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Characterization and Dielectric Behavior of Varied Sintering-Accelerator-Doped Magnesium Titanates at Microwave Frequency

C.-H. Shen

Department of Electronic Engineering, Ming Chuan University, 5 De Ming Rd., Gui Shan District, Taoyuan City 333, Taiwan

received September 19, 2023, received in revised form November 22, 2023, accepted December 12, 2023

Vol. 15, No. 1, Pages 49-54   DOI: 10.4416/JCST2023-00013

Abstract

To lower the phase-forming temperature of magnesium titanate, MgTiO₃, magnesium ions were replaced with 0.05 mole of cobalt ions and diverse low-melting-point materials were as sintering accelerators. The phase formation of 0.9Mg_0.95Co_0.05TiO₃ – 0.1Ca_0.61Nd_0.78/3TiO₃ dielectric ceramics was verified by means of XRD diffraction to observe the crystallites of varied phases. SEM was used to observe the particle growth of the ceramic system and the composition ratio of the particles was analyzed by means of EDS. In contrast with the pure 0.9Mg_0.95Co_0.05TiO₃ – 0.1 Ca_0.61Nd_0.78/3TiO₃ dielectric ceramics, the results show that the sintering temperature can be effectively decreased. The microwave dielectric performances of 0.9Mg_0.95Co_0.05TiO₃ – 0.1Ca_0.61Nd_0.78/3TiO₃ dielectric ceramics are closely related to the density and the growth of particles in the specimens. When 0.25 wt% V₂O₅ were added to the 0.9Mg_0.95Co_0.05TiO₃ – 0.1 Ca_0.61Nd_0.78/3TiO₃, the dielectric ceramics showed an ε_r value of 21.7, a Qf value of 71 000 GHz, and a τ_f value of -22.7 ppm/K, while the sintering temperature was reduced from 1 350 °C to 1 250 ^°C (that is about 100 ^°C). The results are almost identical for the different accelerators, but some of them have a more significant negative effect on the dielectric performance.

Keywords

Dielectric ceramics, low melting point, phase formation, microwave dielectric performances, sintering accelerator

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