Functional advances of microwave dielectrics for next generation

Low temperature sintering and microwave dielectric properties of CoZrNb2O8 ceramics with H3BO3 addition

“…With the development of high frequency wireless communication technology, microwave dielectric ceramics such as duplexers, resonators, antennas, and oscillators have attracted much commercial and scientific attention [1][2][3][4]. For these high frequency wireless communication applications, the microwave dielectric materials should have a high dielectric constant, a high quality factor, and a near-zero temperature coefficient of resonant frequency, which are desirable for minimization of the microwave circuit component, maximum signal intensity and adaptation to environmental temperature changes [5,6].…”

Microstructure and microwave dielectric properties of xSm(Mg0.5Ti0.5)O3–(1 − x)Ca0.8Sr0.2TiO3 ceramics

“…Table 1 illustrates the bulk density and microwave dielectric properties of xSm(Mg 0.5 Ti 0.5 )O 3 -(1 -x)Ca 0.8 Sr 0.2 TiO 3 ceramics sintered at 1,550°C for 3 h. It can be seen that the bulk density of samples increases from 5.15 to 6.41 g/cm 3 with the x-value increasing from 0.50 to 0.95, which is in agreement with the fact that the theoretical density of Sm(Mg 0.5 Ti 0.5 )O 3 ceramic (6.665 g/cm 3 ) is larger than that of Ca 0.8 Sr 0. With the x-value increasing to 0.95, there is a decrease in the Q 9 f of the sample, which needs to be further investigated.…”

“…Three important properties, namely, high dielectric constant (e r ) to reduce the size of devices, low dielectric loss (high quality factor Q 9 f, where Q = 1/tan d) for achieving frequency selectivity and stability, and near-zero temperature coefficient of resonant frequency (s f ) for temperature stability, are required for practical applications [3]. Usually, two or more ceramics separately having negative and positive s f values could be used to adjust the temperature coefficient of resonant frequency (s f ) to zero in an appropriate proportion, forming a solid solution or mixed phases.…”

Structure and optical properties of Sn4+ doped Ba(Mg1/3Nb2/3)O3 transparent ceramics

“…Al 2 O 3 , the representative of transparent ceramics, has a refractive index of 1.76. However, Al 2 O 3 exhibits a birefringence effect due to its hexagonal structure, which causes scattering of light and low transmissivity [5,6]. High transmissivity for the applications utilizing optical transparency requires materials with isotropous cubic crystal structure that do not exhibit birefringence [7].…”