Nanocrystalline bulk and thin films of La1-xSrMnO3 (0≤ x≤0.3)

Nanocrystalline La1-xSrxMnO3 has been prepared by a new solution chemistry technique, and the processing parameters were optimized. The thermal history of the as-prepared gel is investigated by differential thermal (DTA) and thermogravimetric analysis (TGA). Formation of La1-xSrxMnO3 starts at temperatures as low as 575 degreesC. Powder X-ray diffraction analysis was used to check the crystallographic phase purity of nanocrystalline La1-xSrxMnO3. Transmission electron microscopic investigation (TEM) reveals that the grain size of samples prepared at 575 degreesC were in the range of 20-30 nm. The Mn-K edge EXAFS measurements show the nanocrystalline LaMnO3 and La1-xSrMnO3 indicate a distortion in the MnO6 octahedra, yielding two discrete Mn-O distance in contrast to structural data obtained for bulk LaMnO3, in which there are three discrete Mn-O distances. Thin films of La1-xSrxMnO3 were deposited by pulsed laser ablation technique on (100) LaAlO3, (1000) sapphire and polycrystalline alumina substrates. The deposition parameters were optimized to realize the growth of high-quality films. Films deposited on (100) LaAlO3 were highly c-axis-oriented while the films on (1000) sapphire were highly alpha-axis-oriented. The morphology of the films as studied by atomic force microscopic analysis reveal that the films are highly granular with an average grain size in the range of 100-150 nm. (C) 2002 Published by Elsevier Science B.V.