Order-disorder transition and its effect on microwave quality factor Q in Ba(Zn1/3Nb2/3)O3 system

Abstract

Influences of composition deviation from stoichiometry and heat treatment on crystal phases and Q factor in Ba(Zn 1/3 Nb 2/3 )O 3 (BZN) were studied. The structural order and the crystal phases strongly depended on the slight composition deviation from stoichiometric BZN. The maximum Q factor was obtained at the vicinity of the stoichiometric BZN. In the other regions, non-stoichiometric disordered BZN or ordered BZN with secondary phase were formed, and their Q factors were found to be low. For the stoichiometric BZN, the order-disorder phase transition occurred between 1300 and 1400 • C. The crystal-structural ordering of the stoichiometric BZN was improved by post-annealing at below its transition temperature, conserving the density and the grain size. However, no significant Q factor improvement was found. The Q factor of the stoichiometric BZN strongly depends on the density and grain size not on the crystalstructural order. These results suggest that the ceramic microstructure such as the pore and grain boundary, the secondary phase and lattice defect caused by non-stoichiometry affect the variation of the Q factor in BZN system than the crystal-structural ordering.

Microwave dielectric properties of Ba(Co0.56Y0.04Zn0.35)1/3Nb2/3+x O3(x = −0.004 ~ 0.008) ceramics

“…The samples with high ordering degree usually have low dielectric loss values (high Q 9 f values) [11,12]. Besides the 1:2 B-site cation ordering, there existed many literatures suggesting that the high Q 9 f characteristics were attributed to some other factors, such as impurity phases [13,14], porosity [15], lattice distortion (c/a) [16,17], grain size [18] and grain boundary [19], ordering domain structures [1,20,21], and oxygen vacancies [22]. Furthermore, the Q 9 f value of this system was considered to be very sensitive to nonstoichiometry [7,18].…”

Dense Composition with HighQon the Complex Perovskite Compounds

“…Ba(Zn 1/3 Nb 2/3 )O 3 (BZN) with order-disorder transition showed high Q at disorder form sintered over the transition temperature. And, the disordered BZN with high Q annealed at lower temperature changed to order structure without improvement of Q [7].…”

Effects of Y2O3 substitution on microwave dielectric properties of Ba(Co0.6Zn0.38)1/3Nb2/3O3 ceramics

“…The low loss values are obtained when the samples exhibit high ordered degree [3,11]. Besides the 1:2 B-site cation ordering, the high Q 9 f characteristic can also be attributed to some other factors, such as ordering domain structures [4,12,13], lattice distortion (c/a) [14,15], impurity phases [16,17], grain size [18] and grain boundary [19], porosity [20], and oxygen vacancies [21].…”