Investigations of BaFe0.5Nb0.5O3 Nano Powders Prepared by a Low Temperature Aqueous Synthesis and Resulting Ceramics
Journal of the European Ceramic Society 37 (2017) 1509-1516.
40 Pages Posted: 20 Dec 2017
Date Written: December 9, 2016
A facile method to prepare nanoscaled BaFe0.5Nb0.5O3 via synthesis in boiling NaOH solution is described herein. The nano-crystalline powder has a high specific surface area of 55 m2 g−1 and a crystallite size of 15 nm. The as-prepared powder does not show any significant crystallite growth up to 700 °C. 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 for 1 h or after two-step sintering at 1000 °C for 10 h. The average grain sizes of ceramic bodies can be tuned between 0.23 μm and 12 μm. 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 Néel temperature of 20 K. Depending on the sintering regime, the ceramic samples reach permittivity values between 2800 and 137000 at RT and 1 kHz.
Keywords: perovskite, hydrothermal, nanparticle, ceramics, band-gap, thermal expansion coefficient, permittivty, magnetism
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