Modified NiTa.SUB.2.O.SUB.6.-based microwave dielectric ceramic material co- sintered at low temperature and its preparation method

Abstract

The invention belongs to the field of electronic ceramics and its manufacturing, in particular to the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature and its preparation method. Based on the low melting point characteristics of CuO and B.sub.2O.sub.3, and the radius of Cu.sup.2+ ions is similar to that of Ni.sup.2+ and Ta.sup.5+ ions, the chemical general formula of the invention is designed as xCuO-(1-x)NiO-[7.42y+(xy/14.33)]B.sub.2O.sub.3—Ta.sub.2O.sub.5, and the molar content of each component is adjusted from raw materials. The main crystalline phase of NiTa.sub.2O.sub.6 is synthesized at a lower pre-sintering temperature, and NiTa.sub.2O.sub.6-based ceramic material with low-temperature sintering characteristics and excellent microwave dielectric properties are directly synthesized at one time, which broadened the application range in LTCC field.

Claims

1. A modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature is characterized in that a general chemical formula of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature is as follows: xCuO-(1-x)NiO-[7.42y+(xy/14.33)]B.sub.2O.sub.3—Ta.sub.2O.sub.5, wherein 0.02≤x≤0.2; 0.02≤y≤0.08; and the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is prepared by solid-phase method; and a phase composition of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is NiTa.sub.2O.sub.6 structure; wherein a sintering temperature of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 900-975° C., and the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is pre-sintered in an atmosphere environment at 850-900° C.; a dielectric constant of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 16˜23, a quality factor Q×f value of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 12,000˜19,000 GHz, and a temperature of frequency of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 20˜27ppm/° C; and wherein the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature is prepared by following steps: step 1, mixing CuO, NiO, B.sub.2O.sub.3 and Ta.sub.2O.sub.5 original powder according to the general chemical formula: xCuO-(1-x)NiO-[7.42y+(xy/14.33)]B.sub.2O.sub.3—Ta.sub.2O.sub.5, wherein 0.02≤x≤0.2; and 0.02≤y≤0.08; step 2, putting the mixed powder in the step 1 into a ball milling tank, performing planetary ball milling with zirconia balls and deionized water according to a mass ratio of the mixed powder: the zirconia balls: the deionized water of 1: 4-6: 3-5 for 6-8 hours, and then taking out and drying in an oven at 80-120° C., sieving with a 60-80 mesh sieve to obtain sieved powder, and pre-sintering the sieved powder in the atmosphere environment at 850-900° C. for 3-5 hours; step 3, performing the planetary ball milling on the pre-sintered powder in the step 2 again according to a mass ratio of the pre-sintered powder: the zirconium balls: the deionized water of 1: 4-6: 1-3, and performing the planetary ball milling and mixing for 3-6 hours, and then taking out and drying to obtain dried powder, and adding polyvinyl alcohol solution into the dried powder for granulation to obtain ceramic raw material; and step 4, pressing and molding the ceramic raw material obtained in the step 3, discharging at 600-650° C., and then sintering in the atmosphere environment at 900-975° C. for 4-6 hours to obtain the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature.

2. The modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material co-sintered at low temperature according to claim 1 is characterized in that when x=0.1 and y=0.04, the dielectric constant of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 22.4 at the sintering temperature of 925° C., the quality factor Q×f value of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 18531 GHz, and the temperature of frequency of the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material is 25.2 ppm/° C.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows X-ray diffraction (XRD) pattern of ceramic sample corresponding to embodiment 3;

(2) FIG. 2 shows a morphology diagram of the ceramic sample corresponding to the embodiment 3 under a scanning electron microscope (SEM).

DETAILED DESCRIPTION OF THE INVENTION

(3) The present invention will be further explained in detail below with reference to the figures and embodiments.

(4) step 1, mix CuO, NiO, B.sub.2O.sub.3 and Ta.sub.2O.sub.5 original powder In molar ratio according to the general chemical formula: xCuO-(1-x)NiO-[7.42y+(xy/14.33)]B.sub.2O.sub.3—Ta.sub.2O.sub.5(x=0.1; y=0.04);

(5) step 2, put the powder mixed in step 1 into a ball milling tank, take zirconium balls and deionized water as grinding media and perform planetary ball milling with zirconium balls and deionized water according to the mass ratio of powder: zirconium balls: deionized water of 1:6:4 for 6 hours, take it out, dry it in an oven at 100° C., sieve it with a 60 mesh sieve, and pre-sinter it in an atmosphere environment environment at 900° C. for 3 hours;

(6) step 3, perform the second ball milling on the pre-sintered powder, and perform planetary ball milling according to the mass ratio of powder: zirconium balls: deionized water of 1:6:3, for 4 hours, take it out and dry, and add 5%-8% polyvinyl alcohol solution into the obtained powder for granulation;

(7) step 4, put the granulated powder into a mold of φ12 and form it into a cylinder block (size: 12 mm×6 mm) by dry-pressing under pressure of 20 MPa. Then, keep the cylinder block at 650° C. for 2 hours to remove the binder, and then raise it to 900° C.˜975° C. for 4 hours. Finally, the modified NiTa.sub.2O.sub.6-based microwave dielectric ceramic material under the condition of low-temperature sintering is prepared. The molar ratios of its chemical formulas are: CuO—NiO—B.sub.2O.sub.3—Ta.sub.2O.sub.5(4.4:39.2:12.9:43.5 mol %).

(8) Four samples of Embodiments are made according to the above steps. And FIG. 1 shows the X-ray diffraction (XRD) pattern of ceramic sample corresponding to embodiment 3. Compared with the standard card, it is found that the standard card JCPDS card No. 32-0702 of NiTa.sub.2O.sub.6 has a good match. The shift of the X-ray diffraction peak indicates that ions are solid dissolved to the cationic lattices, and the existence of the second phase is not detected in the system, indicating that this type of ceramic belongs to the solid solution of NiTa.sub.2O.sub.6 structure.

(9) FIG. 2 shows a morphology diagram microscope of SEM corresponding to embodiment 3. The crystalline grain growth of the sample is sufficient and the crystalline grain boundary is clearly visible, indicating that its low-temperature sintering characteristics are good.

(10) Components and microwave dielectric properties of specific embodiments as follows:

(11) TABLE-US-00001 Mass of each component/α Sintering Embodiment CuO NiO B.sub.2O.sub.2 Ta.sub.2O.sub.5 temperature ° C. 1 1.479 12.501 3.846 82.174 900 2 1.479 12.501 3.846 82.174 925 3 1.479 12.501 3.846 82.171 950 4 1.479 12.501 3.846 82.174 975

(12) Table 1 shows the components of the samples of each embodiment.

(13) TABLE-US-00002 External Thickness diameter (mm) Dielectric Tanδ τ.sub.f Embodiment (mm) ε.sub.r coefficient (10.sup.−3) Q × f(GHz) (ppm/° C.) 1 11.19 4.53 16.8 7.5 12387 20.6 2 10.74 4.41 19.2 5.8 16215 22.4 3 10.48 4.32 22.4 5.0 18531 25.2 4 10.32 4.25 20.5 6.1 15224 26.8

(14) Table 2 shows the microwave dielectric properties of the samples of each embodiment.

(15) From the above Tables, it can be seen that when x=0.1 and y=0.4, the sintering temperature is in the range of 900˜950° C., the dielectric constant and Q×f value of modified NiTa.sub.2O.sub.6-based ceramic materials first increase and then decrease, and the best values are obtained at 950° C.: ε.sub.r=22.4, tan δ=5.0×10.sup.−4, Q×F=18531 GHz, τ.sub.f=25.2 ppm/° C. And compared with the existing literature reports, the sintering temperature is greatly reduced, and the microwave dielectric property is still relatively excellent at this time, so it can be widely used in LTCC technical field.