Structural dependence of microwave dielectric properties of Ca 3 MgSi 2 O 8 ceramics

This work focuses on the relationship between structure and microwave dielectric properties of Ca 3 MgSi 2 O 8 ceramic via Rietveld refinement, excluded porosity calculation model, complex chemical bond theory, and harmonic oscillator model. A merwinite phase with P21/c space group is confirmed based on analysis of XRD patterns. The permittivity calculated by refractive-ionicity Eq. (12.33) is within 2% of the measured value (12.56). The Ca–O and Si–O bonds play a crucial role in the dielectric constants and dielectric loss, respectively. The temperature coefficient is related to oxygen octahedron distortion [MgO6]. The infrared spectrum is carried out to analyze intrinsic dielectric properties, which indicates the contribution of the active modes in the far-infrared range to the intrinsic permittivity and loss is dominant.