Departmental Papers (EES)

Document Type

Journal Article

Date of this Version

10-2016

Publication Source

Clays and Clay Minerals

Volume

64

Issue

5

Start Page

537

Last Page

551

DOI

10.1346/CCMN.2016.064033

Abstract

The characterization of freshly cleaved mica surfaces for surface structure and chemical composition was briefly reviewed and focused on surface crystal chemistry using X-ray photoelectron spectroscopy (XPS) and other surface-sensitive techniques. This paper considers micas, which are useful as a first approximation for the behavior of many clay surfaces. Emphasis was given to phyllosilicate XPS binding energies (''chemical shift''), which were described and used to obtain oxidation state, layer charge, and chemical bonding information from the chemical shifts of different peaks. The chemical shift of the Si2p binding-energy to lower values can result from a negative charge increase because of Si4+ replacement by Al3+ and/or Fe3+. The apparent interlayer coordination number reduction from twelve to eight at muscovite and tetraferri-phlogopite (001) surfaces was indicated by the XPS measured K2p binding-energy and is consistent with bond relaxation. Although chemical shifts are valuable to distinguish chemical bonding and oxidation state, chemical shifts usually cannot distinguish between different Al coordination environments where Al is in both tetrahedral and octahedral sites.

Embargo Date

10-30-2018

Available for download on Tuesday, October 30, 2018

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Date Posted: 25 April 2017

This document has been peer reviewed.