Dielectric properties and electrical response of yttrium-doped Bi2/3Cu3Ti4O12 ceramics

Abstract

([Formula: see text]Bi[Formula: see text]Cu3Ti4[Formula: see text] ([Formula: see text] 0.00–0.30) ceramics were successfully prepared via the conventional solid-state method. X-ray powder diffraction confirmed the lattice constant gradually decreases with increasing Y[Formula: see text] content. SEM images displayed Y[Formula: see text] substitution for Bi[Formula: see text] gave rise to the large abnormal grains, and the size of abnormal grains became larger with the increase of Y[Formula: see text] substitution. ([Formula: see text]Bi[Formula: see text]Cu3Ti4[Formula: see text] ceramics presented the relatively high dielectric constant of 7400 with the dielectric loss of 0.055 when [Formula: see text] 0.20. The analysis of complex impedance suggested the grains are semiconductive and the grain boundaries are insulating. For pure [Formula: see text]Cu3Ti4[Formula: see text] ceramics, the appearance of additional low-frequency peaks in electrical modulus indicated the grain boundaries are heterogeneous. The investigation of modulus peaks fitting with Arrhenius formula implied that the low-frequency permittivity for all ([Formula: see text]Bi[Formula: see text]Cu3Ti4[Formula: see text] ceramics was ascribed to the Maxwell–Wagner relaxation at grain boundaries. In addition, a set of clear dielectric peaks above [Formula: see text]C associated with Maxwell–Wagner relaxation can be found for all ([Formula: see text]Bi[Formula: see text]Cu3Ti4[Formula: see text] ceramics in the temperature dependence of dielectric constant. This set of clear dielectric peaks showed a tendency to shift to higher temperatures with the increase of Y[Formula: see text] substitution. Meanwhile, a tiny dielectric anomaly at room temperature was found in Y-doped [Formula: see text]Cu3Ti4[Formula: see text] ceramics.