Layer position symbols

Fig.24.a-b Typical d52 volume fraction (1—<))) vs depth z profiles indicating a a depletion b an enrichment in the h66 component, obtained for 90%h66/10%d52 and 30%h66/70%d52 monolayers annealed at 71 °C for 16 and 43 h, respectively [175]. Hatched areas mark positive (b) and negative (a) values of the h66 surface excess z. The free surface locus (z=0) is yielded by - the profile itself (a) - a profile of the control layer measured prior to the annealed sample (as in Fig. 21 a) - the interface created by a reference layer positioned on top of the annealed sample (b) c a phase diagram as outlined by previously determined coexistence compositions [91] (solid line described by %=(0.452/T-1.2Xl(T4)(l+0.031)) and coexistence temperatures [138] (X points). Bulk compositions in one phase region are marked where the surface enrichment (A symbols) or depletion ( points) in h66 is concluded... 

Figure 14.10 Variation of the extensional stiffnesses of injection molded tensile bar of Vectra A with the position along the width. Solid symbols top layer open symbols bottom layer.

ZnO contauns excess metal which is accommodated interstitially, i.e. at positions in the lattice which are unoccupied in the perfect crystal. The process by which ZnO in oxygen gas acquires excess metal may be pictured as follows. The outer layers of the crystal are removed, oxygen is evolved, and zinc atoms go into interstitial positions in the oxide. We represent interstitial zinc by (ZnO). However, the interstitial zinc atoms may ionise to give (Zn O) or even (Zn O). The extra electrons produced in this way must occupy electron levels which would be vacant in the perfect crystal. We represent them by the symbol (eo), and refer to them as free electrons. They can be pictured as Zn ions at normal cation sites. We see therefore that three reactions can be written, each giving non-stoichiometric ZnO ... 

The Alexander model is based on two assumptions that enable simple expressions for these two terms (1) The concentration profile of the layer is step-like. That is, the monomer volume fraction within the layer, (p Na3/d2L, is constant, independent of position (2) The chains are uniformly stretched. That is, all chain ends are positioned on a single plane at a distance L from the surface. [In this paper, we use the symbol to mean approximately equal to or equal to within a numerical factor of order one we use to mean proportional to .] The first assumption simplifies the calculation of Fin, while the second yields a simple expression for Fel. 

Zhdanov or Jagodzinski symbol). The most important structure types of this kind are the following (M atoms dark gray in the figures positions of M atoms in the following layer marked by black circles) ... 

Figure 3.20. A lateral view of different stacking sequences of triangular nets. They correspond to some typical close-packed structures. The first layer sequence shown corresponds to a superimposition according to the scheme ABABAB... (equivalent to BCBCBC... or CACACA... descriptions) characteristic of the hexagonal close-packed, Mg-type, structure. With reference to the usual description of its unit cell, the full stacking symbol indicating the element, the relative position of the superimposed layers and their distance is Mg Mg. The other sequences correspond to the schemes ABC.ABC. (Cu, cubic), ABAC.ABAC. (La, hexagonal), ACACBCBAB. (Sm, hexagonal). For Cu the constant ch of the (equivalent, non-conventional) hexagonal cell is shown which may be obtained by a convenient re-description of the standard cubic cell (see 3.6.1.3). ch = cV 3, body diagonal of the cubic cell.

Figure 5. n-Type semiconductor—electrolyte solution interface with a surface depletion layer, in the dark and with two intensities of illumination. Symbols as in Figure 3 and 4 with Ec and E the band edges of the conduction and valence bands, respectively, under illumination, and Ef(H2) Ef(Om) abbreviations for Ef(H20/h2) and Ep(02/H20)y respectively. The quasi-Fermi levels Ei> and pEp are at different positions in the surface region than in the bulk as a result of the limited penetration of light into the interior. Fermi levels in solution as in Figures 3 and 4(13). 

Figure 4.14. Phase diagram, coverage vs. temperature, of N2 physisorbed on graphite. Symbols used fluid without any positional or orientational order (F), reentrant fluid (RF), commensurate orientationally disordered solid (CD), commensurate herringbone ordered solid (HB), uniaxial incommensurate orientation-ally ordered (UlO) and disordered (UID) solid, triangular incommensurate orientationally ordered (lO) and disordered (ID) solid, second-layer liquid (2L), second-layer vapour (2V), second-layer fluid (2F), bilayer orientationally ordered (2SO) and disordered (2SD) solid. Solid lines are based on experimental results whereas the dashed lines are speculative. Adapted from Marx Wiechert, 1996.

A convenient description of these structures utilizes the symbols A, By and C for the three layers of (dose-packed spheres differing from one another in position. Hexagonal closest packing corresponds to the... 

Figure 2. Simulations and observations of the evolution of the positive ion size distributions deduced from mobility spectra measured within the boundary layer. Hourly-average data (symbols) correspond to a series of observations on October 20, 1994 [78]. The ion size spectra are shown as a function of particle diameter and charge-carrier mobility. From [33].

The transport of the test charge can be pictured as occurring in two steps (Fig. 5.15) First, the charge is brought close (approx. 1 /.an) to the interface. This step is related to the Volta or external potential It depends on the exact position. Also in the case of the electric double layer we used the symbol for the Volta potential. In this case the reference point is not in vacuum but in the bulk liquid phase far away from the interface f (x oo) = 0. 

Figure 17. The electric field dependence of the photogeneration quantum efficiency (580 nm excitation) for photoreceptors with bisazo-based CGMs. Dual-layer photoreceptors (open symbols) with CGL (0.09-0.49 pm) and CTL (22 pm) had a negative surface charge. Single-layer photoreceptors (filled symbols) (0.15 and 0.27 pm) were given negative, and for the thicker sample positive, surface charging. The photolumincscence quenching efficiency (filled diamonds—broken line) was determined on a dual-layer sample CGL (0.15 pm) and CTL (1.9 pm). (Reprinted with permission from Ref [34c].)...

The alternative symbols in Table 4.2 indicate the numbers of layers in the repeat units also the layer sequence may be derived directly from the symbol. The change from A - B- C is represented as a unit vector +1 and in the reverse direction as — 1. A succession of n positive (or negative) units is abbreviated to n ( ), so that 22 stands for 1111. .. and starting from/4 gives the sequence B CB A. 

When an electrode is at equilibrium, the equilibrium partial current densities i and i are equal and they are designated by one symbol, i0. This equality on an atomic scale means that a constant exchange of charge carriers (electrons or ions) takes place across the metal-solution interphase (Fig. 1). When the interphase is not in equilibrium, a net current density i flows through the electrode (the double layer). It is given by the difference between the anodic partial current density i (a positive quantity) and the cathodic partial current density i (a negative quantity) ... 

Figure 8.9 Simplified representations of polytypes (a) wurtzite, 2H, (11) (b) carborundum I, AH, (22) (c) 6H, (33). The zig-zag designs to the right of the structure representations show the sequence of translations in a direction, + or —, summarised in the Zhdanov symbol. In the zig-zags, each circle represents the position of a composite (Zn + S) or (Si + C) layer...

Fig. 11.23 Comparison of the EL spectra of devices consisting of a MeLPPP PtOEP emission layer and with (solid line) or without (open symbols) a PVI< ST1163 hole-injecting layer. The inset shows the relative positions of the HOMO levels of the doped hole injection layer and the MeLPPP PtOEP emission layer [42],...

C) OD symbols. The OD school, inspired by Z symbols, derived the most general symbols to describe mica polytypes (Durovic and Domberger-Schiff 1979 Dornberger-Schiff et al. 1982 Backhaus and Durovic 1984 Durovic et al. 1984 Weiss and Wiewiora 1986). These symbols consist of a sequence of characters referring to one period, placed between vertical bars two lines of characters are used the first line indicates the packet orientations, and the second line the packet-to-packet displacements. A dot separating the orientational characters for packets P2y and q2y+i indicates the position of Oc layer. The OD symbols are thus expressed ... 

ID) TS symbols (Sadanaga and Takeda 1969 Takeda and Sadanaga 1969) give the relative positions of the TS unit layers and are written as a sequence of N symbols L (AXy, AYj),j = -N, where Ly is the type of layer and N is the number of layers in the polytype period. Considering two successive repeats of N layers, (AXy, AYy) are the (a, b) components of the vector connecting the origin of the last (A-th) layer of a repeat and the origin of the y-th layer of the next repeat (Fig. 2). These symbols respect only the homo-octahedral approximation. 

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