Symbols crystal packings

Fig. 6 PE average values of the length of crystal-packed stems (nstem)> °f 1°°PS (wloop)> and of bridges (ftbridge)> giyen as no- °f - CH2 - units. Also reported is the average number of stems per bundle (p), see Figs. 1 and 3 for definition of symbols. Consistent with Fig. 5, calculations were carried out as for previous Model A [9] after changing E from 1.07 to 1.42 kcal/mol...

Figure 12. Breakthrough profiles of equimolar benzene/octene (2 mol%) mixture using heptane solvent at room temperature on columns (0.85 cm3) packed with NaX (full symbols) and NaY (open symbols) crystals.

Fig. 16. Plots showing (a) variation of (c F/2)J. / ) with 1 for O2 (left plot, X, 0.84- 0.72 mm = 20-25 mesh Q 0.42-0.29 mm = 40-50 mesh) and N2 (right plot, on 3.2-mm pellets) in Bergbau-Forschung carbon molecular sieve and (b) variation of HETP with Hquid velocity (interstitial) for fmctose (soHd symbols), and glucose (open symbols) in a column packed with KX 2eoHte crystals. From refs. 22 and 23.

Fig. 7 Relationship between the and 02 values for the 1,3-diene monomers in the crystals. Closed and open symbols represent polymerizable and nonpolymerizable monomers, respectively. Different symbols correspond to the different series of monomers. The curve is calculated for the closed packing of planar monomers with a thickness of 3.5 A and 0] of 90°[59]...

STRONTIUM. [CAS 7440-24-6], Chemical element, symbol Sr, at. no. 38, at. wt. 87.62. periodic table group 2, mp 769°C, bp 1384°C, density 2.54 g/cm- (20°C). Below 215°C, elemental strontium has a face-centered cubic crystal structure between 215-605 C. a hexagonal close-packed crystal structure and above 605°C, a body-cen tered cubic crystal structure. 

ZIRCONIUM. [CAS 7440-67-7]. Chemical element symbol Zr. at. no. 40, at. wt. 91.22, periodic table group 4. mp l,853°C, bp 4,376°C, density 6.44 g/cm3, 6.47 g/cm3 (single crystal). Metallic zirconium is allotropic. Up to about 863°C, the alpha phase (hexagonal close-packed) is stable above this temperature, the metal assumes the beta phase (body-centered cubic). The most common impurity, oxygen, tends to stabilize the alpha phase. 

The coordination number of first nearest neighbors in closed packed structures is 12. Nevertheless, several metals crystallize in the body centered cubic structure (W type, Pearson symbol cI2, Figure 2.5). The coordination number is reduced to 8 but the difference of the distance between the first and the second nearest neighbors (white spheres) is small (15.5%). This structure is known as the CsCl structure. 

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