| Abstract: A New Niobate Ba6LaTi3Nb3O21 was synthesized by high temperature solid state reaction in the BaO-La2O3-TiO2-Nb2O5 system. The chemical compositions, crystal structure, microstructure, density and melting point of the new compound were characterized by EPMA, XRD, DTA and so on. Ba6LaTi3Nb3O21 crystallizes the rhombohedral system with unit cell parameters a=0.57388(2) nm, c=4.928 3(3) nm, and space group R3m, Z=3. The structure may be described as six (Nb,Ti)O6 octahedra corner-sharing along c-axis to form perovskite layer connected by Ba atoms. The Ba6LaTi3Nb3O21 ceramics exhibits high dielectric of 74.1, low dielectric loss of 4.7×10-4 and small temperature coefficient of dielectric constant of -69 ppm·K-1 at 1 MHz due to its close structure and relative high dielectric polarizabilities of Ba2+, La3+, Ti4+ and Nb4+. Ba6LaTi3Nb3O21 might be a suitable candidate of high εr microwave dielectric ceramics. |
