USE OF THE RIETVELD METHOD FOR DESCRIBING STRUCTURE AND TEXTURE IN XRD DATA OF DOLOMITE (CaMg(CO3)2) AND HYDROMAGNESITE (Mg5(CO3)4(OH)2(H2O)4) POWDERS

The generalized spherical-harmonic (GSH) description for preferred orientation correction of Xray and neutron diffraction data of uniaxially pressed molybdite (MoO 3) and calcite (CaCO3) powders in Rietveld analyses (Sitepu, 2002; Sitepu, O’Connor and Li, 2005; Sitepu, 2009) has been extended to describe crystal structure and texture in X-ray diffraction (XRD) data of asreceived powders, as well as uniaxially pressed dolomite [CaMg(CO 3)2] and hydromagnesite [Mg5(CO3)4(OH)2(H2O)4] powders. The results showed that the structural parameters along with the bond lengths agree reasonably well with the single-crystal XRD results. Also, the Rietveld refinement provided reasonable fits for the uniaxially-pressed dolomite and hydromagnesite powders. Moreover, the level of preferred orientation for uniaxially pressured dolomite and hydromagnesite powders is higher than the as-received samples.