Abstract
Dense microwave dielectric ceramics of Ce2[Zr1−x(Al1/2Ta1/2)x]3(MoO4)9 (CZMAT) (x = 0.02–0.10) were prepared by the conventional solid-state route. The effects of (Al1/2Ta1/2)4+ on their microstructures, sintering behaviors, and microwave dielectric properties were systematically investigated. On the basis of the X-ray diffraction (XRD) results, all the samples were matched well with Pr2Zr3(MoO4)9 structures, which belonged to the space group Rbar 3c. The lattice parameters were obtained using the Rietveld refinement method. The correlations between the chemical bond parameters and microwave dielectric properties were calculated and analyzed by using the Phillips—Van Vechten—Levine (P—V—L) theory. Excellent dielectric properties of Ce2[Zr0.94(Al1/2Ta1/2)0.06]3(MoO4)9 with a relative permittivity (εr) of 10.46, quality factor (Q × f) of 83,796 GHz, and temperature coefficient of resonant frequency (τf) of −11.50 ppm/°C were achieved at 850 °C.
Highlights
With the rapid growth of wireless communication industry, microwave dielectric ceramics are widely studied for their use in global positioning system (GPS) patch antennas, resonators in filters or oscillators at microwave frequencies in radar detectors, and mobile telephones [1,2,3]
Tao et al [19] reported that the Ce2Zr3(MoO4)9 ceramics with performance parameters of Q × f = 19,062 GHz, r = 10.69, and τf = −1.29 ppm/°C were attained at 575 °C
The sintered samples belong to the trigonal structure with the R3c space group identified by the X-ray diffraction (XRD)
Summary
With the rapid growth of wireless communication industry, microwave dielectric ceramics are widely studied for their use in global positioning system (GPS) patch antennas, resonators in filters or oscillators at microwave frequencies in radar detectors, and mobile telephones [1,2,3]. The crystal structure and dielectric properties of Ti4+-substituted CaSnSiO5 ceramics were investigated by Du et al [11]. Tao et al [19] reported that the Ce2Zr3(MoO4) ceramics with performance parameters of Q × f = 19,062 GHz, r = 10.69, and τf = −1.29 ppm/°C were attained at 575 °C. Shi et al [20] improved Q × f value by the partial replacement of Mo6+ by W6+ ions in Ce2Zr3(MoO4) ceramic. The effect of Ti4+ doping on Ce2Zr3(MoO4) ceramic properties was analyzed [21]. Improved Q × f values were obtained when (Mg1/3Sb2/3)4+ substituted the Zr-site of Ce2Zr3(MoO4) ceramics [23]. The effect of substituting (Al1/2Ta1/2)4+ for the Zr-sites on the microwave dielectric properties of Ce2[Zr1−x(Al1/2Ta1/2)x]3(MoO4) (CZMAT) ceramics was investigated. To investigate the relationship between the dielectric properties and chemical bond characteristics, the chemical bond theory was used to calculate the bond ionicity, bond energy, lattice energy, and coefficient of thermal expansion
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