Structure and microwave dielectric properties of La5−x Sr x Ti4+x Ga1−x O17 ceramics
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Single phase polycrystalline ceramics in the La5−x Sr x Ti4+x Ga1−x O17 (x = 0–1) system with A5B5O17 type layered perovskite structure were prepared via a mixed-oxide, solid state sintering route. X-ray diffraction revealed orthorhombic, Pnnm symmetry with Raman spectra consistent with this space group. The sintered ceramics exhibited a plate-like grain structure with a relative density, 94–97.5 %. The end member, La5Ti4GaO17 had ε r = 42.31, Q × f o = 17,093 GHz, τ f = −34.53 but τ f could be tuned close to zero by Sr and Ti substitution at the A- and B-sites, respectively. An optimum composition La4.5Sr0.5Ti4.5Ga0.5O17 was achieved at x = 0.5 with ε r = 51, Q × f o = 15,290 GHz and τ f = −2.2 ppm/oC.
KeywordsRelative Permittivity Ga2O3 Microwave Dielectric Property Dielectric Resonator Small Ionic Radius
The authors acknowledge the financial support of the Higher Education Commission of Pakistan under the IRSIP program. The financial support extended by the Khyber Pakhtunkhwa Government through the Directorate of S&T, Peshawar for the upgradation of Materials Research Laboratory, University of Peshawar is highly acknowledged.
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