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Thermally treated soil clays as ceramic raw materials: Characterization by X-ray diffraction, photoacoustic spectroscopy and electron spin resonance

2008; Elsevier BV; Volume: 43; Issue: 2 Linguagem: Inglês

10.1016/j.clay.2008.07.025

1872-9053

Leonardo Mota, Rafael Morán Moya, R FARIAJR, E DASILVA, H. Vargas, I. Delgadillo‐Holtfort,

Soil and Unsaturated Flow

Soil clay used as ceramic raw material under heat treatment was investigated using X-ray diffraction, X-ray fluorescence, photoacoustic spectroscopy — PAS and electron spin resonance — ESR. The results indicated the presence of at least three different sites for the Fe3+ ions, one of them representative of a set of distorted cubic sites. The optical absorption spectra obtained with the photoacoustic technique showed bands associated with d–d transitions of Fe3+ ions. Mullite and hematite were detected in the 1100 °C heated samples. Crystalline–amorphous–crystalline transformations were detected between 110 °C and 1100 °C. The conclusion drawn from photoacoustic and magnetic resonance measurements agreed very well with that obtained by X-ray diffraction.