Microwave dielectric properties and low temperature sintering of Sm2Si2O7 ceramic for substrate applications

Abstract

The Sm2Si2O7 ceramics were synthesized by solid-state ceramic route. The calcination and sintering temperature of Sm2Si2O7 were optimized for the best properties. The crystal structure and microstructure of the ceramic were studied by X-ray diffraction and scanning electron microscopic methods. The low frequency dielectric properties were studied at 1 MHz. The dielectric properties of the ceramic were measured in the microwave frequency range by the cavity perturbation method. Sm2Si2O7 has epsilon(r)=12.5, tan delta=8 x 10(-4), and tau(epsilon)=+63 ppm/degrees C at 1 MHz and a relative permittivity of 10 and tan delta of 6 x 10(-3) in the microwave frequency range. The effect of addition of various low loss glasses such as 50ZnO-50B(2)O(3) (ZB), 60ZnO-30B(2)O(3)-10SiO(2) (ZBS), 27B(2)O(3)-35Bi(2)O(3)-6SiO(2)-32ZnO (BBSZ), 22.2MgO-22.2Al(2)O(3)-55.5SiO(2) (MAS), 35.1Li(2)O-31.7B(2)O(3)-33.2SiO(2) (LBS) and 20Li(2)O-20MgO-20ZnO-20B(2)O(3)-20SiO(2) (LMZBS) on the microwave dielectric properties of Sm2Si2O7 was also investigated. It was found that the addition of 15 wt% LBS glass reduced the sintering temperature from 1375 degrees C to 975 degrees C with epsilon(r)=9.89 and tan delta=0.024. Fifteen weight percent LMZBS glass ceramic decreased the sintering temperature to 950 degrees C with epsilon(r)=9.09 and tan delta=0.009. The results show that Sm2Si2O7 mixed with suitable amounts of selected glasses is a promising material for microwave substrate applications