Processing and Characterization of Carbonate-Free BaTiO 3 Nanoscale Particles Obtained by a Rapid Ultrasound-Assisted We
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INTRODUCTION
RECENTLY, nanoscale ferroelectric materials have received considerable attention[1–8] due to their potential applications in microelectronic, communication, and integrated optic technologies.[9–11] Barium titanate (BaTiO3; BTO) is the most common perovskite ferroelectric material, which has been studied extensively because of its wide band gap and outstanding dielectric and ferroelectric properties.[4–11] The successful synthesis of BTO nanocrystals with unique dielectric properties largely depends on the purity and microstructural characteristics, which in turn is dependent on their preparation method and processing.[4] A large number of researches regarding the synthesis of nanoscale BTO crystals using different synthesis methods are available in the literature.[4–19] BTO synthesis pathways reported in recent years can be divided into the following: (1) solid-state reaction methods such as mixed oxide method,[18,19] and (2) wet chemical processing methods such as sol–gel,[20–23] precipitation, hydrothermal, and sonochemical methods.[4–17] In both groups, considerable progress has been made but it still remains a challenge for the scientific community to obtain highquality BTO nanocrystals at a low temperature of 323 K (50 °C) while avoiding unwanted by-products. The dielectric properties of BTO are largely affected by ROUHOLAH ASHIRI, Lecturer, ABDOLMAJID MOGHTADA and ALI SHAHROUZIANFAR, Graduate Students, are with the Department of Materials Science and Engineering, Islamic Azad University, Dezful Branch, P.O. Box 313, Dezful, Iran. Contact email: [email protected] Manuscript submitted February 13, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
carbonate by-products, which significantly change the dielectric behavior and turn the dielectric nature of BTO to semiconducting one.[20] In this work, it has been tried to develop and describe a new methodology for the synthesis of carbonate-free BTO nanocrystals at low temperature. This methodology provides a one-step, convenient, low-cost, nontoxic, and mass-productive route for the synthesis of BTO nanocrystals. Moreover, the structure and morphology of the nanocrystals have significant effects on their properties and performances. In the sonochemical processing method, preparation conditions of the precursor solution and sonication conditions have crucial roles on the structure and morphology of the obtained nanocrystals. Unfortunately, there is not an elaborated and wide-ranging study in the literature about the role of the processing conditions on the formation, structure, and morphology of the synthesized BTO nanocrystals. Therefore, we have tried to do it. Meanwhile, all the dependences are deeply disclosed and discussed.
II.
EXPERIMENTAL PROCEDURE
A. Materials and Synthesis Pathway Our approach is based on an ultrasound-assisted wet chemical processing method. Titanium chloride, barium chloride, anhydrous sodium hydroxide, and ethanol were used as precursors. All the chemical reagents (see Table I) were of analytical grade and purchased from Mer
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