreous glazes
- C04B 2235/3206: Magnesium oxides or oxide-forming salts thereof
- C04B 2235/3213: Strontium oxides or oxide-forming salts thereof
- C04B 2235/3215: Barium oxides or oxide-forming salts thereof
- C04B 2235/3262: Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
- C04B 2235/3272: Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
- C04B 2235/3275: Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
- C04B 2235/3279: Nickel oxides, nickalates, or oxide-forming salts thereof
- C04B 2235/3281: Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
- C04B 2235/3284: Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
- C04B 2235/3287: Germanium oxides, germanates or oxide forming salts thereof, e.g. copper germanate
- 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 2235/3436: Alkaline earth metal silicates, e.g. barium silicate
- C04B 2235/449: Organic acids, e.g. EDTA, citrate, acetate, oxalate
- C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron
- C04B 2235/5445: submicron sized, i.e. from 0,1 to 1 micron
- C04B 2235/5454: nanometer sized, i.e. below 100 nm
- C04B 2235/6567: Treatment time
- C04B 2235/76: Crystal structural characteristics, e.g. symmetry
- C04B 2235/9607: Thermal properties, e.g. thermal expansion coefficient
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- 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

## Abstract

Ceramics and glass-ceramics have low and/or negative coefficients of thermal expansion. Crystalline phases of the formula AM2Si2-yGeyO7 (A=Sr and Ba and M=Zn, Mg, Ni, Co, Fe, Cu, Mn, with Sr, Ba and Zn necessarily having to be present) can be produced by conventional ceramic processes or by crystallization from glasses. The compositions form solid solutions, where the elements indicated as component M can be replaced by one another in virtually any concentration but the concentration of Zn must always be at least 50% of the sum of all components indicated under M. The stoichiometry of these silicates and also their structure can differ to a greater or lesser extent.

## Claims

### Claim 1

A material based on a crystal phase of composition Ba1-xSrxM2Si2-yGeyO7 with 0.1<x<1 and 0≤y≤2, where M comprises Zn as a constituent such that the material has a negative coefficient of thermal expansion or a coefficient of linear thermal expansion of <1·10−6K−1.

### Claim 2 (depends on 1)

The material as claimed in claim 1, wherein M contains at least one further constituent selected from the group consisting of Mg, Mn, Co, Ni, Fe and Cu.

### Claim 3 (depends on 1)

The material as claimed in claim 1, wherein the crystal phase is present in a volume concentration of >50% and other phases present being other crystal phases or one or more glass phases of a different chemical composition.

### Claim 4 (depends on 1)

The material as claimed in claim 1, wherein the crystal phase has been crystallized from a glass.

### Claim 5 (depends on 1)

A glass-ceramic or ceramic product comprising the material as claimed in claim 1.

### Claim 6 (depends on 1)

A method of producing the material as claimed in claim 1, comprising sintering amorphous powders, with densification by viscous flow commencing before crystallization of the crystal phase occurs at an end portion of the sintering.

### Claim 7 (depends on 1)

A method of producing the material as claimed in claim 1, comprising sintering crystalline powders which contain the crystal phase.

### Claim 8 (depends on 1)

Oven windows comprising the material as claimed in claim 1.

### Claim 9 (depends on 1)

Cookware comprising the material as claimed in claim 1.

### Claim 10 (depends on 1)

Telescope mirrors or other passive elements for optical technologies comprising the material as claimed in claim 1.

### Claim 11 (depends on 1)

Joining material having low coefficients of thermal expansion comprising the material as claimed in claim 1.

### Claim 12 (depends on 1)

Glazing material having low coefficients of thermal expansion comprising the material as claimed in claim 1.

### Claim 13 (depends on 2)

The material as claimed in claim 2, wherein a sum of concentration(s) of the at least one further constituent does not exceed the concentration of Zn.

### Claim 14 (depends on 1)

The material as claimed in claim 1, wherein the composition is selected from the group consisting of Ba0.9Sr0.1Zn2Si2O7, Ba0.8Sr0.2Zn2Si2O7, Ba0.5Sr0.5Zn2Si2O7, Ba0.1Sr0.9Zn2Si2O7, Ba0.01Sr0.99Zn2Si2O7, Ba0.5Sr0.5Zn1.5Mg0.5Si2O7, Ba0.5Sr0.5Zn1.3Mg0.7Si2O7, Ba0.5Sr0.5Zn1.5Co0.5Si2O7, Ba0.5Sr0.5ZnCoSi2O7, Ba0.5Sr0.5Zn1.9Mn0.1Si2O7, Ba0.5Sr0.5Zn1.5Mn0.5Si2O7, Ba0.5Sr0.5Zn1.8Ni0.2Si2O7, Ba0.5Sr0.5Zn1.7Ni0.3Si2O7, Ba0.5Sr0.5Zn1.6Ni0.4Si2O7, Ba0.5Sr0.5Zn1.9Cu0.1Si2O7, Ba0.5Sr0.5Zn1.7Cu0.3Si2O7, Ba0.5Sr0.5Zn1.5Cu0.5Si2O7, Ba0.5Sr0.5Zn2Si1.9Ge0.1O7, and Ba0.5Sr0.5Zn1.7Fe0.3Si2O7.

### Claim 15 (depends on 1)

The material as claimed in claim 1, wherein the composition is selected from the group consisting of Ba0.8Sr0.2Zn2Si2O7, Ba0.5Sr0.5Zn2Si2O7, Ba0.1Sr0.9Zn2Si2O7, Ba0.01Sr0.99Zn2Si2O7, Ba0.5Sr0.5Zn1.5Mg0.5Si2O7, Ba0.5Sr0.5Zn1.5Co0.5Si2O7, Ba0.5Sr0.5Zn1.5Mn0.5Si2O7, Ba0.5Sr0.5Zn1.8Ni0.2Si2O7, Ba0.5Sr0.5Zn1.7Ni0.3Si2O7, Ba0.5Sr0.5Zn1.9Cu0.1Si2O7, Ba0.5Sr0.5Zn2Si1.9Ge0.1O7, and Ba0.5Sr0.5Zn1.7Fe0.3Si2O7.

### Claim 16

A material based on a crystal phase of composition Ba1-xSrxM2Si2-yGeyO7 with 0.1<x<1 and 0≤y≤2, where M comprises Zn as a constituent such that the material has a negative coefficient of thermal expansion or a coefficient of linear thermal expansion of <1·10−6 K−1 and M further contains at least one further constituent selected from the group consisting of Mg, Mn, Co, Ni, Fe and Cu, wherein the crystal phase is present in a volume concentration of >50% and other phases present being other crystal phases or one or more glass phases of a different chemical composition, and a sum of concentration(s) of the at least one further constituent does not exceed the concentration of Zn.