Deeper insights into dodecahedron distortion and microwave dielectric properties of Y3-R Al(Oct)2Al(Tet)3-Si O12 (x = 0.1–0.5; R = Mg, Ca) garnet-type ceramics

Ni–Co Complex Ionic Synergistically Modifying Octahedron Lattice of Cordierite Ceramics for the Application of 5G Microwave–Millimeter-wave Antennas

“…For example, Ohsato et al 14 achieved excellent microwave dielectric properties upon replacement of Mg with Ni 2+ in Mg 1. 8 Ni 0.2 Al 4 Si 5 O 18 , resulting in the following values: ε r = 6.1, Qf = 99 100 GHz@13 GHz, and τ f = −32 ppm/°C. For lattice modification of the cordierite [MgO 6 ] octahedral site, the authors' group has published numerous works discussing how the degree of roundness of [Si 4 Al 2 O 18 ] influences its microwave dielectric properties.…”

“…The cordierite ceramic is gaining prominence due to its lower permittivity (<6), low thermal expansion coefficient (1 × 10 –6 to 3 × 10 –6 °C –1 ), and excellent resistance to high-temperature thermal shock (with a melting point of 1460 °C) and has been widely used as a ceramic shed plate, a sagger, electronic packaging materials, etc. However, its suitability for high-frequency microwave device applications is limited by the values of the temperature coefficient of the resonant frequency ( τ f ) and the high-quality factor ( Qf ). − Elemental doping has been an effective method for improving the sintering characteristics and microwave dielectric properties of cordierite ceramics. − Precious research on cordierite microwave ceramics mainly focused on single ionic substitutions in the [MgO 6 ] octahedral site, such as Ni 2+ , Co 2+ , Zn 2+ , Cu 2+ , Ba 2+ , Ca 2+ , and Mn 2+ . For example, Ohsato et al achieved excellent microwave dielectric properties upon replacement of Mg with Ni 2+ in Mg 1.8 Ni 0.2 Al 4 Si 5 O 18 , resulting in the following values: ε r = 6.1, Qf = 99 100 GHz@13 GHz, and τ f = −32 ppm/°C.…”