Ternary layered oxides

02- LiCo02 has a slightly larger interlayer spacing than the conventional 

A wide range of techniques were used to prepare LCO with different characteristics morphology, size (from micron to nanometer), and size distributirai of grains, aU important factors in the development of efficient cathode materials. In the synthesis of LCO, the rhombohedral structure is obtained at high temperature r 850 °C (called HT-LCO), while a low temperature phase (LT-LCO) was prepared around 400 °C with a spinel structure Li2Co204 [64]. Shao-Hom et al. [65] found that LT-LCO nucleates from an intermediate Li Coi [Co2]04 spinel product before transforming more slowly to HT-LCO. 

In Fig. 5.11a, the charge-discharge characteristics of the Li//LiCo02 cell is reported with the various phase in Li cCo02 in the range 0 r 1 [67, 77]. In the 

02- LiCo02. When Li cCo02 approaches x = 0.5, both materials exhibit a phase transition that possibly is due to lithium ordering. This is a continuous phase transition (H2 M) to the monoclinic phase in 03. If more Li is removed, another continuous transition M - H3 occurs in 03-LiCo02. However, there are some controversies on the crystal chemistry and the phase diagram of delithiated Li,Co02 [80]. 

LiNiOa (LNO) is isostructural with LiCo02 and has the 03 layer structure. The js j3+/4+ a lithium chemical potential //Li(c provides a high cell 

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This chapter provides the relationships between structural and electrochemical properties of lamellar compounds the 3d-transition metal oxides currently studied as for their potential use in LiBs. First, we examine briefly three binary layered oxides, M0O3, V2O5, and LiVsOg which were proposed as intercalation compounds since at the end of 1970s. Then, the ternary layered oxides are considered. Starting from the historical and prototype compound LiCo02, which is the dominant positive electrode material employed by all Li-ion cell manufacturers so far, we state the broad family of layered oxides such as LiM Oy and their derivatives the... 

The properties of the ternary layers formed between Cr J and phenylphosphonate diesters in an organic medium have been investigated spectrophotometrically however, no conclusive evidence in favour of complex formation was obtained.253 Kinetic studies have shown that oxidation of PhP(OH)2 by an aqueous HC104 solution of chromium(vi) is preceded by complex formation between the CrVI and Pm centres and a similar mechanism has been proposed for the analogous oxidation of arsenic(m).254... 

Another type of structures for metal-dielectric mirrors are metallodielectric multilayers. In this case alternating quarterwave or subwavelength stacks of metal and dielectric are deposited. Typical for such multilayers is alow reflection in visible, but large in infrared wavelength range. Thus they basically behave as low-pass optical filters. Such stmctures were denoted in literature as heat mirrors. First heat mirrors were fabricated as early as in 1950s [252]. The simplest heat mirrors consist of three layers only, dielectric-metal-dielectric or, alternatively, dielectric-transparent conductive oxide-dielectric [253]. Full multilayer metal-dielectric reflectors with binary but also ternary layers were also considered [254]. Because of their high reflectance in infrared, but also because of their plasmonic properties [255] metal-dielectric multilayer mirrors are of interest for cavity enhancement of infrared detectors. 

Other alloy additions in commercial use include iron (often a two-layer electroplated coating with less iron—typically 20% —in the under-layer to assist formability and more iron—often 80% —in the outer layer to assist paintability) cobalt (0.15-0.35%) similar amounts of chromium (the zinc/ chromium/chromium-oxide coating known as Zincrox) and a range of ternary alloys and of composite coatings. 

Among the high-temperature superconductors one finds various cuprates (i.e., ternary oxides of copper and barium) having a layered structure of the perovskite type, as well as more complicated oxides on the basis of copper oxide which also include oxides of yttrium, calcium, strontium, bismuth, thallium, and/or other metals. Today, all these oxide systems are studied closely by a variety of specialists, including physicists, chemists, physical chemists, and theoreticians attempting to elucidate the essence of this phenomenon. Studies of electrochemical aspects contribute markedly to progress in HTSCs. 

In ternary oxides AMO3 the second class of structures arises when A and M are the same size and the size is suitable for octahedral co-ordination. These adopt structures in which both ions are 6-coordinate. An example is the lithium nio-bate structure, which contains hexagonally packed anion layers (Figure 11.6(d)). Surprisingly, no known fluoride adopts such a structure. 

The structures of ternary oxides such as spinels, perovskites, pyrochlores, layered cuprates (high-7 c superconductors), and other lamellar oxides are fascinating subjects by themselves and are beyond the scope of the present discussion. 

Table 2.3 lists ternaries that have been deposited, together with indication of when clear single compounds formation was verified. While solid solution formation is usually the goal of these smdies, it should be kept in mind that separate phases, either as a composite or as separate layers, may be required for some purposes. For example, bilayers of CdS/ZnO and CdS/ZnS have been deposited from single solutions. These depositions depend on the preferential deposition of CdS over ZnS and, in the case of the former, the often-encountered greater ease of formation of the oxide (hydroxide) than the sulphide of Zn. 

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