• phase, microstructure, and microwave dielectric properties of naca4−x sr x nb5o17 (x = 0 to 4) ceramics

    نویسندگان :
    جزئیات بیشتر مقاله
    • تاریخ ارائه: 1392/07/24
    • تاریخ انتشار در تی پی بین: 1392/07/24
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      a series of a5b5o17-type naca4−x sr x nb5o17 (x = 0 to 4) compounds were processed through a solid-state mixed-oxide route. all the compositions formed dense single-phase ceramics within the detection limit of an in-house x-ray diffraction facility when sintered at 1300°c. the substitution of sr for ca changed the crystal symmetry from monoclinic (x = 0) to orthorhombic (x = 1 to 4) along with a slight increase in molar cell volume due to the relatively larger ionic radius of sr. the relative permittivity (ε r) and temperature coefficient of resonance frequency (tcf) increased from 46 to 84 and from −117 ppm/°c to +377 ppm/°c, respectively, while the quality factor (q × f) decreased from 11,063 ghz to 559 ghz with an increase in x from 0 to 4. optimum properties were achieved for naca3srnb5o17, which exhibited ε r = 57, q × f = 4628 ghz, and tcf = −41 ppm/°c. compounds in the naca4−x sr x nb5o17 series exhibited high ε r and q × f with adjustable tcf; however, further work is required for simultaneous optimization of all three properties.

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