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 A°3. 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 Fe 2+ and Fe 3+ respectively in the sample. The signal near g ~ 4 is characteristic of isolated Fe 3+ ions in the distorted octahedral or tetrahedral crystalline field. 29 Si NMR spectrum shows a strong signal at -107 ppm corresponding to quartz.Keywords: sand, X-ray diffraction, infrared and Raman spectra, 29 Si nuclear magnetic resonance spectroscopic techniques.Introduction. Silica forms a basic mineral for all types of rocks. Silica exists in many different polymorphs: α-and β-quartz, α-and β-cristobalite, coesite, and stishovite. The most stable phase of silica at ambient conditions is α-quartz. Quartz is one of the most abundant minerals found in the Earth crust (12% of its weight). It was formed under a wide range of P-T conditions prevailing in the crust. In different crustal environments, quartz is crystallized from silicate melt, precipitated from aqueous solution, or formed as a result of solid state transformation during metamorphic events. This mineral belongs to the tectosilicate class and the structure is built from SiO 4 tetrahedra which are linked by sharing each of their corners with another tetrahedron. In the three-dimensional framework thus formed every silicon has four oxygens and every oxygen has two silicons as nearest neighbors [1]. The unit cell of the crystal structure consists of three SiO 2 groups. The three silicons in the unit cell together with the three other silicons belonging to the adjacent cells form an irregular hexagon possessing only the symmetry of a threefold axis. The impurities commonly found in quartz can be classified as substitutional (occupying the place of Si

Spectroscopic Characterization of a Nigerian Standard Sand: Igbokoda Sand

“…Bands at this region also represent Si-O asymmetrical stretching vibration [15]. This observation is similar to that reported by [16,5]) and [17,5] who reported bands at 1150 and 1140cm -1 respectively. Stretching vibration spotted at around 800cm -1 helps to tell apart different forms of silica [5].…”

“…The unit cell of quartz is a rhomb (rhombohedral crystal). This rhomb equate to a hexagonal unit cell [5,6]. X-Ray Diffraction (XRD) helps to answer the question -''is this sample crystalline or amorphous?''.…”

“…X-Ray Diffraction (XRD) helps to answer the question -''is this sample crystalline or amorphous?''. Infra red (IR) spectroscopy has been backed to be one of the most promising instrumental techniques in the structural and mineral constituent elucidation of silica sand [5]. Raman spectroscopy is a complementary instrumental technique to IR.…”

“…Correct identification of bond types is a precursor to establishing the chemical composition and polymorph of quartz. Other techniques like magnetic resonance also help identify quartz [5]. Silica with at least 95% SiO2 is favoured for manufacturing and industrial uses.…”

Suitability of Tanzanian Kaolin, Quartz and Feldspar as Raw Materials for the Production of Porcelain Tiles

“…Generally, the amount of silica is higher in quartz because quartz is the mineral which consists of silica in crystal form [24]. The low amount of alumina can cause formation of the product with high linear shrinkage and hence unstable product [4,25].…”