JP6930827B2 - Glass dielectric - Google Patents

Description

The present invention relates to glass having a high dielectric constant and dielectric breakdown strength, and is suitably used as a dielectric material for circuit boards and electronic components mounted on communication devices and electronic devices, large-capacity high-voltage capacitors, and the like.

In recent years, we have entered an era of advanced information such as mobile communications such as automobile phones and personal radios, mobile phones, satellite broadcasting, satellite communications, and CATV, and information transmission has become faster and higher in frequency. There is a tendency, and further, these devices are required to be miniaturized, and along with this, the circuit elements are also strongly required to be miniaturized.

For example, the size of a microwave circuit element is based on the wavelength of the electromagnetic wave used. That is, the wavelength (λ) of an electromagnetic wave propagating in a dielectric having a dielectric constant (ε) is λ = λ ₀ / (ε ^1/2 _{), where λ 0} is the wavelength in vacuum, and λ is the square root of ε. Inversely proportional. Therefore, in order to reduce the size of the microwave circuit element, a material having a high dielectric constant is required.

In addition, capacitors with high energy storage density used in excimer lasers used in semiconductor processing and vision correction surgery, medical X-rays, power storage devices (industrial high-voltage power supplies, starting power supplies for electric vehicles, etc.), power transmission equipment, etc. Demand for power transmission has increased in recent years. High energy storage because the energy storage density of the capacitor is _{expressed by (1/2) × ε 0} ε r E ² (ε ₀ : vacuum dielectric constant, ε _r : material dielectric constant, E: dielectric breakdown strength) In order to obtain a density, a dielectric having both a high dielectric constant and a high dielectric breakdown strength is desired.

As glass having a high permittivity, for example, Patent Document 1 states that SiO ₂ is 40 to 65 mol%, at least one of MgO, CaO, SrO and BaO is 20 to 45 mol%, and at least one of _{TiO 2} and ZrO _{2 is 5.} It contains ~ 25 mol% _{and 0.5 ~ 15 mol% of NbO 5/2} , respectively, and the total amount of these oxides is 85 mol% or more, and the relative permittivity (1 MHz, 25 ° C.) 9 or more is suitable for fibrosis. A glass composition having the above is described.
Further, for example, in Patent Document 2, the dielectric constant at 1 to 5 GHz is 18 or more, _{the content of TeO 2} is 50 to 95 mol%, and further, Na ₂ O, BaO, ZnO, MoO ₃ , Al ₂ O High dielectric constant tellurite glass containing 5 to 50 mol% of one or more selected from ₃ , Nb ₂ O ₅ , Sb ₂ O ₃ , and Bi ₂ O _{3 is described.}

Japanese Unexamined Patent Publication No. 5-63323 Japanese Unexamined Patent Publication No. 2005-281923

However, conventionally, it has been known that the dielectric breakdown strength tends to decrease as the dielectric constant increases. That is, there is a trade-off relationship between the dielectric constant and the dielectric breakdown strength, and it has been difficult to increase both of them.

The present inventor studied diligently and found a glass dielectric capable of solving the above-mentioned problems with a composition system different from the existing technology, and completed the present invention.
The present invention is the following (1) to (6).
_{(1) P 2} O ₅ component 15.0% to 40.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
TiO ₂ component 1.0% -40.0%,
Nb ₂ O ₅ component 5.0% -40.0%,
Mole sum (BaO + ZnO) 3.0% to 50.0%
A glass dielectric having a dielectric constant of 20 or more at 1 kHz.
_{(2) SiO 2} component 0 to 20.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
B ₂ O ₃ component 0 to 20.0%,
Al ₂ O ₃ component 0 to 10.0%,
ZnO component 0-30.0%,
BaO component 0-30.0%,
SrO component 0-30.0%,
CaO component 0-30.0%,
MgO component 0-30.0%,
Li ₂ O component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 15.0%,
WO ₃ component 0-20.0%,
Ta ₂ O ₅ component 0 to 15.0%
ZrO ₂ component 0 to 15.0%
SnO ₂ component 0 to 10.0%,
Sb ₂ O ₃ component 0-10.0%,
F is 0 to 30.0% by outside discount
The glass dielectric according to (1) above, which comprises.
_{(3) Ln 2} O ₃ component (in the formula, Ln is selected from the group consisting of La, Ce, Gd, Y, Dy, Yb, Lu) in mol% with respect to the total amount of substance of the oxide equivalent composition 1 The molar sum of (more than seeds) is 10.0% or less,
The molar sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 50.0% or less.
The molar sum of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is 10.0% or less.
The molar sum of the M _x O _y components (one or more selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo) is 10.0% or less, the above (1). Or the glass dielectric according to (2).
_{(4) The molar sum of the Nb 2} O ₅ component, the TiO ₂ component and the BaO component (Nb ₂ O ₅ component + TiO ₂ component + BaO component) of the oxide conversion composition is 35.0 to 80.0%, as described in (1) above. ) To (3).
(5) The glass dielectric according to any one of (1) to (4) above, wherein the molar ratio (ZnO + MgO + Rn ₂ O) / (TiO ₂ + Nb ₂ O _{5) is 0.7 or less.}
(6) The glass dielectric according to any one of (1) to (5) above, wherein the molar sum (TiO ₂ + Nb ₂ O _{5) is 25.0 to 70.0%.}

According to the present invention, it is possible to provide a glass dielectric having a high dielectric constant and a high dielectric breakdown strength.

It is a figure which shows the measurement result of the dielectric property of an Example.

The present invention will be described.
_{In the present invention, the P 2} O ₅ component is 15.0% to 40.0% in mol% with respect to the total amount of substance in the oxide equivalent composition.
TiO ₂ component 1.0% -40.0%,
Nb ₂ O ₅ component 5.0% -40.0%,
Mole sum (BaO + ZnO) 3.0% to 50.0%
It is a glass dielectric having a dielectric constant ε of 20 or more at 1 kHz.
Such glass is also referred to as "the glass dielectric of the present invention" below.

Since the glass dielectric of the present invention has a high dielectric constant and a high dielectric breakdown strength, it is suitably used as a dielectric material for circuit boards, electronic components, large-capacity high-voltage capacitors, and the like. Further, since the glass dielectric of the present invention does not easily deteriorate the characteristics at high temperature (generally 90 ° C. or higher), it can also be used as a dielectric of a high temperature capacitor.

<Glass component>
The composition range of each component constituting the glass dielectric of the present invention is described below.
In the following, when simply referred to as "%", it shall mean "mol%".
In addition, the glass composition represented by "%" in the specification of the present application shall mean a percentage of the total amount of substance of the oxide equivalent composition. Here, the "oxide-equivalent composition" refers to a composition assuming that all the oxides, nitrates, etc. used as raw materials for the glass dielectric constituents of the present invention are decomposed by melting and changed into oxides. Therefore, the "percentage of the total amount of substances in the oxide equivalent composition" is the total mass of the produced oxides when all the components are present as oxides, which is 100 mol%, and the abundance of each component with respect to the total mass. Means.
In the following, "outer division" means not included in the above "total amount of substances in the oxide conversion composition", and the ratio of outer division is 100 mol% of the total mass of the above-mentioned produced oxides. It is assumed that it means a value expressed as a percentage of the abundance with respect to this.

The P ₂ O ₅ component is an indispensable component for the glass dielectric of the present invention because it constitutes a network structure of glass and enhances the stability of glass. In particular, by _{containing 15.0% or more of the P 2} O ₅ component, glass can be produced more stably. If it is less than 15.0%, it becomes difficult to produce glass. Therefore, _{the content of the P 2} O ₅ component is preferably 15.0% or more, more preferably 18.0% or more, still more preferably 20.0% or more.
On the other hand, by _{setting the content of the P 2} O ₅ component to 40.0% or less, the desired dielectric constant can be obtained more easily. Therefore, _{the content of the P 2} O ₅ component is preferably 40.0% or less, more preferably 38.0% or less, still more preferably 35.0% or less.

The TiO ₂ component has the effect of increasing the stability and dielectric constant of glass, and is an essential component in the glass dielectric of the present invention. If the content of this component is too high, the stability of the glass tends to decrease. Therefore, it is preferably contained in an amount of 40.0% or less, more preferably 35.0% or less, and 30.0%. It is more preferable to contain the following. On the other hand, in order to obtain the above-mentioned effect, the lower limit addition amount is preferably 1.0% or more, more preferably 3.0% or more, and preferably 5.0% or more. More preferred.

The Nb ₂ O ₅ component has the effect of increasing the stability and dielectric constant of the glass, and is an essential component in the glass dielectric of the present invention. In particular, a desired dielectric constant can be obtained by containing 5.0% or more of _{the Nb 2} O _{5 component.} Therefore, _{the content of the Nb 2} O ₅ component is preferably 5.0% or more, more preferably 7.0% or more, still more preferably 10.0% or more.
On the other hand, by _{setting the content of the Nb 2} O ₅ component to 40.0% or less, glass can be stably produced. Therefore, the content of the Nb ₂ O ₅ component is preferably 40.0% or less, more preferably 38.0% or less, still more preferably 35.0% or less.

In the glass dielectric of the present invention, the molar sum (TiO ₂ + Nb ₂ O ₅ ), that is, the total of the content rate (%) of _{TiO 2 and the content rate (%) of Nb 2} O ₅ is 25.0% or more. Is more preferable, 30.0% or more is more preferable, and 35.0% or more is further preferable. Further, the total is preferably 70.0% or less, more preferably 60.0% or less, and further preferably 58.0% or less. If this total amount is too high, the stability of the glass tends to decrease, and conversely, if it is too low, the dielectric constant tends to decrease.

By setting the total amount (BaO + ZnO) of the BaO component and the ZnO component to 50.0% or less, the stability and dielectric properties of the glass are less likely to deteriorate. Therefore, the total amount of the BaO component and the ZnO component is preferably 50.0%. , More preferably 40.0%, most preferably 37.0%. On the other hand, when the total amount of the BaO component and the ZnO component is set to 3.0% or more, the stability and dielectric properties of the glass are improved. Therefore, the total amount is preferably 3.0%, more preferably 5.0. %, More preferably 7.0%, and most preferably 9.0% as the lower limit.

In the glass of the present invention, _{the molar sum of the Nb 2} O ₅ component, the TiO ₂ component and the BaO component (Nb ₂ O ₅ component + TiO ₂ component + BaO component) is preferably 35.0% or more, preferably 38.0% or more. Is more preferable, and 40.0% or more is further preferable. If this total amount (sum of moles) is too low, the permittivity tends to be low.
The total amount (sum of moles) is preferably 80.0% or less, more preferably 68.0% or less, and further preferably 65.0% or less. If this total amount (sum of moles) is too high, the stability of the glass tends to decrease.

The SiO ₂ component has the effect of increasing the stability of the glass and is an optional component in the glass dielectric of the present invention. The specific content is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 5.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The B ₂ O ₃ component has the effect of increasing the stability of the glass and is an optional component in the glass dielectric of the present invention. The specific content is preferably 20.0% or less, more preferably 10.0% or less, more preferably 7.0% or less, and preferably 5.0% or less. More preferred. If the content of this component is too high, the stability of the glass tends to decrease.

The Al ₂ O ₃ component has the effect of increasing the stability of the glass and is an optional component in the glass dielectric of the present invention. The specific content is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The ZnO component has the effect of increasing the meltability, stability and dielectric constant of the glass, and is a component that can be arbitrarily added to the glass dielectric of the present invention. Therefore, it may be contained preferably more than 0%, more preferably 1.0% or more, still more preferably 3.0% or more. On the other hand, if the content of this component is too high, the stability of the glass tends to decrease. Therefore, it is preferably contained in an amount of 30.0% or less, more preferably 28.0% or less, and 25. It is more preferable to contain 0.0% or less.

The BaO component has the effect of increasing the meltability, stability and dielectric constant of glass, and is a component that can be arbitrarily added to the glass dielectric of the present invention. Therefore, it may be contained preferably more than 0%, more preferably 5.0% or more, still more preferably 10.0% or more. On the other hand, if this component is too high, the stability of the glass tends to decrease, so the content is preferably 30.0% or less, more preferably 28.0% or less, still more preferably 25.0% or less.

The SrO component has the effect of increasing the meltability, stability and dielectric constant of glass, and is a component that can be arbitrarily added to the glass dielectric of the present invention. If the content of this component is too high, the stability of the glass tends to decrease. Therefore, it is preferably contained in an amount of 30.0% or less, more preferably 25.0% or less, and 20.0%. It is more preferable to contain the following.

The CaO component has the effect of increasing the meltability and stability of the glass, and is a component that can be arbitrarily added to the glass dielectric of the present invention. If the content of this component is too high, the stability of the glass tends to decrease. Therefore, it is preferably contained in an amount of 30.0% or less, more preferably 25.0% or less, and 20.0%. It is more preferable to contain the following.

The MgO component has the effect of increasing the meltability and stability of the glass, and is a component that can be arbitrarily added to the glass dielectric of the present invention. If the content of this component is too high, the stability of the glass tends to decrease. Therefore, it is preferably contained in an amount of 30.0% or less, more preferably 20.0% or less, and 15.0%. It is more preferable to contain the following.

The glass dielectric of the present invention has an RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) in mol% with respect to the total amount of substance in the oxide equivalent composition. The molar sum of the above is preferably 50.0% or less, more preferably 40.0% or less, and further preferably 37.0% or less. When the content of the RO component is in the above range, the stability and dielectric properties of the glass tend to be improved.

The Li ₂ O component has the effect of increasing the stability of the glass and is an optional component in the glass dielectric of the present invention. The specific content is preferably 10.0% or less, more preferably 5.0% or less, and even more preferably 3.0% or less. If the content of this component is too high, the dielectric breakdown strength of the glass tends to decrease.

The Na ₂ O component has the effect of increasing the stability of the glass and is an optional component in the glass dielectric of the present invention. The specific content is preferably 10.0% or less, more preferably 5.0% or less, and even more preferably 3.0% or less. If the content of this component is too high, the dielectric breakdown strength of the glass tends to decrease.

K ₂ O component is effective for increasing the stability of the glass, an optional component in the glass dielectric of the present invention. The specific content is preferably 15.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less. If this component content is too high, the dielectric constant and dielectric breakdown strength of the glass tend to decrease.

The glass dielectric of the present invention _{is 10.0% because the total amount of the Rn 2} O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) does not reduce the dielectric breakdown strength. It is preferably less than or equal to, more preferably 5.0% or less, further preferably 3.0% or less, and most preferably not contained.

The glass of the present invention preferably has a molar ratio (ZnO + MgO + Rn ₂ O) / (TiO ₂ + Nb ₂ O ₅ ) of 0.7 or less, more preferably 0.65 or less, and more preferably 0.63 or less. Is even more preferable. If the content of this component is too high, the dielectric properties tend to deteriorate.

The WO ₃ component is effective in improving the stability and dielectric constant of glass, and is an optional component in the glass dielectric of the present invention. The specific content is preferably 20% or less, more preferably 10.0% or less, and even more preferably 8.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The Ta ₂ O ₅ component is effective in improving the stability and dielectric constant of glass, and is an optional component in the glass dielectric of the present invention. The specific content is preferably 15.0% or less, more preferably 10.0% or less, more preferably 5.0% or less, and preferably 3.0% or less. More preferred. If the content of this component is too high, the stability of the glass tends to decrease.

The ZrO ₂ component is an optional component in the glass dielectric of the present invention because it is effective in improving the stability and dielectric constant of glass. The specific content is preferably 15.0% or less, more preferably 10.0% or less, more preferably 8.0% or less, and preferably 5.0% or less. More preferred. If the content of this component is too high, the stability of the glass tends to decrease.

The SnO ₂ component is an optional component in the glass dielectric of the present invention because it is effective in improving the dielectric properties. The specific content is preferably 10.0% or less, more preferably 5.0% or less, and even more preferably 3.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Ce, Gd, Y, Dy, Yb, and Lu) is effective in improving the dielectric properties, and the glass of the present invention. It is an optional component in the dielectric. The total content (sum of moles) of these is preferably 10.0% or less, more preferably 5.0% or less, and even more preferably 3.0% or less. If the content of these components is too high, the stability of the glass tends to decrease.

The M _x O _y component (one or more selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo) is effective in improving the dielectric properties, and the glass dielectric of the present invention is effective. It is an optional component in the body. The total of these contents (sum of moles) is preferably 10.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, and 1.0%. The following is more preferable. If the content of these components is too high, the stability of the glass tends to decrease.

The F component is an optional component in the glass dielectric of the present invention because it enhances the stability of the glass. The content is preferably 30.0% or less, more preferably 15.0% or less, and even more preferably 8.0% or less. If the content of this component is too high, the dielectric properties and dielectric breakdown strength tend to decrease.

The Sb ₂ O ₃ component is an optional component in the glass dielectric of the present invention because it has the effect of a defoaming agent for glass and further contributes to the improvement of the dielectric property. The specific content is preferably 10.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, and preferably 1.0% or less. More preferred. If the content of this component is too high, the stability of the glass tends to decrease.

The glass dielectric of the present invention has a dielectric constant ε of 20 or more at 1 kHz. The dielectric constant ε is preferably 21 or more, and more preferably 24 or more.
In the present invention, the dielectric constant and the dielectric loss were measured over a frequency from 10 Hz to 1 MHz using an impedance analyzer (for example, SI1260 manufactured by Solartron), and the value at 1 kHz was taken as the dielectric constant and the dielectric loss of the present invention.

<Use>
Since the glass dielectric of the present invention can be formed into any shape, it can be used as various dielectrics. For example, it is used as a dielectric material such as a circuit board and an electronic component mounted on a communication device or an electronic device, and a large-capacity high-voltage capacitor. Capacitors are used for buffering, coupling and smoothing current fluctuations in power converters. High-voltage capacitors are indispensable parts for excimer laser equipment used in semiconductor processing and vision correction surgery, medical X-ray equipment, industrial high-voltage power supplies, and renewable energy power transmission systems. In addition to being used alone for the above purposes, these glasses can also be used in the form of composites with other dielectrics in the form of fibers, powders, pastes and the like. Specifically, a dielectric substrate having a pattern electrode formed on the substrate, a laminated substrate material, a dielectric resonance element, a firing aid for the dielectric material, and a dielectric paste (dielectric powder is contained in a vehicle made of an organic compound or the like). It is suspended and is usually used by forming a film on an electrode by screen printing or punching type printing).

<Manufacturing method>
The glass dielectric of the present invention is not particularly limited as long as it is a method for producing ordinary glass, but can be produced by, for example, the following method. Each starting material (oxide, carbonate, nitrate, phosphate, sulfate, etc.) is weighed in a predetermined amount and mixed uniformly. The mixed raw materials are put into a quartz crucible, an alumina crucible or a platinum crucible, and melted in a melting furnace in a temperature range of 1200 to 1450 ° C. for 1 to 12 hours. Then, after stirring and homogenizing, the temperature is lowered to an appropriate temperature and cast into a mold or the like to manufacture glass. When used in the form of fibers, the plate-like glass is remelted to obtain glass fibers, but glass fibers may be obtained directly from the first solution. Also, when used as a firing aid, filler or dielectric paste for ceramic dielectrics, the molded bulk glass may be crushed, or the first solution may be poured into water to obtain cullet and then crushed. You may.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Example 1)
_{Composition: 25P 2 O 5 -15TiO 2 -25Nb} 2 O 5 -15BaO-3SrO-10CaO-7ZnO ( mol%)
_{Raw materials (TiO 2} , Nb ₂ O ₅ , Ba (PO ₃ ) ₂ , Sr (NO ₃ ) ₂ , Ca (PO ₃ ) ₂ , ZnO) are mixed so as to have the above composition, mixed well, and then quartz. It was placed in a crucible and melted at 1260 ° C. for 1 hour. Then, the melt was transferred to a platinum crucible, melted for another 2 hours, homogenized by stirring, and then the melt was poured into a mold to obtain a plate-shaped glass. The obtained glass was processed to about 30 mm × 30 mm × 1 mm, gold electrodes were vapor-deposited on both sides, and then the dielectric property was evaluated by an impedance analyzer (SI1260 manufactured by Solartron Co., Ltd.). The result is shown in FIG. From this figure, it can be seen that both the dielectric constant and the dielectric loss of the glass of this composition hardly changed with frequency. The permittivity ε and the dielectric loss at 1 kHz were 27 and 0.0040, respectively.
The dielectric breakdown strength was 79 kV / mm. The dielectric breakdown strength was measured according to JIS C 2141 using a sample having a thickness of 1 mm.

Examples 2 to 25 and Comparative Example 1 were prepared in a manner similar to that of Example 1. The compositions and dielectric properties of each Example and Comparative Example are summarized in Tables 1-4. The dielectric breakdown strength is summarized in Table 5. It can be seen that the glass dielectric of the present invention has the same dielectric constant as that of Example 1, but the dielectric loss is an order of magnitude lower and the dielectric breakdown strength is more than twice as high.

Claims (5)

The total amount of substance of the oxide composition in terms of, P ₂ O ₅ ingredient 22.0% 40.0% in mol%,
TiO ₂ component 1.0% -40.0%,
Nb ₂ O ₅ component 5.0% -40.0%,
BaO component over 0% to 30.0%,
SiO ₂ component 0 to 5.0% or less B ₂ O ₃ component 0 to 7.0%,
Mole sum (BaO + ZnO) 3.0% to 50.0%,
It contains a molar ratio (ZnO + MgO + Rn ₂ O) / (TiO ₂ + Nb ₂ O ₅ ) of 0.36 or less (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) and has a dielectric constant at 1 kHz. A glass dielectric having a value of 20 or more. _{Al 2} O ₃ component 0 to 10.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
SrO component 0-30.0%,
CaO component 0-30.0%,
MgO component 0-30.0%,
ZnO component 0-30.0%,
Li ₂ O component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 15.0%,
WO ₃ component 0-20.0%,
Ta ₂ O ₅ component 0 to 15.0%
ZrO ₂ component 0 to 15.0%
SnO ₂ component 0 to 10.0%,
Sb ₂ O ₃ component 0 to 10.0%,
F is 0 to 30.0% by outside discount
The glass dielectric according to claim 1, wherein the glass dielectric contains. _{Ln 2} O ₃ component in mol% with respect to the total amount of substance in the oxide conversion composition (Ln is one or more selected from the group consisting of La, Ce, Gd, Y, Dy, Yb, and Lu). The molar sum of is 10.0% or less,
The molar sum of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 50.0% or less.
The molar sum of the Rn ₂ O components is 10.0% or less,
The first or second claim, wherein the molar sum of the MxOy components (one or more selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo) is 10.0% or less. Glass dielectric. _Nb 2 _{O 5} component of the oxide composition in terms of molar sum of TiO ₂ component and BaO components _(Nb 2 _{O 5} component + TiO ₂ component + BaO component) is from 35.0 to 80.0%, of claims 1 to 3 The glass dielectric according to any. The glass dielectric according to any one of claims 1 to 4 , wherein the molar sum (TiO ₂ + Nb ₂ O ₅ ) is 25.0 to 70.0%.

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