JP2006273703A - Dielectric ceramic composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a dielectric ceramic composition which is ≥200 in specific dielectric constant εr, is ≤200 ppm/K in temperature characteristic τε of dielectric constant and is excellent in Q characteristics as well. <P>SOLUTION: The dielectric ceramic composition has the basic composition components expressed by aCaO-bLiO<SB>1/2</SB>-cBiO<SB>3/2</SB>-dREO<SB>3/2</SB>-eTiO<SB>2</SB>[where, RE represents at least one kind selected from La, Ce, Pr, Nd, Sm, Yb, Dy, Y, and a+b+c+d+e=100 (mol%)]. The compositions of the respective components are 10≤a≤25, 10≤b≤20, 8≤c≤15, 2≤d≤10, 50≤e≤60, and are 0.65≤b/(c+d)<1.0, and more preferably 1≤c/d≤5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a dielectric ceramic composition, and relates to a dielectric ceramic composition containing CaO, Li ₂ O, Bi ₂ O ₃ , RE ₂ O ₃ (RE is a rare earth element), TiO _{2 and the} like. .

  For example, in the information communication field, the use frequency band tends to shift to a high frequency, and high frequency in the gigahertz (GHz) band is used in mobile communication such as satellite broadcasting, satellite communication, mobile phone and car phone. Yes.

  In circuit boards and electronic components mounted on equipment used in the high frequency band as described above, the dielectric material used is the frequency used to improve the performance and miniaturization of circuit boards and electronic components. A dielectric material having a high dielectric constant εr in the band is required. This is based on the principle that the wavelength of the electromagnetic wave in the dielectric material is shortened by 1 / √εr. A dielectric material having a higher relative dielectric constant εr can reduce the size of the circuit board or electronic component. . Furthermore, it is necessary that the material has a high Q and a low loss in the high frequency region. Here, Q is the reciprocal of the dielectric loss tangent tan δ, and the higher the Q, the smaller the loss. Since the value of Q varies depending on the frequency, in this specification, the product of Q and the resonance frequency f, that is, Qf is used to represent the loss characteristic of the material. Qf is also called a high-frequency dielectric quality factor, and the higher the Qf, the lower the loss.

  However, in general, the higher the dielectric constant εr, the higher the dielectric constant εr, the worse the temperature characteristic τε of the relative dielectric constant εr and the smaller the Qf value. Therefore, it is difficult to realize a dielectric ceramic composition having a high relative dielectric constant εr, a small temperature coefficient τε of the relative dielectric constant εr, and a certain Qf value, and the dielectric ceramic composition satisfying these characteristics in various directions. Things are being developed.

  For example, Ba-rare earth (RE) -Ti-O-based dielectric porcelain compositions, and dielectric porcelain compositions containing Bi, Pb, etc., have been developed as dielectric ceramic compositions having a small temperature characteristic τε. Has been. However, although these dielectric ceramic compositions have a flat temperature characteristic and a relatively high Q value, the relative dielectric constant εr is as small as about 80 to 100.

Therefore, in order to improve the relative dielectric constant εr, aLi ₂ O—bBi ₂ O ₃ —cTiO ₂ (where 14.2 ≦ a ≦ 19.2 mol%, 14.2 ≦ b ≦ 19.2 mol%, A dielectric ceramic composition containing 20 wt% or more of a composition represented by 61.6 ≦ c ≦ 71.6 mol% and a + b + c = 100 mol% has also been proposed (see, for example, Patent Document 1). The dielectric ceramic composition described in Patent Document 1 has a high relative dielectric constant εr, a high Q × f value, and a low temperature coefficient τf, and can be fired at a temperature of about 1000 ° C.
JP 2000-335964 A

  However, in the dielectric ceramic composition described in Patent Document 1, individual dielectric characteristics, for example, a dielectric ceramic composition having a relatively high relative dielectric constant εr and a dielectric ceramic composition having a low temperature coefficient τε are sometimes found. However, a dielectric ceramic composition that exhibits high values in a balanced manner in all characteristics has not been realized. The dielectric material is not limited to the dielectric material described in Patent Document 1, and the relative dielectric constant εr exceeds 200, the temperature coefficient τε of the dielectric constant is less than ± 200 ppm / K, and the unloaded quality factor Qf (for example, 1000 GHz or more) is high to some extent. In reality, the dielectric ceramic composition having a) is not found at present.

  The present invention has been proposed in view of the above circumstances. That is, an object of the present invention is to provide a dielectric ceramic composition having a high relative dielectric constant εr, a low temperature characteristic τε of dielectric constant, and a certain Qf value.

The present inventors have conducted intensive research for a long time in order to solve the above-mentioned problems. Then, in the titanate, focusing on the fact that the so-called A site can have a positive temperature characteristic τε by simultaneously containing Li and rare earth, BaTiO ₃ , SrTiO ₃ , CaTiO ₃ , Li _1/2 R _{1 / 2} TiO ₃ , Li _1/2 Nd _1/2 TiO ₃ (R is one or more rare earth elements of La, Ce, Pr), etc. So, we have developed a dielectric porcelain composition consisting essentially of an oxide dielectric with a single-phase perovskite structure. Further, the present inventors have the best characteristics when La having the largest ionic radius is used for the rare earth element R, but by using Bi having an ionic radius close to La instead of La, the dielectric constant is further increased. Focusing on realizing the rate ε, Q characteristic, and temperature characteristic, BaTiO ₃ , SrTiO ₃ , CaTiO ₃ , Li _1/2 Bi _1/2 TiO ₃ , Li _1/2 RE _1/2 TiO ₃ (RE is La , Ce, Pr, Nd, Sm, Yb, Dy, Y) and the like have been developed in a specific ratio. However, in such a material, a large number of elements are dissolved, so that a heterogeneous phase is easily generated, and there is a limit to the improvement of characteristics.

  As a result of further research by the present inventors, in this system, the molar amount of Li, which is a monovalent element at the A site, is the sum of the molar amount of Bi, which is a trivalent element, and the molar amount of rare earth element RE. By reducing the number, an oxide dielectric having a substantially single-phase perovskite structure is realized, and knowledge that a material having a higher relative dielectric constant ε, Q characteristic, and flat temperature characteristic is realized is obtained. The present invention has been completed.

The present invention has been completed based on such knowledge, and the basic composition component is aCaO-bLiO _1/2 -cBiO _3/2 -dREO _3/2 -eTiO ₂ [where RE is La, Ce , Pr, Nd, Sm, Yb, Dy, Y represents at least one selected from a + b + c + d + e = 100 (mol%). ],
10 ≦ a ≦ 25
10 ≦ b ≦ 20
8 ≦ c ≦ 15
2 ≦ d ≦ 10
50 ≦ e ≦ 60
And 0.65 ≦ b / (c + d) <1.0
It is characterized by being.

In the composition using Bi, since titanates such as CaTiO ₃ , Li _1/2 Bi _1/2 TiO ₃ , Li _1/2 RE _1/2 TiO _{3 and the} like are dissolved, By making the molar amount of Li as a monovalent element equal to the sum of the molar amount of Bi as a trivalent element and the molar amount of a rare earth element RE, the average valence of the A site in Li, Bi and the rare earth element RE as a whole Must be set to 2. However, when equimolar amounts of monovalent element and trivalent element are blended in this way, the generation of a heterogeneous phase such as Li ₄ Ti ₅ O ₇ is inevitable in a part of the dielectric ceramic composition. From the results of structural analysis, in the dielectric ceramic composition, some Bi and rare earth elements RE are solid-solved in a form such as RE _2/3 TiO ₃ , so that Li remains, and as a result, Li ₄ It is considered that a heterogeneous phase such as Ti ₅ O ₇ is formed.

Therefore, in the present invention, the molar amount of Li is made smaller than the sum of the molar amount of Bi, which is a trivalent element, and the molar amount of the rare earth element RE. By reducing Li in the composition, the generation of heterogeneous phases can be suppressed, and an oxide dielectric having a substantially single-phase perovskite structure can be obtained. However, if Li is reduced too much, the balance of ions in the solid solution is lost, and on the contrary, a heterogeneous phase such as Bi ₂ Ti ₂ O ₇ is generated, which may lead to deterioration of characteristics.

  Therefore, by adjusting the ratio of these elements within the range specified in the present invention, a single-phase solid solution having a perovskite structure can be obtained. As a result, the relative dielectric constant εr and the Qf value are high, and the relative dielectric constant εr A dielectric ceramic composition having a small absolute value of the temperature characteristic τε is realized.

  The composition of each element in the dielectric ceramic composition of the present invention is expressed as an analysis value obtained by analyzing the sintered dielectric ceramic composition (sintered body) by inductively coupled plasma emission spectroscopy and fluorescent X-ray diffraction. Yes.

  According to the present invention, a dielectric ceramic composition that can stably obtain a high relative dielectric constant εr exceeding 200, has a high Qf value, and a small dielectric constant temperature characteristic τε of less than ± 200 ppm / K is provided. Is possible. Therefore, by using the dielectric ceramic composition of the present invention, it is possible to improve the performance of low-temperature fired ceramic substrates and device parts.

  Hereinafter, the dielectric ceramic composition according to the present invention will be described in detail.

The dielectric ceramic composition of the present invention comprises titanates such as CaTiO ₃ , Li _1/2 Bi _1/2 TiO ₃ , Li _1/2 RE _1/2 TiO ₃ (RE is a rare earth element) at a predetermined ratio. It is an oxide dielectric with a perovskite structure in solid solution. Then, the basic composition _{components, aCaO-bLiO 1/2 -cBiO 3/2 -dREO} 3/2 -eTiO 2 [ however, RE is selected La, Ce, Pr, Nd, Sm, Yb, Dy, from Y A + b + c + d + e = 100 (mol%). The composition of each component is
10 ≦ a ≦ 25
10 ≦ b ≦ 20
8 ≦ c ≦ 15
2 ≦ d ≦ 10
50 ≦ e ≦ 60
And 0.65 ≦ b / (c + d) <1.0
Is set to a range.

  FIG. 1 illustrates the composition range. FIG. 1 is a ternary composition diagram showing the compounding ratio of so-called A-site elements in the perovskite structure. In FIG. 1, the composition range of the present invention is represented as a hexagonal shaded region.

  The reason for limitation of the composition of each component in the basic composition component will be described. Ca has a high Qf value (13000 GHz) and a relatively high relative dielectric constant εr (170), and therefore has a Q characteristic (Qf value). And the relative dielectric constant εr has an effect of giving a high value to some extent. However, if there is too much Ca, the temperature characteristic τε of the dielectric constant may be deteriorated. Therefore, from these viewpoints, the content a of Ca in terms of CaO is 10 mol% or more and 25 mol% or less. When a exceeds 25 mol%, the temperature characteristic τε has an absolute value in the negative direction. If the a is less than 10 mol%, the relative dielectric constant εr and the Qf value may decrease. Further, the absolute value of the temperature characteristic τε in the positive direction increases.

  Among the basic composition components, in CaO, a part of Ca may be replaced by an alkaline earth metal element (one or more selected from Sr, Ba, and Mg). By substituting a part of Ca with an element having an ionic radius larger than that of Ca such as Sr or Ba, the relative dielectric constant εr can be increased. Further, when a part of Ca is replaced with an element having an ion radius larger than that of Ca, such as Mg, the Q characteristic can be improved.

If the basic composition component contains too much Li, the relative dielectric constant εr decreases. On the other hand, if the Li content is too small, the absolute value of the temperature characteristic τε increases in the positive direction, and the relative dielectric constant εr and Q characteristic also decrease. Therefore, the content b of Li in terms of LiO _1/2 is 10 mol% or more and 20 mol% or less.

On the other hand, Bi has a stronger function of controlling the temperature characteristic τε than the rare earth element RE, but the deterioration of the Q characteristic is more severe than that of the RE. Accordingly, the Bi amount may be set in consideration of the temperature characteristic τε of the dielectric ceramic composition, but if it is too much, the Q characteristic is deteriorated. Conversely, if Bi is too small, the dielectric constant ε decreases, and the temperature characteristic τε has a large absolute value in the negative direction, making it difficult to adjust to zero. Therefore, the content c of Bi in terms of BiO _3/2 is 8 mol or more and 15 mol% or less.

The rare earth element RE mainly contributes to the control of the temperature characteristic τε of the dielectric ceramic composition. If there is too much RE, the absolute value of the temperature characteristic τε in the positive direction increases. Further, the relative dielectric constant εr and the Q characteristic are also lowered. Conversely, if the RE is too small, the absolute value of the temperature characteristic τε in the minus direction increases. Accordingly, the content d of RE in terms of REO _3/2 is 2 mol% or more and 10 mol% or less.

Of the basic composition components, in REO _3/2 , RE is preferably Nd, and a part thereof is selected from lanthanide group elements (La, Ce, Pr, Sm, Y, Yb, Dy). 1 type or 2 types or more). By setting RE to Nd, the dielectric constant ε, the Q characteristic and the temperature characteristic are well balanced, and the balance between the characteristic and the material cost is also good. Further, by substituting a part of Nd with an element having an ionic radius larger than Nd, such as La, Ce, or Pr, the relative dielectric constant εr can be further increased. By replacing a part of Nd with an element having an ion radius smaller than Nd, such as Sm, Y, Yb, or Dy, the Qf value can be increased.

In the present invention, it is necessary to control the molar ratio b / (c + d) between the monovalent element Li, the trivalent element Bi and the sum of the rare earth elements RE in the basic composition component within an appropriate range. By setting b / (c + d) <1, an oxide dielectric having a substantially single-phase perovskite structure can be obtained. When b / (c + d) ≧ 1, the relative dielectric constant εr decreases due to the generation of a heterogeneous phase composed of Li ₂ O.TiO ₂ . On the other hand, when Li becomes too small, that is, b / (c + d) <0.65, a heterogeneous phase such as Bi ₂ Ti ₂ O ₇ or Bi ₄ Ti ₃ O ₇ is generated, and thereby the relative dielectric constant εr and The Q characteristic decreases, and the absolute value of the temperature characteristic τε in the negative direction increases. Therefore, by setting 0.65 ≦ b / (c + d) <1, more preferably 0.70 ≦ b / (c + d) ≦ 0.90, a high-performance dielectric ceramic composition is realized.

When there is too much Ti, a different phase containing a large amount of Ti such as TiO ₂ is likely to be generated due to excessive Ti more than necessary for the formation of the perovskite crystal phase. On the other hand, if the Ti content is too small, a heterogeneous phase containing a large amount of other metal elements that should enter the A site of the perovskite tends to be generated. In any case, since the characteristics may be greatly deteriorated due to the occurrence of a heterogeneous phase, the content e of Ti in terms of TiO ₂ is set to 50 mol% or more and 60 mol% or less.

  In the present invention, the molar ratio A / B of the A site atom to the B site atom in the perovskite structure, that is, (a + b + c + d) / e is within an appropriate range from the viewpoint of reducing the amount of heterogeneous precipitation and enhancing the characteristics. It is preferable to make it. In the composition of the present invention, since it is considered that some vacancies are formed at the A site, it is necessary for A / B to be smaller than 1 in order to reduce foreign phases and improve characteristics. That is, if (a + b + c + d) / e ≧ 1, a heterogeneous phase is generated, which may lead to deterioration in relative dielectric constant εr and Q characteristics. In addition, even when the molar amount A of atoms at the A site is too small compared with the molar amount B of atoms at the B site, the generation of a different phase may cause deterioration of the relative dielectric constant εr and Qf. As a result of detailed analysis of the results of characteristic evaluation and structural analysis of the obtained dielectric by the inventors changing the composition of each element in various ways, a desirable range of (a + b + c + d) / e is 0.93 ≦ It is confirmed that (a + b + c + d) / e <1, more preferably 0.95 ≦ (a + b + c + d) / e <0.99.

  The above is the reason for limiting the composition of each component constituting the dielectric ceramic composition of the present invention. In the dielectric ceramic composition of the present invention, the molar ratio of Bi and RE is further within an appropriate range. It is more preferable to control. When the molar amount of RE is larger than the molar amount of Bi, that is, when c / d <1, the effect of improving the relative dielectric constant εr is reduced, and the temperature characteristic τε may increase to the negative side. Conversely, if c / d> 5, the effect of improving the relative dielectric constant εr can be obtained, but the Q characteristic is remarkably lowered, and the absolute value of the temperature characteristic τε may increase in the positive direction. Therefore, the c / d is preferably 1 to 5.

  The above-mentioned dielectric ceramic composition of the present invention can be produced, for example, according to the production process shown in FIG. The manufacturing process shown in FIG. 2 includes a mixing step 1, a pre-baking step 2, a pulverizing step 3, a granulating step 4, a forming step 5, and a baking step 6.

  In the production of the dielectric ceramic composition, first, a predetermined amount of the raw material powder is weighed and mixed (mixing step 1). As the raw material powder of the main component, oxide powders and compounds that become oxides upon heating, such as carbonates, hydroxides, oxalates, nitrates, and the like can be used. In this case, not only one kind of metal oxide (compound) but also a composite oxide powder containing two or more kinds of metals may be used as the raw material powder. What is necessary is just to select the average particle diameter of each raw material powder suitably in the range of 0.1 micrometer-3.0 micrometers, for example.

As the mixing method, for example, wet mixing using a ball mill or the like can be employed. After mixing, drying, pulverization, and sieving are performed, and the pre-baking step 2 is performed. In the calcination step 2, for example, an electric furnace or the like is used, and the calcination is performed by maintaining the temperature in a temperature range of 900 ° C. to 1300 ° C. for a predetermined time. The atmosphere at this time may be a non-reducing atmosphere such as O ₂ , N ₂ or air. Moreover, what is necessary is just to select the said holding time in calcination suitably in the range of 0.5 to 5.0 hours, for example.

  After the calcination, in the pulverizing step 3, the calcined body is pulverized until the average particle size becomes about 0.5 μm to 2.0 μm, for example. As the pulverizing means, for example, a ball mill or the like can be used.

  In addition, the timing which adds the raw material powder of each component is not limited only to the said mixing process 1. For example, only raw material powders of some of the necessary raw material powders are weighed, mixed, and calcined. After pulverizing this, a predetermined amount of raw material powders of other components may be added and mixed.

  The powder pulverized in the pulverization step 3 is granulated into granules in the granulation step 4 in order to smoothly execute the subsequent molding step 5. At this time, it is desirable to add a small amount of an appropriate binder such as polyvinyl alcohol (PVA) to the pulverized powder. In addition, the particle size of the obtained granule is desirably about 80 μm to 200 μm.

In the molding step 4, the granulated granule is pressure-molded at a pressure of, for example, 200 MPa to 300 MPa to obtain a molded body having a desired shape. Subsequently, after removing the binder added at the time of shaping | molding, in the baking process 6, a molded object is heat-held for a predetermined time within the range of 1000 to 1400 degreeC, and a sintered compact is obtained. The firing atmosphere in the firing step 6 may be a non-reducing atmosphere such as O ₂ , N ₂ or air. The heating and holding time may be appropriately selected within a range of 2 to 6 hours, for example.

  After firing, surface finishing is performed by polishing or the like as necessary to obtain a sintered body (dielectric ceramic composition). This dielectric ceramic composition has, for example, a relative dielectric constant εr at 3 GHz of 150 to 300, a Qf of 300 to 10000 GHz, and a temperature characteristic τε of dielectric constant (−40 ° C. to 85 ° C.) of 200 ppm / K or less in absolute value. With excellent dielectric properties. Therefore, the dielectric ceramic composition of the present invention is suitable as a material for device parts such as resonators, filters and multilayer capacitors for high frequencies, particularly microwaves, and low-temperature fired ceramic substrates.

  Hereinafter, specific examples to which the present invention is applied will be described based on experimental results.

LiCO ₃ , CaCO ₃ , SrCO ₃ , BaCO ₃ , Bi ₂ O ₃ , Nd ₂ O ₃ , TiO _2, etc. were prepared as raw material powders for the dielectric ceramic composition . The average particle diameter of each raw material powder is 0.1 μm to 1.0 μm.

  These raw material powders were weighed so as to have a predetermined value at a predetermined molar ratio, and wet mixed using a ball mill for 16 hours. After sufficiently drying the obtained slurry, calcining was performed in the atmosphere at 1200 ° C. for 2 hours to obtain a calcined body. After finely pulverizing with a ball mill until the calcined body had an average particle size of 1.0 μm, the finely pulverized powder was dried. Next, an appropriate amount of PVA (polyvinyl alcohol) was added as a binder, granulated and molded, and then fired at a temperature range of 1100 ° C. to 1400 ° C. for 4 hours to obtain a sintered body. This sintered body was vertically polished and finished to a mirror surface with a lapping to obtain a sample having a diameter of 10 mm and a thickness of 5 mm.

  According to the above procedure, dielectric ceramic compositions (Example 1 to Example 26, Comparative Example 1 to Comparative Example 5) were produced. Regarding the compositions of the dielectric ceramic compositions of these examples and comparative examples, Li was analyzed by an inductively coupled plasma emission spectroscopic analyzer, and the remaining elements were analyzed by a fluorescent X-ray diffractometer. The results are shown in Tables 1 and 2. In the table, the unit of a, b, c, d, e is mol%.

Evaluation Each dielectric ceramic composition was produced, dielectric properties (relative permittivity .epsilon.r, Qf value, temperature characteristics Tauipushiron) was measured. The relative dielectric constant εr, Qf value, and resonance frequency were measured by the Hakki-Coleman method. Further, when measuring the relative dielectric constant εr, a frequency characteristic is measured by oscillating a high frequency from one probe of a network analyzer (manufactured by Hewlett Packard, 8510C), and the obtained TE01δ mode resonance frequency peak and sample are measured. The relative dielectric constant εr was determined from the dimensions of. The temperature characteristic τε was measured by a resonance method in a temperature range of −40 ° C. to 85 ° C., and the resonance frequency f0 at the measurement was 2.5 GHz to 3.5 GHz. The results are shown in Tables 1 and 2. In addition, since the densification temperature of each sample is slightly different due to the difference in composition, the characteristics cannot be compared under the same production conditions. Here, data is shown under conditions where the highest firing density and electrical characteristics were obtained for each sample.

  From Table 1, the dielectric ceramic composition in the composition range of the present invention shows a high value of a relative dielectric constant εr200 or more in many examples. Most of the Qf values are high values of 1000 GHz or more, and in particular, the molar ratio A / B between the A-site atoms and the B-site atoms, that is, (a + b + c + d) / e is within an appropriate range (0.93 or more). In all of the examples, less than 1), 1000 GHz or more is achieved. The temperature characteristic τε is an absolute value of 150 ppm / K or less in all examples. In particular, by setting b / (c + d) to be 0.70 or more and 0.90 or less, the balance between the specific dielectric constants εr, Qf and the temperature characteristic τε is further improved. The dielectric ceramic compositions of Example 4 and Example 11 show very excellent values in all of the relative dielectric constants εr, Qf and temperature characteristics τε. Thus, it can be seen that excellent dielectric properties can be achieved by applying the present invention.

  On the other hand, among the comparative examples shown in Table 2, in the comparative example 2 in which the molar ratio b / (c + d) between the monovalent element Li and the sum of the trivalent element Bi and the rare earth element RE exceeds 1, A decrease in dielectric constant εr is observed. As a result of Li being reduced too much, in Comparative Example 1 where b / (c + d) is less than 0.65, Qf is significantly lower than 1000 GHz, the relative dielectric constant εr is also lowered, and the temperature characteristic τε is also an absolute value of 150 ppm / K. Is over. Further, in Comparative Examples 3 to 5 in which the Ti amount is less than 50 mol%, Qf is less than 1000 GHz, and the relative dielectric constant εr tends to decrease.

FIG. 3 is a ternary composition diagram showing a preferred composition range of elements constituting the A site in the dielectric ceramic composition of the present invention. It is a figure which shows an example of the manufacturing process of a dielectric material ceramic composition.

1 mixing process, 2 pre-baking process, 3 grinding process, 4 granulation process, 5 molding process, 6 firing process

Claims (7)

Basic composition _{ingredients, aCaO-bLiO 1/2 -cBiO 3/2 -dREO} 3/2 -eTiO 2 [ provided that at least RE is selected La, Ce, Pr, Nd, Sm, Yb, Dy, from Y 1 It represents a seed, a + b + c + d + e = 100 (mol%). ],
10 ≦ a ≦ 25
10 ≦ b ≦ 20
8 ≦ c ≦ 15
2 ≦ d ≦ 10
50 ≦ e ≦ 60
And 0.65 ≦ b / (c + d) <1.0
A dielectric porcelain composition comprising: 0.70 ≦ b / (c + d) ≦ 0.90
The dielectric ceramic composition according to claim 1, wherein:   The dielectric ceramic composition according to claim 1, wherein 1 ≦ c / d ≦ 5.   The dielectric ceramic composition according to claim 1, wherein 0.93 ≦ (a + b + c + d) / e <1. 5. The dielectric ceramic composition according to claim 1, wherein among the basic composition components, RE is Nd in REO _3/2 .   6. The dielectric ceramic composition according to claim 5, wherein a part of the Nd is substituted with one or more selected from La, Ce, Pr, Sm, Y, Yb, and Dy.   Among the basic composition components, in CaO, a part of Ca is substituted with one or more selected from Sr, Ba, and Mg. The dielectric ceramic composition as described.

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