Raman and Structural Characterization of Spinel Compound Zn 8/5 Al 4/15 TiO 4

Microwave dielectric materials have been attracted enormous attention for their application in microwave communication. A new microwave dielectric material with composition Zn_8/5Al_4/15TiO₄ was synthesized by conventional solid-state reaction method. The structure of Zn_8/5Al_4/15TiO₄ was refined with the cubic P4₃32 space group (number of formula unit per unit cell, Z = 4). The Rietveld refinement study revealed the theoretical density ρ = 4.80 g/cm³ and lattice parameter a = 8.405 Å. This compound was crystallized in cubic spinel structure and 1:3 ordering was observed on the octahedral sites. Raman spectrum of the compound was collected at room temperature. Theoretical Factor group analysis for this compound predicts 40 Raman modes and 22 IR modes. However, experimentally 13 vibrational modes have been observed in the Raman spectrum which can be separated into internal TiO₆ vibration and external rotation and translation TiO₆ modes. Raman modes in the range of 500-800 cm^-1 are assigned to internal vibrational modes.