Preparation, structural and optical characterization of BaWO4 and PbWO4 thin films prepared by a chemical route

• Published in: Journal of the European Ceramic Society Vol. 23; no. 16; pp. 3001 - 3007
• Main Authors: PONTES, F. M, MAURERA, M. A. M. A, SOUZA, A. G, LONGO, E, LEITE, E. R, MAGNANI, R, MACHADO, M. A. C, PIZANI, P. S, VARELA, J. A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.01.2003
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Other semiconductors; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Atomic force microscopy; Scheelite structure; Fourier transformation; Inorganic compounds; Chemical method; Barium Tungstates; Polycrystals; XRD; Infrared spectra; Tungstates; Experimental study; Characterization; Thin films; Lead Tungstates; Optical properties; Crystal growth from solutions; Spinning; Soft chemistry
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/s0955-2219(03)00099-2

Polycrystalline BaWO4 and PbWO4 thin films having a tetragonal scheelite structure were prepared at different temperatures. The thin films were deposited by spinning. The surface morphology and crystal structure of the thin films were investigated using SEM, AFM, XRD, and specular reflectance FTIR spectroscopy. Nucleation stages and surface morphology evolution of thin films on silicon substrates were studied by AFM. XRD characterisation showed that BaWO4 and PbWO4 phases crystallise at 500 C from an inorganic amorphous phase. FTIR spectra revealed the complete decomposition of the organic ligands at 500 C and the appearance of two sharp and intense bands between 1000 and 600 cm-1 assigned to vibrations of the antisymmetric stretches resulting from the high crystallinity of both thin films. The optical properties were also studied. It was found that BaWO4 and PbWO4 thin films have Eg = 5.78 eV and 4.20 eV, respectively, of a direct transition nature. 16 refs.