Intercalation of the layer type transition metal dichalcogenides by a variety of organic molecules, alkali metals, or ‘3d’ transition metals, provides a powerful way to finely tune the electron occupation of the relatively narrow ‘d’ bands met in these solids These transition metal dichalcogenides are highly anisotropic solids, sometimes referred to as ‘two-dimensional’ solids, and the intercalant molecules which are electron donors enter between the layers This can result in profound changes in the electronic properties of the host lattice, and these changes can be understood in terms of charge transfer and increased interlayer separation The phenomena discussed include optical properties, transport properties, super-conductivity, order-disorder phenomena and phase changes, staging, magnetic properties, metal-insulator transitions, Anderson localization, and fast-ion conduction Some possible practical applications are also considered

Electronic properties of intercalation complexes of the transition metal dichalcogenides

Structural and electrochemical properties of the proton / γ-MnO2 system

Selenium-77 nuclear magnetic resonance spectroscopy

Lithium batteries: a new tool in solid state chemistry

Physics and chemistry of electrons and ions in condensed matter

Semiconductor-metal transition upon intercalation in LixZrSe2

The Na-TiS2 system: A critical discussion of the phase boundaries, structural and NMR studies

We have observed lithium ions ordering in the intercalated layer compound Li 0.5 ZrSe 2 through 77 Se NMR. Below 250 K, the lithium ions are frozen, and their screening charge causes a spatial modulation of the 77 Se nuclei hyperfine field. Due to lithium ordering, only two inequivalent selenium sites are observed. As the ions start moving, the hyperfine field modulation becomes time-dependent and its fluctuations cause a sharp peak in the 77 Se spin-spin relaxation around 270 K L'etude montre l'ordre des cations Li en dessous de 250 K. L'effet d'ecran electronique produit une modulation spatiale du champ hyperfin de 77 Se. Deux sites du selenium sont observes. Le mouvement des ions donne un pic de relaxation spin-spin vers 270 K.

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Lattice gas ordering and associated charge density modulation observed by 77Se NMR in the intercalated layered compound Li 0.5ZrSe2

NMR evidence for lithium ordering in Li0.29ZrSe2

We previously reported on a semiconductor to metal transition induced upon intercalation in the system LixZrSe2. Considering recent 77Se NMR data, which give evidence of a large interaction between ions and conduction electrons and provide a tool to study short range order of the intercalated ions, we give a new description of this system, taking into account previous 77Se NMR X-rays, EPR and magnetic susceptibility measurements on powder samples. Discrepancy with results of transport measurements by other authors on single crystals intercalated in the same way, as the non observation of PLD/CDW, are also discussed.

P. Segransan

Papers

Semiconductor-metal transition upon intercalation in LixZrSe2

The Na-TiS2 system: A critical discussion of the phase boundaries, structural and NMR studies

Lattice gas ordering and associated charge density modulation observed by 77Se NMR in the intercalated layered compound Li 0.5ZrSe2

NMR evidence for lithium ordering in Li0.29ZrSe2

Ion-Electron Interaction and Intercalation Induced Semiconductor to Metal Transition in the Intercalated Dichalcogenide LixZrSe2