Investigations of BaFe0.5Nb0.5O3 nano powders by an aqeous synthesis and resulting ceramics

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Full-text: https://www.researchgate.net/publication/311620459_Investigations_of_BaFe05Nb05O3_nano_powders_prepared_by_a_low_temperature_aqueous_synthesis_and_resulting_ceramics Abstract. 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.

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