화학공학소재연구정보센터
Journal of the American Ceramic Society, Vol.103, No.12, 7259-7266, 2020
Novel scheelite-type [Ca-0.55(Nd1-xBix)(0.3)]MoO4 (0.2 <= x <= 0.95) microwave dielectric ceramics with low sintering temperature
Novel scheelite-type [Ca-0.55(Nd1-xBix)(0.3)]MoO4(0.2 <= x <= 0.95) ceramics were prepared using the solid-state reaction method. According to the X-ray diffraction data, a solid solution was formed in 0.2 <= x <= 0.95 and all the samples belong to pure scheelite phase with the tetragonal structure. As revealed by Raman spectroscopy, the number of vibrational modes decreased with the increase inxvalue, which further indicated that Bi(3+)ions occupied A-site of scheelite structure. As thexvalue increased, the sintering temperature decreased from 740 degrees C to 660 degrees C; the permittivity increased from 12.6 to 20.3; the Qf value first decreased slightly and gradually remained stable. Based on the infrared reflectivity spectrum analysis, the calculated permittivity derived from the fitted data shared the same trend with the measured value. The [Ca-0.55(Nd0.05Bi0.95)(0.3)]MoO(4)ceramic sintered at 660 degrees C attained a near-zero value temperature coefficient similar to tau(f)(-7.1 ppm/degrees C) and showed excellent microwave dielectric properties with ae(r) similar to 20.3 and a Qf similar to 33 860 GHz, making this system a promising candidate in the ultralow temperature cofired ceramic (ULTCC) technology.