US 11,897,815 B2
Mg—Ta based dielectric ceramic for multi-layer ceramic capacitor and low-temperature preparation method thereof
YuanYuan Yang, Huzhou (CN); XiaoZhen Li, Kunming (CN); MengJiang Xing, Kunming (CN); YanLing Luo, Wuxi (CN); HongYu Yang, Xi'an (CN); and QingYang Fan, Xi'an (CN)
Assigned to Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou (CN)
Filed by Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou (CN)
Filed on Apr. 27, 2023, as Appl. No. 18/140,342.
Claims priority of application No. 202210472764.5 (CN), filed on Apr. 29, 2022.
Prior Publication US 2023/0348332 A1, Nov. 2, 2023
Int. Cl. C04B 35/495 (2006.01); C04B 35/626 (2006.01); C04B 35/64 (2006.01); C04B 35/653 (2006.01); H01G 4/12 (2006.01)
CPC C04B 35/495 (2013.01) [C04B 35/6262 (2013.01); C04B 35/64 (2013.01); C04B 35/653 (2013.01); H01G 4/1227 (2013.01); C04B 2235/3206 (2013.01); C04B 2235/3215 (2013.01); C04B 2235/3217 (2013.01); C04B 2235/3255 (2013.01); C04B 2235/3262 (2013.01); C04B 2235/3281 (2013.01); C04B 2235/3409 (2013.01); C04B 2235/3418 (2013.01); C04B 2235/442 (2013.01); C04B 2235/6562 (2013.01); C04B 2235/6567 (2013.01); C04B 2235/76 (2013.01)] 1 Claim
OG exemplary drawing
 
1. A magnesium-tantalum (Mg—Ta) based dielectric ceramic for multi-layer ceramic capacitor, comprising a ceramic material and a modifier;
wherein a chemical formula of the ceramic material is MgTa2O6;
a formula of the modifier is A2CO3—BO—C2O3—SiO2 with a mass ratio of 31:17:36:16, A2CO3 consists of 20 wt. % of Li2CO3 and 11 wt. % of K2CO3; BO consists of 2 wt. % BaO, 5 wt. % of MnO and 10 wt. % of CuO; and C2O3 consists of 30 wt. % of B2O3 and 6 wt. % of Al2O3;
a formula of the Mg—Ta based dielectric ceramic is MgTa2O6+2 wt. % of the modifier, the Mg—Ta based dielectric ceramic is prepared by a solid-state method, a main crystal phase of the Mg—Ta based dielectric ceramic is MgTa2O6 phase with a Trirutile structure; under a sintering temperature of 1150 degrees Celsius (° C.), a dielectric constant of the Mg—Ta based dielectric ceramic is 26.87, a dielectric loss of the Mg—Ta based dielectric ceramic is 1.71×10−4, and a value of a quality factor Q×f of the Mg—Ta based dielectric ceramic is 44398 GHz; and a temperature coefficient τε of the dielectric constant is stable and meets M2G temperature characteristics of (−55° C.: τε=−118 parts per million (ppm)/° C.; 85° C.: τε=−110 ppm/° C.);
the Mg—Ta based dielectric ceramic for multi-layer ceramic capacitor is prepared through the following steps:
step 1, mixing raw powders of magnesium oxide (MgO) and Ta2O5 according to the chemical formula MgTa2O6 to obtain a mixed powder;
step 2, putting the mixed powder prepared in step 1 into a ball milling tank, using zirconium balls and deionized water as a grinding medium and performing planet ball milling for 4-6 hours according to a mass ratio of the mixed powder:the zirconium balls:the deionized water of 1:4-5:2-4 to obtain a mixed slurry, drying the mixed slurry in an oven after the planet ball milling and then sieving with a 60-100 mesh sieve to obtain a sieved powder; and sintering the sieved powder in an atmosphere of 900-1000° C. for 3-5 hours to obtain MgTa2O6;
step 3, mixing raw powders of Li2CO3, K2CO3, BaO, MnO, CuO, B2O3, Al2O3, and SiO2 according a mass ratio of Li2CO3:K2CO3:BaO:MnO:CuO:B2O3:Al2O3:SiO2 of 20:11:2:5:10:30:6:16 to obtain a second mixed powder; using the zirconium balls and alcohol as a grinding medium and performing planet ball milling for 6-8 hours according to a mass ratio of the second mixed powder:the zirconium balls:the alcohol of 1:4-5:4-6 to obtain a ball-milled material, sintering the ball-milled material at a temperature of 600-650° C. for 3-6 hours after drying the ball-milled material and then heating to a temperature of 1450-1550° C. for melting for 3-5 hours to obtain a melted material, pouring the melted material into the deionized water for cooling to obtain a cooled material, and grinding the cooled material to a uniform power as the modifier;
step 4, mixing the modifier prepared in step 3 into MgTa2O6 prepared in step 2 according to the formula of the Mg—Ta based dielectric ceramic MgTa2O6+2 wt. % to obtain a third mixed power, performing planetary ball milling for 3-5 hours according to a mass ratio of the third mixed powder:the zirconium balls:the deionized water of 1:4-5:3-5 to obtain a second ball-milled material, and adding a polyvinyl alcohol solution, as a binder, into the second ball-milled material after drying the second ball-milled material to perform granulation to obtain a granular material; and
step 5: performing press-molding on the granular material prepared in step 4, heating at a heating rate of 2-5° C./minutes (min) and discharging glue at 600-650° C. for 3-5 hours, and then heating at the same heating rate to a temperature of 1150° C. and keeping the temperature for 4-6 hours, thereby obtaining a modified MgTa2O6 dielectric ceramic material.