Crystal parameters for

Poly(butyleneterephthalate) (PBT), 20 31. See also PBT entries Poly(l,4-butyleneterephthalate) (PBT) chemical properties of, 20 65 crystal parameters for, 20 64t economic aspects of, 20 67-68 flame retardant, 20 64-65 mechanical properties of, 20 65-66 physical properties of, 20 64-65 principal world manufacturers of, 20 67t uses for, 20 63-64 Poly(butyl methacrylate)-5/oc -... 

J. H. P. Colpa, Dipole fields and electric field gradients in their dependence on the macroscopic and microscopic crystal parameters for orthorhombic and hexagonal lattices. I, Physica 56 185-204 (1971). 

The Miller indices (hkl) represent a series of parallel planes in a crystal with spacing of d i-Combining Equations 2.3 and 2.4, we obtain the following relationship between diffraction data and crystal parameters for a cubic crystal system. 

In many respect the fifteen acinides [Ac(Z = 89) to Fm(Z = 103)] with their 5/ configurations, are similar to their lanthanide counterpart. Thus the chemical properties like the extraction behaviour, complex formation and the spectroscopic properties often show close parallelism with those of the lanthanides. The Lande parameter, f5y, is some two to two and half times larger in the 5/series than in the corresponding 4/ series. As a result of this, the deviation from the Russell-Sauders coupling in the 5/ series is much more pronounced than in the 4/series. However, it has been shown earlier by Sinha 58) that the hydration entropies, enthalpies and the crystal parameters for the fluorides of the tri- and tetravalent actinides (Fig. 55, 56) also follow a linear L-dependence and give rise to the inclined W plots like those for the lanthanides. 

The crystallization behavior and kinetics under isothermal conditions of iPP/SBH and HDPE/SBH blends, compatibilized with PP-g-SBH and PE-g-SBH copolymers, respectively, have been investigated (71). It has been established that the LCP dispersed phase in the blends plays a nucleation role for the polyolefin matrix crystallization. This effect is more pronounced in the polypropylene matrix than in the polyethylene matrix, due to the lower crystallization rate of the former. The addition of PP-g-SBH copolymers (2.5-10 wt%) to 90/10 and 80/20 iPP/SBH blends provokes a drastic increase of the overall crystallization rate of the iPP matrix and of the degree of crystallinity. Table 17.4 collects the isothermal crystallization parameters for uncompatibilized and compatibilized iPP/SBH blends (71). On the contrary, the addition of PE-g-SBH copolymers (COP or COP 120) (2.5-8 wt%) to 80/20 HDPE/SBH blends almost does not change or only slightly decreases the PE overall crystallization rate (71). This is due to some difference in the compatibilization mechanism and efficiency of both types of graft copolymers (PP-g-SBH and PE-g-SBH). The two polyolefin-g-SBH copolymers migrate to blend interfaces and... 

Table 17.4 Isothermal Crystallization Parameters for Uncompatibilized and Compatibilized iPP/SBH Blends.

X-ray powder patterns of GaN produced by the present method are in excellent agreement with those reported for a sample which was analyzed as 99.9% pure GaN and which was prepared by the older technique. The crystal parameters for the Wurtzite structure agree very closely with those tabulated by Wyckoff for GaN. The nitride is stable toward water and most acids, but when heated in air is slowly transformed to the oxide. 

Figure 9. Crystal parameters for ferric lotu-spm forms of various heme proteins...

Figure 17. Crystallization parameters for Suppocire AT obtained by isothermal DSC. Ts,max, time of maximal solidification rate t , nucleation time A//, heat of solidification released [30]. (With permission from Elsevier.)...

Controlling Parameters in Photonic Crystals In order to develop an optofluidic characterization technique based on a photonic crystal, parameters for band-gap engineering must be established ... 

TABLE 4 Crystallization Parameters for a Fractionated Polypropylene Sample. (Data from Ref. 200.)... 

Coercivity of Thin-Film Media. The coercivity ia a magnetic material is an important parameter for appHcations but it is difficult to understand its physical background. It can be varied from nearly zero to more than 2000 kA/m ia a variety of materials. For thin-film recording media, values of more than 250 kA / m have been reported. First of all the coercivity is an extrinsic parameter and is strongly iafluenced by the microstmctural properties of the layer such as crystal size and shape, composition, and texture. These properties are directly related to the preparation conditions. Material choice and chemical inborn ogeneties are responsible for the Af of a material and this is also an influencing parameter of the final In crystalline material, the crystalline anisotropy field plays an important role. It is difficult to discriminate between all these parameters and to understand the coercivity origin ia the different thin-film materials ia detail. 

The process of growing a pure crystal is sensitive to a host of process parameters that impact the iacorporation of impurities ia the crystal, the quality of the crystal stmcture, and the mechanical properties of the crystal rod. For example, the crystal-pulling mechanism controls the pull rate of the crystallisa tion, which affects the iacorporation of impurities ia the crystal, and the crystal rotation, which affects the crystal stmcture. 

If all the molecules are perfectly parallel, S would equal 1. In an isotropic Hquid, f 6) is constant so that < cos 0 > equals 1/3 and S is therefore 2ero. The order parameter for Hquid crystals falls somewhere between these limits and decreases somewhat with increasing temperature. 

Other crystallization parameters have been determined for some of the polymers. The dependence of the melting temperature on the crystallization temperature for the orthorhombic form of POX (T = 323K) and both monoclinic (T = 348K) and orthorhombic (T = 329K) modifications of PDMOX has been determined (284). The enthalpy of fusion, Aff, for the same polymers has been determined by the polymer diluent method and by calorimetry at different levels of crystallinity (284). for POX was found to be 150.9 J/g (36.1 cal/g) for the dimethyl derivative, it ranged from 85.6 to 107.0 J/g (20.5—25.6 cal/g). Numerous crystal stmcture studies have been made (285—292). Isothermal crystallization rates of POX from the melt have been determined from 19 to —50 C (293,294). Similar studies have been made for PDMOX from 22 to 44°C (295,296). 

In the case of monotropic behavior, the isotropiza-tion endotherm and the corresponding thermodynamic parameters for the mesophase-isotropic transition can be obtained by isolating the mesophase when cooling from the melt and holding the temperature in a region where the transformation into the crystal is very slow... 

Figure 3. The temperature dependence of the crystal distortion for VjSi, (0), derived from the data in Figure 2 [curves (a) and (c)], as discussed in reference 5. The dot-dashed curve shows the same distortion parameter for In-26.5 at%Tl derived from the data in Figure 1. The inset shows in detail the data below the super-c-nducting critical temperature, Tc. (From reference 5)...

Table 28 presents structural characteristics of compounds with X Me ratios between 6 and 5 (5.67, 5.5, 5.33, 5.25). According to data provided by Kaidalova et al. [197], MsNbsC Fu type compounds contain one molecule of water to form M5Nb303Fi4-H20, where M = K, Rb, Cs, NH4. Cell parameters for both anhydrous compounds [115] and crystal-hydrates [197] were, nevertheless, found to be identical. Table 28 includes only anhydrous compound compositions because IR absorption spectra of the above compounds display no bands that refer to vibrations of the water molecule... 

In sodium thiosulphate crystals, interionic S exchange occurs [810] between 563 and 623 K without detectable decomposition and the reported activation parameters are AH = 245 kJ mole"1 and AS = 74 J K"1 mole"1. Values of the same parameters for the first-order disporpor-tionation... 

The packing energy of an organic crystal can be easily calculated by a lattice sum over pairwise interactions. The potential parameters for these calculations are summarized in Table 15. The packing energy is usually a quite accurate estimate of the crystal sublimation energy. 

The spectra of Pu3+ LaCl3 (29) and isostructural PUCI3 (30) have been examined and the energy-level analysis has been refined using extensive crystal-field data. Consequently, the results included in Table IV are well established. As already indicated, they serve as one basis for estimating parameters for higher-valent species. 

The electrostatic and spin-orbit parameters for Pu + which we have deduced are similar to those proposed by Conway some years ago (32). However, inclusion of the crystal-field interaction in the computation of the energy level structure, which was not done earlier, significantly modifies previous predictions. As an approximation, we have chosen to use the crystal-field parameters derived for CS2UCI6 (33), Table VII, which together with the free-ion parameters lead to the prediction of a distinct group of levels near 1100 cm-. Of course a weaker field would lead to crystal-field levels intermediate between 0 and 1000 cm-1. Similar model calculations have been indicated in Fig. 8 for Nplt+, Pu1 "1 and Amlt+ compared to the solution spectra of the ions. For Am t+ the reference is Am4" in 15 M NHhF solution (34). 

Table VII. Crystal-Field Parameters for Hexahalide 5f -Actinide Ions.

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