Transport Properties and Lithium Insertion of Compounds Metal-Halogen-Chalcogenides
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TRANSPORT PROPERTIES AND LITHIUM INSERTION OF COMPOUNDS METAL-HALOGEN-CHALCOGENIDES C. JULIEN*, L. EL-FARH*, I. SAMARAS*, I. RIESS*, M. BALKANSKI*, S. ZIOLKIEWICZ** and A. CHEVY***
*Laboratoire de Physique des Solides, associ6 au CNRS Universit6 P. et M. Curie, 4 place Jussieu, 75252 Paris Cedex 05, France **Laboratoire d'Optique de la Mati~re Condensde et Ultrasons, associ6 au CNRS Universitd P. et M. Curie, 4 place Jussieu, 75252 Paris Cedex 05, France ***Laboratoire de Physique des Milieux Condensds, associ6 au CNRS Universitd P. et M. Curie, 4 place Jussieu, 75252 Paris Cedex 05, France
ABSTRACT The transport properties and far-infrared reflectivity of BiSI, BiTel, SbTeI, Bi Se 3 and Bi2S3 have been studied, and the results show a good agreement between the two techniques. Lithium insertion within metal-chalcogen-halogen compounds has been carried out using Li/LiC1O 4 -PC/MChI galvanic cells at room temperature. Electrochemical potential spectroscopy measurements show the different regimes involved in the insertion reaction. INTRODUCTION For many years much interest has been maintained in several low-dimensional materials because of their ability to receive guest atoms without dramatic modifications of their structural entity. The most popular materials of this family are the transition metal dichalcogenides MX 2 , such as TiS 2 [1l, MOS 2 [2], VS [3], and NbSe 2 [4] which have been used as intercalation host materials. Among the semiconductors with a certain open structure favouring insertion of guest species, the compounds of the type metal-chalcogen-halogen (MChI) where M=Bi or Sb and the bismuth chalcogenides (MCh) typically exhibits either needle or layer-like structures, and consequently anisotropic electronic properties. They crystallize into structure mainly formed by sequences along the c-axis which are more complex than of MX 2 compounds, but similar van der Waals bonds link one pseudo-unit cell to each other [5]. Investigations of electrochemical intercalation in chalcogenides of As, Sb and Bi phases were performed early by Besenhard [6]. Redox properties of these compounds were investigated in molten salt and organic Li+-electrolytes. Even at room temperature, Bi S 3 , Bi 2 Se 3 and Bi 2 Te3 were reduced with about complete material efficiency to Li 3 Bi as final product. The reduction of Bi 2 S 3 to Bi° and Li2 S was found to be reversed in organic electrolytes. More recently, intercalation of lithium in similar structure such as indium sesquiselenide In 2 Se 3 was studied [7]. Few works are concerned with the properties of MChI compounds in the literature, only the structure has been reported recently [8]. In this present paper we report the electrical and optical measurements of the MCh (Bi 2 Se 3 and Bi 2S 3 ) and MChI (BiSI, BiTel and SbTeI) compounds. The electrical transport properties are studied as a function of the temperature. Analysis of the far-infrared (FIR) reflectivity data are in good agreement with the electrical parameters. Lithium insertion properties within MCh and BiTel has b
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