Bond characteristics, vibrational spectrum and optimized microwave dielectric properties of chemically substituted NdNbO4.

Coordination chemistry, bond state and vibrational spectrum of co-substituted microwave dielectric NdNb 1- x (Zr 0.5 W 0.5) x O 4 ceramics (x = 0.01∼0.05) were investigated. Raman spectra and XRD refinement showed a solid solution was formed. The compressed and elongated chemical bonds are responsible for the variations of crystal parameters and cell volume. Calculated chemical bond parameters indicated bond covalency, lattice energy and Nb-site bond energy act on the fluctuations of the permittivity, quality factor and temperature coefficient, respectively. Meanwhile, the infrared vibrational spectrum is fitted to quantify the contributions of observed IR mode to the intrinsic loss. Compact ceramic possesses excellent properties: ε r ∼ 19.2, Q × f ∼ 55282 GHz and τ f ∼ -11.36 ppm/°C with x = 0.04, at 1250°C. [ABSTRACT FROM AUTHOR]