Individual crystal

Experiment 3. When equal volumes of 0.0005 M Ba(SCN)2 and 0.0005 M MgS04 are mixed, the complete precipitation of BaS04 requires 2-3 h. Individual crystals of BaS04 obtain lengths of approximately 0.005 mm. 

Silver chloride crystals are face-centered cubic (fee), having a distance of 0.28 nm between each ion in the lattice. Silver chloride, the most ionic of the halides, melts at 455°C and boils at 1550°C. Silver chloride is very ductile and can be roUed into large sheets. Individual crystals weighing up to 22 kg have been prepared (10). 

Smectites are stmcturaUy similar to pyrophylUte [12269-78-2] or talc [14807-96-6], but differ by substitutions mainly in the octahedral layers. Some substitution may occur for Si in the tetrahedral layer, and by F for OH in the stmcture. Deficit charges in smectite are compensated by cations (usually Na, Ca, K) sorbed between the three-layer (two tetrahedral and one octahedral, hence 2 1) clay mineral sandwiches. These are held relatively loosely, although stoichiometricaUy, and give rise to the significant cation exchange properties of the smectite. Representative analyses of smectite minerals are given in Table 3. The deterrnination of a complete set of optical constants of the smectite group is usually not possible because the individual crystals are too small. Representative optical measurements may, however, be found in the Uterature (42,107). 

Figure 7. 5. Time evolution of crystallographic texture [(0002) pole figures] along the axis of an explosively driven, hemispherical, titanium liner [66]. A high density of contours near the center of the circle indicate the c-axes of individual crystals are all normal to liner surface.

A separate study was the improvement of magnetic permeability in soft alloys such as are used in transformers and motors by lining up the orientations of individual crystal grains, also known as a preferred orientation this became an important subspeciality in the design of transformer laminations made of dilute Fe-Si alloys, introduced more than 100 years ago and still widely used. 

In a study of crystal precipitation of calcium carbonate during the batch carbon-ation of lime water, individual crystals and agglomerated particles were observed as shown in Figure 8.18(a), (b) and (c), respectively (Wachi and Jones, 1991b). 

Solid Both tautomers can be isolated as individual crystal forms 94JCS(CC)1143... 

The particle size of precipitated potassium heptafluorotantalate is one of the more important parameters. In order to achieve a certain particle size, potassium salts are added to the hot tantalum strip solution as a hot solution. The mixture is cooled down at a specific rate in order to enable the precipitation and ciystallization of K-salt in the form of small, individual crystals. 

Values of X for hydrogen peaks on individual crystal planes of tungsten and molybdenum were found to be about 1-3 kcal/monolayer (101). A stronger dependence of Ed and n, resulted for nitrogen on tungsten (98). 

The high sensitivity of the MS [160] makes it a particularly appropriate tool for the investigation of nucleation and growth processes, since it is possible to measure rates during the early part of the reaction using small samples or individual crystals. The influence of residual gases [160] on the initiation of reaction can also be determined. Short scan times enable very rapid reactions e.g. detonations, to be studied, and it is also possible to measure simultaneously the rate of evolution of several different product molecules. 

By melting the calculated amounts of magnesium and tin in an iron crucible under a mixture of potassium and magnesium chlorides, and cooling slowly, a mass of magnesium stannide was obtained from which individual crystals could be cleaved. The X-ray data were obtained from Laue and spectral photographs, treated as described by Dickinson.3 I wish to express my thanks to Dr. Roscoe G. Dickinson for his advice and active interest in this research. 

Emission of li t accompanying the crystallization of certain crystals from solution and probably arising from cleavages occurring during the growth of individual crystals. Thus, it is a form of triboluminescence. Luminescence which appears when crystals dissolve is termed lyoluminescence. 

It is never found in large individual crystals, usually found in compact or lamellar masses and also seen as inclusions in quartz as fibers and powder-like masses. 

Metals are crystalline in structure and the individual crystals contain positive metal ions. The outer valency electrons appear to be so loosely held that they are largely interspersed amongst the positive ions forming an electron cloud which holds the positive ions together. The mobility of this electron cloud accounts for the electrical conductivity. The crystal structure also explains the hardness and mechanical strength of metals whereas the elasticity is explained by the ability of the atoms and ions to slide easily over each other. Metals can be blended with other metals to produce alloys with specific properties and applications. Examples include ... 

For materials which are available not in the form of substantial individual crystals but as powders, the technique pioneered by Debye and Scherrer is employed (Moore, 1972). The powder is placed into a thin-walled glass capillary or deposited as a thin film, and the sample is placed in the X-ray beam. Within the powder there are a very large number of small crystals of the substance under examination, and therefore all possible crystal orientations occur at random. Hence for each value of d some of the crystallites are correctly oriented to fulfil the Bragg condition. The reflections are recorded as lines by means of a film or detector from their positions, the d values are obtained (Mackay Mackay, 1972). 

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