Synthesis and Characterization of BaTiO 3 Nanopowders and BaTiO 3 /CoFe 2 O 4 Nanocomposites
- PDF / 825,972 Bytes
- 6 Pages / 612.12 x 792.12 pts Page_size
- 15 Downloads / 253 Views
Synthesis and Characterization of BaTiO3 Nanopowders and BaTiO3/CoFe2O4 Nanocomposites Yanling Gao and Doru C. Lupascu University of Duisburg-Essen, Institute for Materials Science, 45141 Essen, Germany ABSTRACT Highly stable, organic-based barium titanate (BaTiO3) sols were developed by the low cost and straightforward “organosol”-precipitation and auto-combustion process of amorphous organic precursors. BaTiO3/CoFe2O4 nanocomposites with core/shell structures embedded in a BaTiO3 matrix were also obtained using this process. The particles are systematically characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TGA/DTA), infrared spectroscopy (IR) and by laser granulometry for particle size distribution determination. INTRODUCTION Barium titanate (BT) is one of the most widely used ferroelectric ceramic materials in the electronic industry. The synthesis methods have great effect on the desired characteristics of the ceramic powders influencing their end application. Among the various synthesis methods such as chemical co-precipitation, micro emulsion, mixed oxide, hydrothermal, auto combustion, etc., the sol-precipitation method seems to be convenient since crystalline nanoparticles of BT are directly obtained at low temperature without calcinations and annealing [1]. The auto-combustion synthesis method has also many potential advantages such as low processing cost, energy efficiency and high production rate. In the present work, BT nanoparticles were synthesized by two different processes: “organosol”-crystallization and auto-combustion [2, 3]. BT nanoparticles as obtained directly by the first method without calcinations were crystalline and cubic in structure with particle size ranging from 10~15 nm. The auto-combustion method is an extremely facile, time-saving and energy-efficient route for the preparation of higher amounts of product. During the combustion, exothermic redox reactions associated with metal component decomposition and oleate oxidation take place. Gases such as N2, H2O, and CO2 evolve, favoring the formation of fine particle ashes after only a few minutes. Multiferroic nanocomposites formed by combining a piezoelectric ceramic and a magnetostrictive material, such as in the BaTiO3-CoFe2O4 (BT-CFO) system, have been attracting much interest for their magnetoelectric coupling. The auto-combustion method proved to be a possible route for the preparation of CFO-BT core/shell nanostructures. EXPERIMENT Two ways of BT preparation from BT organic precursor solution were used in our case “organosol”-crystallization and auto-combustion, as shown in Fig.1. The organosol crystallization method presented here uses aqueous sodium hydroxide (4M NaOH, pH=14) for the direct synthesis of crystalline particles. This method is based on the hydrolysis of the organosol, followed by the crystallization of BT precursor from the alkaline organic slurry
(1) (2)
(3) )
Figure 1. Flow charts of crystalline BT nanoparticles prepared by
Data Loading...
