Synthesis Of BaTi₂O₅ By Hydrothermal Method

In the field of ferroelectric materials, BaTi2O5 is a lead-free ferroelectric material which has higher dielectric constant along b-axis. The Curie Temperature of BaTi2O5 is about 430℃. It can be used in Multilayer ceramic capacitors and Ferroelectric memory, etc. However the preparation of BaTi2O5 has a little difficult. So far, the preparation method of BaTi2O5 has solid-state reaction, molten salt method, sol-gel method, spark plasma sintering and floating zone method, etc. But there is few report about the BaTi2O5 was prepared by hydrothermal method.In this article, BaTi2O5 was prepared by hydrothermal method. The reactant were Ba(OH)2·H2O and Ti Cl4 with the mineralizer was NaOH. The concentration of Ba2+ was 0.062mol/L and the molar ratio of Ba/Ti was 1:2. The temperature of hydrothermal was 180℃ for 36 hours. The product was heated to 1050℃ for 4 hours. Then the BaTi2O5 was obtained. The morphology was observed by SEM, and the results shows that the BaTi2O5 was rod structure with the length about 10 microns, but uneven width. The dielectric property was measured by Precision impedance analyzer and the results showed that the curie temperature of Ba Ti2O5 was 389℃.The BaTi2O5 was also prepared by hydrothermal method that the reactant was Ba(OH)2·H2O, tetrabutyl titanate, NaOH and H2 O. The influences of hydrothermal reaction time, concentration of NaOH and temperature of heat treatment on the product were also studied. So the reaction mechanism of BaTi2O5 prepared by hydrothermal method should be as follows: at the beginning of the reaction, the precursor powders obtained by hydrothermal method using Ti4+ and Ba(OH)2 as raw materials. The precursor was composed of a variety of compounds. Then through the heat treatment, the BaTi2O5 was got by the reaction between the precursor powders and remaining Ba2+.