Crystal structure, Raman spectroscopy and microwave dielectric properties of xBa3MgNb2O9–(1-x)Ba2InNbO6 [x = 0.4, 0.6, 0.8]. (April 2018) - Dutta, Alo
Graphical abstract: Highlights: xBa3 MgNb2 O9 –(1-x)Ba2 InNbO6 [x = 0.4, 0.6, 0.8] are synthesized for the first time. Tetragonal crystal symmetry confirms from Rietveld refinement of XRD & Raman spectra. τf linear with octahedral-distortion. Variation of Qf with FWHM of ν1 (O) is analyzed. Mixing of BIN with BMN improves the microwave dielectric properties of BMN. For all the materials εr > 36 and x = 0.4 and 0.8 materials show high Qf value than BMN. Abstract: The dependence of the microwave dielectric properties of xBa3 MgNb2 O9 –(1-x)Ba2 InNbO6 [x = 0.4, 0.6, 0.8] on the structural parameters is investigated. The solid-state reaction technique is applied to synthesize these materials and the structural parameters are obtained from the Rietveld refinement of the X-ray diffraction (XRD) data of the samples. The Rietveld refinement confirms the tetragonal crystal structure of all the samples with space group P4/mnc ( D 4 h 6 ). It has been observed that the Raman shift of the stretching mode ν1 (BO6 ) and the ionic polarizability of the cations strongly influenced the dielectric constant (εr ) whereas the value of the quality factor Qf depends upon the width of ν1 (BO6 ) mode. It is observed that the temperature coefficient of resonant frequency (τf ) increases with the increase of the octahedral-distortion in the crystal structure. The factors affecting the microwave dielectric properties are discussed based on the vibrational and structural data.