The synthesis method of lithiated d-metal oxides using molten formate mixtures as precursors has been developed and the isothermal (800 °C) cross section of pseudo ternary Li–Mn–Co oxide system under ...ambient oxygen pressure has been investigated by XRD,
7
Li NMR, and galvanostatic electrochemical methods. Special attention has been paid to the compositions inside the quadrangle restricted by solid solutions LiCoO
2
–LiCo
0.85
Mn
0.15
O
2
with the layered structure of α-NaFeO
2
and solid solutions LiMn
2
O
4
–LiMnCoO
4
with the structure of spinel. It was found that, depending on the composition, three types of equilibrium phases could be formed: spinels LiLi,Mn,Co
2
O
4
with a part of Li atoms in octahedral sites, cation-deficit layered compounds Li
1 −
δ
Co,MnO
2
, and Li
2
MnO
3
. Areas of (co)existence of these phases were plotted on the composition plane of the pseudo-ternary Li–Mn–Co system. Electrochemical properties of the compositions inside the quadrangle LiCoO
2
–LiCo
0.85
Mn
0.15
O
2
–LiMn
2
O
4
–LiMnCoO
4
are determined by the content and average oxidation number of Mn atoms, which is higher than in the normal spinels LiMn,Co
2
O
4
. Thus, the specific capacities of the polyphase compositions are lower in comparison with the binary solid solutions LiMn,Co
2
O
4
or pure LiCoO
2
.
Products of thermal decomposition of lithium permanganate LiMnO
4
·3H
2
O, which are formed in temperature range 160–900 °C, have been characterized by powder XRD and chemical analysis. It has been ...found that the decomposition of the permanganate results in the formation of an equimolar mixture of manganate(IV) Li
2
MnO
3
and stoichiometric spinel LiMn
2
O
4
at the temperatures above 700 °C. Intermediate products with spinel structure are formed at lower temperatures with oxidation number of manganese being between +4 and +3.5. These compounds can be related to
overstoichiometric
spinel phases with general formula Li
a
Mn
(1 + 0.5
a
)
Li
(1 − 0.5
a
)
O
4
, where
a
> 1. Electrochemical properties of these intermediates with regard to the reaction of Li extraction were investigated. The data are of interest for the development of synthesis methods for mixed oxides containing lithium and manganese with lithium permanganate as the lithiating reagent.
The model of scattering for a crystal with the disturbed surface layer (DSL) and randomly distributed defects (RDD) is proposed and developed within the framework of dynamical theory of the total ...integrated reflective power in Bragg-diffraction geometry. Within this model, the crystal is separated on three layers. The first layer is a layer heavily disturbed by the plastic deformation; within it, the diffraction is completely absent. This layer may be detected only due to the X-rays absorption within it. The first layer elastically deforms the second layer. Within it, a length of the scattering coherence is less than the extinction length, and consequently, the scattering within it has a kinematical character. The third layer is the dynamically scattering layer, which contains the RRD. On the base of this model, the new physical effects are revealed at Bragg-diffraction in such crystals, and consequently, the methods are proposed for the unique non-destructive quantitative diagnostics of the nanoscale characteristics of both DSL and RRD.
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