High-Dielectric-Constant and Low-Loss Microwave Dielectric in the (1−x)Nd(Zn1/2Ti1/2)O3–xSrTiO3 System with a Zero Temperature Coefficient of Resonant Frequency
High-dielectric-constant and low-loss ceramics in the (1−x)Nd(Zn1/2Ti1/2)O3–xSrTiO3 system have been prepared by the conventional mixed-oxide route and their microwave dielectric properties have been investigated. A two-phase system was confirmed by the X-ray diffraction patterns, the energy-dispersive X-ray spectrometer analysis, and the measured lattice parameters. Addition of SrTiO3, having a much smaller grain size in comparison with that of Nd(Zn1/2Ti1/2)O3, could effectively hold back abnormal grain growth in the Nd(Zn1/2Ti1/2)O3 matrix. Evaporation of Zn at high temperatures caused an increase in the dielectric loss of the system. The temperature coefficient of resonant frequency increases with increasing SrTiO3 content and tunes through zero at x=0.52. Specimens with x=0.52 possessed an excellent combination of microwave dielectric properties: r∼54.2, Q×f∼84 000 GHz, and f∼0 ppm/°C. It is proposed as a suitable candidate material for today's 3G passive components and small-sized GPS patch antennas.
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Document Type: Research Article
Affiliations: Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Publication date: 01 July 2008