CMAS, system

There are two main projection schemes that are used for the major element compositions of basaltic rocks. One is the CMAS system, in which an analysis of a basalt is approximated by the four oxides Ca0-Mg0-Al2O3-SiO2. The other is a normative scheme based upon the main minerals observed in basalts — nepheline-diopside-olivine-anorthite and quartz. This projection is based upon the classification scheme for basalts proposed by Yoder and Tilley (1962) in which the... 

CMAS diagrams The components of the CMAS system (CaO-MgO-Al203-Si02) comprise aibout 70-85 wt % of most basalts and more than 90 wt % of most mantle peridodtes. For this reason the CMAS system is used by experimental petrologists as a simplified analogue of more complex basalt and mantle systems. The CMAS projecdon... 

Figure 3.28 Normative nepheline-oUvine-diopside-hypersthene-quartz projection after Thompson (1984), showing the compositions of initial melts in the CMAS system, MORE source and fertile anhydrous mantle at a range of pressures (in kb). The inset shows the relationship of the diagram to the surface of the Yoder-Tilley basalt tetrahedron.

Adiun J., 1988, Dry, hydrous and COj-bearing Uquidus phase relationships in the CMAS system at 28 kb, iand their bearing on the origin of alk basalts, y. CeoLy 96, 709-720. Addy S.K. and Garlick G.D., 1974, Oxygen isotope fractionation between rutile and water. Contrib. Mineral Petrely 45, 119-121. 

Figure 6 Compositional areas in a cut of CMAS system corresponding to silica content 60 wt. % built as a result of properties calculation (except for glass forming ability Gr) satisfying the following criteria glass-forming ability Gr positive (a), batch cost c < 230 units (b), forming range temperature T3 < 1280°C (c), and specific tensile module Esp > 35 GPa cmVg.

Fig. 8. Compositional areas corresponding to glass-forming melts on ternary phase diagrams representing sections of tetrahedron of quatanary CMAS system at 47,54, and 63 wt. % of SiO .

THERMOCHEMISTRY OF GARNETS AND ALUMINOUS PYROXENES IN THE CMAS SYSTEM... 

Newton, R.C. Thermochemistry of garnets and alimiinous pyroxenes in the CMAS system. This volume (19T6). 

CMA systems consisting of two axial-focusing analysers in series have been applied for XPS instruments. This combination gives an improved resolution at the cost of sensitivity. 

In order to optimize energy resolution, a can be adjusted so that where w = the slit width. Similar to the CMA system, photoelectrons are retarded to preselected pass energies via planar grids across the entrance slit as they enter... 

One CMA system intermediate between periodic crystals and approximant CMAs is g-Al4Cu9(110) [147-149]. This is a simple cubic (SC) phase with 54 atoms in the unit cell, and while not strictly an approximant, it is closely linked to QCs. Its formation on a surface was first observed following annealing of a thin Cu film deposited on the 5-f surface of i-Al-Pd-Mn [200], and the surface was later studied in more detail using STM and LEED [147]. Duguet et al. [148] suggested its use as an interfacial buffer layer between quasicrystaUine and periodic materials and demonstrated its formation on i-Al-Cu-Fe. Recently, the (110) surface of the bulk material has also been studied [149]. The results from aU of these studies are consistent with the general conclusions for approximant surfaces outlined earlier. 

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