# Patent

## Title
Glass-ceramic as dielectric in the high-frequency range

## Abstract

A glass-ceramic is disclosed, this glass-ceramic includes at least the following constituents (in mol % on oxide basis): SiO2 1-30, Al2O3 0-20, B2O3 0-25, TiO2 10-70, RE2O3 0-35, BaO 5-35, SiO2+Al2O3+B2O3<25, where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part, preferably up to 10%, by Zr, Hf, Y, Nb, V, Ta. A principal phase in the glass-ceramic is BaTi4O.

## Background
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is a continuation of international patent application PCT/EP2012/073177, filed on Nov. 21, 2012 designating the U.S., which international patent application has been published in German language and claims priority from German patent application 10 2011 119 798.6, filed on Nov. 24, 2011. The entire contents of each of these priority applications being incorporated herein by reference.


BACKGROUND OF THE INVENTION
The invention relates to a glass-ceramic which can be employed as a dielectric in the high-frequency range (frequency>200 MHz), more particularly in the gigahertz range (frequency f>1 GHz).
For a series of applications in the high-frequency range, specific materials are needed which combine an extremely high relative permittivity ∈ with an extremely low dielectric loss (tan δ). In order on the one hand to allow small antenna constructions and on the other to prevent close-range detuning by the body of a user (referred to as “body loading”), particular significance attaches to dielectric charging in the case of antennas, filters, and other devices. Required for this purpose are dielectrics which have a high relative permittivity, with ∈≧15, and also a low dielectric loss (tan δ) of not more than 10−2, preferably lower, in the high-frequency range. Furthermore, the temperature dependence of the resonance frequency τf is to be extremely low. Lastly, a material of this kind is to be able to be processed extremely simply and inexpensively in order to allow near net shapes at favorable cost.
Known in the prior art are a series of ceramic materials which are processed by sintering operations. Glass-ceramics are likewise known—cf., e.g., a BiNbO4 system, which is disclosed in Mirsaneh et al., “Circularly Loaded Dielectric-Loaded Antennas: Current Technology and Future Challenges”, Adv. Funct. Materials 18, (2008), pp. 1-8, for application with dielectrically charged antennas for the gigahertz range. This material can be utilized for producing the three principally utilized forms of antennas: the circularly polarized DLA helix antenna (D-LQH antenna) and the square patch antenna, and also SMD antennas. For this purpose, a glass with a composition of 30 mol % Bi2O3, mol % Nb2O5, 30 mol % B2O3, and 10 mol % SiO2 is first melted conventionally at 1250° C. for two hours.
This glass was poured into cylindrical molds, relaxed at 500 to 520° C., and cooled slowly to room temperature. This was then followed by crystallization at various temperatures between 600° C. and 1000° C. Specified as an optimum value for antenna applications in the case of heat treatment at 960° C. is a relative permittivity ∈ of 15, with a quality factor Q·f0 of 15 000 GHz and a temperature coefficient of the resonance frequency τf of −80 MK−1. The crystalline phase characterized in this case was substantially orthorhombic BiNbO4.
This system, using bismuth and niobium is expensive in terms of the raw materials.
In addition there are a series of sintered ceramic materials (cf. U.S. Pat. No. 6,184,845 B1, US 2007/063902 A1). Specified therein as dielectric material for the ceramic core of a dielectrically charged D-LQH antenna is a sintered ceramic material based on zirconium titanate and, respectively, based on zirconium tin titanate, with a relative permittivity of about 36. The material is said to be produced by extrusion or pressing and subsequent sintering.
Further sintered materials are specified in the review by M. T. Sebastian et al., “Low loss dielectric materials for LTCC applications”, International Materials Reviews, Vol. 53, 2008, pp. 57-90. Although these materials are in some cases identified as “glass-ceramics”, they are in fact sintered materials, since they are produced by the sintering of a mixture of vitreous and crystalline powders.
US 2002/0037804 A1 and US 2004/0009863 A1 further disclose dielectric ceramics which are said to form diverse crystal phases, such as, for instance, CaTiO3, SrTiO3, Ba Ti4O9, La2Ti2O7, Nd2Ti2O, Ba2Ti9O20, Mg2TiO4, Mg2SiO4, Zn2TiO4, etc., which are said to be responsible for high quality factors. These as well are sintered ceramics.
Dielectrics produced by sintering have a series of disadvantages: Every sintering operation is always associated with a certain shrinkage, leading to geometrical inaccuracies and corresponding final machining. Furthermore, every sintering operation produces a certain residual porosity, which is disadvantageous in the context of metalizing of the surface. The metal penetrates the pores and raises the dielectric loss of the dielectric.
Moreover, the production of sintered materials is fundamentally relatively inconvenient and expensive.
JP 2006124201 A, moreover, discloses a lead-free glass which is said to be used for producing a dielectric for a printed circuit, having a high dielectric constant and a low electrical loss. The glass contains (in mol %): 25 to 45 SiO2, 5 to 25 BaO, 18 to 35 TiO2, 1 to 10 Al2O3, 0 to 15 B2O3, 0 to 15 MgO+CaO+SrO, 0 to 7 WO+ZrO2, with ZnO<1. It is said to crystallize on heat treatment as BaTi4O9.
JP 2011-195440 A, which corresponds to German patent application DE 10 2010 012 524.5, discloses, in addition, a glass-ceramic comprising the following constituents (in mol % on oxide basis):
SiO2 5-50
Al2O3 0-20
B2O3 0-25
BaO 0-25
TiO2 10-60
RE2O3 5-35
where Ba may be replaced in part by Sr, Ca, Mg, where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part by Zr, Hf, Y, Nb, V, Ta.
This glass-ceramic can be used to produce high-quality dielectrics, which are suitable in particular for high-frequency applications, such as antennas. It has nevertheless emerged as being disadvantageous here that this glass-ceramic as well is not optimized for the production of antennas, which necessitates subsequent metalizing of the surface. The residual porosity is still relatively high for this. Moreover, the raw materials costs of the known glass-ceramic with RE-Ti system and Nb—Ti systems are fairly high.
SUMMARY OF THE INVENTION
In view of this it is one object of the invention to disclose an improved material which can be employed as a dielectric for high-frequency applications.
It is a second object of the invention to disclose an improved dielectric material which having a high relative permittivity and a low dielectric loss.
It is a third object of the invention to disclose an improved dielectric material which is amenable to production and processing in an extremely simple and inexpensive way.
It is a forth object of the invention to disclose an improved dielectric material which suitable for the production of antennas.
According to one aspect of the invention these and other objects are solved by a glass-ceramic comprising at least the following constituents (in mol % on oxide basis):
SiO2 1-30
Al2O3 0-20
B2O3 0-25
TiO2 10-70
RE2O3 0-<5
BaO 5-35
SiO2+Al2O3+B2O3<25
wherein RE is selected from the group consisting of lanthanum, another lanthanoid, and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.
It has emerged that with a glass composition of this kind it is possible to melt homogeneous glasses which can be subsequently converted by a ceramizing treatment into a homogeneous glass-ceramic that features a high relative permittivity, a low dielectric loss, and a low temperature dependence of the resonance frequency. The material can be produced as a glass-ceramic in a simple and inexpensive way and permits near net shaping by melting processes, more particularly by pouring or, if appropriate, by pressing.
In the context of this specification, the term “glass-ceramic” refers to a material which, starting from a homogeneous glass produced by melting, is converted by a deliberate temperature treatment into a partially crystalline body, with a multiplicity of crystallites being embedded in substantially homogeneous distribution in a vitreous residual phase.
Where this specification specifies compositions by stating that certain constituents are present therein, or that they have certain constituents, these specifications shall always be understood to mean that any desired further constituents may be included therein (open composition).
In another embodiment of the invention, however, the stated compositions are also to be understood to mean that only the respectively indicated constituents are included (closed composition), apart from unavoidable impurities arising from the nature of glass manufacture. Depending on the purity of the raw materials used, such unavoidable impurities are restricted to a maximum of 1 wt %, preferably to 0.5 wt %, more preferably to 0.1 wt %, more preferably to 0.05 wt %, or even to 0.01 wt %.
Where this specification specifies compositions by stating that they consist of certain constituents, these compositions are always to be understood to mean that only the stated constituents are included therein (closed composition), albeit with the proviso that unavoidable impurities, arising from the nature of glass manufacture, may be present. Depending on the purity of the raw materials used, such unavoidable impurities are restricted to a maximum of 1 wt %, preferably to 0.5 wt %, more preferably to 0.1 wt %, more preferably to 0.05 wt %, or even to 0.01 wt %.
Where this specification specifies certain constituents in working examples by listing them, the statements are to be understood as closed compositions, albeit with the proviso that unavoidable impurities, arising from the nature of glass manufacture, may be present. Depending on the purity of the raw materials used, such unavoidable impurities are restricted to a maximum of 1 wt %, preferably to 0.5 wt %, more preferably to 0.1 wt %, more preferably to 0.05 wt %, or even to 0.01 wt %.
In an advantageous development of the invention, the glass-ceramic comprises the following constituents in mol % on oxide basis):
SiO2 2-20
Al2O3 0-15
B2O3 0-20
TiO2 25-55
ZrO2 1-15
RE2O3 0-<5
BaO 10-30
SiO2+Al2O3+B2O3≦20,
where RE is lanthanum, another lanthanoid or yttrium, and where Ti may be replaced in part, preferably up to 10% of the obligatory fraction, by Hf, Nb, V, Ta (solid solution).
In advantageous development of the invention, the glass-ceramic comprises the following constituents:
SiO2 2-20
Al2O3 0-15
B2O3 0-5
TiO2 40-65
ZrO2 5-12
RE2O3 0-<5
BaO 10-30
10≦SiO2+Al2O3+B2O3≦20,
where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part, preferably up to 10% of the obligatory fraction, by Hf, Nb, V, Ta (solid solution).
According to a further-preferred embodiment of the invention, the RE2O3 content is 0.1 to 4.9 mol %, more preferably 0.5 to 4.5 mol %, more preferably 0.5 to 4 mol %, very preferably 1 to 3.5 mol %, where RE is preferably only lanthanum or another lanthanoid.
The glass-ceramic may further comprise refining agents in customary amounts, which may preferably involve 0.01 to 3 mol % of a refining agent selected preferably from the group formed by Sb2O3 and As2O3.
The glass-ceramic of the invention preferably has a dielectric loss (tan δ) of not more than 10−2, preferably of not more than 10−3 in the case of high-frequency applications (f>200 MHz).
Furthermore, the glass-ceramic preferably has a relative permittivity ∈ of at least 15, preferably >18, preferably in the range from 20 to 80.
The glass-ceramic of the invention is further notable preferably for a temperature dependence of the resonance frequency τf of not more than 200 ppm/K, preferably not more than 50 ppm/K, more preferably of not more than 10 ppm/k.
In further-advantageous embodiment of the invention, the glass-ceramic of the invention comprises at least one solid solution phase based on RE, Ti, Si, O, and optionally Ba, where Ba may be replaced at least in part by Sr, Ca, Mg, where RE is a lanthanoid or yttrium, and where Ti may be replaced at least in part by Zr, Hf, Y, Nb, V, Ta (solid solution).
More particularly the glass-ceramic of the invention may comprise at least one solid solution phase selected from the group formed by (BaO)x(RE2O3)y(SiO2)z(TiO2)u, e.g. RE2Ti2O7, RE2Ti2SiO9, BaTi4O9 and RE4Ti9O24, where RE is lanthanum, another lanthanoid, or yttrium, where up to 10% of Ba may be replaced by Sr, Ca, Mg, and where up to 10% of Ti may be replaced by Zr, Hf, Y, Nb, V, Ta (solid solution).
According to one preferred embodiment, the glass-ceramic comprises as predominant solid solution phase BaTi4O9 where Ba may be replaced in part by La, Ca, or Sr, and where Ti may be replaced in part by Zr, Hf, Y, Nb, V, Ta (solid solution).
A glass-ceramic of this kind can be produced with high quality and nevertheless very low raw materials costs, which are lower by a factor of approximately 10 to 100 than in the case of glass-ceramics with La—Ti and Nb—Ti systems.
According to one preferred embodiment, the glass-ceramic comprises as predominant solid solution phase (BaO)x(RE2O3)y(Al2O3)z(TiO2)u, more particularly Ba4Al2Ti10O27, where Ba may be replaced in part by La, Ca, or Sr, and where Ti may be replaced in part by Zr, Hf, Y, Nb, V, Ta.
With the predominant solid solution phase Ba4Al2Ti10O27, particularly good results have been found, with high stability of the precursor glass prior to ceramizing, and with very high-quality glass-ceramics, in conjunction with very low raw materials costs.
The glass-ceramic of the invention may preferably have a crystalline fraction of least 30 vol %, preferably up to 95 vol %.
The average crystallite size is preferably 10 nm to 50 μm and is situated preferably in the range from 100 nm to 1 μm.
The glass-ceramic of the invention is suitable in particular as a dielectric for a dielectric resonator, an electronic frequency filter element, or an antenna element, in the high-frequency range (f>200 MHz).
Suitable more particularly is its use as a dielectric for a cylindrical antenna element or a patch antenna element.
A dielectric of the invention having a dielectric loss of not more than 10−2 in the high-frequency range can be produced with the following steps:

    
    
        melting and homogenizing a starting glass which comprises the following constituents (in mol % on oxide basis):
    
    


SiO2 1-30
Al2O3 0-20
B2O3 0-25
TiO2 10-70
RE2O3 0-<5
BaO 5-35
SiO2+Al2O3+B2O3<25
where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part, preferably up to 10% of the obligatory fraction, by Zr, Hf, Y, Nb, V, Ta;
pouring the starting glass into a desired shape;
cooling the starting glass to room temperature;
ceramizing the starting glass by a heat treatment.
Preference is given in this context to the use of a starting glass which comprises at least the following constituents (in mol % on oxide basis):
SiO2 2-20
Al2O3 0-15
B2O3 0-20
TiO2 25-65
ZrO2 1-15
RE2O3 0-<5
BaO 10-30
SiO2+Al2O3+B2O3≦20,
where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part, preferably up to 10% of the obligatory fraction, by Hf, Nb, V, Ta.
Used with further preference in this context is a starting glass which comprises at least the following constituents (in mol % on oxide basis):
SiO2 2-20
Al2O3 0-15
B2O3 0-5
TiO2 40-65
ZrO2 5-12
RE2O3 0-<5
BaO 10-30
10≦SiO2+Al2O3+B2O3≦20,
where RE is lanthanum, another lanthanoid, or yttrium, and where Ti may be replaced in part, preferably up to 10% of the obligatory fraction, by Hf, Nb, V, Ta.
The starting glass is brought preferably by a melting process into a near net shape.



BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention will become apparent from the description hereinafter of preferred working examples, with reference to the drawing. In the drawing:
FIG. 1 shows the result of a DTA of a first working example;
FIG. 2 shows the result of a DTA of a second working example;
FIG. 3 shows a compilation of the key properties of an experimental series of inventive glass-ceramics, comprising Ba4Al2Ti10O27 as predominant solid solution phase, as a function of the ceramizing temperature;
FIG. 4 shows an x-ray diffractometer analysis (XRD) and a DTA analysis of two samples comprising as predominant solid solution phase Ba4Al2Ti10O27;
FIG. 5 shows an x-ray diffractometer analysis (XRD) and a DTA analysis of a further sample with the predominant solid solution phase Ba4Al2Ti10O27 with small additions of ZnO and B2O3; and
FIG. 6 shows the state diagram of B2O3—CaO, which was added as a flux agent in eutectic composition in the case of the sample according to FIG. 5.



EXAMPLES
Assembled in table 1 are various glass compositions for a starting glass in the Ba—Ti—Zr—Si—O system, in some cases with additions of Al, B, RE.
The various glass samples of examples 1 to 7 are first of all conventionally melted and homogenized using customary starting materials; platinum crucibles, Pt/Ir crucibles, Pt/Rh crucibles, fused silica crucibles, or aluminum oxide crucibles may be used. The samples are melted first at 1350° C. for 2 hours, then refined at 1400° C. for 30 minutes, stirred and homogenized for 20 minutes with a platinum stirrer, allowed to stand for 10 minutes, and then poured off into suitable molds made of steed, graphite, aluminum oxide, or fused silica, for instance, and hence brought into a near net shape.
After cooling to room temperature, the glass is subjected to a ceramizing step.
A typical ceramizing cycle by means of an infrared furnace is as follows:

    
    
        heating at 300 K/min to 1050° C.;
        holding at 1050° C. for 7 seconds;
        heating to 1203° C. at a heating rate of 50 K/min;
        holding at 1200° C. for 15 minutes;
        cooling to about 500° C. by switching off the furnace, with a cooling rate of about 50 K/min;
        removal of the sample from the furnace when a temperature of about 500° C. is reached.
    
    


An alternative option is to carry out a ceramizing cycle in a conventional oven, by heat treatment at 925° C. over 0.5 to 20 hours.
Where necessary, the moldings, after having been poured, may be further finished by a grinding or polishing treatment or, in the case of the production of cylindrical moldings, may be subjected to centerless cylindrical grinding.
FIG. 1 shows a differential thermal analysis (DTA) of example 5 as per table 1. The peaks show the formation of different crystal phases, with the predominant crystal phase being BaTi4O9.
FIG. 2 shows a DTA of example 6 as per table 1. The peaks show the formation of crystal phases, with the peak at the lowest temperature, at 841° C. indicating the formation of BaTi4O9.
In the case of the glass compositions in the BaO—SiO2—TiO2 system as per table 1, the relevant glasses lie outside of the range in which stable glasses are likely according to the BaO—SiO2—TiO2 state diagram. Only by Ti→Zr, Ba→La, and Si→Al, B replacement, in other words by the use of solid solutions, in other words disorder in the crystal phase as well at the Ba and Ti site, was it possible to extend the glass formation range accordingly (stable starting glasses are of course a basic prerequisite for reproducible glass-ceramics having homogeneous properties).
The volume fraction of the crystalline phase in the case of examples 1 to 7 according to table 1 lies in the order of magnitude of about 30 to 60 vol %.
The relative permittivities ∈r of samples 1 to 7 were measured, and were all greater than 15 and situated in the range from 20 to 50.
The samples are further notable for a low dielectric loss and a high quality.
Quality Q is the reciprocal of the dielectric loss (tan δ):

Q=1/tan(δ).

The quality is measured by the Hakki-Coleman resonance method. In this case, the quality factor is determined as a product of quality Q and measuring frequency f0. The measurements were conducted at about 7 to 8 GHz.
Apart from example 1, all examples had a quality factor Q·f0 in the range of more than 1000 GHz. For example 5, a quality Q of 418 was measured at 7.547 GHz, in other words a quality factor of 3155 GHz.
The absolute value of the temperature coefficient of the resonance frequency is very low for all of the samples measured.
In the case of applications as a dielectric for antennas that are suitable in particular as mobile GPS antennas for cell phones, the frequency range is located above 200 MHz, more particularly in the range from about 800 MHz to 70 GHz. The dielectric charging of the antenna reduces the sensitivity of the antenna to detuning by the user.
Summarized in Table 2 are the compositions of a series of further inventive glasses as precursor glasses. The associated ceramizing data are given in tables 2a and 2b. The melt 39976 corresponds in its composition to the melt 39998. It is, however, a melt in a liter volume, with which ceramizing tests were run additionally, in accordance with table 2b, at different temperatures. For the glass-ceramics in question, the solid solution phase formed primarily was Ba4Al2Ti10O27; cf. the associated FIG. 4 with XRD (x-ray diffractometer) and DTA of a number of samples from table 2a. It is found that ceramizing in a conventional oven at 1000° C. to 1010° C. over 6 hours is optimal, with similar results at 1058° C. over 15 minutes.
Tables 3 and 3a compile further melts and glass-ceramics produced from them, with the associated properties.
In these cases, the melts, consisting of BaO, TiO2, ZrO2, SiO2, Al2O3, La2O3, were admixed with small additions, of between 0.0125 mol % and 0.075 mol %, of ZnO and B2O3 in a eutectic composition. As is apparent from table 3a, even very small additions of 0.0125 mol % lead to high quality factors and very low dielectric losses.
Further precursor glasses, melted with small additions (0.0125-0.075 mol %) of CaO and B2O3 in the very low-melting eutectic composition of 35.5 mol % CaO and 64.5 mol % B2O3 (cf. FIG. 6), are summarized in table 4. The associated ceramizing conditions for the glass-ceramics produced from them, and the properties measured, are summarized in table 4a. FIG. 5 shows an XRD and a DTA of the sample 40171 (DEM-65). The peak in the DTA at about 1280° C. indicates the formation of the solid solution phase Ba4Al2Ti10O27. As is evident from the XRD, the glass-ceramic comprises predominantly the solid solution phase Ba4Al2Ti10O27.
The precursor glasses in question are stable and can be melted at low temperature in accordance with the procedure described above. The glass-ceramics produced therefrom are notable for particularly good properties. The raw materials for producing them are particularly favorable, and so they are suitable for mass production.
A compilation of the properties of the various glass-ceramics of tables 2 to 4, in which the predominant solid solution phase formed is Ba4Al2Ti10O27, is contained in FIG. 3. The quality factors are situated in the range from about 1000 GHz to about 6000 GHz, with temperature dependencies |τf| obtainable, depending on ceramizing temperature, that are lower than 100 ppm/K and can be brought to close to zero by means of optimized ceramizing conditions (ceramizing time 6 h). The relative permittivities ∈r are in the range from about 25 to 33.









TABLE 1








Composition/mol %
Properties





















No.
BaO
TiO2
ZrO2
SiO2
Al2O3
B2O3
La2O3
f/GHz
Q
Qf/GHz
d/mm
h/mm
εr
tan δ
























1
25
51
9
15



8.212
93
764
9.86
5.11
25.52
0.0106


2
25
52.5
7.5
6
9


9.1257
213
1944
10.05
4.69
22.5
0.0045


3
23
52.5
7.5
6
9

2
8.8686
182
1614
10.05
4.71
23.75
0.0053


4
25
52.5
7.5
5.5
7.5
2

9.178
193
1771
10.03
4.63
22.64
0.005


5
16.5
60
7.5
4.5
8

3.5
7.547
418
3155
10.04
4.82
31.9
0.0023


6
20.5
60
7.5
4
6

2
7.952
223
1773
10.04
4.71
29.55
0.0043


7
20.5
57.5
7.5
6.25
6.25

2
8.105
197
1597
10.04
4.72
28.35
0.0049
























mol %

wt %









39778














BaO
23
BaO
33.6359



TiO2
52.5
TiO2
40.0488



SiO2
6
ZrO2
7.0515



ZrO2
7.5
SiO2
4.2963



Al2O3
9
Al2O3
8.7523



La2O3
2
La2O3
6.2152






100











39779














BaO
22.5
BaO
32.6363



TiO2
52.5
TiO2
39.722



SiO2
6
ZrO2
6.994



ZrO2
7.5
SiO2
4.2613



Al2O3
9
Al2O3
8.6808



La2O3
2.5
La2O3
7.7056






100











39780














BaO
23
BaO
33.6617



TiO2
52.5
TiO2
40.0795



SiO2
5.85
ZrO2
6.8805



ZrO2
7.5
SiO2
4.2996



Al2O3
9
Al2O3
8.759



La2O3
2
La2O3
6.22



B2O3
0.15
B2O3
0.0997






100











39781














BaO
23.5
BaO
34.6522



TiO2
52.5
TiO2
40.3809



SiO2
6
ZrO2
7.11



ZrO2
7.5
SiO2
4.3319



Al2O3
9
Al2O3
8.8249



La2O3
1.5
La2O3
4.7001






100


























TABLE 2a





Melt
Ceram.
Tcer./
Freq./

Qf/
d/
h/




No.
No.
° C.
GHz
Q
GHz
mm
mm
εr
tan δ
























39778
Glass

10.08
200
2016
9.91
4.41
20.1
0.0048


39778
 26
 859-6 h
10.32
160
1651.2
10.14
3.64
24.1
0.0059


39778
843
1011-6 h
7.61
297
2260.17
9.99
4.81
31.6
0.0032


39778
844
1058-6 h
7.447
689
5130.98
10
4.82
32.9
0.0013


39779
Glass

10.05
189
1899.45
9.89
4.42
20.2
0.005


39779
 27
 865-6 h
9.859
209
2060.53
10.24
3.64
26.9
0.0049


39779
 30
1006-6 h
7.367
1151
8479.42
10.17
4.81
33.28



39779
845
1006-15 min
7.553
305
2303.67
9.99
4.82
32
0.0032


39779
846
1053-15 min
7.23
509
3680.07
9.95
4.82
34.1
0.0019


39780
Glass

10.11
202
2042.22
9.89
4.42
19.95
0.0047


39780
847
 985
8.186
161
1317.946
10
4.83
27.1
0.0061


39780
891
1031
7.549
405
3057.345
10.28
4.68
32.9
0.0023


39780
 31
1033
7.406
857
6346.94
10.19
4.82
32.8



39781
Glass

10.15
191
1938.65
9.9
4.42
19.75
0.005

























TABLE 2B





Melt No.
Ceram. No.
Tcryst./° C.
Freq./ GHz
Q
Qf/GHz
d/mm
h/mm
εr
tan δ

























39976
Glass


9.207
199
1832.193
10.36
5.03
19.82 
0.0048


39976
DEM-40
840-6
h
8.62
193
1663.66
10.4
4.68
24.6
0.005


39976
DEM-68
875-6
h
8.048
242
1947.616
10.36
4.94
26.6
0.004


39976
DEM-69
900-6
h
8.086
227
1835.552
10.36
5.05
25.62
0.0043


39976
DEM-50
950-6
h
7.354
520
3824.08
10.25
4.95
32
0.0018


39976
DEM-51
975-6
h
7.289
595
4336.955
10.25
4.96
32.52
0.0016


39976
DEM-52
1000-6
h
7.305
807
5895.135
10.27
4.95
32.4
0.0011


39976
DEM-41
1010-6
h
7.307
804
5874.82
10.31
5.05
31.5
0.0011


39976
DE-893
1058-15
min
7.781
525
4084.5
10.33
4.68
30.4
0.0018


39778
DEM-26
859-6
h
10.32
160
1651.2
10.14
3.64
24.1
0.0059


39778
DE-843
1011-15
min
7.61
297
2260.17
9.99
4.81
31.6
0.0032


39778
DE-844
1058-15
min
7.447
689
5130.98
10
4.82
32.9
0.0013


















TABLE 3






mol %
wt %





















40169 mol %




















BaO
23
98.9875
22.99713
BaO
22.99713
BaO
33.33165


TiO2
52.5

52.49344
TiO2
52.49344
TiO2
39.68647


ZrO2
7.5

7.499063
ZrO2
7.499063
ZrO2
8.734625


SiO2
6

5.99925
SiO2
5.99925
SiO2
3.405951


Al2O3
9

8.998875
Al2O3
8.998875
Al2O3
8.673096


La2O3
2

1.99975
La2O3
1.99975
La2O3
6.15899






ZnO
0.008925
ZnO
0.006866






B2O3
0.003575
B2O3
0.002353


ZnO
71.4
0.0125
0.008925



100


B2O3
28.6

0.003575

















40170




















BaO
23
99.975
22.99425
BaO
22.99425
BaO
33.32857


TiO2
52.5

52.48688
TiO2
52.48688
TiO2
39.68281


ZrO2
7.5

7.498125
ZrO2
7.498125
ZrO2
8.73382


SiO2
6

5.9985
SiO2
5.9985
SiO2
3.405637


Al2O3
9

8.99775
Al2O3
8.99775
Al2O3
8.672296


La2O3
2

1.9995
La2O3
1.9995
La2O3
6.158423






ZnO
0.01785
ZnO
0.013733






B2O3
0.00715
B2O3
0.004706


ZnO
71.4
0.025
0.01785



100


B2O3
28.6

0.00715

















40171




















BaO
23
99.95
22.9885
BaO
22.9885
BaO
33.32243


TiO2
52.5

52.47375
TiO2
52.47375
TiO2
39.67549


ZrO2
7.5

7.49625
ZrO2
7.49625
ZrO2
8.732209


SiO2
6

5.997
SiO2
5.997
SiO2
3.405009


Al2O3
9

8.9955
Al2O3
8.9955
Al2O3
8.670696


La2O3
2

1.999
La2O3
1.999
La2O3
6.157287












ZnO
0.0357
ZnO
0.027469


















B2O3
0.0143
B2O3
0.009412


ZnO
71.4
0.05
0.0357



100


B2O3
28.6

0.0143

















40172




















BaO
23
99.925
22.98275
BaO
22.98275
BaO
33.31628


TiO2
52.5

52.46063
TiO2
52.46063
TiO2
39.66817


ZrO2
7.5

7.494375
ZrO2
7.494375
ZrO2
8.730597


SiO2
6

5.9955
SiO2
5.9955
SiO2
3.40438


Al2O3
9

8.99325
Al2O3
8.99325
Al2O3
8.669096


La2O3
2

1.9985
La2O3
1.9985
La2O3
6.156151






ZnO
0.05355
ZnO
0.041206






B2O3
0.02145
B2O3
0.014119


ZnO
71.4
0.075
0.05355



100


B2O3
28.6

0.02145

























TABLE 3A





Melt No.
Ceram. No.
Tcryst./° C.
Freq./GHz
Q
Qf/GHz
d/mm
h/mm
εr
tan δ


















(39778 − 99.925) · ((0.714ZnO · 0.286B2O3) − 0.075)



















40172
DEM-64
1040
7.4102
1238.17
9175.087
10.27
4.73
33.27
6.88*10−4











(39778 − 99.95) · ((0.714ZnO · 0.286B2O3) − 0.05)




















40171
DEM-65
1040
7.4239
1196.04
8879.281
10.26
4.73
33.18
7.17*10−4











(39778 − 99.975) · (0.714ZnO · 0.286B2O3) − 0.025)




















40170
DEM-66
1041
7.3872
1206.91
8915.686
10.24
4.72
33.64
7.15*10−4










(39778 − 99.9875) · (0.714ZnO · 0.286B2O3) − 0.0125)



















40169
DEM-67
1041
7.3839
1233.6 
9108.779
10.33
4.73
33.36
6.78*10−4





Ceramizing time: 6 h


















TABLE 4






mol %
mol %


wt %





















40173




















BaO
23
99.9875
22.99713
BaO
22.99713
BaO
33.33217


TiO2
52.5

52.49344
TiO2
52.49344
TiO2
39.68709


ZrO2
7.5

7.499063
ZrO2
7.499063
ZrO2
8.734761


SiO2
6

5.99925
SiO2
5.99925
SiO2
3.406004


Al2O3
9

8.998875
Al2O3
8.998875
Al2O3
8.673231


La2O3
2

1.99975
La2O3
1.99975
La2O3
6.159087






B2O3
0.008063
B2O3
0.005306






CaO
0.004438
CaO
0.002352


CaO
35.5
0.0125
0.004438



100


B2O3
64.5

0.008063

















40174




















BaO
23
99.975
22.99425
BaO
22.99425
BaO
33.32961


TiO2
52.5

52.48688
TiO2
52.48688
TiO2
39.68405


ZrO2
7.5

7.498125
ZrO2
7.498125
ZrO2
8.734092


SiO2
6

5.9985
SiO2
5.9985
SiO2
3.405743


Al2O3
9

8.99775
Al2O3
8.99775
Al2O3
8.672567


La2O3
2

1.9995
La2O3
1.9995
La2O3
6.158615






B2O3
0.016125
B2O3
0.010613






CaO
0.008875
CaO
0.004705


CaO
35.5
0.025
0.008875



100


B2O3
64.5

0.016125

















40175




















BaO
23
99.95
22.9885
BaO
22.9885
BaO
33.32451


TiO2
52.5

52.47375
TiO2
52.47375
TiO2
39.67797


ZrO2
7.5

7.49625
ZrO2
7.49625
ZrO2
8.732754


SiO2
6

5.997
SiO2
5.997
SiO2
3.405221


Al2O3
9

8.9955
Al2O3
8.9955
Al2O3
8.671238


La2O3
2

1.999
La2O3
1.999
La2O3
6.157671






B2O3
0.03225
B2O3
0.021228






CaO
0.01775
CaO
0.009411


CaO
35.5
0.05
0.01775



100


B2O3
64.5

0.03225

















40176




















BaO
23
99.925
22.98275
BaO
22.98275
BaO
33.3194


TiO2
52.5

52.46063
TiO2
52.46063
TiO2
39.67189


ZrO2
7.5

7.494375
ZrO2
7.494375
ZrO2
8.731415


SiO2
6

5.9955
SiO2
5.9955
SiO2
3.404699


Al2O3
9

8.99325
Al2O3
8.99325
Al2O3
8.669909


La2O3
2

1.9985
La2O3
1.9985
La2O3
6.156727






B2O3
0.048375
B2O3
0.031845






CaO
0.026625
CaO
0.014118


CaO
35.5
0.075
0.026625



100


B2O3
64.5

0.048375

























TABLE 4a





Melt
Ceram.
Tcryst./
Freq./

Qf/
d/
h/




No.
No.
° C.
GHz
Q
GHz
mm
mm
εr
tan δ


















(39778 − 99.9875) · ((0.355CaO•0.645B2O3) − 0.075)/mol %



















40176
DEM-70
864
8.155
195
1590.22
10.28
4.97
25.8
0.005 


40176
DEM-74
950
7.831
282
2208.34
10.36
5.05
27.31
0.0034


40176
DEM-73
975
7.016
402
2820.43
10.36
5.07
33.9
0.0024


40176
DEM-72
1000
6.965
647
4506.355
10.37
5.07
34.37
0.0015


40178
DEM-60
1041
7.419
1223
9073.437
10.27
4.74
33.11
6.97*10−4










(39778 − 99.85) · ((0.355CaO•0.645B2O3) − 0.05)/mol %



















40175
Glass

9.243
181
1672.983
10.36
5.03
19.66
0.0053


40175
DEM-61
1039
7.425
1196.62
8884.904
10.27
4.72
33.22
6.14*10−4










(39778 − 99.975) · ((0.355CaO•0.645B2O3) − 0.025)/mol %



















40174
DEM-80
863
8.146
205
1669.93
10.35
5.07
25.1
0.0047


40174
DEM-79
950
7.785
292
2273.22
10.36
5.07
27.52
0.0033


40174
DEM-78
975
7.109
418
2971.562
10.35
5.06
33.13
0.0023


40174
DEM-77
1000
6.984
667
4658.328
10.35
5.07
34.25
0.001 


40174
DEM-62
1041
7.408
1154.11
8549.647
10.29
4.74
33.15
7.47*10−4










(39778 − 99.9875) · ((0.355CaO•0.645B2O3) − 0.0125)/mol %



















40173
Glass

9.218
185
1705.33
10.36
5.03
19.77
0.0052


40173
DEM-63
1044
7.418
1192.11
8840.888
10.3
4.73
33.14
7.15*10−4





Ceramizing time: 6 h

## Claims

1. A glass-ceramic comprising at least the following constituents (in mol % on oxide basis):
SiO2 1-<25
Al2O3 0-20
B2O3 0-<24
TiO2 10-70
RE2O3 0.1-<4.9
BaO 5-35
SiO2+Al2O3+B2O3<25
wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

2. The glass-ceramic of claim 1, comprising at least the following constituents (in mol % on oxide basis):
SiO2 2-20
Al2O3 0-15
B2O3 0-18
TiO2 25-65
ZrO2 1-15
RE2O3 0.1-<4.9
BaO 10-30
SiO2+Al2O3+B2O3≦20,
wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

3. The glass-ceramic of claim 2, comprising at least the following constituents (in mol % on oxide basis):
SiO2 2-20
Al2O3 0-15
B2O3 0-5
TiO2 40-65
ZrO2 5-12
RE2O3 0.1-<4.9
BaO 10-30
10≦SiO2+Al2O3+B2O3≦20,
wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

4. The glass-ceramic of claim 1, comprising at least the following constituents (in mol % on oxide basis):
SiO2 4-8
Al2O3 7-11
B2O3 0-1
TiO2 45-55
ZrO2 5-10
RE2O3 0.1-<4.9
BaO 15-30
10≦SiO2+Al2O3+B2O3≦20,
wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

5. The glass-ceramic of claim 1, comprising at least the following constituents (in mol % on oxide basis):
SiO2 4.5-7
Al2O3 8-10
B2O3 0-0.5
TiO2 48-55
ZrO2 6-9
RE2O3 0.1-<4.9
BaO 20-26
wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

6. The glass-ceramic of claim 1, comprising at least 0.005 mol % of a melting additive.

7. The glass-ceramic of claim 6, wherein the melting additive is a low-melting additive of a eutectic composed of glass-forming components.

8. The glass-ceramic of claim 1, comprising 0.01 up to 3 mol % of at least one refining agent selected from the group consisting of As2O3 and Sb2O3.

9. The glass-ceramic of claim 1, comprising a dielectric loss (tan δ) of not more than 10−2 in the high-frequency range at a frequency f>200 MHz.

10. The glass-ceramic of claim 1, having a relative permittivity ∈ of at least 15.

11. The glass-ceramic of claim 1, having a resonance frequency with a certain temperature dependence, wherein an absolute value of said temperature dependence of said resonance frequency |τf| not more than 200 ppm/K.

12. The glass-ceramic of any of claim 1, comprising at least one solid solution phase based on Ba, Ti, and O, wherein Ba may be replaced at least in part by at least one constituent selected from the group consisting of Sr, Ca, and Mg, and wherein Ti may be replaced at least in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

13. The glass-ceramic of claim 12, wherein said least one solid solution phase based on Ba, Ti, and O, further comprises at least one selected from the group consisting of Al, RE, and Si, wherein RE is selected from the group consisting of a lanthanoid and yttrium.

14. The glass-ceramic of claim 1, comprising at least one solid solution phase of the formula (BaO)x(RE2O3)y(SiO2)z(TiO2)u, wherein RE is selected from the group consisting of a lanthanoid, and yttrium, wherein x, y, and z are all positive integer numbers smaller than five, wherein up to 10% of Ba may be replaced by at least one constituent selected from the group consisting of Sr, Ca, and Mg, and wherein up to 10% of the obligatory fraction of Ti may be replaced by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta.

15. The glass-ceramic of claim 1, comprising as predominant solid solution phase BaTi4O9, wherein Ba may be replaced in part by at least one constituent selected from the group consisting of La, Ca, and Sr, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Y, Nb, V, and Ta.

16. The glass-ceramic of claim 1, comprising as predominant solid solution phase Ba4Al2Ti10O27, wherein Ba may be replaced in part by at least one constituent selected from the group consisting of La, Ca, and Sr, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Y, Nb, V, and Ta.

17. The glass-ceramic of claim 1, having an average crystallite size of 10 nanometers to 50 micrometers.

18. A dielectric resonator, electronic frequency filter element, or antenna element for the high-frequency range, having a dielectric comprising a glass-ceramic according to claim 1.

19. A method of producing a dielectric having a dielectric loss of not more than 10-2 in the high-frequency range, comprising the following steps:
melting and homogenizing a starting glass which comprises the following constituents (in mol % on oxide basis):
SiO2 1-<25
Al2O3 0-20
B2O3 0-25
TiO2 10-70
RE2O3 0.1-<4.9
BaO 5-35
SiO2+Al2O3+B2O3<25

wherein RE is selected from the group consisting of a lanthanoid and yttrium, and wherein Ti may be replaced in part by at least one constituent selected from the group consisting of Zr, Hf, Nb, V, and Ta;
pouring the starting glass into a desired shape;
cooling the starting glass to room temperature;
ceramizing the starting glass by a heat treatment.

20. The glass-ceramic of claim 1, wherein the RE2O3 is present (in mol % on oxide basis) in an amount of 1 to 3.5.