على مخططات انعراج الأشعة السينية(Rietveld)التحديد الكمّي للمركَّبات البلورية في رمل كثبان ورقلة، باستعمال طريقة ريتفلد

Abstract

In this work, Rietveld refinement of XRD data of natural and heated (at temperatures 800 °C, 1000 °C, 1200 °C) Ouargla dunes sand using MAUD software (Materials Analysis Using Diffraction Data) was carried out. The crystalline phases that make up this sand were qualitatively and quantitatively determined. The structural parameters (lattice parameters), the structural and microscopic parameters (crystalline size and microstress) were also determined for each phase. Rietveld refinements showed that the natural Ouargla sand dune has two main components: -quartz (SiO2) and gypsum (CaSO4.2H2O) with a ratio of 72.11% and 23.77%, respectively, in addition to bassanite (CaSO4.0.67H2O) as a secondary phase with 4.34. %. Rietveld refinements of heated sand XRD data showed that heating has a clear effect on the crystalline structures that make up the sand; that the heating of sand at 800 °C turned the gypsum and bassanite into anhydrite (CaSO4) by about 36.16%, while the quartz decreased by about 10%. When sand heated at 1000 °C, -wollastonite (Ca3Si3O9) has been appeared with about 0.74%. Quartz decreased by about 10%, and anhydrite increased by about 10% as well. Heating at 1200 °C caused a partial phase transformation of quartz into cristobalite (SiO2) with about 1.48%.