Crystal Structures and Dielectric Properties of Bi ₂ (( Zn _1/3 Nb _2/3 ) _{1− x} Ti _x ) ₂ O ₇ Ceramics

Abstract

B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 ceramics with 0 ≤ x ≤ 0.4 were synthesized using solid‐state reaction method. The crystal structure is pure zirconolite type for the compositions with 0 ≤ x ≤ 0.15, single weberite type for the compositions with 0.3 ≤ x ≤ 0.4, and mixture of zirconolite and weberite for the compositions with 0.15 < x < 0.3. The weberite ceramics with only B i as the A‐site cation are first reported. A possible correlation between the crystal structure transformation and T i content in system of B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 with 0 ≤ x ≤ 0.4 was suggested. Dielectric constant (ε), dielectric loss (tan δ) and temperature coefficient of capacitance (TCC) are ~85, ~0.001, and ~200 ppm/°C for the zirconolite solid solutions, ~140, 0.004, and between −120 and −200 ppm/°C for the weberite solid solutions, respectively, at 1 MHz. Ceramics with a near zero TCC consisting of the zirconolite and weberite phases were obtained. High ε, low tanδ, and low sintering temperatures (~950°C) make the novel ceramic system of B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 potential dielectrics for applications in low‐temperature co‐fired ceramic and multiplayer ceramic capacitors.