Crystal lattice constant

Only body-centered cubic crystals, lattice constant 428.2 pm at 20°C, are reported for sodium (4). The atomic radius is 185 pm, the ionic radius 97 pm, and electronic configuration is lE2E2 3T (5). Physical properties of sodium are given ia Table 2. Greater detail and other properties are also available... 

YeUow metal face centered cubic crystals lattice constant, a at 25°C 4.0786A density 19.3 g/cm hardness 2.5-3.0 (Mohs), 18.5 (BrineU) melts at 1,064°C vaporizes at 2,856°C electrical resistivity 2.051 microhm-cm at 0°C and 2.255 microhm-cm at 25°C Young s modulus 11.2x10 psi at 20°C (static) Poisson s ratio 0.52 thermal neutron capture cross section 98.8 barns insoluble in almost all single acids or hydroxide solutions dissolves in aqua regia. 

Silvery-white metal close-packed cubic crystals lattice constant 3.8394A at 20°C density 22.42 g/cm (highest among metals) melts at 2410°C vaporizes at 4,130°C hardness 6-6.5 Mohs electrical resistivity 4.71 j,ohm-cm Young s modulus 3.75 x 10 tons/in magnetic susceptibility 0.133 x 10 cm3/g thermal neutron absorption cross section 440 barns. 

In all three TiOz modifications one titanium atom in the lattice is surrounded octahedrally by six oxygen atoms, and each oxygen atom is surrounded by three titanium atoms in a trigonal arrangement. The three modifications correspond to different ways of linking the octahedra at their corners and edges. Crystal lattice constants and densities are given in Table 10. 

Other important properties for photovoltaic materials are their refractive index, stability, brittleness, toxicity, crystal lattice constant, thermal expansion coefficient, temperatures required for processing into cells, energy investment for cell production, ability to be doped both types, level of technological knowledge and industrial maturity, cost, and abundance. Issues particular to passivation and the trapping of weakly absorbed light include the availability of compatible and affordable passivation and surface texturing methods. ... 

As we have seen, the Frenkel exciton and the Wannier-Mott exciton correspond to two limiting situations related to the electron-hole binding process. In the first case one visualizes the electrons and the holes as localized on a given molecule, and their interaction with electrons of other molecules plays a secondary role. In this case the wavefunctions of exciton can be constructed from the wavefunctions of isolated molecules. In the case of Wannier-Mott excitons the mean electron-hole distance is much greater than the crystal lattice constant. It is clear that in this case the interaction energy of electrons and holes strongly depends on the properties of the medium. As can be seen from eqn (1.3), the electron-hole interaction in this simple model is determined by the dielectric permittivity of the medium. 

Alloy or Crystal Lattice constants a300 (Am2/kg) ipK (degrees) ... 

The screw/helix/spiral motive [11a] has more often been applied. Thus, irradiation of achiral 15, which crystallizes in the chiral space group P2i2i2i yields optically active 16 without external seeding. [24] In seven of ten crystallizations from hexane the (-t-)-enan-tiomer 16 predominated, in three cases the (-)-enantiomer 16. The optical yields (10% ee at 0°C, 75% chemical yield) can be improved by reducing the temperature (40 % ee at -40 °C, 70% yield no reaction at -78 °C however, formation of racemic 16 in solution also at -78 °C). This is again a reminder of the necessity of phase rebuilding and finally phase transformation to give the product lattice in solid-state reactions. Both processes are accompanied by extensive molecular movements (on the scale of the crystal lattice constants) in all known cases. [14, 15] Evidently, as a result of these, the chiral con-formers 15 have - as in solution - the opportunity for racemization and further conformational alterations. Nevertheless, the... 

The yield is >75% based on bismuth. The product is best characterized by X-ray diffraction either as single crystal lattice constants or by a powder pattern. 

Density values (except at 0 °C) and the thermal expansion coefficient were calculated from the temperature variation in the crystal lattice constants of ice (see Ref 1). The thermal expansion coefficient appears to become negative around -200 °C, but there is considerable scatter in the data. 

Rare earth Crystal Lattice constants (A) Metallic radius Atomic volume Density... 

The crystal lattice constant and relative crystallinity of Y zeolite were measured by XRD (X-ray diffraction) method on a D/max-IIIA diffractometer. CuKa was used as radiation source with Ni filter. Tube voltage was 30 kV. Tube current was 25mA. Step scanning span was 0.01° in 23.4-24.6°. 

Ca in EAH-USY did not evidently affect the crystal lattice constant. Reduction of Ni oxide in EAH-USY zeolite required higher temperature than Fe and V. V interacted with EAH-USY at high temperature and completely destroyed the structure. Fe destroyed the zeolite structure over a wide temperature range, but the structure of EAH-USY did not completely collapse due to the interaction between Fe and the zeolite. 

The study of silicon samples processed by a compression plasma flow has established that in the range of initial MPC voltage of 2.8-3.2 kV periodic structures are formed on silicon, and at 3.4-3.6 kV the formation of craters is observed. X-ray analysis has shown, that after plasma processing there is an increase of the silicon lattice constant in the surface layer. Its monocrystallinity is kept independently of periodic structures are formed on the surface or not. The decrease of the band-gap energy is connected with an increase of the silicon crystal lattice constant during crystallization after action of the compression plasma. 

Sid] Sidorenko, A.F., Dmitriev, E.A., Apasova, EA., Crystal Lattice Constants in Some Quasi-binary Alloys Based on FeSi (in Russian), Trudy Uralsk. Politekhn. Inst., (167), 124-127 (1968) (Crys. Structure, Experimental, 3)... 

The crystal lattice constants of alite (a,b,c) and unit cell volume (V), determined by XRD, were studied in relation to alite double refraction (Ono, 1984). Alite with high double refraction was characterized by long a and short b and c, V was decreased, and (a/bY was large. Laboratory-prepared alite, burned at high temperature for a long time, had a small V, large (a/ bY, and a high double refraction. Therefore, XRD can be used in much the same way as the microscope in the quality control of clinker. 

Fig. 24. Charge densit y distribution of a T1 (see Fig. 23) surface state at = (3/8,1/4)2ir/a (with a the bulk crystal lattice constant) plotted on (a) the (110) plane and (b) the (100) plane. Charge density is given in relative units. (from Ref. 77)...

Phases Crystal lattice constant/nm Phases Crystal lattice constant/nm... 

Theoretical density. The density calculated by volume and mass of the ideal crystal particle with regular arrangement of atoms is theoretical density of solid material. Usually XRD is used to measure phase and its crystal lattice constant for calculation. It is also known as the cell density or X-ray density. For example, the crystal structure changes of molten iron catalyst before and after reduction could be shown as Fig. 7.7. 

Fei xO has the halite-type of face centered cubic crystal lattice base on ions close packing, where the unit cell consists of four molecules of Fei xO, and its side length of unit cell is ao (i.e., crystal lattice constant), and then the theoretical density (p°) of Fei xO (that is the true density of Fei j 0) is ... 

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