Structural, morphological and vibrational properties of LaAlO3 nanocrystals produced by four different methods

Abstract

This work deals with the synthesis of samples of lanthanum aluminate (LaAlO3 - LAO) and their structural, morphological and vibrational properties. The samples were produced by four routes: Sol-Gel with Copaiba Oil; Sol-Gel with coconut oil; Sol-Gel with coconut water and; Modified Pechini. The modified Pechini synthesis was the route used as a reference, as it is well known. In all the rotes, the samples were calcined for 4 h. LAO samples with single-crystalline phase were obtained from 600 °C by Sol-Gel with coconut oil. In the samples obtained via Pechini this phase occurred from 700 °C, and from 800 °C by the other routes. The structural characterization was carried out using X-ray diffraction (XRD) and Fourrier-transform infrared (FTIR) and Raman spectroscopy techniques. The collected XRD patterns were refined by Rietveld method. Morphological characterization was performed with scanning electron microscopy (SEM) and to elemental characterization energy-dispersive X-ray spectroscopy (EDX) was used. Even though the syntheses with natural reagents may leave traces of contaminant elements in samples, they proved to be efficient in producing LAO nanocrystals in the R-3c phase at lower temperatures than those employed in conventional routes.