Investigation of the structural, dielectric, and reflective characteristics of thermally stable magnesium titanate ceramics

A series of substituted magnesium titanates with general formula (0.96 Co x Mg 1-x TiO 3 —0.04 ySrTiO 3 ); (x = 0.00, 0.05, 0.075; y = 0.00, 1) was synthesized by auto-ignition combustion method. The effects of SrTiO 3 addition on structural, dielectric and reflection properties of synthesized ceramics were investigated. A single-phase system with MgTiO 3 as the major phase was confirmed by X-ray diffraction (XRD) examination of the generated compositions. In addition, a small amount of SrTiO 3 was detected in the compositions y = 1.0. The MgTiO 3 phase was found to have trigonal symmetry with space group R¯3 by Rietveld refinements., In contrast, the SrTiO 3 phase exhibited cubic symmetry and a space group Pm¯3 m.The existence of 10 Raman active modes in all the compositions was confirmed by Raman Spectroscopy. However, it was observed that as the concentration of Co increased from composition x = 0.00 to x = 0.075 the modes were shifted toward higher wavenumber. The dielectric properties of all the studied samples were evaluated using an impedance analyzer at a frequency of 100 kHz. The composition 95 MCST (0.96 Mg 0.95 Co 0.05 TiO 3 —0.04 SrTiO 3 ) with (τ f = 3.17 ppm/°C, tan δ = 1.97 × 10 –3 , and ε r = 20.77 at a frequency of 100 kHz) had the most desirable set of dielectric characteristics. This composition also possesses more than 90% reflection for a bandwidth of 4.83 GHz and 1.36 GHz in the Ku and K frequency bands respectively. Due to its low-to- medium ε r , low tan δ, almost zero τ f , and favorable reflection properties, the 0.96 Mg 0.95 Co 0.05 TiO 3 – 0.04 SrTiO 3 composition can be used for 5G applications as well as a microwave absorber or shielder.