类钙钛矿新铌酸盐Ba4LaTiNb3O15的合成、结构与介电特性

A new niobate compound Ba₄LaTiNb₃O₁₅ has been synthesized and characterized. Through Rietveld refinement of X-ray powder diffraction data, Ba₄LaTiNb₃O₁₅ is identified as the A₅B₄O₁₅ type cation-deficient perovskites with space group of P3m1(164) and lattice constants a=0.572 38(1) nm, c=1.169 48(1) nm, V=0.331 81(1) nm³, and Z=1. The crystal structure can be described as consisting of identical perovskite-like blocks, four corner-sharing (Ba,La)O₆ octahedra thick, separated by layers of vacant octahedral. The (Ba,La)-O bond lengths range from 0.267 to 0.321 nm and the (Ti,Nb)-O bond lengths range from 0.175 to 0.213 nm. The Ba₄LaTiNb₃O₁₅ ceramic has a high dielectric constant of 53.3, high quality factors (Q) 3 650 (at 6.402 5 GHz), and low temperature variation of resonant frequency (τ_f) +69.3 × 10^-6 K^-1.