# US 8,772,188 B2 · Glass-ceramic having at least two crystal phases, process for producing a glass-ceramic and its use

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- Number: US 8,772,188 B2
- Document ID: US8772188B2
- Status: Granted
- Kind: B2
- Application number: 13/417,540
- Filed: 2012-03-12
- Published: 2013-09-12
- Granted: 2014-07-08
- Earliest claimed: 2012-03-12
- Assignees: Schott AG
- Applicants: Martin Letz; Stephan Knoener; Martina Dressler; Daniela Seiler; Bernd Hoppe; Michael Kluge
- Inventors: Martin Letz; Stephan Knoener; Martina Dressler; Daniela Seiler; Bernd Hoppe; Michael Kluge
- Web page: https://patentgrep.com/patent/US8772188B2

## CPC

- C03B 32/02: Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles {(C03B27/012 takes precedence)}
- C03C 3/068: containing rare earths
- C03C 4/16: for dielectric glass
- C03C 10/0054: {containing PbO, SnO2, B2O3}
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- 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

## Abstract

A glass-ceramic having at least two crystal phases, wherein at least one crystal phase has a positive temperature dependence of the resonance frequency τf, at least one crystal phase has a negative temperature dependence of the resonance frequency τf and the glass-ceramic has a resulting temperature dependence of the resonance frequency τf of 0 ppm/K with a maximum deviation of +/−20 ppm/K, is described. Furthermore, a process for producing such a glass-ceramic and the use of the glass-ceramic are described.

## Claims

### Claim 1

A glass-ceramic having at least two crystal phases, wherein at least one crystal phase has a positive temperature dependence of the resonance frequency τf, at least one crystal phase has a negative temperature dependence of the resonance frequency τf and the glass-ceramic has a resulting temperature dependence of the resonance frequency τf of 0+/−20 ppm/K, and
wherein the glass-ceramic has at least the following constituents (in mol % on an oxide basis):
SiO2
5-50
Al2O3
0-20
B2O3
0-25
BaO
0-25
TiO2
10-60
RE2O3
5-45,
where Ba can be partly replaced by Sr, Ca, and Mg, where RE is lanthanum, another lanthanide or yttrium and where Ti can be partly replaced by Zr, Hf, Y, Nb, V, Ta, Mn, and Cr.

### Claim 2 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic has a dielectric loss (tan δ) of not more than 10−2.

### Claim 3 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic has a relative permittivity ∈ of at least 15.

### Claim 4 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic contains at least one mixed crystal phase based on RE, Ti, Si, O and Ba, where Ba can be at least partly replaced by Sr, Ca, Mg, where RE is a lanthanide or yttrium and where Ti can be at least partly replaced by Zr, Hf, Y, Nb, V, Ta, Mn, and Cr.

### Claim 5 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic contains at least one mixed crystal phase selected from the group consisting of mixed crystals based on Ba, RE, TiO, RE2Ti2O2, RE2Ti2SiO9 and RE4Ti9O24, where RE is lanthanum, another lanthanide or yttrium, where up to 10% of Ba can be replaced by Sr, Ca, Mg and where up to 10% of Ti can be replaced by Zr, Hf, Y, Nb, V, Ta, Mn, and Cr.

### Claim 6 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic has a proportion of crystalline material of at least 30% by volume.

### Claim 7 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass-ceramic has an average crystallite size of from 10 nanometers to 50 micrometers.

### Claim 8 (depends on 1)

The glass-ceramic according to claim 1 wherein the glass ceramic is a dielectric configured for use as a device selected from the group consisting of a dielectric resonator, an electronic frequency filter element, an antenna element for the high-frequency range, a cylindrical antenna element, and a patch antenna element.

### Claim 9

A glass-ceramic having at least two crystal phases, wherein at least one crystal phase has a positive temperature dependence of the resonance frequency τf, at least one crystal phase has a negative temperature dependence of the resonance frequency τf and the glass-ceramic has a resulting temperature dependence of the resonance frequency τf of 0+/−20 ppm/K, wherein the glass-ceramic contains at least one mixed crystal phase based on RE, Ti, Si, O, and Ba, where Ba can be at least partly replaced by Sr, Ca, and Mg, where RE is a lanthanide or yttrium and where Ti can be at least partly replaced by Zr, Hf, Y, Nb, V, Ta, Mn, and Cr.

### Claim 10 (depends on 9)

The glass-ceramic according to claim 9 wherein the glass-ceramic has a dielectric loss (tan δ) of not more than 10−2.

### Claim 11 (depends on 9)

The glass-ceramic according to claim 9 wherein the glass-ceramic has a relative permittivity ∈ of at least 15.

### Claim 12 (depends on 9)

The glass-ceramic according to claim 9 wherein the glass-ceramic has a proportion of crystalline material of at least 30% by volume.

### Claim 13 (depends on 9)

The glass-ceramic according to claim 9 wherein the glass-ceramic has an average crystallite size of from 10 nanometers to 50 micrometers.

### Claim 14 (depends on 9)

The glass-ceramic according to claim 9 wherein the glass ceramic is a dielectric configured for use as a device selected from the group consisting of a dielectric resonator, an electronic frequency filter element, an antenna element for the high-frequency range, a cylindrical antenna element, and a patch antenna element.