Layered Al ₂ O ₃ -TiO ₂ compositedielectric resonators

Evaluation of electronic state of Mg4(Nb2−xSbx)O9 microwave dielectric ceramics by first principle calculation method

“…The commercially utilized high-Q material such as Al 2 O 3 have a high sintering temperature. 1 Thus, there is considerable interest in the development of new microwave dielectric ceramics with high Q·f value that can be used for the high frequency microwave devices. Recently, Ogawa et al 2 reported the microwave dielectric properties of a corundum-type of Mg 4 (Nb 2−x Ta x )O 9 (MNT) solid solutions; it was found that the Q·f values of the solid solutions increased with the substitution of Ta for Nb ((Q·f) max = 347,000 GHz at x = 2).…”

Sintering and dielectric properties of Al2O3 ceramics doped by TiO2 and CuO

“…These results suggest that the t f values change to negative values with the increase of CuO content and to positive values with the increase of TiO 2 content. The t f values of Al 2 O 3 and TiO 2 are −60 and 450 ppm/°C, respectively [5,6]. According to the XRD patterns, as shown in Fig.…”

“…Al 2 O 3 ceramics exhibits good microwave dielectric properties of low dielectric constant (ɛ r ∼10) and good quality factor (Qf∼50,000 GHz). However, Al 2 O 3 ceramics requires a very high sintering temperature (1600°C) and have a very large temperature coefficients of resonant frequency (t f =−60 ppm/°C) [5]. For practical applications, it is necessary to reduce the sintering temperature and temperature coefficients of resonant frequency of Al 2 O 3 ceramics.…”

Microstructure and microwave dielectric properties of ZnO-B2O3 added (Ca0.254Li0.19Sm0.14)TiO3 ceramics

“…To adjust τ f value close to zero, employing two or more compounds with negative and positive τ f values to form a solid solution or mixed phases should be an essential solution as well as a practical approach [9][10][11][12][13].…”