Microwave Dielectric Properties of SrRE_4Si_3O_(13) (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, and Y) Ceramics

摘要

The apatite type SrRE_4Si_3O_(13) (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, and Y) ceramics have been prepared by the conventional solid-state ceramic route. The phase purity and surface morphology of the sintered ceramics were studied using X-ray diffraction and scanning electron microscopy methods. These materials showed poor sinterability and was improved by the addition of a small weight percentage of zinc borosilicate glass. The microwave dielectric properties of these materials were studied for the first time. SrRE_4Si_3O_(13) ceramics have a low relative permittivity (ε_r) in the range 9-16, a Q-factor (Q_u×f) upto 26 000 GHz and a low temperature coefficient of resonant frequency (ι_f). The SrLa_4Si_3O_(13) ceramics possessed a high Q_u× f of nearly 26 000 GHz but with a high negative ι_f of -46 ppm/℃. The ι_f of SrLa_4Si_3O_(13) ceramics was tuned by the addition of suitable amount of TiO_2.