Modified NiO-Ta2O5-based Microwave Dielectric Ceramic Material 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 NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material sintered at low temperature and its preparation method. It is guided by ion doping modification, not only considering the substitution of ions with similar radius, such as Zn.sup.2+ replacing Ni.sup.2+ ions, V.sup.5+ replacing Ta.sup.5+ ions; Meanwhile, the selected doped oxide still has the property of low melting point. Therefore, the microwave dielectric properties of NiO-Ta.sub.2O.sub.5-based ceramic material can be improved and the appropriate sintering temperature can be reduced. In the invention, by adjusting the molar content of each raw material, the NiO-Ta.sub.2O.sub.5-based ceramic material with low-temperature sintering, stable temperature and excellent microwave dielectric property is directly synthesized at one time, which can be widely applied to the technical field of LTCC.

Claims

1. A modified NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material sintered at low temperature is characterized in that the general chemical formula of the modified NiO-Ta.sub.2O.sub.5--based microwave dielectric ceramic material sintered at low temperature is: (1.587y-0.198xy)ZnO-(2.597y-0.324xy)CuO-(1-x)NiO-(1.855y-0.231xy)B.sub.2O.sub.3-3 xSnO.sub.2-(1-x)Ta.sub.2O.sub.5-(0.284y-0.035xy)V.sub.2O.sub.5; wherein 0.1≤x≤0.2; 0.03≤y≤0.09; and prepared by solid-phase method; and the crystal type is NiTa.sub.2O.sub.6 structure; the sintering temperature of the microwave dielectric ceramic material is 875-950° C., and the microwave dielectric ceramic material is pre-sintered in the atmosphere environment of 850-900° C.; in addition, the dielectric constant is 17-21, the quality factor Q×f value is 14,000-23,000 GHz, and the temperature coefficient of resonance frequency is 5~10 ppm/°C.

2. The modified NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material sintered at low temperature according to claim 1 is characterized in that when x=0.15 and y=0.06, the dielectric constant of the material is 20.2 at the sintering temperature of 925° C., the quality factor Q×f value is 22417 GHz, and the temperature coefficient of resonant frequency is 8.7 ppm/°C.

3. The preparation method of the modified NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material sintered at low temperature is characterized in that it comprises the following steps: step 1, mix ZnO, CuO, NiO, B.sub.2O.sub.3, SnO.sub.2, Ta.sub.2O.sub.5 and V.sub.2O.sub.5 powder according to the general chemical formula: (1.587y-0.198xy)ZnO-(2.597y-0.324xy)CuO-(1-x)NiO-(1.855y-0.231xy)B.sub.2O.sub.3-3 xSnO.sub.2-(1-x)Ta.sub.2O.sub.5-(0.284y-0.035xy)V.sub.2O.sub.5;(x = 0.1 ~ 0.2y=0.03~0.09); step 2: put the powder mixed in step 1 into a ball milling tank, and perform ball milling with zirconia balls and deionized water according to the mass ratio of powder: zirconia balls: deionized water of 1:5-7:3-5, perform the planetary ball milling for 6-8 hours, take it out, dry it in an oven at 80-120° C., sieve it with a 40-60 mesh sieve, and pre-sinter it in an atmosphere environment environment at 850-900° C. for 3~5 hours; step 3: perform ball milling on the powder pre-sintered in step 2 again according to the mass ratio of powder: zirconium balls: deionized water of 1:4-6:1-3, and perform planetary ball milling and mixing for 3-6 hours, take it out and dry, and add polyvinyl alcohol solution into the obtained powder for granulation; step 4, press and mold the ceramic raw material prepared in step 3, discharge the glue at 600-650° C., and then sinter in the atmosphere environment environment at 875-950° C. for 4-6 hours to obtain the modified NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material sintered at low temperature.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0017] FIG. 1 shows X-ray diffraction (XRD) pattern of ceramic sample corresponding to embodiment 3;

[0018] 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

[0019] The present invention will be further explained in detail below with reference to the figures and embodiments. [0020] step 1, mix ZnO, CuO, NiO, B.sub.2O.sub.3, SnO.sub.2, Ta.sub.2O.sub.5 and V.sub.2O.sub.5 powder in molar ratio according to the general chemical formula: (1.587y-0.198xy)ZnO-(2.597y-0.324xy)CuO-(1-x)NiO-(1.855y-0.231xy)B.sub.2O.sub.3-3 xSnO.sub.2-(1-x)Ta.sub.2O.sub.5-(0.284y-0.035xy)V.sub.2O.sub.5;(x = 0.1 ~ 0.2y=0.03~0.09); [0021] step 2, put the powder weighted in step 1 into a ball milling tank, and perform planetary ball milling with zirconia balls and deionized water according to the mass ratio of powder: zirconia balls: deionized water of 1:6:3 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; [0022] step 3, perform the second ball milling on the pre-sintered powder, and perform planetary ball milling according to the mass ratio of powder: zirconia balls: deionized water of 1:6:2, for 4 hours, take it out and dry, and add polyvinyl alcohol solution into the obtained powder for granulation; [0023] step 4, put the granulated powder into a mold of φ12 and form it into a cylinder 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 875° C. ~ 950° C. for 4 hours. Finally, the modified NiO-Ta.sub.2O.sub.5-based microwave dielectric ceramic material under the condition of low-temperature sintering is prepared. The molar ratios of its chemical formulas are: ZnO-CuO-NiO-B2O3-SnO2-Ta2O5-V2O5(3.7: 6.1: 33.7: 4.3: 17.8: 33.7: 0.7 mol %).

[0024] In order to better illustrate the effect of the present invention, four embodiments are made according to the above steps. FIG. 1 shows the X-ray diffraction (XRD) pattern of ceramic sample corresponding to embodiment 3. After searching, the phase composition of ceramics corresponds to the standard card JCPDS card No.32-0702 of NiTa.sub.2O.sub.6. At this time, no second phase diffraction peak is found in the system, which means that this type of ceramics belongs to the solid solution with NiTa.sub.2O.sub.6 structure.

[0025] FIG. 2 is the morphology diagram of the ceramic sample corresponding to the embodiment 3 under a scanning electron microscope (SEM). It can be seen that the grain growth of the ceramic sample is sufficient, and the grain boundary is clearly visible, indicating that its low-temperature sintering characteristics are good, but the microscopic pores still exist at this time.

[0026] Components and microwave dielectric properties of each embodiment are as follows:

[0027] Table 1 shows the components of the sample groups of each embodiment.

[0028] Table 2 shows the microwave dielectric properties of the samples of each embodiment.

[0029] From the data shown in Table 1 and Table 2, it can be seen that when x = 0.15 and y = 0.06, the sintering temperature is in the range of 875 ~ 925° C., the dielectric constant and Q×f value of modified NiO-Ta.sub.2O.sub.5-based ceramic materials first increase and then decrease, and the best values are obtained at 925° C.: ε.sub.r= 20.2, tanδ = 4.1× 10.sup.-4, Q×F = 22417 GHz, .sub.Tf= 8. 7 ppm/°C. And compared with the existing literature reports, the sintering temperature is greatly reduced, while excellent temperature stability and microwave dielectric properties are maintained, which can be widely used in LTCC technical field.