Sodium high pressure structure

Despite the observation of profuse spectroscopic changes on compression and decompression of NaNs, the in situ high-pressure structures of the various phases remain unknown. The small sample size required by high pressure studies and large hysteresis due to the strain and stress make difficult in situ diffraction measurements. At high temperature conditions, however, the transformation from an azide to a polynitrogen phase may be more readily characterized as the requisite transformation pressures may be much lower and less subject to hysteresis. Here we describe the heating experiments on pure sodium azide and a... 

Ingalls R, Crozier E D, Whitmore J E, Seary A J and Tranquada J M 1980 Extended x-ray absorption fine structure of sodium bromide and germanium at high pressure J. Appl. Phys. 51 3158... 

When levuhnic acid (CH3CCH2CH2CO2H) was hydrogenated at high pressure over a nickel catalyst at 220°C a single product C5Hg02 was isolated in 94% yield This compound lacks hydroxyl absorption in its IR spectrum and does not immediately liberate carbon dioxide on being shaken with sodium bicarbonate What is a reasonable structure for the compound" ... 

Although the structure of CsCl is quite different from that of NaCl, even CsCl can be transformed into the sodium chloride structure when heated to temperatures above 445 °C. Some of the other alkali halides that do not have the sodium chloride structure under ambient conditions are converted to that structure when subjected to high pressure. Many solid materials exhibit this type of polymorphism, which depends on the external conditions. Conversion of a material from one structure to another is known as a phase transition. 

As was discussed in Chapter 7, there are numerous solids that can exist in more than one form. It is frequently the case that high pressure is sufficient inducement for the structure to change. An example of this type of behavior is seen in KC1, which has the sodium chloride (rock salt) structure at ambient pressure, but is converted to the cesium chloride structure at high pressure. Other examples illustrating the effect of pressure will be seen throughout this book (see especially Chapter 20). It should be kept... 

Lochhead and Bray (1995) studied Eu3+ doped sodium disilicate glass with a high-pressure fluorescence line-narrowing technique. This technique was used to characterize the local structure of the Eu3+ ions up to a pressure of 21 GPa. For the crystal-field analysis they assumed a C2v site symmetry which allowed for a complete splitting of the crystal-field components. The crystal-field strength was determined according to eq. (11). The effect of pressure... 

The so-called metaborates of empirical formula B02 can take several forms. The infinite linear (B02) T ion is found in the low-temperature form of LiB02 (449), Ca(B02)2 (275), and Sr(B02)2 (46). At high temperatures and pressures, the lithium compound possesses a sphaleritelike structure with boron in four-coordination (278). The triborate isolated B3Or group is found in the barium (297), sodium (276), and potassium (361) compounds, and the framework B30 " group, in which all the boron atoms are tetrahedral, exists for a high-pressure calcium metaborate phase (280) and copper metaborate (284). Two other anhydrous calcium metaborates are known to give the series... 

The value for rc/ra for CsCl is 0.934 and as expected the structure has eight Cl- ions surrounding each Cs+ ion. However, it is interesting to note that even CsCl has the sodium chloride structure at temperatures above 445 °C. Some of the other alkali halides that normally have the sodium chloride structure exhibit the CsCl structure when subjected to very high pressure. 

Rubidium chloride has the sodium chloride structure at normal pressures but assumes the cesium chloride structure at high pressures. What ratio of densities is expected for these two forms Does this change in structure make sense on the basis of simple models ... 

Some recent developments in the research of the structure and dynamics of solvated ions are discussed. The solvate structure of lithium ion in dimethyl formamide and preliminary results on the structure of sodium chloride aqueous solutions under high pressures are presented to demonstrate the capabilities of the traditional X-ray diffiraction method at new conditions. Perspectives of solution chemistry studies by combined methods as e.g. diffraction results with reverse Monte Carlo simulations, are also shown. 

Viscosity of aqueous cesium chloride (CsCl) solution was measured in the range of 0.1-5.0 mol kg-i and 0.1-375 MPa at 25 °C. The Jones-Dole B coefficient of CsCl was obtained from the concentration dependence of the viscosity. It is negative not only at atmospheric pressure but also at high pressure, having a maximum against pressure at about 160 MPa. Similar maximum of the B was observed for aqueous sodium chloride (NaCl) solution. The similarity is discussed in terms of the water structure and dielectric friction theory. 

Sodium bicarbonate is also used in cleaning products on both a household and industrial level. Many householders use commercial baking soda, such as that sold by the Arm Hammer company, to clean kitchen and bathroom appliances, such as sinks, stoves, and toilet bowls. Industries also use sodium bicarbonate filters to remove sulfur dioxide and other pollutants in flu gases released from factory smokestacks. The compound is also used in the treatment of wastewater to maintain proper acidity, remove certain odors (such as those of sulfur dioxide), and destroy bacteria. Some communities have used aqueous solutions of sodium bicarbonate sprayed at high pressure to remove graffiti paint soot and smoke residues and mold from buildings, walls, and other public structures. 

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