Analysis and Characterization of Phase Evolution of Nanosized BaTiO 3 Powder Synthesized Through a Chemically Modified S
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emands for high-quality electronic ceramics increase rapidly and the physical properties of materials as they progress from the bulk to the nanoscale regime (1 to 100 nm) continue to be of immense interest and increasing importance for future technological applications. Nanocrystals display properties that are generally found to be scientifically different from the bulk material or the atomic or molecular species from which they can be derived.[1] The properties of the nanocrystals frequently are better than traditional bulk materials that have led to an increase in tendency for preparation of this type of materials by using of economic processes. Indeed, the economic consideration of mass production of nanocrystals is a major issue concerning the research and development. ROUHOLAH ASHIRI, formerly Graduate Student, Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Tehran, Iran, is now a first-year Ph.D. Student, Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan, Iran, and Lecturer, Department of Materials Science and Engineering, Dezful Branch, Islamic Azad University, P.O. Box 313, Dezful, Iran. Contact e-mail: [email protected] Manuscript submitted January 16, 2012. Article published online June 12, 2012 4414—VOLUME 43A, NOVEMBER 2012
The ferroelectric nature of nanocrystals occurs because the center of mass of all the negative ions does not coincide with the center of mass of the positive ions, resulting in spontaneous electric polarization.[2] Ferroelectric materials have been under investigation because the stable polarization states could be used to encode the 0 and 1 of the Boolean algebra that form the basis of memory and logic circuitry (FRAM).[1] The rapid advances in the miniaturization of electromagnetic devices have led to a particular need for ceramics with tunable dielectric constants and low losses at microwave frequencies. Ferroelectric materials possess significant tenability, i.e., change of dielectric constant under applied electric field.[3] Among the ferroelectrics, barium titanate is a well-known compound that has been widely used both in academic research and industrial product in the last decades. Barium titanate (BaTiO3) has been used extensively in the manufacture of electronic applications, such as piezoceramic devices, electro-optic elements, highpermittivity ceramic capacitors, positive temperature coefficient resistors, transducers,[4] tunable phase shifters[3] thermistors, gas, temperature and humidity sensors infrared detectors, ferroelectric memories,[5,6] and printed circuit boards.[2] In recent years, high-performance multilayer ceramic capacitors (MLCCs) have developed a toward smaller size and higher capacity, resulting in thinner (below1 lm) green sheets required to produce METALLURGICAL AND MATERIALS TRANSACTIONS A
MLCCs. These high-performance multilayer ceramic capacitors recently are commercialized by BaTiO3 nanopowders (200 nm size).[7] Miniaturization requires downsizing
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