Structural, lattice vibrational, optical and microwave dielectric studies on Ca1−xSrxMoO4 ceramics with scheelite structure

• Microwave dielectric properties of scheelite Ca1−xSrxMoO4 ceramics are studied.
• ϵr correlated with unit cell volume in contrast to polarizability.
• Q × f of these compositions explained with MoO bond strength.
• Interesting correlation between τf and Raman shift of A1g mode is observed.
• Non monotonic variation in band gap is observed and fitted with bowing equation.

Structural, optical and microwave dielectric properties of Ca1−xSrxMoO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) compositions were studied with help of Rietveld refinement and Raman spectroscopy measurements. All these compositions were prepared by solid state reaction method and observed to possess tetragonal scheelite structure with I41/a space group. Microwave dielectric properties such as dielectric constant (ϵr), quality factor (Q×f) and temperature coefficient of resonant frequency (τf) were measured using Hakki–Coleman method, reflection technique and invar cavity attached to hot plate respectively. ϵr, (Q × f) and τf are correlated with molar volume (Vm), MoO bond strength and Raman shift of A1g mode respectively. All these compounds show good microwave dielectric properties (ϵr = 6.7–9.6, Q × f = 35,000–52,000 GHz and τf = −28 to −17 ppm/°C). Band gap of these compositions was observed in the range 3.3–3.5 eV and variation in band gap was fitted with Bowing equation.

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