KR100276273B1 - Dielectric ceramic composition - Google Patents

Abstract

The present invention relates to a high frequency dielectric composition, the object of which is to add a phase synthesis temperature by mixing with the starting material from the beginning by using a compound synthesized a material capable of achieving a eutectic point below 1000 ℃ with one of the main components as an additive And it is to provide a high frequency dielectric composition that can simultaneously lower the sintering temperature, and also can control the temperature coefficient of the resonance frequency as an additive, the object.

The present invention for achieving the above object is represented by (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ and the Ln is made of Sm, Nd, La, Pr In constructing the modified perovskite solid solution, which is one or two or more elements selected from the group, x, y, w is in the numerical range such as 0≤x≤1.0, 0.3≤y≤1.0, 0≤w≤0.25 The gist of the present invention relates to a high frequency dielectric composition comprising, as a starting material, a raw material selected by adjusting a content ratio so as to satisfy a content ratio, and a Li ₂ OB ₂ O ₃ composite having a weight ratio of 0.1-10%.

Description

High frequency dielectric composition

The present invention relates to a high frequency dielectric composition used as a dielectric filter of a mobile phone, and more particularly, (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ It relates to a high frequency dielectric composition constituting the modified perovskite type solid solution shown.

Currently, BaO-Nd ₂ O ₃ -TiO ₂ systems having a dielectric constant of about 90 and BaO-TiO ₂ systems having a dielectric constant of about 37 are used as high frequency dielectric filter materials. In general, the length of the dielectric filter becomes inversely small as the square of the permittivity when the permittivity becomes large due to the relationship of "l (length) ∝ 1 / k ^1/2 ". As a property to be used as a high frequency dielectric filter material, the dielectric loss must be small for the selectivity of the frequency. That is, the Q value, which is the inverse of the dielectric loss tanδ, should be large. In addition, the temperature coefficient of the resonance frequency should be close to zero for the stability of the resonance frequency.

The BaO-Nd ₂ O ₃ -TiO ₂ -based composition having a dielectric constant of 90 has a Q value, which is the inverse of the dielectric loss, is about 5000 at 1 GHz, and the temperature coefficient of the resonant frequency is also good as 10 ppm / ° C. filter). However, the limit of the dielectric constant that can be obtained by the BaO-Nd ₂ O ₃ -TiO ₂ -based composition is about 90, the sintering temperature is also very high as 1350 ℃. However, studies on the development of a composition and the development of an additive composition for miniaturizing a monoblock filter and lowering a sintering temperature have been insufficient.

Existing dielectric composition for high frequency is BaO-Nd ₂ O ₃ -TiO ₂ system with dielectric constant of about 90, which can change the dielectric properties according to the composition ratio of three materials, but the composition range with temperature coefficient of stable resonance frequency is very limited. . The dielectric constant of about 90 while adding Bi ₂ O ₃ as an additive to control the temperature coefficient of the resonance frequency.

However, even if the composition is changed or the type of the additive is changed, the dielectric constant is difficult to obtain a value of 100 or more. In addition, the sintering temperature is also relatively high as 1350 ℃.

Meanwhile, US Patent 5444028 uses ZnO, CoO, NiO, and MgO as a composition range and additive of wLi ₂ O-x CaO-yA ₂ O ₃ -zTiO ₂ (A = Sm, Nd), and has a dielectric constant of 100 or more and a Qf value. A dielectric composition with a temperature coefficient of 0 ppm / 占 폚 at a resonant frequency of more than 4000 and a sintering temperature of around 1300 占 폚 is proposed. This US Patent 5444028 relates to a microwave dielectric ceramic composition, which is described in more detail as follows.

That is, as shown in the claims, it is represented by the composition of wLi ₂ O—x CaO—yA ₂ O ₃ —zTiO ₂ , wherein A is selected from Sm and Nd, and w, x, y and z are

0.0 mol% <w≤25.0 mol%

0.0 mol% <x≤50.0 mol%

0.0 mol% <y ≤ 30.0 mol%

In a microwave dielectric ceramic composition having 0.0 mol% <z ≤ 80.0 mol%, the microwave dielectric ceramic composition has w + x + y + z = 100 mol% and 0 selected from zinc oxide, cobalt oxide, nickel oxide, and magnesium oxide. -5 parts by weight is included in the wLi ₂ O-xCaO-yA ₂ O ₃ -zTiO ₂ .

However, the US patent 5444028 has to be sintered at a high temperature of about 1300 ℃, and has a problem that the adjustment of the resonant frequency by adjusting the ratio of the main component.

In order to solve the above problems, the present inventors have repeatedly studied and experimented and proposed the present invention based on the results. The present invention provides a substance capable of achieving a eutectic point below 1000 ° C. with one of the main components as an additive. By using the synthesized compound, it is intended to provide a high-frequency dielectric composition that can be mixed with the starting material from the beginning to lower the image forming temperature and the sintering temperature at the same time, and also to control the temperature coefficient of the resonance frequency as an additive.

The present invention for achieving the above object is represented by (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ and the Ln is made of Sm, Nd, La, Pr In constructing the modified perovskite solid solution, which is one or two or more elements selected from the group, x, y, w is in the numerical range such as 0≤x≤1.0, 0.3≤y≤1.0, 0≤w≤0.25 The raw material selected by adjusting the content ratio to satisfy the

A high frequency dielectric composition comprising a Li ₂ OB ₂ O ₃ composite, which is 0.1-10% by weight, as a starting material.

Hereinafter, the present invention will be described in detail.

The present invention relates to a composition that can replace the BaO-Nd ₂ O ₃ -TiO ₂ material of the existing dielectric constant 90 material, (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 Based on} a modified perovskite solid solution composition of _{/ 3-w} TiO ₃ (Ln = Sm, Nd, La, Pr).

In the present invention, based on CaTiO ₃ and Li _1/2 Ln _1/2 TiO ₃ (Ln = Sm.Nd, La, Pr) having a perovskite structure, the composition in which both materials are dissolved and A- in the ABO ₃ structure The basic composition is based on the substitution of lanthanide ions at the site.

That is, represented by (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ (Ln is one or two or more elements selected from Sm, Nd, La, Pr) The composition that satisfies is made as the basic composition

X has a range such as 0 ≦ x ≦ 1.0. In addition, y has a range such as 0.3 ≦ y ≦ 1.0, which is a composition range such that the temperature coefficient of the resonance frequency has a value close to zero. In addition, w has a range such as 0 ≦ w ≦ 0.25, which is a solid solution range capable of maintaining a perovskite structure.

In the present invention, the starting material is designed to satisfy such basic composition. Typical examples of the starting material include Li ₂ CO ₃ , CaCO ₃ , Ln ₂ O ₃ (Ln is selected from Sm, Nd, La, and Pr), and TiO ₂ . That is, when the composition of the desired final material is determined, the molar ratio of the materials is calculated and taken as a starting material.

In the present invention, the Li ₂ O, B ₂ O ₃ by selecting the B ₂ O ₃ having a composition of Li ₂ O and the eutectic melting point of the main phase as an additive to 1: 2.2 by a mole ratio of the composite composition: 0.3 to 1 Simultaneous addition with the starting materials promoted the syntheses and simultaneously reduced the sintering temperature.

After selecting B ₂ O ₃ having a common point with Li ₂ O included in the main component as the additive, a ratio of Li ₂ O: B ₂ O ₃ was synthesized in an area composition of 1: 0.3 to 1: 2.2, before calcination. It is effectively added to the perovskite phase by preventing the formation of Sm (Ln) ₂ Ti ₂ O ₇ , which leads to a decrease in dielectric properties by adding together when the main components are synthesized. In addition, it promotes sintering at the time of sintering, thereby lowering the sintering temperature between 1250 ° C. and 1300 ° C., thereby enabling sintering at about 1150 ° C. without a large decrease in dielectric properties.

The ratio of Li ₂ O: B ₂ O ₃ is in the range of 1: 0.3 to 1: 2.2, which means that if the ratio of B ₂ O ₃ is less than 0.3, the synthesis into a desired compound is insignificant. This is because there is a problem falling.

The Li ₂ OB ₂ O ₃ composite is preferably composed of a main component Li ₂ B ₂ O ₄ .

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

As the additive composition, Li ₂ O which is a component of the main raw material and B ₂ O ₃ having a eutectic point were selected. 1 eseo 0.3:: high purity (> 99%) of Li ₂ CO ₃ and a B ₂ O ₃ molar ratio of 1 to a synthetic stabilized by weighing a value between 2.2 (weighing) hanhu solvent of ethyl alcohol (95%) ZrO ₂ The ball was wet mixed for 24 hours and then dried. The dry powder was heat treated at 600 ° C. for 1 hour to obtain a Li ₂ OB ₂ O ₃ composite.

Li ₂ CO ₃ , CaCO ₃ , Ln ₂ O ₃ , Sm ₂ O ₃ , TiO ₂ as a starting material for synthesizing the composition were weighed in the molar ratio as shown in Table 1, and the content of Li ₂ OB ₂ O ₃ obtained was shown in Table 1 After weighing as described above, the mixture was wet mixed with ethyl alcohol (95%) using a stabilized ZrO ₂ ball for 24 hours and then dried. The dry powder is heat treated at 900 ° C. for 1 hour. The heat-treated powder is wet mixed again for 12 hours and then dried. 1wt% of the binder was added to the dry powder, mixed, sieved through a 200mesh sieve, and uniaxially formed at a pressure of 1.5ton using a 14mm mold to measure the TE01δ mode. Sintering was performed for 3 hours between 1100 degreeC-1150 degreeC.

In order to measure the high frequency dielectric properties, the mirror surface was polished to a diameter: height = 1: 0.45, and the dielectric constant (k) was measured using a post resonant method, and the cavity method was used. The Q value was measured. The temperature coefficient (TCF) of the resonance frequency was measured between -35 ° C and 80 ° C. After the measurement, these results are shown in Table 1 below.

Ln B ₂ O ₃ / Li ₂ O molar ratio Content of B ₂ O ₃ -Li ₂ O composite (wt%) x y w k Qf TCF (ppm / ° C) Sm 0.3 1.0 0.5 0.5 0.2 108 1400 18 Sm 0.5 1.0 0.5 0.5 0.2 107.6 3000 0 Sm One 1.0 0.5 0.5 0.2 106.5 4650 -5 Sm 1.5 1.0 0.5 0.5 0.2 103 4000 -9 Sm 2.0 1.0 0.5 0.5 0.2 100 2400 -11 Sm 2.2 1.0 0.5 0.5 0.2 90 1200 -19

As can be seen from Table 1, when the B ₂ O ₃ / Li ₂ O molar ratio satisfies the range of 0.3-2.2, the characteristics of the obtained dielectric were satisfied as a high frequency dielectric material.

On the contrary, when it is out of the said range, sinterability falls or the effect of the additive did not appear correctly.

Example 2

As the additive composition, Li ₂ O which is a component of the main raw material and B ₂ O ₃ having a eutectic point were selected. For the synthesis, a molar ratio of high purity (> 99%) of Li ₂ CO ₃ and B ₂ O ₃ was measured at a value of 1: 1, and then stabilized with ethyl alcohol (95%) as a solvent for 24 hours using a stabilized ZrO ₂ ball. Wet mixing followed by drying. The dry powder was heat treated at 600 ° C. for 1 hour to obtain a Li ₂ OB ₂ O ₃ composite.

Li ₂ CO ₃ , CaCO ₃ , Ln ₂ O ₃ , Ln ₂ O ₃ , TiO ₂ as a starting material for synthesizing the composition was weighed in the molar ratio as shown in Table 2, and the content of the resulting Li ₂ OB ₂ O ₃ composite was After weighing as shown in Table 2, ethyl alcohol (95%) was used as a solvent, wet mixed for 24 hours using a stabilized ZrO ₂ ball, and dried. The dry powder was heat treated at 900 ° C. for 1 hour. The heat-treated powder was wet mixed again for 12 hours and then dried. 1wt% of the binder was added to the dry powder, mixed, sieved through a 200mesh sieve, and uniaxially formed at a pressure of 1.5ton using a 14mm mold to measure the TE01δ mode. Sintering was performed for 3 hours between 1100 degreeC-1150 degreeC.

In order to measure the high frequency dielectric properties, the mirror surface was polished to a diameter: height = 1: 0.45, and the dielectric constant was measured using a post resonant method, and the Q value was measured using a cavity method. Measured. The temperature coefficient of the resonant frequency was measured between -35 ° C and 80 ° C. After the measurement, these results are shown in Table 2 below.

Ln x y w Content of B ₂ O ₃ -Li ₂ O composite (wt%) k Qf TCF (ppm / ℃) Inventive Example 1 Sm 0.0 0.7 0.167 0.1 116 3700 12 Inventive Example 2 Sm 0.0 0.7 0.167 0.5 117 3600 5 Inventive Example 3 Sm 0.0 0.7 0.167 1.0 116 3500 0 Inventive Example 4 Sm 0.0 0.7 0.167 2.0 116.5 3550 -2 Inventive Example 5 Sm 0.0 0.7 0.167 5.0 115 3500 -5 Inventive Example 6 Sm 0.0 0.7 0.167 9.0 113 3000 -10 Comparative example Sm 0.0 0.7 0.167 12.0 102 900 -25 Inventive Example 7 Sm 0.0 0.7 0.05 0.5 110 4200 4 Inventive Example 8 Sm 0.0 0.7 0.05 5.0 107 4000 0 Inventive Example 9 Nd 0.0 0.7 0.167 0.1 119 3500 8 Inventive Example 10 Nd 0.0 0.7 0.167 0.5 117 3400 2 Inventive Example 11 Nd 0.0 0.7 0.167 1.0 116 3350 -2 Inventive Example 12 Pr 0.0 0.7 0.167 0.5 115 4000 6 Inventive Example 13 Pr 0.0 0.7 0.167 2.0 112 3800 2 Inventive Example 14 La 0.0 0.7 0.05 0.5 125 3000 10 Inventive Example 15 La 0.0 0.7 0.05 2.0 122 2500 8 Inventive Example 16 Sm 0.5 0.5 0.2 0.1 105 5100 3 Inventive Example 17 Sm 0.5 0.5 0.2 0.2 105.5 5080 0 Inventive Example 18 Sm 0.5 0.5 0.2 0.5 106 4800 -2 Inventive Example 19 Sm 0.5 0.5 0.2 1.0 106.5 4650 -5 Inventive Example 20 Sm 0.5 0.5 0.17 0.1 104 5240 0 Inventive Example 21 Sm 0.5 0.5 0.17 0.5 103 5130 -3 Inventive Example 22 Sm 0.5 0.5 0.17 1.0 102 4900 -7

As can be seen from Table 2, in the case of Inventive Example (1-22) satisfying the conditions of the present invention, the dielectric constant, Qf value, and the temperature coefficient of the resonance frequency were superior to the existing high frequency dielectric composition.

However, in the comparative example outside the content range of the B ₂ O ₃ —Li ₂ O composite among the conditions of the present invention, the Qf value and the temperature coefficient of the resonance frequency were poor.

According to the present invention as described above, the composition of the dielectric is (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ (Ln = Sm, Nd, La, Pr) Based on the modified perovskite solid solution composition, by selecting Li ₂ O as the additive and B ₂ O ₃ having a eutectic point and synthesizing it into a composite of Li ₂ OB ₂ O ₃ and applying it to the dielectric material, The dielectric constant of BaO-Nd ₂ O ₃ -TiO _{2 is} improved by more than 20, and low-temperature sintering is possible at a temperature lower than 200 ℃ compared to 1350 ℃, and the temperature of Qf and resonance frequency Water also has excellent high-frequency dielectric properties, and by accumulating new composition development techniques that can freely change dielectric properties, it is possible to design powders suitable for device characteristics.

Claims (4)

(1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ , wherein Ln is one or two or more selected from the group consisting of Sm, Nd, La, and Pr In constructing the modified perovskite solid solution, which is an element, x, y, w are selected by adjusting the content ratio such that 0 ≤ x ≤ 1.0, 0.3 ≤ y ≤ 1.0, 0 ≤ w ≤ 0.25 With raw materials, A high frequency dielectric composition comprising a composite of Li ₂ OB ₂ O ₃ at 0.1% by weight as a starting material The method of claim 1, Raw materials selected to satisfy the (1-y) Ca _1-x Ln _{2x / 3} TiO ₃ -yLi _3w Ln _{2 / 3-w} TiO ₃ are Li ₂ CO ₃ , CaCO ₃ , Ln ₂ O ₃ , TiO ₂ And wherein Ln is selected from Sm, Nd, La, and Pr. The method of claim 1, The Li ₂ OB ₂ O ₃ composite is obtained by synthesizing Li ₂ O and B ₂ O ₃ in a ratio of 1: 0.3 to 2.2 by molar ratio. The method according to claim 1 or 3, The Li ₂ OB ₂ O ₃ composite is a high frequency dielectric composition, characterized in that Li ₂ B ₂ O ₄ is the main component