Tetragonal close packing

Using these equations and the conductance distribution functions listed in Table 6.1, the corrugation amplitudes for a tetragonal close-packed surface with different tip states and sample states can be obtained. For example, for a Is state, using Eq. (6.32), we have... 

The term porous should apply to a specific host phase and not simply to the host molecules as an amorphous or mutating collective. Therefore, in principle, the host framework should remain sub stantially unaffectedby guest uptake and removal. This requirement means that we do not describe, for example, the close-packed, tetragonal a phase of urea as porous, however the description would be appropriate for an empty, hexagonal urea apohost phase (Section 7.3)... 

In the MnOj family, the / -polymorph is the most stable. It has a rutile-type structure and tetragonal symmetry (Fig. lb). The oxygen ions are arranged in a distorted hexagonal close-packed array (in rutile, sometimes referred to as tetragonal close packing [21]). The Interstitial space in the - MnOj structure consists of narrow (1 X 1) channels. Murphy has reported that crystalline y -MnOj can reach a limiting composition of Lig,2 062 [22], which corresponds to a low electrochemical capacity of 62 mAh g . Crystalline y -MnOj electrodes are, therefore, of little interest as insertion electrodes. Studies have shown that — materials... 

Fig. 6.5. Close-packed surface with tetragonal symmetry, (a) The square lattice in real space. There is an atom on each lattice point, (b) The reciprocal space.

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