Tubes sealed gold

The basic structures of Tl-compounds are tetragonal body centered layer structures with layers normal to the c-axis. The lattice constants are a = 3.8A, and c - 29.4A (for 2212), 35.4A (for 2223), 22A (for 1245) and so on. The common structural features are Tl-O layers sandwiched by Ba-O sheets and blocks of Cu-O layers separated by Ca intermediate layers. The structures differ from each other by the number of Cu-O layers. For example, the number of Cu-O layers in the 2212 phase is two three in 2223 and five in the 1245 structure. A schematic representation of the 1245 structure is shown in Figure 14. The samples are normally prepared from the component oxides in sealed gold tubes to avoid problems with the toxicity and loss of Tl... 

Gold tubes sealed under vacuum are generally used. Other preparation methods can be used ... 

A 35° API gravity Devonian oil from the WCSB in Alberta, Canada was topped at 35°C for 2.5 h under vacuum and the C9+ fraction was used as the starting material for the pyrolysis experiments The topped oil stable carbon isotope ratio is — 29.47%o relative to PDB. The composition of the topped oil is 64% saturates, 23% aromatics, 6.5% resins and 6.5% asphaltenes. The oil falls into the Cynthia shale oil family of Exploration Staff, Chevron Standard Limited (1979) and Allan and Creaney (1991). Oil pyrolysis was performed isothermally in sealed gold tubes at temperatures ranging from 350°C to 400°C, time ranging from 3 to 33 days and pressure of 650 bars. Details of the experimental procedure were discussed previously (Hill et al, 1994, 1996, 2003). 

An alternative is the reaction of the respective sesquioxides with (NH4)Hp2, in analogy to the ammonium chloride (bromide) route. In principle, this is a two-step procedure with the formation of a ternary fluoride first and, secondly, its thermal decomposition (see below). When elemental fluorine is available, the direct fluorination of the rare earths or any of their salts is also a possibility. Ternary fluorides are obtained by a solid state reaction of the respective binary components in sealed gold or platinum tubes. 

Figure 17 (left). The hydrogen sensor of Chou and Eugster (1976), Hydrogen sensors are in sealed Pt tubes, the oxygen buffer in an open tube and the electrolyte in a sealed gold tube. K(w) is Ky and f the fugacity of pure i at P and T. 

Mix iron and hematite powder, pelletize the mixture and heat to 837 °C in a sealed silica or gold tube for 24 h. After heating, quench in liquid N2 (Battle and Cheetham, 1979). 

Radon can be isolated from radium by several methods. An aqueous solution of radium salt such as radium bromide is heated, liberating radon. Radioactive bombardment then decomposes water to oxygen and hydrogen. Radon is separated from the gaseous mixture by condensation in tiny tubes placed in liquid air. The tubes then are sealed by melting. A gold or platinum coating is applied to form the radon seeds used in radiation therapy. 

In another procedure (49), the reactants (n2Os, Ba(NOs)2, CaO, and CuO) were heated in two steps, the first in a lidded Pt crucible (1000 C, 15-25 min), and the second (as pellets wrapped in gold foil) in a sealed silica tube (865-905°C, 3-10 h) that had been flushed with oxygen. Products were multiphase, but a... 

Silver nitrate in ammoniacal solution may be completely reduced to silver by aqueous arsenious oxide. The reduction is hindered by the presence of ammonium sulphate, owing to the decrease in concentration of the hydroxyl ions 5 neutral salts such as sodium sulphate or sodium nitrate have no effect. Similarly, auric chloride may be reduced to gold.6 At 20° C. an aqueous solution of vitreous arsenious oxide reacts 4 to 5 times as rapidly as an aqueous solution of the octahedral form 7 the greater rate of dissolution in water of the former variety has been mentioned (p. 137), but from supersaturated solutions of the two forms there is no appreciable difference in the rates of deposition. The explanation of the inferior reducing power of the crystalline variety may be that there exist anisotropic molecules which only slowly lose their anisotropic properties. An ammoniacal solution of arsenious oxide heated with cupric sulphate in a sealed tube at 100° C. causes reduction... 

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