Phase development and microwave dielectric properties of BaO–xSm2O3–4.5TiO2 (x = 0–1.25) ceramics

Effects of Strontium on the Structural, Optical, and Microwave Dielectric Properties of Ba2Ti9O20 Ceramics Synthesized by a Mixed Oxide Route

“…a high value of the relative permittivity (ε r = 38.4), a good temperature coefficient of the resonant frequency (τ f = +20 ppm °C –1 ), a high quality factor ( Q f = 3300 GHz), and low dielectric loss (tan σ = 0.00056), and solid solutions of doped concentrations of Ca, Sr, Zr, or Sn in Ba 2 Ti 9 O 20 ceramics are very suitable for making good dielectric resonator antennas. − For Ba 2 Ti 9 O 20 sintered ceramics, it is necessary to get maximum values of the quality factor ( Q f × f ) and low values of the temperature coefficient at the resonant frequency (τ f ). BaSnO 3 and BaWO 4 have negative τ f values, which when they are added to the aforementioned dopants give positive τ f values to give a nearly zero τ f value, but the adjustment of τ f and Q f × f is very difficult. − Many researchers have studied the effects of different dopants on the structural and microwave dielectric properties of Ba 2 Ti 9 O 20 sintered ceramics …”

Formation mechanism and microstructure evolution of Ba2Ti9O20 ceramics by reaction sintering method

“…In addition, excessive sintering temperature leads to the decomposition of Ba 2 Ti 9 O 20 phase and the reduction in Ti 4+ ion. [7][8][9] Jung et al prepared Ba 2 Ti 9 O 20 ceramics at 1350°C for 4 hours, 10 and Xiao et al prepared Ba 2 Ti 9 O 20 ceramics at 1240°C by conventional mixed oxide method. 11 Another vital difficulty in the synthesis of Ba 2 Ti 9 O 20 phase ceramics is that there are various thermo-dynamical stable compounds in the vicinity of the desired composition of TiO 2 -rich BaO-TiO 2 system: Ba 6 12,13 Therefore, when preparing Ba 2 Ti 9 O 20 ceramics by solid phase reaction method, the stoichiometry and preparation parameters must be precisely controlled.…”