Dielectric porcelain composition, method for producing dielectric porcelain composition, and multilayer ceramic electronic component

Abstract

A dielectric porcelain composition having a main component of a lead-free perovskite type compound at least containing Ba, Ca, Ti, and Sb, and having a Curie temperature Tc of 140 C. or higher.

Claims

1. A dielectric porcelain composition comprising a lead-free perovskite compound having a main component at least containing Ba, Ca, Ti, and Sb, the dielectric porcelain composition having a Curie temperature Tc of 140 C. or higher, and wherein the Sb is in the form of a solid solution at an A site of the lead-free perovskite compound.

2. The dielectric porcelain composition according to claim 1, wherein the Sb is contained in an amount of 0.1 to 5 parts by mol with respect to 100 parts by mol of the Ti.

3. The dielectric porcelain composition according to claim 1, wherein the Ba is contained in an amount of 80 parts by mol or more with respect to 100 parts by mol of the Ti.

4. The dielectric porcelain composition according to claim 1, wherein the Ca is contained in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

5. The dielectric porcelain composition according to claim 2, wherein the Ba is contained in an amount of 80 parts by mol or more with respect to 100 parts by mol of the Ti.

6. The dielectric porcelain composition according to claim 5, wherein the Ca is contained in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

7. The dielectric porcelain composition according to claim 2, wherein the Ca is contained in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

8. A multilayer ceramic electronic component comprising: a plurality of dielectric layers; and a plurality of internal electrode layers deposited alternately with respective dielectric layers of the plurality of dielectric layers, wherein the internal electrode layers comprise a base metal material, and the dielectric layers are formed from the dielectric porcelain composition according to claim 1.

9. A method for producing a dielectric porcelain composition, the method comprising: preparing a main component powder from a ceramic raw material at least including a Ba compound, a Ca compound, a Ti compound, and an Sb compound; a shaping the main component powder into a ceramic shaped body; and firing the ceramic shaped body in a reducing atmosphere to produce a ceramic sintered compact having a Curie temperature Tc of 140 C. or higher, wherein Sb is in the form of a solid solution at an A site of a lead-free perovskite compound of the ceramic sintered compact.

10. The method for producing a dielectric porcelain composition according to claim 9, wherein the reducing atmosphere has an oxygen partial pressure of 10.sup.7 to 10.sup.11 MPa, and the firing is done at 1100 to 1400 C.

11. The method for producing a dielectric porcelain composition according to claim 9, wherein the main component powder is prepared by calcining the ceramic raw material in a reducing atmosphere so as to synthesize the main component powder.

12. The method for producing a dielectric porcelain composition according to claim 9, wherein the Sb is contained in the ceramic sintered compact in an amount of 0.1 to 5 parts by mol with respect to 100 parts by mol of Ti.

13. The method for producing a dielectric porcelain composition according to claim 9, wherein Ba is contained in the ceramic sintered compact in an amount of 80 parts by mol or more with respect to 100 parts by mol of Ti.

14. The method for producing a dielectric porcelain composition according to claim 9, wherein Ca is contained in the ceramic sintered compact in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

15. The method for producing a dielectric porcelain composition according to claim 12, wherein Ba is contained in the ceramic sintered compact in an amount of 80 parts by mol or more with respect to 100 parts by mol of the Ti.

16. The method for producing a dielectric porcelain composition according to claim 15, wherein Ca is contained in the ceramic sintered compact in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

17. The method for producing a dielectric porcelain composition according to claim 12, wherein Ca is contained in the ceramic sintered compact in an amount of 15 parts by mol or less with respect to 100 parts by mol of the Ti.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The FIGURE is a cross-sectional view showing one embodiment of a multilayer ceramic capacitor fabricated by using the dielectric porcelain composition of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) Hereinafter, an embodiment of the present invention will be described in detail.

(3) A dielectric porcelain composition as one embodiment of the present invention has a main component composed of a lead-free perovskite type compound (represented by a general formula of ABO.sub.3) at least containing Ba, Ca, Ti, and Sb, and has a Curie temperature Tc of 140 C. or higher. And this allows even a dielectric porcelain composition having a main component composed of a lead-free BaTiO.sub.3-based compound to have a high Curie temperature and ensure a desired dielectric characteristic even in a region of high temperature of 140 C. or higher and be thus suitable for applications at high temperature.

(4) That is, a BaTiO.sub.3-based perovskite type compound is widely known as a dielectric porcelain composition capable of providing a high relative dielectric constant.

(5) However, as has been discussed herein above, BaTiO.sub.3 has a low Curie temperature Tc of about 127 C., and even if it contains Ca, it has a Curie temperature Tc of about 137 C. at the maximum, and its ferroelectricity disappears once the Curie temperature has been exceeded. Thus, simply substituting a portion of Ba with Ca does not reliably provide a dielectric porcelain composition which can be used for applications at high temperature of 140 C. or higher.

(6) As a result of a diligent research by the present inventor, it has been found that when Sb is added to (Ba, Ca)TiO.sub.3 and a heat treatment is applied thereto in a reducing atmosphere a Curie temperature Tc of 140 C. or higher can be obtained. A reason for this is presumed as follows:

(7) When Sb is added to (Ba, Ca)TiO.sub.3 and a heat treatment is applied thereto in the air, Sb forms a solid solution at a B site. That is, as the Sb's compound forms, there normally exist a trivalent Sb compound such as Sb.sub.2O.sub.3 and a pentavalent Sb compound such as Sb.sub.2O.sub.5. In that case, when synthesizing the main component powder or firing the main component powder after it is synthesized is performed in the air, the trivalent Sb compound is oxidized to be pentavalent, and the pentavalent Sb compound maintains its valence. Since the pentavalent Sb has an ionic radius of about 0.060 nm and Ti has an ionic radius of about 0.061 nm, the pentavalent Sb forms a solid solution at a B site in a form of substituting a portion of Ti having a similar ionic radius.

(8) In contrast, when synthesizing the main component powder or firing the main component powder after it is synthesized is performed in a reducing atmosphere, the trivalent Sb compound maintains its valence, and the pentavalent Sb compound is reduced to be trivalent. And as the trivalent Sb has an ionic radius of about 0.076 nm, which is larger than Ti's ionic radius (0.061 nm), it is difficult for the trivalent Sb to form a solid solution at a B site where Ti is coordinated. Furthermore, when the main component powder is calcined and thus synthesized in the air and fired in a reducing atmosphere, Sb becomes trivalent with a large ionic radius from being pentavalent with a small ionic radius, and accordingly, it is believed that even if Sb forms a solid solution at a B site after the calcination and synthesis, Sb is separated from the B site by the firing treatment in the reducing atmosphere, and forms a solid solution at an A site where Ba having as large an ionic radius as 0.135 nm is coordinated in a form of substituting a portion of Ba.

(9) As a result of Sb forming a solid solution at an A site as described above, Sb is covalently bonded to an O atom and thus displaced from the center position of the A site, which increases the ratio c/a between a c axis and an a axis in the crystal axis and hence improves tetragonal crystallinity and hence a temperature at which ferroelectricity is maintained, that is, the Curie temperature Tc. That is, while the perovskite type compound, at the Curie temperature Tc or therebelow, has a crystal structure maintaining tetragonal crystallinity and presenting ferroelectricity, once the Curie temperature Tc is exceeded, the crystal structure undergoes a phase transition from tetragonal to cubic, and thereby ferroelectricity disappears. It is believed that when Sb is reduced by a heat treatment in a reducing atmosphere and forms a solid solution at an A site, Sb is covalently bonded to an O atom, and as a result, Sb is displaced from the center position of the A site, and tetragonal crystallinity is improved and the Curie temperature Tc rises.

(10) In addition, as the dielectric porcelain composition of the present invention is lead-free and accordingly, also reduces an environmental burden, and furthermore, it is obtained through a heat treatment in a reducing atmosphere, it can be co-fired together with a base metal material such as Ni and Cu, and can thus be a dielectric porcelain composition suitable for applications at high temperature.

(11) In so far as the perovskite type compound contains at least Ba, Ti, Ca, and Sb as components and has a Curie temperature Tc of 140 C. or higher, the content of each component is not particularly limited. In other words, the components can be blended in contents allowing the Curie temperature Tc to be 140 C. or higher.

(12) An example of a preferable range of each component is as follows:

(13) Ba is a main element for implementing a dielectric porcelain composition having a high relative dielectric constant together with Ti. In order to obtain a desired high relative dielectric constant at a high Curie temperature Tc of 140 C. or higher, 80 parts by mol or more of Ba are preferable with respect to 100 parts by mol of Ti.

(14) Ca is contained in a BaTiO.sub.3-based compound to contribute to improvement of the Curie temperature Tc, and accordingly, it is an essential component in the present invention. However, when the content of Ca exceeds 15 parts by mol with respect to 100 parts by mol of Ti, the Curie temperature Tc rather tends to decrease, and may decrease to lower than 140 C., and accordingly, 15 parts by mol or less of Ca are preferable.

(15) Sb can be subjected to a heat treatment in a reducing atmosphere to form a solid solution in the main component to contribute to improvement of the Curie temperature Tc, as has been discussed above, and allows the Curie temperature Tc to be 140 C. or higher. And to do so, the Sb content is preferably 0.1 part by mol or more with respect to 100 parts by mol of Ti. In contrast, if Sb is contained excessively, the Ba content is relatively decreased, which may invite a reduced relative dielectric constant, and accordingly, the Sb content is preferably 5 parts by mol or less with respect to 100 parts by mol of Ti.

(16) While the perovskite compound has an A site/B site ratio of 1.000 when represented as a stoichiometric ratio, it is not limited as such and can for example be adjusted as appropriate to have a ratio of (Ba+Ca)/Ti falling within a range of 0.95 to 1.00 as converted to a molar ratio.

(17) Further, the present dielectric porcelain composition is only required to have the above-described perovskite type compound to constitute a main component (for example, 80 mol % or more, preferably 90 mol % or more, more preferably 95 mol % or more), and may contain various additives as a sub component.

(18) Hereinafter, a method for producing the present dielectric porcelain composition will be described in detail.

(19) Initially, as ceramic raw materials, a Ba compound, a Ti compound, a Ca compound, and an Sb compound are prepared. Then, these ceramic raw materials are weighed by prescribed amounts. Note that Sb is a volatile element and volatilized when subjected to a heat treatment in a reducing atmosphere, and accordingly, the Sb compound is excessively weighed.

(20) Subsequently, the weighed materials are charged into a ball mill together with a grinding medium, such as PSZ (Partially Stabilized Zirconia) balls, and pure water, mixed and ground sufficiently in a wet manner, dried and thereafter calcined in a reducing atmosphere or the air and thus synthesized to prepare a main component powder.

(21) When the weighed materials are calcined in a reducing atmosphere, they are calcined for about 1 hour at 900 to 1100 C. in a reducing atmosphere of N.sub.2H.sub.2H.sub.2O with an oxygen partial pressure adjusted to allow the Sb compound to be reduced, e.g., 10.sup.7 to 10.sup.11 MPa.

(22) When the weighed materials are calcined in the air, they are calcined in the air at 900 to 1100 C. for about 1 hour.

(23) Subsequently, the main component powder is put into a ball mill together with an organic binder, an organic solvent and a grinding medium, wet-mixed, dried, and thereafter pressed to produce a ceramic shaped body.

(24) Thereafter, the ceramic shaped body is heated in the air at 250 to 350 C. to have the binder burnt and thus removed therefrom, and furthermore, the ceramic shaped body is fired at a prescribed temperature for about 2 hours in a reducing atmosphere of gaseous H.sub.2N.sub.2H.sub.2O with an oxygen partial pressure adjusted to disallow the Sb in the main component to be oxidized, e.g., 10.sup.7 to 10.sup.11 MPa, to produce a dielectric porcelain composition which is a ceramic sintered compact having a Curie temperature Tc of 140 C. or higher.

(25) While the ceramic shaped body may be fired at any temperature allowing the ceramic shaped body to be sintered, it is preferable that the temperature be set in a range of 1100 to 1400 C. More specifically, when the ceramic shaped body is fired at a temperature lower than 1100 C., which is excessively low, it may be difficult to sinter the ceramic shaped body. From the viewpoint of energy conservation, it is preferable that the ceramic shaped body be fired at 1400 C. or lower.

(26) Thus the method for producing a dielectric porcelain composition as described above allows a high Curie temperature Tc to be obtained through firing in a reducing atmosphere, and can thus produce a dielectric porcelain composition which can be co-fired with a base metal material and has a high Curie temperature Tc.

(27) Hereinafter, a multilayer ceramic electronic component of the present invention will be described in detail.

(28) The FIGURE is a cross-sectional view schematically showing one embodiment of a multilayer ceramic capacitor serving as a multilayer ceramic electronic component produced using the dielectric porcelain composition according to the present invention.

(29) In the multilayer ceramic capacitor, internal electrode layers 2a to 2f are buried in a ceramic sintered compact 1, external electrodes 3a and 3b are formed at opposite ends of ceramic sintered compact 1, and first plating films 4a and 4b and second plating films 5a and 5b are formed on surfaces of external electrodes 3a and 3b.

(30) That is, ceramic sintered compact 1 is formed by alternately stacking and firing dielectric layers 6a to 6g formed of the dielectric porcelain composition of the present invention and internal electrode layers 2a to 2f, and internal electrode layers 2a, 2c and 2e are electrically connected to external electrode 3a and internal electrodes 2b, 2d and 2f are electrically connected to external electrode 3b. Internal electrode layers 2a, 2c, 2e have surfaces opposite to those of internal electrode layers 2b, 2d, 2f, respectively, and electrostatic capacitance is formed between these opposite surfaces.

(31) In the present multilayer ceramic capacitor, internal electrode layers 2a to 2f are formed of a base metal material and dielectric layers 6a to 6g are formed of the above-described dielectric porcelain composition, and even in a case with internal electrode layers 2a to 2f formed using a base metal material, a multilayer ceramic capacitor which ensures a desired dielectric characteristic in a high temperature region of 140 C. or higher and is thus suitable for applications at high temperature, can be obtained.

(32) The above multilayer ceramic capacitor can be easily produced in the following method:

(33) Initially, a main component powder is prepared in the same method and procedure as described for the method for producing the dielectric porcelain composition as described above.

(34) Subsequently, the main component powder is charged into a ball mill together with an organic binder, an organic solvent and a grinding medium and wet-mixed to prepare a ceramic slurry, which is in turn shaped through a RIP process, a doctor blade process, or the like to prepare a ceramic green sheet to have a thickness of about 2 m or less after it is fired.

(35) Subsequently, a conductive paste for the internal electrodes which contains a base metal material such as Ni, Cu or the like is prepared. Subsequently, the conductive paste for the internal electrodes is used to provide screen-printing on the ceramic green sheet to form a conductive film of a predetermined pattern on a surface of the ceramic green sheet.

(36) Subsequently, a plurality of such ceramic green sheets each having the conductive film formed thereon are stacked in a predetermined direction and a ceramic green sheet which does not have the conductive film formed thereon is placed as a topmost layer, and the ceramic green sheets are compressed together and cut to have a predetermined dimension to thus produce a multilayer shaped body.

(37) After that, the binder is removed under the same condition as described above, and subsequently, a firing treatment is performed to produce ceramic sintered compact 1.

(38) Subsequently, a conductive paste for the external electrodes is applied to opposite end surfaces of ceramic sintered compact 1 and baked at 600 to 800 C. to form external electrodes 3a and 3b.

(39) The conductive paste for the external electrodes contains a conductive material, which is also not particularly limited, although from the viewpoint of cost reduction a material containing Ag, Cu, or an alloy thereof as a main component is preferably used.

(40) External electrodes 3a and 3b may be formed in a method as follows: the conductive paste for the external electrodes is applied to the opposite end surfaces of the multilayer shaped body and fired together with the multilayer shaped body simultaneously.

(41) Finally, electrolytic plating is performed to form first plating films 4a, 4b made of Ni, Cu, a NiCu alloy or the like on the surfaces of external electrodes 3a, 3b, and furthermore, second plating films 5a, 5b made of solder, tin, or the like are formed on the surfaces of first plating films 4a, 4b to thus produce a multilayer ceramic capacitor.

(42) It should be noted that the present invention is not limited to the above embodiment. While in the above embodiment a multilayer ceramic capacitor is indicated as a multilayer ceramic electronic component by way of example, it is needless to say that the present invention is applicable to various multilayer ceramic electronic components for applications at high temperature containing a BaTiO.sub.3-based perovskite type compound as a main component.

(43) The ceramic raw materials such as a Ba compound and a Ti compound can also be appropriately selected, such as carbonate, oxide, nitrate, hydroxide, organic acid salt, alkoxide, a chelate compound, etc., depending on the form of the synthesis reaction.

(44) Furthermore, the method for synthesizing the main component powder is not limited to the above-mentioned solid phase method, either, and a synthesis method such as a coprecipitation method, a hydrothermal method, an oxalic acid method, etc. may be used.

EXAMPLES

(45) Hereinafter, examples of the present invention will be described in detail.

(46) [Preparing Samples]

(47) BaCO.sub.3, CaCO.sub.3, TiO.sub.2, and Sb.sub.2O.sub.3 were prepared as ceramic raw materials and weighed such that after they were fired Ba, Ca, and Sb in parts by mol with respect to 100 parts by mol of Ti were as shown in Table 1. As it was assumed that Sb.sub.2O.sub.3 would be volatilized when fired in a reducing atmosphere, Sb.sub.2O.sub.3 was excessively weighed by 50 to 100% by mol.

(48) Subsequently, these weighed materials were charged into a ball mill together with PSZ balls and pure water, sufficiently wet mixed and thus ground, and dried, and thereafter fired at 1100 C. for about 1 hour in a reducing atmosphere of gaseous H.sub.2N.sub.2H.sub.2O with an oxygen partial pressure adjusted to 10.sup.8.5 MPa, and ground to obtain calcined powder (i.e., the main component powder).

(49) Subsequently, polyvinyl alcohol was added to the calcined powder such that the polyvinyl alcohol has a weight ratio of 2 wt % to obtain a mixture. Subsequently, this mixture was subjected to a pressure of 1000 MPa by a uniaxial press to provide a ceramic shaped body having a diameter of 10 mm and a thickness of 0.5 mm.

(50) Subsequently, the ceramic shaped body was fired at 1000 to 1400 C. for about 1 hour in a reducing atmosphere of gaseous H.sub.2N.sub.2H.sub.2O with an oxygen partial pressure adjusted to 10.sup.7 to 10.sup.11 MPa or the air with an oxygen partial pressure of 10.sub.1.7 MPa to provide a ceramic sintered compact.

(51) Subsequently, a conductive paste containing Ag as a main component was applied to opposite end surfaces of the ceramic sintered compact and baked at 600 C. to form an external electrode to thus produce sample Nos. 1-38.

(52) [Assessment of Samples]

(53) The ceramic sintered compacts of Sample Nos. 1 to 38 were subjected to a structural analysis in an XRD method (X-ray diffraction method) before the external electrodes were formed. As a result, it was confirmed that the ceramic sintered compacts all had a perovskite type crystal structure.

(54) Furthermore, the ceramic sintered compacts of Sample Nos. 1 to 38 were dissolved and analyzed through ICP-AES (Inductively Coupled Plasma-Emission Spectroscopy), and it was confirmed that they contained Ba, Ca, and Sb in parts by mol with respect to 100 parts by mol of Ti, as shown in Table 1.

(55) Subsequently, sample Nos. 1 to 38 had measured their relative dielectric constants cr and Curie temperatures Tc.

(56) Relative dielectric constant cr was measured with an LCR meter (E4980A, manufactured by Agilent Technologies) with a measurement frequency of 1 kHz and a measurement voltage of 0.5 Vrms at a temperature of 253 C.

(57) Curie temperature Tc was measured as follows: the above LCR meter and a constant-temperature bath were used to measure a relative dielectric constant in a temperature range of 55 to +160 C. and a temperature at which the relative dielectric constant is maximized is set as a Curie temperature Tc.

(58) Table 1 shows the compositions, firing temperatures, firing atmospheres, relative dielectric constants r, and Curie temperatures Tc of Sample Nos. 1 to 38.

(59) TABLE-US-00001 TABLE 1 content with relative to 100 relative Curie parts by mol of Ti firing dielectric temperature sample (in parts by mol) temperature firing constant Tc Nos. Ba Ca Sb ( C.) atmosphere r ( C.) 1* 100.00 0 0.00 1300 reducing 2513 124 2* 95.00 5.00 0.00 1300 reducing 2014 136 3* 90.00 10.00 0.00 1300 reducing 1687 131 4* 85.00 15.00 0.00 1300 reducing 1212 121 5 94.91 5.00 0.10 1300 reducing 2816 140 6 94.05 4.95 1.00 1300 reducing 2897 140 7 90.25 4.75 5.00 1300 reducing 2431 143 8* 95.00 5.00 0.00 1300 the air 2769 136 9* 94.91 5.00 0.10 1300 the air 1897 132 10* 94.05 4.95 1.00 1300 the air 975 124 11* 90.25 4.75 5.00 1300 the air 642 101 12* 95.00 5.00 0.00 1000 reducing 13* 94.91 5.00 0.10 1000 reducing 14* 94.05 4.95 1.00 1000 reducing 15* 90.25 4.75 5.00 1000 reducing 16* 95.00 5.00 0.00 1100 reducing 1521 136 17 94.91 5.00 0.10 1100 reducing 1432 141 18 94.05 4.95 1.00 1100 reducing 521 141 19 90.25 4.75 5.00 1100 reducing 435 143 20* 95.00 5.00 0.00 1400 reducing 2578 136 21 94.91 5.00 0.10 1400 reducing 2916 141 22 94.05 4.95 1.00 1400 reducing 2697 142 23 90.25 4.75 5.00 1400 reducing 2231 145 24* 99.90 0 0.10 1300 reducing 2912 131 25 94.91 5.00 0.10 1300 reducing 2816 140 26 89.91 9.99 0.10 1300 reducing 1762 142 27 84.92 14.99 0.10 1300 reducing 1132 140 28* 79.92 19.98 0.10 1300 reducing 652 134 29* 99.00 0 1.00 1300 reducing 3018 132 30 94.05 4.95 1.00 1300 reducing 2897 140 31 89.10 9.90 1.00 1300 reducing 1782 143 32 84.15 14.85 1.00 1300 reducing 1231 141 33* 79.20 19.80 1.00 1300 reducing 579 135 34* 95.00 0 5.00 1300 reducing 2678 128 35 90.25 4.75 5.00 1300 reducing 2431 143 36 85.50 9.50 5.00 1300 reducing 1457 145 37 80.75 14.25 5.00 1300 reducing 1121 142 38* 76.00 19.00 5.00 1300 reducing 782 134 *departing from the scope of the present invention

(60) Sample Nos. 1 to 4, 16, and 20 were subjected to a firing treatment in a reducing atmosphere, however, their ceramic sintered compacts did not contain Sb, and accordingly, had a Curie temperature Tc of 121 to 136 C., i.e., lower than 140 C.

(61) Sample No. 8 provided a ceramic sintered compact which did not contain Sb and was also fired in the air, and accordingly, had a Curie temperature Tc of 136 C., i.e., also lower than 140 C.

(62) Sample Nos. 9 to 11 presented a Curie temperature Tc of 101 to 132 C., i.e., less than 140 C. It is believed that this is because although the samples' ceramic sintered compacts contained Sb, they were fired in the air, and accordingly, Sb did not form a solid solution at an A site but a B site, and accordingly, they were unable to have improved tetragonal crystallinity and hence an increased Curie temperature Tc.

(63) Sample Nos. 12 to 15 had their ceramic shaped bodies fired at an excessively low temperature of 1000 C. and were thus unable to have them sintered.

(64) Sample Nos. 24, 29 and 34 provided ceramic sintered compacts which did not contain Ca and accordingly, had as low a Curie temperature Tc as 128 to 132 C.

(65) Sample Nos. 28, 33, 38 presented a Curie temperature Tc of 134 to 135 C., i.e., less than 140 C. It is believed that this is because they had a small Ba content less than 80 parts by mol with respect to 100 parts by mol of Ti on one hand, and a Ca content exceeding 15 parts by mol with respect to 100 parts by mol of Ti on the other hand.

(66) In contrast, Sample Nos. 5 to 7, 17 to 19, 21 to 23, 25 to 27, 30 to 32, and 35 to 37 presented a Curie temperature Tc of 140 C. or higher and hence presented it satisfactorily. In other words, it has been found that by appropriately controlling Ba, Ca, Ti, and Sb contents and a firing condition, a dielectric porcelain composition can be obtained which is lead-free and still has a Curie temperature Tc of 140 C. or higher and is thus suitable for applications at high temperature. Note that in the present example, a dielectric porcelain composition having a Curie temperature of 140 C. was able to be obtained by setting Ba, Ca and Sb contents to 80 parts by mol or more, 15 parts by mol or less, and a range of 0.1 to 5 mol parts, respectively, with respect to 100 mol parts of Ti, and firing at 1100 to 1400 C. in a reducing atmosphere with an oxygen partial pressure of 10.sup.7 to 10.sup.11 MPa.

(67) A lead-free dielectric porcelain composition which does not have a dielectric characteristic impaired even when fired in a reducing atmosphere and has a high Curie temperature and is thus suitable for applications at high temperature, and a multilayer ceramic electronic component, such as a multilayer ceramic capacitor, are implemented.

REFERENCE SIGNS LIST

(68) 1: ceramic sintered compact 2a-2f: internal electrode layer 6a-6g: dielectric layer