Microwave dielectric properties of alkaline earth orthosilicates M_2Si0_4 (M=Ba, Sr, Ca)

摘要

Alkaline earth orthosilicates M_2Si0_4 (M=Ba, Sr, Ca) ceramics were prepared by solid state ceramic route and their microwave dielectric properties were investigated. M_2Si0_4 ceramics have £r in the range 8.5-13. At microwave frequencies, the Qu x f obtained were 17,900 GHz, 19,100 GHz and 26,100 GHz for Ba_2SiO_4, Sr_2Si0_4 and Ca_2Si0_4 respectively. The Tf of Ba_2SiO_4 was -17 ppm/℃, whereas Sr2Si04 and Ca_2SiO_4 exhibited high values of τ_f -205 ppm/℃ and -89 ppm/℃ respectively. The coefficient of thermal expansion (α) of the orthosilicates was also studied.