Preparations of Single Crystals

Crystal growth by a chemical transport reaction is done in Mo crucibles. The transporting agent for YbSe was I2 and for EuSe was I2 and EUI2. Mass spectroscopically pure EuSe crystals are obtained 1850°C for example, with 2.76 mg/cm I2 at an average temperature of 2010°C, an apparent supercooling AT = 22°C, and a linear growth rate of 4.0 x 10 cm/s. Crystals were contaminated by molybdenum at lower temperatures (-1650°), Kaldis [20, pp. 96/7, 162/5]. 

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The preparation of single crystals of tetrabutylammonium octachloroditech-netate(III) has been described by Cotton et al. [35], The crystals were studied by... 

Adsorption of acetic acid on Pt(lll) surface was studied the surface concentration data were correlated with voltammetric profiles of the Pt(lll) electrode in perchloric acid electrolyte containing 0.5 mM of CHoCOOH. It is concluded that acetic acid adsorption is associative and occurs without a significant charge transfer across the interface. Instead, the recorded currents are due to adsorption/desorption processes of hydrogen, processes which are much better resolved on Pt(lll) than on polycrystalline platinum. A classification of adsorption processes on catalytic electrodes and atmospheric methods of preparation of single crystal electrodes are discussed. 

Lawson, W. D. and Nielsen, S. Preparation of Single Crystals (Butterworths, London, 1958). 

Oblique texture electron diffraction patterns (Fig.7) are main experimental material for the electron diffraction structure analysis since they have a large number of reflections, so that only one pattern can provide an almost three dimensional set of diffraction reflections. The formation of textures in specimens is achieved by the use of orienting agents. As in the preparation of single crystal films, use can be made of orienting supports, mechanical action or even the application of an electrical field. Electron... 

The preparation of single crystals is difficult, but is successful in some case, so that we are well informed about the structures (1,6,17,21,22,23). The structures of the plastic phases are related to the well-known intermetallic phase Li3Bi, where the centres of the polycyclic P7 or Pn anions surround the positions of the Bi atoms in LisBi. The orientation of the polyanions is disordered (dynamically ). For these structures this orientation leads to a typical electron density distribution of a seemingly octahedral unit. In contrast the orientation of the anions is fixed for the crystalline phases. The symmetry of the unit cells as well as the distribution of cations and anions in these M3P7 and M3P11 type structures reflect the direct relationship to the structures of the plastic phases. 

The chemical vapour deposition (CVD) technique can be regarded as an extension of the sublimation method used for the preparation of single crystals discussed before, but adapted to thin him growth implying deposihon on substrates. A schematic diagram of a horizontal hot-wall CVD apparatus is shown in Fig. 3.15. 

Fig. 8. Apparatus for the preparation of single crystals by the Van Arkel procedure i. quartz ampoule 2. tube with iodine 3. feed material 4. RF heated W sphere or plate 5. resistance furnace 6. RF coil...

It is a pleasure to express my hearty thanks especially to Drs. T. Araki, N. Oguni, H. Yasuda, T. Aoyagi, K. Lee, and N. Ueyama whose skill and spirit have enabled us to overcome difficulties encountered in the preparation and purification of pure substances and in the preparation of single crystal for X-ray analyses, which were conducted under dry argon atmosphere, to Prof. M. Kakudo, Prof. N. Kasai, Dr. N, Yasuoko, and Dr. Y. Kai for their ingenious X-ray crystal analyses, and to Prof. J. K. Stille for reading the manuscript. 

The reaction between dimercury(I) salts and molecules with an electron-pair-donating atom normally destroys the metal-metal bond of the dimercury(I) ion Hg+—Hg+ by disproportionation, forming metallic mercury and a mercury(II) compound, but the use of nonpolar solvents, weak Lewis bases and dialytic crystallization methods has contributed to the successful preparation of single crystals of several dimercury(I) coordination compounds in the past 25 years.9,30,31 The myth that the dimercury(I) species Hg + forms few coordination compounds has been exploded. 

The preparation of single crystals. The need for fundamental studies of the mechanical, electrical, and surface properties of carbides and nitrides have necessitated the preparation of single crystals.27 Carbide single crystals are prepared by the Vernouil technique, the floating zone technique, and methods involving precipitation from liquid metals. Nitride single crystals are prepared by vapor transport processes. 

The polymer is highly crystalline, which facilitates structure analysis, but has thwarted attempts to measure its properties in solution. The preparation of single crystals has been useful with regard to the characterization of its structure. Its crystal structure is known, but not much is known about typical molecular weights. The S-N and N-S bonds are essentially identical in length, with a bond order that is intermediate... 

This also proves to be a good approach for the preparation of single crystals suitable for X-ray diffraction strucmre determination). The AgFBiFs has also been made by displacement of a weak acid from its alkali salt ... 

In addition to flame annealing methods for the preparation of single crystal faces of metals with extended atomically smooth terraces [5.10-5.13], the already traditional technique of electrolytic growth of single crystals [5.6-S.9] has remained unrivaled for the preparation of perfect, screw dislocation-free faces or faces with single, isolated screw dislocations. ... 

The single crystal diffraction technique is covered well in many other texts and will not be discussed in detail here. The preparation of single crystals from solid state materials is rather different from the preparation of single crystals from molecular systems and is therefore described in Chapter 4. 

Understand the particular methodology for preparation of single crystals from solid materials... 

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