Microstructure and electrical properties of Mn-modified bismuth-layer Na 0.25K 0.25Bi 2.5Nb 2O 9 Ceramics

Bismuth layer-structured ferroelectric ceramics Na 0.25K 0.25Bi 2.5Nb 2O 9+xmol% MnCO 3 (NKBN-Mn) were synthesized by a traditional solid-state reaction. The effects of Mn addition on the microstructure and electrical properties of ceramics have been investigated in details. It was found that the ceramics possess a pure phase of bismuth oxide layer-type structure. The Curie temperature T c gradually decreases from 653 to 624 °C with increasing the Mn modification. The electrical properties of NKBN-based ceramics are improved significantly by the addition of Mn. The piezoelectric constant d 33, dielectric loss tan δ, mechanical quality factor Q m and remanent polarization P r for the NKBN ceramics with 3.0 mol% MnCO 3 modification were found to be 25 pC/N, 0.28%, 2817, 14.50 μC/cm 2, respectively, together with the high T c (∼643 °C) and stable piezoelectric properties, demonstrating that the Mn modified NKBN-based ceramics are the promising candidates for high-temperature applications. © 2012 Elsevier B.V. All rights reserved.