Study of structure and dielectric properties of Bi_1.5Zn_1+xNb_1.5O_7+x ceramics

ABSTRACT

Bi_1.5Zn_1+xNb_1.5O_7+x (x = 0.005, 0.01, 0.015, 0.02) ceramics were prepared and the structure, crystal chemistry and dielectric properties were investigated. The results revealed that the samples showed a cubic pyrochlore structure when x ≤ 0.015 mol and the second phase occurred at x = 0.02 mol. With the increase of x, the lattice constant and the average distance R(A-O′) increased and the bond valance theory showed that the AV(O′)[A₄] and oxygen ξ parameter of 48f(O) gradually decreased. The dielectric constant decreased and the dielectric loss increased. The activation energy increased from 0.2925eV to 0.3043eV by using the Arrhenius equation.

KEYWORDS:

• Dielectric relaxation
• pyrochlore structure
• bond valance
• activation energy

Funding

The work was supported by National Natural Science Foundation of China under Grant No 11074203, Project of Sichuan provincial department of education under grant No 14ZB0126 and the graduate innovation foundation of Xihua University under Grant No YCJJ2014049, YCJJ 2014046 and YCJJ 2014050.