Investigations of BaFe0.5Nb0.5O3 nano powders prepared by a low temperature aqueous synthesis and resulting ceramics

A facile method to prepare nanoscaled BaFe(0.5)Nba(0.5) O-3 via synthesis in boiling NaOH solution is described herein. The nano-crystalline powder has a high specific surface area of 55 m(2) g(-1) and a crystallite size of 15 nm. The as-prepared powder does not show any significant crystallite growth up to 700 C-o. The activation energy of the crystallite growth process was calculated as 590 kJ mol(-1). Dense ceramics can be obtained either after sintering at 1200 C-o for 1 h or after two-step sintering at 1000 C-o for 10 h. The average grain sizes of ceramic bodies can be tuned between 0.23 p.m and 12 p.m. The thermal expansion coefficient was determined as 11.4(3).10-6 K-1.The optical band gap varies between 2.90(5) and 2.63(3) eV. Magnetic measurements gave a Neel temperature of 20 K. Depending on the sintering regime, the ceramic samples reach permittivity values between 2800 and 137,000 at RT and 1 kHz. (C) 2016 Elsevier Ltd. All rights reserved.