Li-Mg-Si system

After the discovery of the Al6Mn i-QC [1], development of QCs were limited for almost a decade to ternary systems with a major A1 constituent, such as Al-(Pd,Mn)-Si, Al-Zn-(Li,Mg), Al-Cu-TM (TM = Fe, Ru, Os), Al-Pd-(Mn,Re) [2,25,26], (This may be the reason why jargon such as Al-based QCs was coined.) After all, most QC discoveries were achieved by chemical additions to, or substitutions in, known compounds. From the mid-1990s to about 2000, QCs were also found in Zn-Mg-R (R = rare-earth-metal), Cd-Mg-R, and (Yb,Ca)-Cd systems, the last being the first stable binary i-QC at room temperature. Experience and insight are worth a lot — Tsai and coworkers produced 90% of these i-QCs [27],... 

Aluminum, boron, carbon, iron, nitrogen, oxygen, phosphorus, sulfur and titanium are the common impurities in the SoG-Si feedstock. Arsenic and antimony are frequently used as doping agents. Transition metals (Co, Cu, Cr, Fe, Mn, Mo, Ni, V, W, and Zr), alkali and alkali-earth impurities (Li, Mg, and Na), as well as Bi, Ga, Ge, In, Pb, Sn, Te, and Zn may appear in the SoG-Si feedstock. A thermochemical database that covers these elements has recently been developed at SINTEF Materials and Chemistry, which has been designed for use within the composition space associated with the SoG-Si materials. All the binary and several critical ternary subsystems have been assessed and calculated results have been validated with the reliable experimental data in the literature. The database can be regarded as the state-of-art equilibrium relations in the Si-based multicomponent system. 

A self-consistent thermodynamic description of the Si-Ag-Al-As-Au-B-Bi -C-Ca-Co-Cr Cu Fe-Ga-Ge-In Li Mg Mn Mo N-Na-Ni-O-P-Pb-S-Sb-Sn-Te-Ti-V-W-Zn-Zr system has recently been developed by SINTEF... 

The studies on the hydrothermal systems at midoceanic ridges during the last three decades clearly revealed that the seawater-basalt interaction at elevated temperatmes (ca. 100-400°C) affects the present-day seawater chemistry (Wolery and Sleep, 1976 Edmond et al., 1979 Humphris and Thompson, 1978). For example, a large quantity of Mg in seawater is taken from seawater interacting with midoceanic ridge basalt, whereas Ca, K, Rb, Li, Ba and Si are leached from basalt and are removed to seawater (Edmond et al., 1979 Von Dammet al., 1985a,b). 

Au, Sb and Hg are more enriched into the ores of back-arc basins compared with midoceanic ridge and thus it is likely that back-arc basin hydrothermal flux for these elements is higher than midoceanic ridge hydrothermal flux. However, the concentrations of these elements in back-arc basin hydrothermal solution have not been analyzed. Thus, we need to accumulate analytical data on the concentration of these elements in back-arc basin hydrothermal solution. Further, H2O flux from back-arc basin has to be estimated based on various methods ( He/He, Mg concentration, Li isotope, Sr isotope, Ge/Si ratio) which was argued for midoceanic ridge hydrothermal system by Elderfield and Schultz (1996), but not for back-arc basin by the previous workers. 

Two series of irradiations were made with the UCI 250-kW TRIG A Mark I reactor. The first run consisted of irradiation for 30 s at a thermal neutron flux of 4.8 X 109 neutrons cm-2 s 1 using the facility s pneumatic transfer system. Samples were permitted to decay for 1 min and then counted for 2 min on a Ge-Li detector (21% efficiency) at a distance of 1.3 cm from the crystal and a gain setting of 0.8 keV per channel. Elements determined in this run were Al, Mg, Mn, Si, Sn, V, and Zr. 

A hydrothermal solution is a multicomponent system containing com-poimds of Na, K, Si, Ca, Mg, Al, Fe, Cl, S, O, C, B, Li, As, Cu, Zn, Ag, Au, and other elements in ionic and molecular forms. Silicon has one of the highest concentrations. Silica, together with other compounds, passes into this hydrothermal solution due to the chemical interaction of water with aluminosilicate minerals of rocks of hydrothermal fields at a depth in regions of thermal anomalies at high temperatures and pressures. 

A revised, updated suinmary of equilibrium constants and reaction enthalpies for aqueous ion association reactions and mineral solubilities has been compiled from the literature for common equilibria occurring in natural waters at 0-100 C and 1 bar pressure. The species have been limited to those containing the elements Na, K, Li, Ca, Mg, Ba, Sr, Ra, Fe(II/III), Al, Mn(II,III,IV), Si, C, Cl, S(VI) and F. The necessary criteria for obtaining reliable and consistent thermodynamic data for water chemistry modeling is outlined and limitations on the application of equilibrium computations is described. An important limitation is that minerals that do not show reversible solubility behavior should not be assumed to attain chemical equilibrium in natural aquatic systems. 

Al/Si ratio—viz, 1/2. However, there have been no ion exchange investigations of the systems, Na-K, Na-Ca, or K-Ca in analcites of higher or lower than normal Al/Si ratios. Whereas earlier attempts to effect cation exchange of normal analcite by Li, Cs, Mg, Ca, and Ba were met with only limited success, indirect methods of exchange or direct synthesis from gels provided means whereby Li, K, Ca, Cs, and Pb2+ forms were said to have been obtained (1, 3, 4, 5). 

Most elements have NMR-active nuclei, i.e., nuclei possessing a magnetic moment. For surfactant systems, the situation is very good in that H and C nuclei, which occur in most surfactant molecules, have good NMR properties. For relaxation work, however, it is often advantageous to use NMR on selectively deuterated compounds. F NMR is very useful for the study of fluorocarbon surfactants, P NMR for phospholipids, and Si NMR for silicon surfactants. For studies of water molecules we have a choice between three good alternatives H, H, and NMR. Many common counterions, e.g., Na, Li, Rb, Cs, F, Cl, Br, and I, have highly sensitive nuclei, whereas others, such as K" ", Mg " ", Ca ", and SO ", have lower sensitivity and are more difficult to study. 

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