JP7027128B2 - Dielectric - Google Patents

Description

The present invention relates to a glass ceramic dielectric having 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 the electromagnetic wave propagating in the dielectric of the 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 relative permittivity 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, start-up power supplies for electric vehicles, etc.), power transmission equipment, etc. Demand for laser has been increasing in recent years. High energy storage because the energy storage density of the condenser is expressed by (1/2) × ε ₀ ε _r E ² (ε ₀ : vacuum dielectric constant, ε _r : material permittivity, E: insulation breakdown strength) In order to obtain the density, a dielectric having both a high dielectric constant and a high insulation breakdown strength is desired.

Proposals have been made to use glass ceramics as a dielectric material used for circuit boards and electronic components (for example, Patent Documents 1 to 4). In all of the proposals of Patent Documents 1 to 4, since the glass powder and the inorganic filler are mixed, molded and fired, the denseness is low, pores and voids are generated, and the material becomes a uniform material. It is difficult to obtain the desired dielectric constant and dielectric breakdown strength due to the reaction of the inorganic filler with the glass.

On the other hand, although dielectric glass ceramics in which SrTiO ₃ crystals are precipitated by heat-treating SiO ₂ -TIO ₂ -SrO-based glass (for example, Patent Document 5), the dielectric constant is as low as about 30. ..

Japanese Unexamined Patent Publication No. 2004-339049 JP-A-2007-217274 Japanese Patent Application Laid-Open No. 2003-192430 Japanese Patent No. 3805173 Japanese Unexamined Patent Publication No. 2011-230960

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 is difficult to increase either of them.

The present inventor has diligently studied and found a glass-ceramic dielectric that can solve 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 (5).
(1) P ₂ O ₅ component 15.0% to 50.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
Mole sum (TIM ₂ + Nb ₂ O ₅ ) 15.0% -70.0%
A glass-ceramic dielectric having a dielectric constant of 25 or more at 1 kHz.
(2) TIO ₂ component 1% to 40.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
Nb ₂ O ₅ component 10.0% to 50.0%,
The glass-ceramic dielectric according to (1) above, which comprises.
(3) 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 0-20.0%,
Al ₂ O ₃ component 0 to 15.0%,
BaO component 0-30.0%,
SrO component 0-30.0%,
CaO component 0-30.0%,
MgO component 0-30.0%,
ZnO component 0-45.0%,
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%,
Total amount of Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Ce, Gd, Y, Dy, Yb, Lu), 0 to 10.0%,
Total amount of M _x O _y components (in the formula, M _x O _y is one or more selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo) 0 to 10.0 %,
Sb ₂ O ₃ component 0 to 10.0%,
F is 0 to 30.0% by outside discount
The glass-ceramic dielectric according to (1) or (2) above.
(4) 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) is 15.0% or less, and the RO component (in the formula, R is Mg, Any of the above (1) to (3), wherein the total amount of the ZnO component (one or more selected from the group consisting of Ca, Sr, and Ba) and the ZnO component is in the range of 3.0% to 50.0%. The glass-ceramic dielectric according to the description.
(5) The main crystal phase is composed of a phosphorus-niobium oxide compound, a tungsten bronze type crystal, a perovskite type crystal, a TiNb ₂ O ₇ crystal, a TiO ₂ crystal, a BaTi ₂ O ₅ crystal, a CaTi ₂ O ₅ crystal and a solid solution thereof. The glass-ceramic dielectric according to any one of (1) to (4) above, which comprises one or more selected from the group.

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

It is a figure which shows the relationship between the dielectric constant and the frequency in Example 1. FIG. It is a figure which shows the dielectric constant and the dielectric loss in Example 1. FIG. It is a figure which shows the dielectric breakdown strength in Example 1. FIG. It is a figure which shows the XRD pattern in Example 1. FIG. It is a figure which shows the relationship between the dielectric constant and the frequency in Example 2. FIG. It is a figure which shows the dielectric breakdown strength of Examples 24, 25 and 26. It is a figure which shows the energy storage density of Examples 24, 25 and 26.

The present invention will be described.
In the present invention, the P ₂ O ₅ component is 15.0% to 50.0% in mol% with respect to the total amount of substance in the oxide equivalent composition.
Mole sum (TiO ₂ + Nb ₂ O ₅ ) 20.0 to 70.0%
It is a glass ceramic dielectric having a dielectric constant ε of 25 or more at 1 kHz.

The glass-ceramic dielectric of the present invention is also called crystallized glass because it is a material obtained by precipitating a crystal phase in a glass phase by heat-treating the glass. The glass ceramic dielectric includes not only a material composed of a glass phase and a crystal phase, but also a material in which the glass phase is completely changed to a crystal phase, that is, a material having a crystallinity (crystallinity) of 100% by mass in the material. good. The preferred type of crystal phase contained in the glass-ceramic dielectric of the present invention and the preferred value of the crystallization rate will be described later.

Since the glass-ceramic 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, the glass-ceramic dielectric of the present invention can be used as a dielectric of a high-temperature capacitor because the characteristics at high temperature (generally 90 ° C. or higher) do not easily deteriorate.

<Glass component>
The composition range of each component constituting the glass-ceramic 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 means 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 constituent components of the glass-ceramic dielectric of the present invention are decomposed by melting and changed into oxides. .. Therefore, for the "percentage of the total amount of substance in the oxide equivalent composition", the total mass of the produced oxides when all the components are present as oxides is 100 mol%, and the abundance of each component with respect to the total mass is 100 mol%. Means.
In the following, "outer split" means not included in the above "total amount of substances in the oxide equivalent composition", and the ratio of outer split is 100 mol% of the total mass of the above-mentioned produced oxides. It shall mean the value expressed as a percentage of the abundance with respect to this.

The P ₂ O ₅ component constitutes the network structure of the glass, enhances the stability of the glass, and may be a component of the dielectric crystal. Therefore, it is an indispensable component for the glass ceramic dielectric of the present invention. .. 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 50.0% or less, the desired dielectric constant can be obtained more easily. Therefore, the content of the P ₂ O ₅ component is preferably 50.0% or less, more preferably 40.0% or less, still more preferably 35.0% or less.

The TiO ₂ component has the effect of enhancing the stability of the glass, and may be a constituent component of the dielectric crystal or a nucleating agent thereof, and is therefore a component that can be arbitrarily added to the glass ceramic 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 is a component that can be arbitrarily added to the glass-ceramic dielectric of the present invention because it enhances the stability of the glass and may be a constituent component of the dielectric crystal. 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 50.0% or less, more preferably 40.0% or less, and 35.0%. It is more preferable to contain the following. On the other hand, in order to obtain desired dielectric properties, the lower limit addition amount is preferably 10.0% or more, more preferably 15.0% or more, and further preferably 20.0% or more.

In the glass-ceramic dielectric of the present invention, the sum of molars (TiO ₂ + Nb ₂ O ₅ ), that is, the total of the content of TiO ₂ (%) and the content of Nb ₂ O ₅ (%) is 15.0%. The above is preferable, 18.0% or more is more preferable, and 20.0% or more is further preferable. Further, the total is preferably 70.0% or less, more preferably 65.0% or less, and further preferably 60.0% 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 of the glass-ceramic dielectric tends to decrease.

The SiO ₂ component is an optional component in the glass-ceramic dielectric of the present invention because it has the effect of enhancing the stability of the glass. The specific content is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 5.0% or less. If this component content is too high, the stability of the glass will decrease, and the dielectric constant of the glass-ceramic dielectric will also decrease.

The B ₂ O ₃ component is an optional component in the glass-ceramic dielectric of the present invention because it has the effect of enhancing the stability of the glass. The specific content is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 7.0% or less. If this component content is too high, the stability of the glass will decrease, and the dielectric constant of the glass-ceramic dielectric will also decrease.

The Al ₂ O ₃ component is an optional component in the glass-ceramic dielectric of the present invention because it has the effect of enhancing the stability of the glass. The specific content is preferably 15.0% or less, more preferably 7.0% or less, and even more preferably 3.0% or less. If this component content is too high, the stability of the glass will decrease, and the dielectric constant of the glass-ceramic dielectric will also decrease.

The BaO component is a component that can be arbitrarily added to the glass-ceramic dielectric of the present invention because it enhances the stability of the glass and may be a constituent component of the dielectric crystal. 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 the content of this component is too high, the stability of the glass tends to decrease, so that it is preferably contained in an amount of 30.0% or less, more preferably 28.0% or less, and 25. It is more preferably contained in an amount of 0.0% or less.

Since the SrO component enhances the stability of the glass and may be a constituent component of the dielectric crystal, it is a component that can be arbitrarily added to the glass-ceramic 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.

Since the CaO component enhances the stability of the glass and may be a constituent component of the dielectric crystal, it is a component that can be arbitrarily added to the glass-ceramic 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 is a component that can be arbitrarily added to the glass-ceramic dielectric of the present invention because it enhances the stability of the glass and may be a constituent component of the dielectric crystal. 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.

Since the ZnO component enhances the stability of the glass and may be a constituent component of the dielectric crystal, it is a component that can be arbitrarily added to the glass-ceramic 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, so that it is preferably contained in an amount of 45.0% or less, more preferably 40.0% or less, and 38. It is more preferably contained in an amount of 0.0% or less.

The glass-ceramic dielectric of the present invention preferably contains 50.0% or less of the RO (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) component. By setting the total amount of the RO components to 50.0% or less, the stability of the glass and the dielectric properties of the glass ceramic dielectric are less likely to deteriorate. Therefore, the total amount of the RO components is preferably 50.0%, more preferably 50.0%. Is 40.0%, most preferably 38.0%. On the other hand, since the stability of the glass and the dielectric properties of the glass ceramic dielectric are improved by setting the total amount of the RO components to 1.0% or more, the total amount of the RO components is preferably 1.0%, more preferably 1.0%. The lower limit is 3.0%, most preferably 5.0%.

Further, in the glass-ceramic dielectric of the present invention, the total amount (molar sum) of the RO (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) component and the ZnO component is used. It is preferably contained in an amount of 50.0% or less. By setting the total amount of RO component and ZnO component (RO + ZnO) to 50.0% or less, the stability of the glass and the dielectric properties of the glass ceramic dielectric are less likely to deteriorate, so the total amount of the RO component and ZnO component (RO + ZnO) ) Is preferably 50.0%, more preferably 45.0%, and most preferably 40.0%. On the other hand, since the stability of the glass and the dielectric property of the glass ceramic dielectric are improved by setting the total amount of the RO component and the ZnO component to 3.0% or more, the total amount (RO + ZnO) is preferably 3.0. %, More preferably 5.0%, and most preferably 8.0%.

In the glass-ceramic dielectric of the present invention, among the RO (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) component and the ZnO component, the BaO component and the ZnO component in particular. Is most preferable to include either or both because the effect of enhancing the stability of the glass and the dielectric property of the glass ceramic dielectric is more remarkable.

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

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

The K ₂ O component is an optional component in the glass-ceramic dielectric of the present invention because it has the effect of enhancing the stability of the glass. The specific content is preferably 15.0% or less, more preferably 10.0% or less, and even more preferably 7.0% or less. If this component content is too high, the dielectric constant and dielectric breakdown strength of the glass-ceramic dielectric tend to decrease.

The glass-ceramic dielectric of the present invention preferably has a total amount of Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) of 15.0% or less. It is more preferably 10.0% or less, further preferably 5.0% or less, and most preferably not contained. If this component content is too high, the dielectric breakdown strength of the glass-ceramic dielectric tends to decrease.

The WO ₃ component is an optional component in the glass ceramic dielectric of the present invention because it enhances the stability of the glass and contributes to the improvement of the dielectric constant of the glass ceramic dielectric. The specific content is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 7.0% 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 an optional component in the glass ceramic dielectric of the present invention because it enhances the stability of the glass and also contributes to the improvement of the dielectric constant of the glass ceramic dielectric. 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 ZrO ₂ component is an optional component in the glass ceramic dielectric of the present invention because it enhances the stability of the glass, plays the role of a nucleating agent for the dielectric crystal, and contributes to the improvement of the dielectric constant. The specific content is 15.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The SnO ₂ component serves as a nucleating agent for the dielectric crystal and contributes to the improvement of the dielectric property, and is therefore an optional component in the glass-ceramic 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 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 thus the present invention. It is an optional component in glass-ceramic dielectrics. The total of these contents is preferably 10.0% or less, more preferably 5.0% or less, still more preferably 3.0% or less. If the content of these components is too high, the stability of the glass tends to decrease.

Since 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, the glass of the present invention is used. It is an optional component in ceramic dielectrics. The total of these contents is preferably 10.0% or less, more preferably 3.0% or less, still more preferably 1.0% or less. If the content of these components is too high, the stability of the glass tends to decrease.

The F component enhances the stability of the glass and acts as a nucleating agent for the dielectric crystal, and is therefore an optional component in the glass ceramic dielectric of the present invention. 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 has the effect of a defoaming agent for glass and further contributes to the improvement of the dielectric property, and is therefore an optional component in the glass ceramic dielectric of the present invention. The specific content is preferably 10% or less, more preferably 3.0% or less, and even more preferably 1.0% or less. If the content of this component is too high, the stability of the glass tends to decrease.

The glass ceramic dielectric of the present invention has a phosphorus-niobium oxide compound, a tungsten bronze type crystal, a perovskite type crystal, a TiNb ₂ O ₇ crystal, a TiO ₂ crystal, a BaTi ₂ O ₅ crystal, and a CaTi ₂ O ₅ crystal as the main crystal phase. And one or more selected from the group consisting of these solid solutions. Examples of the above-mentioned phosphorus / niobium oxide compounds include NbPO ₅ , Nb ₉ PO ₂₅ , Nb ₁₈ P _2.5 O ₅₀ , BaTiP ₂ O ₈ , BaNb ₂ P ₂ O ₁₁ , ZnNb ₄ P ₂ O ₁₇ crystals, and these. It is particularly preferable to contain one or more selected from the group consisting of solid solutions. It is particularly preferable that the above-mentioned tungsten bronze type crystals include one or more selected from the group consisting of BaNb ₂ O ₆ , SrNb ₂ O ₆ , CaNb ₂ O ₆ , ZnNb ₂ O ₆ crystals and solid solutions thereof. It is particularly preferable that the above-mentioned perovskite type contains one or more selected from the group consisting of BaTiO ₃ , SrTIO ₃ , CaTiO ₃ and a solid solution thereof.

The crystallization rate and the size of the crystal phase of the glass ceramic dielectric of the present invention can be precisely controlled by adjusting the heat treatment conditions, but the crystallization rate is 3.0 in order to obtain the desired dielectric property. % Or more, more preferably 5.0% or more, and most preferably 10.0% or more. The average size of the crystals is preferably in the range of nano-order to tens of microns.

The glass-ceramic dielectric of the present invention has a dielectric constant ε of 25 or more at 1 kHz. The dielectric constant ε is preferably 27 or more, and more preferably 30 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 values at 1 kHz were taken as the dielectric constant and the dielectric loss of the present invention.

<Use>
Since the glass-ceramic 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, as well as medical X-ray equipment, industrial high-voltage power supplies, and renewable energy power transmission systems. These glass-ceramic dielectrics can be used alone in the above-mentioned applications, or can also be used in a composite form 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 baking 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 printing).

<Manufacturing method of glass-ceramic dielectric>
The glass-ceramic dielectric of the present invention is
(I) The steps of melting the mixed raw materials at a predetermined ratio and cooling the melt to obtain glass, and (ii) heat-treating the glass at a temperature equal to or higher than the glass transition point to convert it into a glass ceramic dielectric. It includes a crystallization step to be performed.

(1) Step (i)
The raw materials are mixed so that each component is within the predetermined content range, mixed uniformly, and then charged into a platinum crucible, a quartz crucible or an alumina crucible, and the temperature range is 1200 to 1500 ° C. in an electric furnace or a combustion furnace. In this step, the crucible is melted for 1 to 24 hours, homogenized by stirring, and then the melt is cooled to obtain glass. The raw material is not particularly limited, and raw materials used for ordinary glass such as oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and metaphosphate compounds may be appropriately selected. The conditions for vitrification may be appropriately set according to the glass composition, the amount of dissolution, and the like. Further, the shape of the glass body obtained in this step is not particularly limited, and may be plate-shaped, fibrous, granular or the like depending on the intended use.

(2) Step (ii)
This is a crystallization step of converting the glass obtained in the above step (i) into a glass-ceramic dielectric by heat-treating it. This heat treatment is performed at a temperature above the glass transition point of the glass. The glass transition point (Tg) varies depending on the composition, but is generally in the range of 600 ° C to 750 ° C. The upper limit of the heat treatment temperature is not particularly limited, but it is preferable that the upper limit is a temperature 300 ° C. higher than the temperature showing the crystallization peak seen in the DTA measurement. The maximum crystallization temperature of the glass of the present invention varies greatly depending on the composition, but is generally in the range of 650 ° C to 1000 ° C. The heat treatment time is a time that can be converted into a glass-ceramic dielectric, and is short when the heat treatment temperature is high and long when the heat treatment temperature is low, and is usually in the range of 0.1 to 100 hours. The crystallization step may be a one-step heat treatment or a two-step or higher heat treatment step.

The step (ii) is the most suitable method for producing a bulk glass ceramic dielectric from bulk glass, but it is necessary to appropriately set the heat treatment temperature in the step (ii) according to the shape of the glass. For example, the glass obtained in step (i) is a powder, and when a sheet-shaped glass-ceramic dielectric is produced by a sintering method using the powder, the glass is changed to a glass-ceramic dielectric for densification. The changing temperature (firing temperature) may be higher than the upper limit of the heat treatment temperature described above.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

(Example 1)
Composition: 25P ₂ O _{5-10TIO 2-30Nb 2 O 5-17.5} BaO-14CaO-3.5ZnO (mol%)
Raw materials (TiO ₂ , Nb ₂ O ₅ , Ba (PO ₃ ) ₂ , BaCO ₃ , Ca (PO ₃ ) ₂ , CaCO ₃ , ZnO) are mixed so as to have the above composition, and after mixing well, a quartz crucible is used. And dissolved at 1260 ° C. for 1 hour. Then, the melt was transferred to a platinum crucible, melted for another 2 hours, stirred and homogenized, and then the melt was poured into a mold to obtain a plate-shaped glass. The transition temperature (Tg) of the glass measured by DTA was around 700 ° C., and the crystallization peaks were around 765 ° C. and 900 ° C. Based on these temperature characteristics, it was converted into a glass-ceramic dielectric by performing heat treatment under various conditions. The obtained glass-ceramic dielectric was processed into a size of about 30 mm × 30 mm × 1 mm and subjected to the following physical property evaluation.
FIG. 1 shows the dielectric properties of the glass-ceramic dielectric obtained by heat treatment under various conditions. The dielectric characteristics were measured by an impedance analyzer (SI1260 manufactured by Solartron Co., Ltd.). As can be seen in FIG. 1, the permittivity hardly changes with frequency, but increases with increasing heat treatment temperature or time.
FIG. 2 shows the dielectric constant and the dielectric loss at 1 kHz. It can be seen that even if the dielectric constant is greatly increased by the heat treatment, the dielectric loss does not increase and is suppressed to 0.01 or less.
FIG. 3 shows the dielectric breakdown strength of Example 1 produced under various heat treatment conditions. The dielectric breakdown breaking strength was measured according to JIS C 2141 using a sample having a thickness of 1 mm. It was found that the dielectric breakdown strength varies greatly depending on the heat treatment conditions, but shows a value of 30 kV / mm or more under any of the conditions.
As a result of confirming the crystal phase of the glass ceramic dielectric with an X-ray diffractometer (manufactured by Phillips, trade name: X'Pert-MPD), when the heat treatment temperature is 800 ° C. or lower, a tungsten bronze type crystal is used as the main crystal phase. A certain (Ba, Ca) Nb ₂ O ₆ crystal phase was precipitated, but when the heat treatment temperature was higher, the precipitation of Nb ₉ PO ₂₅ became remarkable, and as shown in FIG. 4, the Nb ₉ PO ₂₅ crystal was almost formed at 950 ° C. Precipitated in a single phase.

(Example 2)
Composition: 4.5SiO 2-2.5Al ₂ O _{3-32P 2} O _5-28TiO 2-23Nb ₂ O _{5-9.5ZnO - 0.5SnO 2 (} mol%)
Mix SiO ₂ , Al (PO ₄ ) ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , Nb ₂ O ₅ , Zn (PO ₃ ) ₂ , ZnO and SnO ₂ as raw materials so as to have the above composition. After mixing, put it in a platinum pot and incubate it at 700 ° C. for 3 hours, then raise it to 1450 ° C., melt it at this temperature for 2 hours, stir and homogenize it, and then pour the melt into a mold to make a plate-shaped glass. Obtained. The transition temperature (Tg) of the glass measured by DTA was around 635 ° C, and the crystallization peak was around 800 ° C. Based on these temperature characteristics, it was converted into a glass-ceramic dielectric by performing heat treatment under various conditions. The obtained glass-ceramic dielectric was processed into a size of about 30 mm × 30 mm × 1 mm and used for evaluation of various physical properties. FIG. 5 shows the frequency dependence of the dielectric constant of the glass ceramic dielectric obtained by heat-treating the glass composition of this example under various conditions. It can be seen that the permittivity increases significantly as the frequency decreases. The main crystal phases precipitated on the glass-ceramic dielectric were NbPO ₅ and TiO ₂ .

Examples 3 to 26 and Comparative Example 1 were prepared in a manner similar to Example 1 or Example 2. The permittivity (1 kHz) and main crystal phase of the glass-ceramic dielectric are summarized in Table 1. It can be seen that the permittivity of the examples is much higher than that of the comparative examples.

FIG. 6 shows the dielectric breakdown strength of Examples 24, 25 and 26. These dielectric breakdown fracture strengths were measured according to JIS C 2141 using a sample having a thickness of 0.5 mm. It was found that all the examples showed a value of 80 kV / mm or more.
FIG. 7 shows the energy storage densities of Examples 24, 25 and 26. It was found that it is possible to obtain an energy density of 1.5 J / cm ³ or more as a value.

Claims (4)

P ₂ O ₅ component 15.0% to 50.0% in mol% with respect to the total amount of substance in the oxide equivalent composition,
TiO ₂ component 1% -40.0%,
Nb ₂ O ₅ component 10.0% to 50.0%,
Mole sum (TIM ₂ + Nb ₂ O ₅ ) 15.0% -70.0% ,
ZnO component 0-7%
A glass-ceramic dielectric having a dielectric constant of 25 or more at 1 kHz. 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 0-20.0%,
Al ₂ O ₃ component 0 to 15.0%,
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%,
Total amount of Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Ce, Gd, Y, Dy, Yb, Lu), 0 to 10.0%,
Total amount of M _x O _y components (in the formula, M is one or more selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo), 0 to 10.0%,
Sb ₂ O ₃ component 0 to 10.0%,
F is 0 to 30.0% by outside discount
The glass-ceramic dielectric according to claim 1 . 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) is 15.0% or less, and the RO component (in the formula, R is Mg, Ca, Sr). The glass-ceramic dielectric according to claim 1 or 2 , wherein the total amount of the ZnO component (one or more selected from the group consisting of Ba) and the ZnO component is in the range of 3.0% to 50.0%. The main crystal phase is selected from the group consisting of phosphorus / niobium oxide compounds, tungsten bronze type crystals, perovskite type crystals, TiNb ₂ O ₇ crystals, TiO ₂ crystals, BaTi ₂ O ₅ crystals, CaTi ₂ O ₅ crystals and solid solutions thereof. The glass-ceramic dielectric according to any one of claims 1 to 3 , which comprises one or more of the above.

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