Journal of Crystal Growth, Vol.307, No.1, 185-191, 2007
Effect of capping ligands on the synthesis and on the physical properties of the nanoparticles of LiTaO3
This paper reports the synthesis of lithium tantalate (LiTaO3) nanoparticles by a sol-gel process involving the use of capping ligands. When the sol was allowed to form gel and then annealed at 600 degrees C for 1 h in the presence of oxygen, hexagonal crystallites of size 2-5 mu m were formed. But when the sol was heat treated at 600 degrees C for 1 h in the presence of oxygen before gelation, agglomerated nanoparticles were formed. The addition of aniline before gelation (a neutral capping ligand with N-donor atom) not only restricted gelation, but also helped in the formation of well-separated and irregular nanoparticles of sizes 40-70 nm, which was confirmed from TEM and XRD studies. The anionic-ligand oleic acid (lipophilic ligand with O-donor atoms) restricted gelation. by arresting the surface of LiTaO3, and spherical nanoparticles of size 20-40 nm were formed after heating the so]. Comparison of ferroelectric and dielectric properties between bulk particle and spherical nanoparticles (obtained using oleic acid) are reported by characterizing these particles using Raman spectroscopy and differential scanning calorimetry (DSC). The Curie temperature decreases with decreasing the particle size of LiTaO3. (C) 2007 Elsevier B.V.. All rights reserved.
Keywords:differential scanning calorimetry;scanning electron microscope;transmission electron microscope;X-ray diffraction;nanomaterials;ferroclectric materials