Synthesis, structure and dielectric properties of the Sr₃Ti_{1-: X}Zr_xNb₄O₁₅, (0 ≤ x ≤ 1), series of tungsten bronze type compounds

Compounds across the Sr3Ti1-xZrxNb4O15, (0 ≤ x ≤ 1), composition range were synthesised. Structure refinements were performed against synchrotron X-ray powder diffraction data and constant wavelength and time-of-flight neutron powder diffraction data. All members of the composition range were found to form tungsten bronze type structures with orthorhombic Pna21 symmetry at RT. Variable temperature diffraction data revealed that all compositions underwent a transition to a high temperature tetragonal structure on heating, with the transition temperature increasing with the zirconium content of the sample. Variable temperature dielectric measurements were performed for both end members showing maxima in the dielectric constant coinciding with the observed phase transition temperatures.