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Dehydroxylation and the Vibrational Spectroscopy of Aluminum (Oxo)Hydroxides Using Infrared Emission Spectroscopy. Part III: Diaspore

1999; SAGE Publishing; Volume: 53; Issue: 7 Linguagem: Inglês

10.1366/0003702991947405

1943-3530

Ray L. Frost, J. Theo Kloprogge, Shane C. Russell, Jennifer Szetu,

X-ray Diffraction in Crystallography

Dehydroxylation of diaspore has been followed by a combination of differential thermal analysis (DTA) and infrared emission spectroscopy (IES). The DTA endotherm of diaspore is not simple, and two inflections are observed at 505 and 531 °C. Dehydroxylation shows that diaspore loses 15% of its weight upon dehydroxylation. The Mn-substituted diaspore shows major endotherms at 620 and 649 °C with a broad endotherm at 539 °C. Infrared absorption bands of diaspore were observed at 3365, 3284, and 3095 cm −1 in the hydroxyl stretching region and at 911, 755, 706, 668, 649, 570, and 544 cm −1 in the low-frequency region. Infrared emission bands were observed at 3239 and 2958 cm −1 in the hydroxyl stretching region. Low-frequency infrared emission bands in agreement with the absorption bands were observed at around 916, 752, 706, 668, 649, 570, and 544 cm −1 . The variation of intensity of the hydroxyl stretching frequencies with temperature follows a pattern similar to that for the DTA curves.