Discussions

╳Discussions

Groups

Recent Images in Discussions

Mineralogical ClassificationRondorfite-type structure—XPS and UV–vis study

13th Feb 2016 16:19 UTCUwe Kolitsch Manager

Dulski, M. et al. (2015): Rondorfite-type structure—XPS and UV–vis study. Materials Research Bulletin 70, 920-927.

http://www.sciencedirect.com/science/article/pii/S0025540815003992

This paper focuses on X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy of two different (green, orange) rondorfite samples. The differences in the sample color originate from various O/Cl ratios. The orange color was found to be related either to the isomorphic substitution of Fe3+/Al3+ for Mg2+, the presence of atypical [MgO4] tetrahedrons in crystal structure or electronegativity of the sample. The tetrahedron is known to be very prone to accumulation of impurities and substitute atoms. Moreover, the XPS data showed tetrahedrally coordinated Mg2+ and isomorphic substitution of Al3+/Fe3+ for Mg2+, which influences local disordering and the point defects density and distribution. Non-equilibrium chlorine positions inside the crystal cages as well as Ca-Cl bonds have also been found. The XPS measurements as a function of temperature indicate occurrence of a structural transformation at about 770 K which is accompanied by a rotation of silicate tetrahedra within magnesiosilicate pentamer and luminescence disappearance.

Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 24, 2024 14:21:06

Go to top of page