JP5142651B2 - Dielectric porcelain and capacitor - Google Patents

Description

  The present invention relates to a dielectric ceramic made of crystal particles mainly composed of barium titanate and a capacitor using the dielectric ceramic.

  At present, the spread of digital electronic devices such as mobile computers and mobile phones is remarkable, and in the near future digital terrestrial broadcasting is going to be deployed nationwide. There are liquid crystal displays, plasma displays, and the like as digital electronic devices that are receivers for digital terrestrial broadcasting, and many LSIs are used for these digital electronic devices.

Therefore, many bypass capacitors are mounted on the power supply circuits that make up these digital electronic devices such as liquid crystal displays and plasma displays, but the capacitors used here require high capacitance. In some cases, a high dielectric constant monolithic ceramic capacitor (see, for example, Patent Document 1) is adopted. On the other hand, when temperature characteristics are important even with a low capacitance, a temperature compensation type monolithic ceramic capacitor (eg, a small capacitance change rate) , See Patent Document 2).
JP 2001-89231 A JP 2001-294482 A

  However, since the multilayer ceramic capacitor having a high dielectric constant disclosed in Patent Document 1 is composed of crystal grains of dielectric ceramic having ferroelectricity, the temperature change rate of relative permittivity is large, and electric field-dielectric There was a problem that the hysteresis in polarization characteristics was large.

  In addition, a capacitor formed by using a ferroelectric dielectric ceramic disclosed in Patent Document 1 tends to generate a “sounding” phenomenon due to an electrically induced strain on a power supply circuit. It was an obstacle when using it.

  On the other hand, temperature compensated monolithic ceramic capacitors have the advantage that the dielectric porcelain constituting them is paraelectric, so that the hysteresis in the electric field-dielectric polarization characteristics is small, and the electrical induced strain peculiar to ferroelectricity does not occur. However, since the dielectric ceramic has a low relative dielectric constant, there is a problem in that the storage capacity is low and the performance as a bypass capacitor is not satisfied.

  Accordingly, an object of the present invention is to provide a dielectric ceramic having a high dielectric constant and low hysteresis in electric field-dielectric polarization characteristics, and a capacitor using the dielectric ceramic.

The dielectric ceramic of the present invention is a dielectric ceramic comprising crystal grains mainly composed of barium titanate and a grain boundary phase formed between the crystal grains, and the barium 1 constituting the barium titanate. With respect to mol, magnesium is in a proportion of 0.01 to 0.06 mol in terms of MgO, yttrium is in a proportion of 0 to 0.03 mol in terms of YO _3/2 , and manganese is in a proportion of 0.005 to 0 in terms of MnO. In the X-ray diffraction chart of the dielectric ceramic when the niobium is solid-dissolved at a ratio of 0.07 to 0.3 mol in terms of NbO _5/2 at a ratio of 0.03 mol, and using Cukα rays, the difference between the half value width _{(d 0.99)} in half-width _{(d 25)} and 0.99 ° C. at 25 ° C. of the diffraction peak 2θ appears in the range of 44.7~45.5 ° _{(d 25 -d 150)} 0.05 Ri der below, room temperature ( Relative dielectric constant at 25 ° C.) is 500 to 860, polarization charge in an electric field 0V is characterized 14~30nC / cm ² der Rukoto.

  The capacitor of the present invention is characterized in that it is composed of a laminate of a dielectric layer made of the above dielectric ceramic and a conductor layer.

According to the dielectric ceramic of the present invention, it has crystal particles mainly composed of barium titanate and contains magnesium, yttrium, manganese and niobium in the above-mentioned ratio in terms of oxides, and is obtained by these components. In the X-ray diffraction chart using Cukα rays of dielectric ceramic, the half-value width (d ₂₅ ) at 25 ° C. and the half-value width at 150 ° C. of the diffraction peak appearing in 2θ in the range of 44.7 to 45.5 ° ( by the difference between the d _0.99) and _{(d 25 -d 150)} 0.05 or less, it has a high dielectric constant compared to the dielectric ceramic having a conventional paraelectric, small dielectric dielectric polarization Porcelain can be obtained.

  In addition, according to the capacitor of the present invention, a capacitor having a higher capacity than that of a conventional capacitor can be formed by applying the above dielectric ceramic having a high dielectric constant and a small dielectric polarization as the dielectric layer. Further, even when this capacitor is used in a power supply circuit, it is possible to suppress the occurrence of a “sounding” phenomenon caused by electrically induced distortion.

The dielectric porcelain of the present invention contains barium titanate as a main component and contains magnesium, yttrium, manganese and niobium. The content of magnesium is 0.000 in terms of MgO with respect to 1 mol of barium. In a proportion of 01 to 0.06 mol, yttrium in a proportion of 0.0 to 0.03 mol in terms of YO _3/2 , manganese in a proportion of 0.005 to 0.03 mol in terms of MnO, and niobium in a proportion of NbO _In the X-ray diffraction chart of the dielectric porcelain when using Cukα rays, 2θ is in the range of 44.7 to 45.5 ° while being contained at a ratio of 0.07 to 0.3 mol in terms of _5/2. the difference between the half value width _{(d 0.99)} at a 0.99 ° C. half width _{(d 25) (d 25 -d} 150) is characterized in that 0.05 or less at 25 ° C. of the diffraction peaks appearing in.

When the difference in half width of the X-ray diffraction chart at 25 ° C. and 150 ° C. (d ₂₅ −d ₁₅₀ ) is in the above range, the relative dielectric constant at room temperature (25 ° C.) is 500 or more. In addition, a dielectric ceramic having a small dielectric polarization with a polarization charge of 30 nC / cm ² or less at an electric field of 0 V can be formed.

FIG. 1A is an X-ray diffraction diagram of the (200) plane or (002) plane when the dielectric ceramic of the present invention is measured at 25 ° C., and FIG. 1B is the dielectric ceramic of the present invention. Is an X-ray diffraction diagram of (200) plane and (002) plane when measured at 150 ° C. FIG. In the X-ray diffraction diagrams of FIGS. 1 (a) and 1 (b), the arrow means the half width of the diffraction peak. In this case, the full width at half maximum (d ₂₅ ) at 25 ° C. and the full width at half maximum (d ₁₅₀ ) at 150 ° C. are the half of the diffraction peak that appears in the range of 2θ of 44.7 to 45.5 ° in the measured X-ray diffraction diagram. Apply the value of the price range to the Bragg equation. At this time, even when the diffraction peaks of the (200) plane and the (002) plane overlap, the full width at half maximum is obtained for the entire diffraction peak in the range of 2θ.

The dielectric porcelain of the present invention is obtained by dissolving magnesium, yttrium, manganese and niobium in barium titanate having a tetragonal crystal structure and ferroelectricity, and using the dielectric ceramic Cukα ray. In the line diffraction chart, the difference (d ₂₅ −d ₁₅₀ ) between the half-value width (d ₂₅ ) at ₂₅ ° C. and the half-value width (d ₁₅₀ ) at 150 ° C. of the diffraction peak appearing in the range of 2θ of 44.7 to 45.5 °. ) Of 0.05 or less, as seen in FIGS. 1A and 1B, similar X-ray diffraction patterns are obtained at 25 ° C. and 150 ° C., and 2θ is 44.7 to 45.5. It can have a large diffraction peak in the range of °.

  Therefore, the crystal structure of the crystal grains constituting the dielectric ceramic at the upper and lower temperatures across the Curie temperature (125 ° C.) of barium titanate can be mainly composed of a cubic system, Almost no crystal phase is contained, whereby the ferroelectricity resulting from the tetragonal crystal structure is lowered, the paraelectric property can be increased, and the dielectric polarization can be reduced by increasing the paraelectric property.

2 (a) and 2 (b) show X-ray diffraction patterns at 25 ° C. and 150 ° C. of dielectric ceramics different from the present invention in which magnesium, yttrium, manganese and niobium are solid-dissolved in barium titanate. Having different X-ray diffraction patterns at 25 ° C. and 150 ° C., and the difference in half width of the diffraction peaks at 25 ° C. and 150 ° C. (d ₂₅ −d ₁₅₀ ) is larger than 0.05. In a body porcelain, since there are many tetragonal crystal phases, the ferroelectricity increases, so that the dielectric polarization cannot be reduced.

  Further, in the dielectric ceramic according to the present invention, magnesium, yttrium and manganese have an effect of lowering the ferroelectricity of barium titanate by being dissolved in crystal grains mainly composed of barium titanate. By dissolving in crystal particles containing barium titanate as a main component, the ferroelectricity of barium titanate is lowered and the coarsening of the crystal particles is suppressed.

  As described above, the dielectric ceramic according to the present invention, in which magnesium, yttrium, manganese, and niobium are solid-solved in barium titanate and contains almost no tetragonal crystals, is mainly composed of cubic crystals. As described above, in the temperature range above and below the Curie temperature (125 ° C) of barium titanate, there is almost no change in the crystal structure due to the tetragonal and cubic phase transitions, and the paraelectric mainly composed of the cubic system Since it is a body, the change in relative dielectric constant at 25 ° C. is small.

By the way, the contents of magnesium, yttrium and manganese in the dielectric porcelain are 0.01 to 0.06 mol of magnesium (Mg) in terms of MgO with respect to 1 mol of barium, and yttrium (Y) is YO. It is important to contain manganese (Mn) in a proportion of 0 to 0.03 mol in terms of _3/2 and 0.005 to 0.03 mol in terms of MnO.

That is, when the content of magnesium with respect to 1 mol of barium is less than 0.01 mol in terms of MgO or when the content of manganese is less than 0.005 mol in terms of MnO, the dielectric when using Cukα rays is used. In the X-ray diffraction chart of the body porcelain, the difference between the half-value width (d ₂₅ ) at ₂₅ ° C. and the half-value width (d ₁₅₀ ) at 150 ° C. (d ₁₅₀ ) of the diffraction peak appearing in the range of 2θ of 44.7 to 45.5 ° (d _25- d ₁₅₀ ) is 0.1 or more, so that the dielectric constant of the dielectric ceramic is high, but the polarization charge is larger than 30 nC / cm ² , and the content of magnesium relative to 1 mol of barium is When it is more than 0.06 mol in terms of MgO, when the yttrium content is more than 0.03 mol in terms of YO _3/2 , and when the manganese content is M This is because when the amount is more than 0.06 mol in terms of nO, the dielectric constant of each dielectric ceramic at 25 ° C. is lower than 500.

Further, it is important to contain 0.07 to 0.3 mol of niobium (Nb) in terms of NbO _5/2 with respect to 1 mol of barium contained in barium titanate.

That is, when the content of Nb with respect to 1 mol of barium is less than 0.07 mol in terms of NbO _5/2 , although the dielectric constant of the dielectric ceramic is high, the polarization charge is greater than 30 nC / cm ² , On the other hand, if the content of Nb with respect to 1 mol of barium is more than 0.3 mol in terms of NbO _5/2 , the relative dielectric constant at 25 ° C. becomes lower than 500.

The preferred contents of magnesium, yttrium, manganese and niobium are 0.017 to 0.023 mol in terms of MgO and 0 to yttrium (Y) in terms of YO _{3/2 with} respect to 1 mol of barium. .0015 to 0.01 mol, manganese (Mn) is 0.008 to 0.03 mol in terms of MnO, and niobium (Nb) is in the range of 0.11 to 0.159 mol in terms of NbO _5/2. Some have good composition range, and in the X-ray diffraction chart of the dielectric ceramic when using the Cukα ray, 2θ is 25 ° C. of the diffraction peak appearing in the range of 44.7 to 45.5 °. By setting the difference (d ₂₅ -d ₁₅₀ ) between the half-value width (d ₂₅ ) at 150 ° C. and the half-value width (d ₁₅₀ ) at 150 ° C. to 0.02 or less, the dielectric at 25 ° C. The relative permittivity of the body porcelain can be increased to 548 or more, and the polarization charge at 0 V can be increased to 25 nC / cm ² or less in the electric field-dielectric polarization characteristics.

  The dielectric ceramic of the present invention may contain components other than barium titanate, magnesium, yttrium, manganese and niobium in a range of 2% by mass or less with respect to the dielectric ceramic. In order to improve the property, a sintering aid such as silicon oxide can be contained.

  Next, a method for manufacturing the dielectric ceramic according to the present invention will be described.

First, BaCO ₃ powder, TiO ₂ powder, MgO powder, Y ₂ O ₃ powder, MnCO ₃ powder, and Nb ₂ O ₅ powder each having a purity of 99% or more are used as the raw material powder. These raw material powders are composed of 0.01 to 0.06 mol of MgO powder and 1 to 0 of Y ₂ O ₃ powder in terms of YO _3/2 with respect to 1 mol of barium constituting barium titanate. In a ratio of 0.03 mole, MnCO ₃ powder is blended in a ratio of 0.005 to 0.03 mole, and Nb ₂ O ₅ powder is blended in a ratio of 0.07 to 0.3 mole in terms of NbO _5/2 .

  Next, the mixture of the raw material powders described above is wet mixed. At this time, one type selected from a polyacrylic acid type dispersing agent, a polyacrylic acid ammonium type dispersing agent, a polyoxyalkylene monoalkyl ether grafted type dispersing agent and the like is used as a dispersing agent, and water, ethanol, and By selecting and using one selected from a mixed solution of toluene, the dispersibility of the mixed powder can be enhanced. In addition, by adopting a bead mill apparatus for pulverizing the calcined powder, the composition of the calcined powder and the uniformity of the particle size can be improved.

  Next, after the wet-mixed mixed powder is dried, it is calcined in a temperature range of 900 to 1130 ° C. and pulverized, so that magnesium, yttrium, manganese, and niobium are formed on the main component barium titanate. Is prepared, and a calcined powder whose crystal structure mainly shows a cubic system is prepared. In this case, when the calcining temperature is 900 ° C. or higher, there is an advantage that a calcined powder having a small amount of unreacted material and uniform and high cubic crystallinity can be obtained, while the calcining temperature is 1150 ° C. or less. This is because, together with high sinterability, there is little generation of coarse particles, and a fine calcined powder with high cubic crystallinity as described later can be obtained.

FIG. 3 is an X-ray diffraction diagram of the calcined powder for forming the dielectric ceramic of the present invention when the calcining temperature is changed. The composition of the calcined powder of this X-ray diffraction pattern is such that MgO powder is 0.02 mol in terms of MgO and Y ₂ O ₃ powder is in terms of YO _3/2 with respect to 1 mol of barium constituting barium titanate. And 0.01 mol of MnCO ₃ powder in terms of MnO and 0.11 mol of Nb ₂ O ₅ powder in terms of NbO _5/2 .

  Also, FIG. 4 shows that only magnesium, yttrium and manganese are added to the main component barium titanate in the same amount as that contained in the calcined powder shown in FIG. 3 to change the calcining temperature. It is an X-ray diffraction diagram of the calcined powder at the time. That is, it indicates a calcined powder not containing niobium.

  As shown in FIG. 3, the calcined powder obtained by adding a predetermined amount of magnesium, yttrium, manganese and niobium to barium titanate shows a substantially single peak of cubic system at a calcining temperature of 1025 ° C. to 1100 ° C. Even if the calcining temperature is increased to 1250 ° C., the change to the tetragonal system is small. Such a calcined powder has a large amount of additive elements such as Nb dissolved in barium titanate. Therefore, in order to produce a dielectric ceramic that is a sintered body, the calcined powder has a temperature higher than the calcining temperature. There is little formation of a tetragonal crystal phase even when heated, and for this reason, there is little change in crystal structure when the Curie temperature as shown in FIGS. 1A and 1B is used as a boundary. A body porcelain can be easily obtained.

  On the other hand, the calcined powder shown in FIG. 4 is primarily cubic until the calcining temperature reaches 1100 ° C., but changes to tetragonal when the calcining temperature reaches 1250 ° C.

  In this way, in the calcined powder in which niobium is not dissolved in the main component barium titanate, when the main body is used for firing and a dielectric porcelain is produced, the calcined powder is often used together with a cubic crystal phase. Since the tetragonal crystal phase tends to precipitate, it may be difficult to maintain paraelectricity. In addition, such an event also occurs in a calcined powder in which niobium is not sufficiently solid-solved with barium titanate, which is the main component. The generation of the crystal phase increases, resulting in a dielectric ceramic having a large change in crystal structure when the Curie temperature as shown in FIGS.

  The X-ray diffraction pattern of the calcined powder shown in FIG. 4 does not contain niobium among the components constituting the calcined powder, but does not contain magnesium or manganese other than niobium, or barium titanate. 4 also has a tendency to change to a tetragonal system when the calcining temperature is 1250 ° C. or higher, as in FIG. Is difficult to maintain.

  In the present invention, the average particle size of the calcined powder is set to 0.1 μm or less, and this is sintered to grow grains, thereby obtaining a dielectric ceramic having a paraelectric property and a high dielectric constant. It becomes possible.

  The pulverized calcined powder is formed into a pellet and subjected to main firing in the air or in a reducing atmosphere at a temperature range of 1050 ° C. or higher and 1150 ° C. or lower to obtain the dielectric ceramic of the present invention. Here, the main firing temperature is set to 1050 ° C. or higher and 1150 ° C. or lower because when the firing temperature is lower than 1050 ° C., the dielectric ceramic cannot be sufficiently densified, and the density of the dielectric ceramic This is because it is difficult to obtain a dielectric ceramic having a cubic system after firing because there are many unreacted materials. When the firing temperature is higher than 1150 ° C., the dielectric This is because the tetragonal crystal phase tends to increase in the porcelain, and the crystal grains grow too much, so that the reactivity is lowered in subsequent firing and it becomes difficult to densify.

Further, in order to improve the sinterability of the dielectric ceramic, glass powder containing SiO ₂ as a main component is mixed at a ratio of 0.5 to 2 parts by mass with respect to 100 parts by mass of the calcined powder. It doesn't matter.

  FIG. 5 is a schematic cross-sectional view showing an example of the capacitor of the present invention. The following capacitor can be formed using the dielectric ceramic of the present invention.

  The capacitor of the present invention has an external electrode 12 provided at the end of the capacitor body 10, and the capacitor body 10 is a laminate in which dielectric layers 13 and conductor layers 14 as internal electrode layers are alternately laminated. Consists of the body. It is important that the dielectric layer 13 is formed by the above-described dielectric ceramic of the present invention.

  According to such a capacitor of the present invention, the dielectric layer 13 exhibits temperature characteristics of a high dielectric constant and a stable relative dielectric constant, and applies the above-mentioned dielectric ceramic having a small spontaneous polarization. In addition, a capacitor having a high capacity and stable capacitance-temperature characteristics can be formed. For this reason, when this capacitor is used in a power supply circuit, it is possible to suppress the occurrence of a “sounding” phenomenon caused by electrically induced distortion.

  The conductor layer 14 is preferably a base metal such as Ni or Cu in that the manufacturing cost can be suppressed even if the layer is made highly stacked. In particular, the conductor layer 14 can be simultaneously fired with the dielectric layer 13 constituting the capacitor of the present invention. Ni is more desirable. The conductor layer 14 preferably has an average thickness of 1 μm or less.

Further, when producing such a capacitor, the mixed powder described above is formed into a green sheet, and a conductor paste to be a conductor layer 14 is prepared and printed on the surface of the green sheet, and then laminated and fired. To form a laminate. Thereafter, a conductor paste is further printed on the end face of the laminate 1 and fired to form the external electrode 12, whereby a capacitor can be obtained. As the mixed powder to form a green sheet, using a mixing ratio of 0.5 to 2 parts by weight of a glass powder containing SiO ₂ as a main component as a sintering agent to the calcined powder It is preferable that the sintering aid is contained in this manner, so that it can be fired simultaneously with the conductor layer 14 which is the internal electrode layer.

Hereinafter, dielectric ceramics of the present invention and dielectric ceramics other than the present invention were produced, and the relative dielectric constant and polarization charge were measured. First of all, Nb ₂ O ₅ powder was prepared by mixing BaCO ₃ powder, TiO ₂ powder, MgO powder, Y ₂ O ₃ powder, MnCO ₃ powder and Nb ₂ O ₅ powder with a purity of 99.9%. Next, the mixed powder was calcined at a temperature of 1000 ° C. to prepare a calcined powder, and the obtained calcined powder was pulverized so that the average particle diameter was 0.1 μm. Thereafter, glass powder having a composition of SiO ₂ —B ₂ O ₃ (molar ratio 60:40) was mixed at a ratio of 1 part by mass with respect to 100 parts by mass of the calcined powder. Thereafter, the mixed powder was granulated and formed into pellets having a diameter of 16.5 mm and a thickness of 1 mm.

  Next, 10 pellets of each composition were fired at a temperature shown in Table 1 in the air.

  The average grain size of the crystal grains that make up the dielectric porcelain is the outline of the crystal grains shown in the photograph after the fracture surface of the dielectric porcelain is polished and a picture of the internal structure is taken using a scanning electron microscope. The image was processed, the area of each particle was determined, the diameter when replaced with a circle having the same area was calculated, and the average value of about 50 calculated crystal particles was determined. The magnification of the photograph was about 30000 times, the number of observation points was 2 for each sample, and the average value was obtained.

  In addition, a conductor layer of indium gallium is printed on the surface of the fired sample, the capacitance is measured at a frequency of 1.0 kHz and an input signal level of 1.0 V using an LCR meter 4284A, and the diameter and thickness of the sample are measured. The relative dielectric constant was calculated from the area of the conductor layer. In these measurements, the number of samples was 10 and the average value was obtained.

  Moreover, the magnitude | size (polarization charge) of the electrically induced distortion was calculated | required by the dielectric polarization measurement about the obtained dielectric ceramic. In this case, the evaluation was based on the value of the charge amount (residual polarization) at 0 V when the voltage was changed in the range of ± 1250 V.

Next, the crystal structure of the dielectric ceramic obtained by the X-ray diffractometer was identified. The X-ray tube is Cukα, the scanning angle is an angle (2θ = 44 to 46 °) of the (200) plane and (002) plane of barium titanate, and measured at room temperature (25 ° C.) and 150 ° C. The diffraction peak of the (002) plane and the (200) plane appeared, and the half width (d ₂₅ ) of the diffraction peak at 25 ° C. with 2θ ranging from 44.7 to 45.5 ° and the half width of the diffraction peak at 150 ° C. and it obtains the difference between _{(d 150) (d 25 -d} 150). The number of measurements was 3 for each sample, and the average value was obtained. In this case, the full width at half maximum (d ₂₅ ) at 25 ° C. and the full width at half maximum (d ₁₅₀ ) at 150 ° C. are values of the full width at half maximum when expressed by 2θ of the diffraction peak of the (002) plane of the measured X-ray diffraction diagram. It was calculated by applying the Bragg equation.

  Furthermore, the composition analysis of the sample was performed by ICP analysis or atomic absorption analysis. In this case, the obtained dielectric porcelain mixed with boric acid and sodium carbonate and dissolved in hydrochloric acid is first subjected to qualitative analysis of the elements contained in the dielectric porcelain by atomic absorption spectrometry, and then specified. The diluted standard solution for each element was used as a standard sample and quantified by ICP emission spectroscopic analysis. Further, the amount of oxygen was determined using the valence of each element as the valence shown in the periodic table. In this case, the composition of the produced sample coincided with the composition shown in Table 1.

Table 1 shows the composition and firing temperature, and Table 2 shows the result of the characteristics of the dielectric ceramic after firing. Sample No. 33 is a sample No. 33. The composition of 4, the composition excluding the _Nb 2 _{O 5,} the calcined powder prepared at a temperature of 1000 ° C., with respect to calcined powder obtained by grinding, samples _Nb 2 _{O 5} powder No. The sample was added in the amount shown in FIG. This was also evaluated in the same manner as the dielectric ceramic of the present invention.

As is apparent from the results in Tables 1 and 2, sample No. In 3 to 8, 10 to 15, 18 to 22, 24 to 28, 30, and 31, in the X-ray diffraction chart of the dielectric ceramic when using the Cukα ray, 2θ is in the range of 44.7 to 45.5 °. the difference _{(d 25 -d 150)} becomes 0.05 or less of a half-value width _{(d 0.99)} in half-width _{(d 25)} and 0.99 ° C. at 25 ° C. of the diffraction peaks appearing in, more than 500 relative dielectric constant at 25 ° C. The polarization charge was 30 nC / cm ² or less.

In particular, magnesium is 0.017 to 0.023 mol, yttrium is 0.0015 to 0.01 mol in terms of YO _3/2 , manganese is 0.008 to 0.03 mol in terms of MnO, and niobium is NbO _5/2. Sample No. in terms of 0.11 to 0.159 mol in terms of conversion. In 4 to 7, 12 to 14, 19 to 20, 25 to 28, 30, and 31, in the X-ray diffraction chart of the dielectric ceramic when using the Cukα ray, 2θ is in the range of 44.7 to 45.5 °. the difference _{(d 25 -d 150)} becomes 0.02 or less of a half-value width _{(d 0.99)} in half-width _{(d 25)} and 0.99 ° C. at 25 ° C. of the diffraction peaks appearing in, is 548 or more relative dielectric constant at 25 ° C. The polarization charge was 25 nC / cm ² or less.

On the other hand, in a sample outside the scope of the present invention, the relative dielectric constant at 25 ° C. is less than 500, or in the X-ray diffraction chart of the dielectric ceramic when using the Cukα ray, 2θ is 44. The difference (d ₂₅ −d ₁₅₀ ) between the half width at 25 ° C. (d ₂₅ ) and the half width at 150 ° C. (d ₁₅₀ ) of the diffraction peak appearing in the range of 7 to 45.5 ° is greater than 0.05, There was hysteresis in the polarization, and the polarization charge was greater than 30 nC / cm ² .

(A) is an X-ray diffraction pattern of the (200) plane or (002) plane when the dielectric ceramic of the present invention is measured at 25 ° C., and (b) is the dielectric ceramic of the present invention at 150 ° C. It is an X-ray diffraction pattern of (200) plane or (002) plane when measured. (A) is an X-ray diffraction diagram of the (200) plane or (002) plane when a dielectric ceramic outside the present invention is measured at 25 ° C., and (b) is a diagram illustrating 150 dielectric dielectrics outside the present invention. FIG. 2 is an X-ray diffraction diagram of a (200) plane or a (002) plane when measured at ° C. It is an X-ray-diffraction figure of calcining powder for forming the dielectric ceramic of the present invention when calcining temperature is changed (sample No. 4). It is an X-ray diffraction pattern of calcined powder when magnesium, yttrium, and manganese are contained with respect to the main component barium titanate and the calcining temperature is changed. (Sample No. 33). It is a cross-sectional schematic diagram which shows the example of the capacitor | condenser of this invention.

Explanation of symbols

10 Capacitor body 12 External electrode 13 Dielectric layer 14 Conductor layer

Claims (2)

A dielectric ceramic comprising crystal grains mainly composed of barium titanate and a grain boundary phase formed between the crystal grains, and magnesium is MgO with respect to 1 mol of barium constituting the barium titanate. Niobium at a rate of 0.01 to 0.06 mol in terms of conversion, yttrium at a rate of 0 to 0.03 mol in terms of YO _3/2 , and manganese at a rate of 0.005 to 0.03 mol in terms of MnO. the _{NbO 5/2} Rutotomoni 0.07 to 0.3 is dissolved at a ratio of moles converted, the X-ray diffraction chart of the dielectric ceramic when using Cukα line, 2 [Theta] is from 44.7 to 45. 5 the difference between the half value width _{(d 0.99)} ° at 25 ° C. of the diffraction peak appears in the range of 0.99 ° C. in half-width _{(d 25) (d 25 -d} 150) is Ri der 0.05, at room temperature (25 C)) But 500 to 860, the dielectric ceramic polarization charge in the electric field 0V is characterized 14~30nC / cm ² der Rukoto.   A capacitor comprising a laminate of a dielectric layer made of the dielectric ceramic according to claim 1 and a conductor layer.

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