Spectroscopic characterization of indian standard sand

Abstract

The characterization of Indian standard sand (IS650:1991 as per B.I.S. approval) was performed by X-ray diffraction, IR and Raman spectroscopy, and nuclear magnetic resonance techniques. The principal reflections occurring at the d-spacings of 4.2408, 3.3440, and 1.8292 A confirm the presence of α-quartz crystalline structure in the sample. The calculated unit cell parameters are: a = 4.9294 A, c = 5.4093 A, and V = 113.832 A3. Mid-IR spectrum shows the characteristic doublet for α-quartz at 797 and 778 cm–1. The Al/Al+Si ratio has been calculated from the position of the absorption band at 1100 cm–1. Raman spectrum of the sample has two strong peaks at 203 cm–1 and at 462 cm–1 for A1 vibrational mode characteristic of α-quartz. Two bands at 1410 and 1930 nm in near-IR spectrum indicate the presence of both molecular water and an OH group. A broad double band centered near 1210 nm and a weak band at 1050 nm attest the presence of Fe2+ and Fe3+ respectively in the sample. The signal near g ∼ 4 is characteristic of isolated Fe3+ ions in the distorted octahedral or tetrahedral crystalline field. 29Si NMR spectrum shows a strong signal at –107 ppm corresponding to quartz.