Microstructure and electrical properties of BaFe 0.5Nb 0.5O 3 Doped with GeO 2 (1-5 wt.%)

• Main Authors: Kantha P., Pisitpipathsin N., Pengpat K., Rujijanagul G., Guo R., Bhalla A.S.
• Format: Article
• Language: English
• Published: 2014
• Online Access: http://www.scopus.com/inward/record.url?eid=2-s2.0-84855784982&partnerID=40&md5=0e29e18bec16eae6d345eb45095e987c; http://cmuir.cmu.ac.th/handle/6653943832/6419
• Institution: Chiang Mai University

In this work, the effects of GeO 2 dopant on the electrical properties of BaFe 0.5Nb 0.5O 3 (BFN) perovskite ceramics were investigated. The BFN powder was prepared by a conventional mixed-oxide method using stoichiometric amounts of BaCO 3, Fe 2O 3 and Nb 2O 5. Afterward the GeO 2 contents, ranging from 1 to 5 wt.% were added to the calcined BFN powder and mixed via vibro-milling method. The mixtures were pressed and sintered at 1125-1150°C for 4 h to form dense ceramics. We showed that the addition of GeO 2 caused a reduction of grain size and formation of secondary phases: Ba 3Fe 2Ge 4O 14 and BaGeO 3. The maximum densities of these BFN doped with GeO 2 ceramics were slightly lower than those of the pure BFN due to the occurrence of pores. We also found that the GeO 2 doping could improve the dielectric properties of these ceramics at room temperature (25°C). The 1 wt.% GeO 2 doped sample exhibited higher dielectric constant of about 1800 and lower dielectric loss of 0.45 comparing to that of pure BFN. However, the dielectric constant values of these ceramics at high temperature (>25°C) were decreased significantly with the increase of GeO 2 concentration. In addition, the GeO 2 additive gave a weak ferroelectric behavior, leading to change in the pyroelectric coefficient and spontaneous polarization of the GeO 2 doped BFN ceramics. Copyright © Taylor & Francis Group, LLC.