UNSPECIFIED. (2000) Fabrication and characterization of aqueous sol-gel-derived LaFeO3 thin films. MODERN PHYSICS LETTERS B, 14 (22-23). pp. 801-808. ISSN 0217-9849

Abstract

A novel all-inorganic aqueous sol-gel process has been developed to fabricate LaFeO3 thin films by dip-coating. Stable, positively charged colloidal sol pal-tides of hydrous lanthanum ferrite with an average particle size (Z(av)) of 7 nm were prepared and coated onto quartz plates under controlled conditions. The sols have been characterized using photon correlation spectroscopy (PCS) for Z(av) and size distribution. The redispersible gel was characterized by thermogravimetric and differential thermal analysis (TG-DTA) and also by isothermal heating followed by X-ray diffraction to identify the reaction sequence to form LaFeO3. The sol-gel films as deposited were X-ray amorphous on heating up to 500 degreesC, partially crystalline at 600 degreesC, fully crystalline and single phase at 650 degreesC and above. These films were continuous, polycrystalline, single phase, had uniform thickness in the range between 180 to 1000 nm, depending on deposition conditions, and showed about 80% optical transmittance The optical band gap varied from 2.7 to 3.3 eV as a function of the annealing temperature. The refractive index increased with increase in annealing temperature from 1.55 at 500 degreesC to 1.86 at 800 degreesC.

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