Journal of the American Ceramic Society, Vol.97, No.11, 3531-3536, 2014
Structure Evolution and Enhanced Microwave Dielectric Characteristics of (Sr-1 (-) Ca-x(x))La2Al2O7 Ceramics
(Sr1-xCax)La2Al2O7 (0.1x0.5) ceramics were prepared by a standard solid-state reaction method. Their densification behavior and microwave dielectric properties were investigated together with the structural evolution. X-ray diffraction analysis indicated that the major phase of Ruddlesden-Popper structure with n=2 was obtained for all the compositions investigated here. Partial Ca substitution improved the sintering behavior of SrLa2Al2O7 ceramics. More importantly, microwave dielectric characteristics were enhanced in (Sr1-xCax)La2Al2O7 ceramics with compositions of x=0.1-0.3. The stacking fault was confirmed by TEM observation in the present ceramics, and the microwave dielectric loss was influenced by it. The best combination of microwave dielectric characteristics was achieved for the composition of x=0.1: epsilon(r) = 19.9, Qf=135400GHz and (f)=-18.5ppm/degrees C.