Crystal structure and microwave dielectric properties of CaTiO3 modified Mg2Al4Si5O18 cordierite ceramics

Abstract

In this work, CaTiO 3 modified Mg 2 Al 4 Si 5 O 18 (MAS) of (1-x)MAS-xCaTiO 3 (0 ≤x≤0.35) cordierite ceramics were fabricated by traditional solid phase sintering method. The densification sintering temperatures of (1-x)MAS-xCaTiO 3 ceramics are effectively lowered from 1460C to 1250C with increasing addition of CaTiO 3. X-ray diffraction spectra show that (1-x)MAS-xCaTiO 3 ceramics present cordierite phase as 0<x≤0.05, and the composite phases of cordierite, perovskite-structured CaTiO 3 and monoclinic feldspar phase of CaAl 2 Si 2 O 8 as 0.10≤x≤0.35. Rietveld refinement of XRD data show the six-membered rings of [(Si 4 Al 2)O 18 ] transit from non-symmetry rings to centro-symmetry equilateral rings in (1-x)MAS-xCaTiO 3 (0<x≤0.10). The optimal dielectric properties of Q×f = 55490 GHz (at 15.3GHz),  r = 7.2 and  f =-28.3 ppm/C are obtained at x=0.5, which are better than those of pure MAS cordierite ceramics.

Enhanced Microwave Dielectric Properties in Mg2Al4Si5O18 Through Cu2+ Substitution

“…where f 85 � C ð Þ and f 25 � C ð Þ represent the resonant frequency at the testing temperature of 85°C and 25°C, respectively. [16]…”

“…The near-zero τ f values of Mg 2 Al 4 Si 5 O 18 ceramics were also investigated through adding CaTiO 3 , TiO 2 and SrTiO 3 . [16][17][18] Although the near-zero τ f values were obtained, the ɛ r values increased. In addition, the low sintering temperature of Mg 2 Al 4 Si 5 O 18 ceramic was realized by adding BaCu(B 2 O 5 ), whereas the Qf value was deteriorated.…”

“…But the Ga 2 O 3 as starting material would increase cost, which severely limited its commercial application, and its Qf value was deteriorated. The near‐zero τ f values of Mg 2 Al 4 Si 5 O 18 ceramics were also investigated through adding CaTiO 3 , TiO 2 and SrTiO 3 [16–18] . Although the near‐zero τ f values were obtained, the ϵ r values increased.…”

A new broadband near-infrared emitting Mg2Al4Si5O18:Cr3+ phosphor for night-vision imaging

“…The batch was then heated at 1000 °C for 2 h in the air so that carbon dioxide and water could be removed from the mixture. 27 The pre-sintered sample was then ground evenly and transferred to an alumina crucible. Finally, the alumina crucible was heated to 1430 °C at a heating rate of 5 degrees per minute for 6 h to synthesize the sample.…”

Effect of Mixing Ratio and Heating Rate on Sintering Properties of SiO2/Glass Composite

“…Therefore, as an antenna substrate material used in the millimeter wave band, a material having a low relative dielectric constant and low loss is in the spotlight. [ 8–10 ]…”