Synthesis And Characterization Of Plate-like BaTi₂O₅Nanoparticle By Molten-salt Method And Research Of Growth Mechanism

BaTi₂O₅is a multielement oxygenization of Ti rich in the BaO-TiO2system,which is a new lead-free ferroeletric material with friendly environment. Because ofthe high Curie temperature（430℃） and fine dielectric property along b-aixs ofBaTi₂O₅，it will be used widely of great value in the capacitor element andferroelectric film in future. Thermodynamically stable over a very narrow temperaturerange between1220¹230℃, so it’s difficult to obtained by conventional solid statesintering method. As BaTi₂O₅shows very large anisotropy in the dielectric properties,it’s the key to synthetized the single-crystal BaTi₂O₅particle grow with b-axis.In this article, precursor （HTO） be synthetized via molten-salt method, then HTOand BaCO₃be used to raw material, KCl and NaCl as the salt, obtained plate-likeBaTiO₃and BaTi₂O₅particles by molten-salt method. SEM photograph shows that theresults of1μm small flake BaTiO₃particles arranged in a particular direction to formsheet morphology, with5⁸μm wide,10¹5μm length, when the molar ratio ofBa:Ti=1:1, under the condition of780⁸40℃heat preservation for5h. In the molarratio of Ba:Ti=1:2, pure phase BaTi₂O₅be synthetized at820⁸70℃thermaltreatment for5h. At low temperature obtained BaTi₂O₅powders SEM photographdisplays that mainly for rod-shaped particles, at the same time accompanied by asmall amount of lamellar particles.The length and wide about1μm, Thickness ofabout0.2μm. With the increase of reaction temperature rod-shaped particles reduce,flaky particles increased and the size also increases gradually. At870℃the size ofplate-like BaTi₂O₅closed to template’s, it is worth noting that the BaTi₂O₅samples inthe different temperature and reaction time are also found in rod and sheet shapeparticles, just the shape of particles in different proportion. According to the abovephenomenon infered two kinds of reaction mechanism: one is HTO templatetransform into rod-shaped particles arranged closely in a particular direction, thendispersed into a single rod-shaped particles finally; another is ioning exchangebetween H+in the interlayered structure of HTO and Ba2+in the molten salt，flake ofBaTi₂O₅particles been obtained by a in situ topotactic transformation reaction.Studies have shown that this experiment method reduces the BaTi₂O₅ thermodynamic stable temperature, but also broaden the thermodynamic stabilityrange, Platelet BaTi₂O₅particles was prepared successfully. How to synthetizeplate-like morphology particles only and structure characteristics of flake BaTi₂O₅remains to be further research.