Development of Forsterite with High Q and Zero Temperature Coefficient τ_f for Millimeterwave Dielectric Ceramics

Abstract

High-Q pure forsterite (Mg 2 SiO 4 ) ceramics with Qf = 240,000 GHz were developed by the usual solid sintering process, using raw materials of highly purified MgO and SiO 2 .The τ f (temperature coefficient of the resonant frequency) was a large and negative: -60 to -70 ppm/ºC. To adjust the τ f value to zero, rutile (TiO 2 ) with high τ f (450 ppm/ºC) was added. When sintering temperature was selected as low as possible, TiO 2 remained in the forsterite specimen, which raised τf from a negative to positive values. For instance, the 30 wt% TiO 2 added forsterite ceramics sintered at 1200ºC yield a high density (3.3 g/cm 3 ), which same as that of the same forsterite ceramics sintered at 1350ºC. A part of added TiO 2 works for sintering aid and residual ones do for arising the τf value from negative to positive. Improved forsterite ceramics have τ f = 0 ppm/˚C, ε r = 11 and Qf = 82,000 GHz, when they contains 24 wt% of TiO 2 and sintered at 1200ºC for 2h.

Synthesis and Microwave Dielectric Properties of MgO-xmol%B2O3(x= 33 and 25) Ceramics in MgO-B2O3System

“…Some ceramics of the silicate series, which have the low constant, are considered to be the appropriate candidates for the commercial applications at the high frequency because of the high Q · f and the low ε r values. For example, the forsterite, i.e., Mg 2 SiO 4 , is known to have the Q · f value of 102/ [332] Makio Nishizuka et al 210000 GHz and the dielectric constant of approximately 6 [1]. Moreover, the compensation of τ f value to be achieved 0 ppm/ • C and the low temperature co-fired ceramic (LTCC) of the Mg 2 SiO 4 ceramic were also reported in the literature [2][3][4].…”

Zirconia nucleating agent on microstructural and electrical properties of a CaMgSi2O6 diopside glass–ceramic for microwave dielectrics

“…For example, Tsunooka et al [3] mentioned that forsterite (Mg 2 SiO 4 ) possesses a low e r of 6.8 and a high Q Â f of 242,000 GHz. Zhang et al [4] reported that the CaMgSi 2 O 6 ceramic sintered at 1300 8C has a relatively lowpermittivity (7.46) and high Q Â f value (59,700 GHz).…”

Effect of two-step sintering on the microwave dielectric properties of Zn1.8SiO3.8 ceramics

“…In recent years, a number of dielectric ceramics with low K and high Qf values have been investigated, such as Al 2 O 3 [1], MgAl 2 O 4 [2], ZnAl 2 O 4 [3], and Mg 2 SiO 4 [4]. In particular, Zn 2 SiO 4 ceramic systems have been widely studied due to their high Qf values.…”