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Calcium hafnium titanate, Ca(HfxTi1-x)O3 (CHT) was prepared using the conventional solid state reaction route. The X-ray diffraction patterns were used for analyzing the phase compositions. The XRD patterns revealed the arrangement of a single phase perovskite structure and therefore the structure is transformed from non-centrosymmetric orthorhombic (Pbnm) to centrosymmetric cubic (Pm-3m) at 0.4 ≤ x. Lattice parameter, crystallite size, densities and porosity were calculated. The SEM morphology of CHT at various hafnium (x), which is comprises of round-rod shaped grains with small pores microstructure. The substitution of Hf4+ ions over Ti4+, the microwave dielectric constant (ε r) decreases from 145 to 52, while the quality factor (Qxf) increases from 8105 to 24305 GHz and temperature coefficient of resonant frequency tuned towards zero τ f ∼ 4.5 ppm °C−1. Good combination of microwave dielectric material properties was accomplished for the composition x = 0.8 (at 3 GHz).

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The lead-free Ca­(Sn x Ti1–x )­O3, (0 ≤ x ≤ 0.8) sample has been successfully prepared through the ball milling process, sintered at 1200 °C for 3 h. The structural, morphological, vibrational, and microwave dielectric properties of synthesized samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and impedance analysis. All the samples have an orthorhombic phase structure with a space group of Pbnm formation, and the crystalline size and strain changes with respect to Sn4+ doping were observed in the XRD analysis. From a morphological point of view, on increasing the content “x”, the grain size reduces from 3.29 to 1.37 μm. The existence of vibrations and the bridging stretching mode of Ti–O–Ti and Ti–O–Sn both are associated with the broadband in the region below 800 cm–1 verified by FT-IR. The variation in electrons hopping off the host compound with respect to Sn4+ ions was analyzed in AC conductivity. The changes of dielectric properties such as complex permittivity, modulus spectroscopy, and dielectric loss at room temperature with a different frequency range of 1.00–2.00 GHz are discussed.

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