Novel scheelite‐type [Ca <sub>0.55</sub> (Nd <sub>1‐</sub> <i> <sub>x</sub> </i> Bi <i> <sub>x</sub> </i> ) <sub>0.3</sub> ]MoO <sub>4</sub> (0.2 ≤ <i>x</i> ≤ 0.95) microwave dielectric ceramics with low sintering temperature
Shu‐Zhao Hao, Di Zhou, Fayaz Hussain, Jinzhan Su, Wenfeng Liu, Dawei Wang, Qiu‐Ping Wang, Zeming Qi
Abstract
Abstract Novel scheelite‐type [Ca 0.55 (Nd 1‐ x Bi x ) 0.3 ]MoO 4 (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 in x value, which further indicated that Bi 3+ ions occupied A‐site of scheelite structure. As the x value increased, the sintering temperature decreased from 740°C to 660°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 (Nd 0.05 Bi 0.95 ) 0.3 ]MoO 4 ceramic sintered at 660 °C attained a near‐zero value temperature coefficient ~τ f (−7.1 ppm/°C) and showed excellent microwave dielectric properties with a ɛ r ~ 20.3 and a Qf ~ 33 860 GHz, making this system a promising candidate in the ultralow temperature cofired ceramic (ULTCC) technology.