Dielectric ceramic composition

Abstract

Disclosed herein is a dielectric ceramic composition based on a lead-based perovskite-type complex compound containing nickel, characterized in that the amount of nickel is smaller than the stoichiometric amount. The dielectric ceramic composition can contain .alpha. mol % (0<.alpha..ltoreq.100) of lead-based perovskite-type complex compound represented by the formula belowPb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3where A denotes at least one element selected from elements having a valance of +5, D denotes at least one element selected from elements having a valance of +6, 0<x<1, 0<y<1, and 0.ltoreq.a.ltoreq.1, with the amount of nickel being .gamma. mol % (0<.gamma..ltoreq.20) which is smaller than the stoichiometric amount (where .gamma.=.alpha..times.(a.times.x.times.1/3+(1-a).times.y.times.1/2)). The dielectric ceramics composition which has a high dielectric constant and yet has nearly constant capacity-temperature characteristics.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dielectric ceramics compound.

2. Description of the Related Art

Barium titanate series ceramics have been in general use as a high dielectric material in electronic parts such as for ceramic capacitors. Unfortunately, they have such a high firing temperature (1300.degree.-1400.degree. C.) that laminated ceramic capacitors employing these need internal electrodes of expensive platinum or palladium.

Although there have been available materials having nearly temperature-independent properties, they are not suitable for capacitors because of their low dielectric constant (about 2000 at the highest).

There has recently been reported lead-based perovskite-type complex compounds as a high dielectric material capable of sintering at low temperatures. These include ternary ones composed of lead magnesium-niobate Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3, lead nickel-niobate Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3, and lead titanate PbTiO.sub.3. These have an extremely high dielectric constant but suffer the disadvantage of fluctuating somewhat in the value with temperature.

OBJECT AND SUMMARY OF THE INVENTION

The present invention was completed in view of the foregoing. It is an object of the present invention to provide a dielectric ceramics composition which has nearly constant capacity-temperature characteristics despite its high dielectric constant.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The dielectric ceramics composition of the present invention is based on a lead-based perovskite-type complex compound containing nickel which is characterized in that the amount of nickel is smaller than the stoichiometric amount.

In a preferred embodiment of the present invention, the dielectric ceramics composition contains .alpha. mol % (0&lt;.alpha..ltoreq.100, preferably 10.ltoreq..alpha..ltoreq.52) of a lead-based perovskite-type complex compound represented by the formula below

Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 (where A denotes at least one element having a valance of +5, D denotes at least one element having a valance of +6, 0&lt;x&lt;1, 0&lt;y&lt;1, 0.ltoreq.a.ltoreq.1, with the amount of nickel being .gamma. mol % (0&lt;.gamma..ltoreq.25, preferably 0.48.ltoreq..alpha..ltoreq.20) which is smaller than the stoichiometric amount (where .gamma.=.alpha..times.(a.times.x.times.1/3+(1-a).times.y.times.1/2)).

In the following, the embodiments of the present invention are explained.

The dielectric ceramics composition of the present invention is based on a lead-based perovskite-type complex compound containing nickel which is characterized in that the amount of nickel is smaller than the stoichiometric amount.

The fact that the amount of nickel is smaller than the stoichiometric amount required to form the perovskite structure is responsible for the dielectric ceramics composition which has nearly constant capacity-temperature characteristics despite its high dielectric constant.

An example of the dielectric ceramic composition according to the present invention is one which is based on a lead-based perovskite-type complex compound represented by the formula below

Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 where A denotes at least one element having a valance of +5, D denotes at least one element having a valance of +6, 0&lt;x&lt;1, 0&lt;y&lt;1, and 0.ltoreq.a.ltoreq.1. A and D in the formula above are exemplified by Nb and Ta, and W, respectively.

The dielectric ceramic composition may contain the above-mentioned lead-based perovskite-type complex compound in an amount of .alpha. mol % (0&lt;.alpha..ltoreq.100), in which case the amount of nickel should be .gamma. mol % (0&lt;.gamma..ltoreq.25) and which is smaller than the stoichiometric amount (where .gamma.=.alpha..times.(a.times.x.times.1/3+(1-a).times.y.times.1/2)).

If the amount of nickel exceeds about 20 mol %, the resulting composition would have a dielectric constant lower than 3000. If the amount of nickel is zero, the resulting composition would have an extremely low dielectric constant which is not desirable. The amount of nickel should preferably be .gamma. mol %, with .gamma. most preferably in the range of 0&lt;.gamma..ltoreq.10.

The invention will be described in more detail with reference to the following examples which are not intended to restrict the scope of the invention.

EXAMPLES

Samples of the dielectric ceramic composition of the present invention were prepared according to different formulations.

Each sample was prepared from Pb.sub.3 O.sub.4, NiO, Nb.sub.2 O.sub.5, TiO.sub.2, MnO, CuO and WO.sub.3, whose amounts were so selected as to establish the desired composition. These starting materials were mixed by wet ball-milling. The resulting mixture was dried and then calcined at 750.degree. C. for 2 hours. The resulting powder (100 pbw) was mixed with vinyl acetate (5 pbw) as a binder by wet ball-milling. The resulting mixture was dried and crushed into powder. The powder was formed into a disk, 10 mm in diameter and 1.2 mm thick, by compression under a pressure of 2.5 t/cm.sup.2. The disk was fired in an atmosphere of Pb by using an electric furnace. The fired disk was provided with an electrode formed from Ag paste by baking.

The thus prepared sample was measured for dielectric constant (.epsilon.) and dielectric loss (tan .delta.) at 1 kHz, 1 V, and 20.degree. C. The sample was also measured for resistivity, with a voltage of 250 V applied for 2 minutes. The sample was tested for capacity-temperature characteristics at 1 kHz and 1 V. The capacity-temperature characteristics is expressed as the change (%) in capacity that occurs when the temperature is raised or lowered by 50.degree. C. from the reference temperature at which the capacity is maximum. The expression in this manner is more convenient for comparison of samples than the rate of change in capacity at -25.degree. C. and +85.degree. C. because some samples have the transition point away from normal temperature.

The samples vary in the amounts of principal and auxiliary components, the firing temperature, and the electrical properties as shown in Tables 1 to 8. Incidentally, the amount (wt %) of auxiliary components is based on the amount (as 100%) of principal components.

In Table 1 to 8, .alpha. denotes the lead-based perovskite-type complex compound containing nickel and .beta.1 and .beta.2 denote a lead-based perovskite-type complex compound not containing nickel.

Each amount (in mol %) of .alpha., .beta.1, and .beta.2 are such that their total amount is 100 mol %, although their ratio is arbitrary.

TABLE 1__________________________________________________________________________ Lead-based perovskite-type complex compound containing nickel Lead-based .alpha. = Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 perovskite-type complexSample .gamma. = .alpha. .times. (a .times. x .times. 1/3 + (1 - a) .times. y .times. 1/2) compound not containing nickelNo. .alpha. (mol %) a x A y D .gamma. .beta.1 mol % .beta.2 mol %__________________________________________________________________________ 1 * 72 1 -0.04 Nb -0.96 PbTiO.sub.3 28 2 * 72 1 0 Nb 0.00 PbTiO.sub.3 28 3 72 1 0.02 Nb 0.48 PbTiO.sub.3 28 4 72 1 0.04 Nb 0.96 PbTiO.sub.3 28 5 72 1 0.06 Nb 1.44 PbTiO.sub.3 28 6 72 1 0.12 Nb 2.88 PbTiO.sub.3 28 7 72 1 0.2 Nb 4.80 PbTiO.sub.3 28 8 72 1 0.3 Nb 7.20 PbTiO.sub.3 28 9 72 1 0.5 Nb 12.00 PbTiO.sub.3 2810 72 1 0.7 Nb 16.80 PbTiO.sub.3 2811 72 1 0.9 Nb 21.60 PbTiO.sub.3 2812 * 50 0.4 0 Nb W 0.00 PbTiO.sub.3 5013 50 0.4 0.06 Nb 0.06 W 1.30 PbTiO.sub.3 50__________________________________________________________________________ TABLE 2__________________________________________________________________________ Change of Change of capacity at capacity at reference reference Firing temperature temperatureSample Amounts of auxiliary components tempera- Dielectric Dielectric Resistivity minus 50.degree. C. plus 50.degree. C.No. wt % wt % ture (.degree.C.) constant loss (%) (.OMEGA. cm) (%) (%)__________________________________________________________________________ 1 * MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 14200 0.22 7.9 .times. 10.sup.12 -50.2 -32.2 2 * MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 13600 0.25 7.6 .times. 10.sup.12 -46.3 -28.0 3 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 12100 0.51 6.8 .times. 10.sup.12 -34.2 -25.4 4 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 10300 0.62 6.9 .times. 10.sup.12 -15.8 -24.1 5 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 9200 0.65 5.1 .times. 10.sup.12 -16.2 -23.2 6 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 7900 0.70 5.5 .times. 10.sup.12 -15.7 -21.5 7 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 6800 0.74 4.9 .times. 10.sup.12 -14.2 -17.2 8 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 5400 1.23 4.2 .times. 10.sup.12 -11.2 -12.1 9 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 4300 1.30 3.6 .times. 10.sup.12 -10.5 -11.210 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 3200 1.35 3.1 .times. 10.sup.12 -8.6 -9.811 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 2500 1.41 3.2 .times. 10.sup.12 -7.9 -8.712 * 1000 9600 2.30 2.7 .times. 10.sup.12 -38.6 -30.513 1050 7200 2.39 3.5 .times. 10.sup.12 -32.5 -28.6__________________________________________________________________________ TABLE 3__________________________________________________________________________ Lead-based perovskite-type complex compound containing nickel .alpha. = Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 Lead-based perovskite-Sample .gamma. = .alpha. .times. (a .times. x .times. 1/3 + (1 - a) .times. y .times. 1/2) type complex compound not containing nickelNo. .alpha. (mol %) a x A y D .gamma. .beta.1 mol % .beta.2 mol %__________________________________________________________________________14 * 45 1 0 Nb 0.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3015 45 1 0.04 Nb 0.60 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3016 45 1 0.1 Nb 1.50 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3017 45 1 0.2 Nb 3.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3018 45 1 0.3 Nb 4.50 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3019 45 1 0.35 Nb 5.25 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3020 * 70 1 0 Nb 0.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 521 70 1 0.06 Nb 1.40 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 522 70 1 0.2 Nb 4.67 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 523 70 1 0.4 Nb 9.33 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 524 70 1 0.8 Nb 18.67 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 525 70 1 0.9 Nb 21.00 PbTiO.sub.3 25 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 526 * 70 1 0 Nb 0.00 PbTiO.sub.3 20 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 527 70 1 0.06 Nb 1.40 PbTiO.sub.3 20 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 5__________________________________________________________________________ TABLE 4__________________________________________________________________________ Change Change of capacity of capacity Firing at reference at referenceSample Amounts of auxiliary components temperature Dielectric Dielectric Resistivity temperature temperatureNo. wt % wt % (.degree.C.) constant loss (%) (.OMEGA. cm) minus 50.degree. C. plus 50.degree. C. (%)__________________________________________________________________________14 * Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 11000 1.24 2.9 .times. 10.sup.12 -34.0 -44.915 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 9400 1.51 2.7 .times. 10.sup.12 -33.0 -39.016 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 7800 1.56 2.5 .times. 10.sup.12 -26.7 -24.517 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 5400 1.64 2.6 .times. 10.sup.12 -20.6 -19.518 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 3700 1.63 2.2 .times. 10.sup.12 -14.6 -15.319 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1050 2900 2.10 1.9 .times. 10.sup.12 -9.5 -10.220 1050 9300 2.23 2.8 .times. 10.sup.12 -38.9 -42.321 1050 8300 2.45 3.9 .times. 10.sup.12 -35.6 -32.122 1050 7400 2.52 2.7 .times. 10.sup.12 -29.4 -27.623 1050 5200 2.51 2.4 .times. 10.sup.12 -15.2 -20.124 1050 3400 2.64 1.9 .times. 10.sup.12 -12.5 -15.725 * 1050 1700 2.71 1.5 .times. 10.sup.12 -9.4 -13.126 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 0.5 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 2 1000 10500 0.29 7.2 .times. 10.sup.12 -46.0 -29.127 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 0.5 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 2 1000 9400 0.58 6.9 .times. 10.sup.12 -36.1 -17.8__________________________________________________________________________ TABLE 5__________________________________________________________________________ Lead-based perovskite-type complex compound containing nickel .alpha. = Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 Lead-based perovskite-Sample .gamma. = .alpha. .times. (a .times. x .times. 1/3 + (1 - a) .times. y .times. 1/2) type complex compound not containing nickelNo. .alpha. (mol %) a x A y D .gamma. .beta.1 mol % .beta.2 mol %__________________________________________________________________________28 * 65 1 0 Nb 0.00 PbTiO.sub.3 15 PbZrO.sub.3 2029 65 1 0.05 Nb 1.08 PbTiO.sub.3 15 PbZrO.sub.3 2030 * 40 1 0 Nb 0.00 PbTiO.sub.3 30 Pb(Fe.sub.2/3 W.sub.1/3)O.sub.3 3031 40 1 0.08 Nb 1.07 PbTiO.sub.3 30 Pb(Fe.sub.2/3 W.sub.1/3)O.sub.3 3032 * 40 1 0 Nb 0.00 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 10 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5033 40 1 0.08 Nb 1.07 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 10 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5034 40 1 0.2 Nb 2.67 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 10 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5035 40 1 0.4 Nb 5.33 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 10 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5036 * 10 0 0 W 0.00 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 40 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5037 10 0 0.1 W 0.50 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 40 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5038 10 0 0.4 W 2.00 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 40 Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 5039 * 20 0 0 W 0.00 PbTiO.sub.3 25 Pb(Mg.sub.1/2 Nb.sub.1/2)O.sub.3 5540 20 0 0.1 W 1.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 5541 * 20 0 0 W 0.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 5542 20 0 0.1 W 1.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 5543 20 0 0.3 W 3.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 5544 20 0 0.5 W 5.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 55__________________________________________________________________________ TABLE 6__________________________________________________________________________ Change Change of capacity of capacity Firing at reference at referenceSample Amounts of auxiliary components temperature Dielectric Dielectric Resistivity temperature temperatureNo. wt % wt % (.degree.C.) constant loss (%) (.OMEGA. cm) minus 50.degree. C. plus 50.degree. C. (%)__________________________________________________________________________28 * Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 9300 0.53 4.6 .times. 10.sup.12 -46.9 -24.729 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 8500 0.61 3.8 .times. 10.sup.12 -41.1 -20.130 * MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 5700 3.29 7.8 .times. 10.sup.12 -120.0 -95.131 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 3700 4.07 5.6 .times. 10.sup.12 -101.2 -88.132 * MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 9200 3.10 7.6 .times. 10.sup.12 -25.6 -35.733 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 7300 3.33 8.1 .times. 10.sup.12 -22.1 -25.634 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 6500 3.56 7.9 .times. 10.sup.12 -15.6 -14.535 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 4300 4.23 6.8 .times. 10.sup.12 -8.6 -10.236 * 1050 8500 2.90 4.8 .times. 10.sup.12 -28.6 -23.637 1050 7600 3.10 4.3 .times. 10.sup.12 -20.5 -18.638 1050 5400 3.56 3.6 .times. 10.sup.12 -15.6 -14.239 * Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1000 11000 5.60 3.9 .times. 10.sup.12 -48.6 -49.340 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1000 9200 6.50 3.7 .times. 10.sup.12 -39.1 -38.941 * Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3 1.5 1000 9800 4.30 4.9 .times. 10.sup.12 -45.3 -46.842 Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3 1.5 1000 8200 4.70 4.3 .times. 10.sup.12 -30.5 -30.843 Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3 1.5 1000 6300 5.32 2.3 .times. 10.sup.12 -19.7 -24.544 Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3 1.5 1000 4900 5.95 1.5 .times. 10.sup.12 -11.3 -12.4__________________________________________________________________________ TABLE 7__________________________________________________________________________ Lead-based perovskite-type complex compound containing nickel .alpha. = Pb�Ni.sub.(1-x)/3 A.sub.2/3 !.sub.a �Ni.sub.(1-y)/2 D.sub.1/2 !.sub.(1-a) O.sub.3 Lead-based perovskite-Sample .gamma. = .alpha. .times. (a .times. x .times. 1/3 + (1 - a) .times. y .times. 1/2) type complex compound not containing nickelNo. .alpha. (mol %) a x A y D .gamma. .beta.1 mol % .beta.2 mol %__________________________________________________________________________45 * 30 1 0 Nb 0.00 Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 7046 30 1 0.1 Nb 1.00 Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 7047 30 1 0.3 Nb 3.00 Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 7048 30 1 0.5 Nb 5.00 Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 7049 * 50 0.4 0 Nb, Ta 0 W 0.00 PbTiO.sub.3 5050 50 0.4 0.08 Nb, Ta 0.04 W 1.13 PbTiO.sub.3 5051 * 45 1 0 Nb, Ta 0.00 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 3052 45 1 0.06 Nb, Ta 0.90 PbTiO.sub.3 25 Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 30__________________________________________________________________________ TABLE 8__________________________________________________________________________ Change Change of capacity of capacity Firing at reference at referenceSample Amounts of auxiliary components temperature Dielectric Dielectric Resistivity temperature temperatureNo. wt % wt % (.degree.C.) constant loss (%) (.OMEGA. cm) minus 50.degree. C. plus 50.degree. C. (%)__________________________________________________________________________45 * MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 17200 0.34 4.5 .times. 10.sup.12 -45.7 -57.846 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 13800 0.40 4.3 .times. 10.sup.12 -35.6 -32.547 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 5800 0.58 2.9 .times. 10.sup.12 -24.5 -19.848 MnO 0.1 Pb(Cu.sub.1/2 W.sub.1/2)O.sub.3 3 1000 3200 0.89 1.9 .times. 10.sup.12 -14.3 -12.149 * 1070 9300 2.35 2.6 .times. 10.sup.12 -37.5 -30.850 1070 6900 2.63 2.9 .times. 10.sup.12 -33.4 -27.651 * Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1070 10800 1.54 3.6 .times. 10.sup.12 -35.0 -45.352 Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3 1 1070 9100 1.63 2.9 .times. 10.sup.12 -32.1 -38.6__________________________________________________________________________

In Tables 1 to 8, comparative samples are marked with a star. Comparative samples Nos. 1 and 2 correspond to samples Nos. 3 to 11. Comparative sample No. 12 corresponds to sample No. 13. Comparative sample No. 14 corresponds to samples Nos. 15 to 19. Comparative sample No. 20 corresponds to samples Nos. 21 to 25. Comparative sample No. 26 corresponds to sample No. 27. Comparative sample No. 28 corresponds to sample No. 29. Comparative sample No. 32 corresponds to samples Nos. 33 to 35. Comparative sample No. 36 corresponds to samples Nos. 37 and 38. Comparative sample No. 30 corresponds to samples Nos. 31 and 32. Comparative sample No. 35 corresponds to samples Nos. 36 to 38. Comparative sample No. 39 corresponds to sample No. 40. Comparative sample No. 41 corresponds to samples Nos. 42 to 44. Comparative sample No. 45 corresponds to samples Nos. 46 to 48. Comparative sample No. 49 corresponds to sample No. 50. Comparative sample No. 51 corresponds to sample No. 52.

It is apparent from Tables 2, 4, 6, and 8 that the samples decrease in temperature dependence of capacity while keeping the dielectric constant as the amount of nickel deviates from the stoichiometric amount. All the samples excel their corresponding comparative samples.

The dielectric ceramics composition of the present invention is based on a lead-based perovskite-type complex compound containing nickel which is characterized in that the amount of nickel is smaller than the stoichiometric amount. Therefore, it has a high dielectric constant and yet has nearly constant capacity-temperature characteristics.

Claims

1. A dielectric ceramic composition comprising a lead-based perovskite-type complex compound containing nickel in which the amount of nickel is smaller than the stoichiometric amount and in which said lead-based perovskite-type complex compound is represented by the formula

Pb(Ni.sub.(1-x)/3 A.sub.2/3).sub.a (Ni.sub.(1-y)/2 D.sub.1/2).sub.(1-a) O.sub.3

where A denotes at least one element having a valance of +5, D denotes at least one element having a valance of +6, 0&lt;x&lt;1, 0&lt;y&lt;1, 0.ltoreq.a.ltoreq.1, and the amount of nickel is .gamma. mol % which is smaller than the stoichiometric amount, where .gamma.=.alpha..times.(a.times.x.times.1/3+(1-a).times.y.times.1/2), 0&lt;.alpha..ltoreq.100 and 0&lt;.gamma..ltoreq.25.

2. A dielectric ceramic composition as defined in claim 1 in which A is Nb or Ta, and D is W.

3. A dielectric ceramic composition as defined in claim 2 in which .gamma..ltoreq.20.

4. A dielectric ceramic composition as defined in claim 3 in which 0.48.ltoreq..gamma..ltoreq.10.

5. A dielectric ceramic composition as defined in claim 3 in which 0&lt;.gamma..ltoreq.10.

6. A dielectric ceramic composition as defined in claim 5 in which said lead-based perovskite-type complex compound is less than 100 mol % of said dielectric ceramic composition.

7. A dielectric ceramic composition as defined in claim 6 in which said lead-based perovskite-type complex compound is about 10 to 52% of said composition.

8. A dielectric ceramic composition as defined in claim 2 in which said lead-based perovskite-type complex compound is less than 100 mol % of said dielectric ceramic composition.

9. A dielectric ceramic composition as defined in claim 8 in which said lead-based perovskite-type complex compound is about 10 to 52% of said composition.

10. A dielectric ceramic composition as defined in claim 1 in which said lead-based perovskite-type complex compound is less than 100 mol % of said dielectric ceramic composition.

11. A dielectric ceramic composition as defined in claim 10 in which said lead-based perovskite-type complex compound is about 10 to 52% of said composition.

12. A dielectric ceramic composition as defined in claim 1 in which .gamma..ltoreq.20.

13. A dielectric ceramic composition as defined in claim 12 in which 0.48.ltoreq..gamma..ltoreq.10.

14. A dielectric ceramic composition as defined in claim 12 in which 0&lt;.gamma..ltoreq.10.

15. A dielectric ceramic composition as defined in claim 12 in which said lead-based perovskite-type complex compound is about 10 to 52% of said composition.