6.3 Two-Phase Layered–Spinel Region
81
Fig. 6.6 Lattice parameters
obtained in the layered–spinel
coexistence region as a
function of the distance to the
SM line. The spinel lattice
parameter is a cub while the
layered lattice parameters are
a hex and c hex . The lines are
guides for the eye
a way that both endpoints change, resulting in all three lattice parameters changing
nearly linearly in this region in Fig. 6.6. Since the tie-line through (0.5, 0.45) is
nearly parallel to the SM line, it is reasonable to assume that the tie-lines continue
to run parallel to the SM line and this is how they were drawn in Fig. 5.2.
The lever rule was used, as described previously in Sect. 2.4, for the quenched
samples in order to help determine the single-phase boundary of the layered region
between the M-layered phase and Li 2 MnO 3 . Figure 6.1b shows the points generated
by this method as well as the positions of samples as determined by atomic absorption.
Clearly, these observations are nearing the precision limits of the elemental analysis,