Spectroscopic characterization of a Nigerian standard sand: Igbokoda sand

Abstract

The characterization of the Nigerian Igbokoda Standard Sand was performed by X-ray diffraction, IR and Raman Spectroscopy, and nuclear magnetic resonance techniques. The principal reflections occurring at the d-Spacings of 4.25745, 3.34359, 2.45705, 2.28172, 2.23697, 2.12754, 1.98036, 1.81827, 1.54178 and 1.37190 Å confirm the presence of a-quartz crystalline structure in the cample. The calculated unit cell parameters are: a = 4.9133(2) Å, c = 5.4053 Å, V = 113.00 Å. Presence of Si-O asymmetrical stretching vibrations at 1119.61 – 967cm-1, Si-O asymmetrical stretching vibration at 1180 – 1120cm-1 and Si-O Symmetrical Bending Vibration 693cm-1 reveal the presence of quartz and that it is in the crystalline form. Bands at around 800cm-1 - 822.79cm-1 and 786.23cm-1, reveal that the silica is in the form of a-Quartz. The Raman spectrum of the sample has two peaks at around 203cm-1 and 463.07cm-1 for A1 vibrational mode characteristic of quartz. These peaks reflect that the sample studied belongs to the low temperature quartz. The occurrence of the Raman shift at 463.07cm-1 supports the observation from XRD studies which establishes that the quartz observed in this work is a-Quartz. The 29Si NMR spectrum shows a prominent signal at –107.95 ppm correlating to quartz.