Preparation and Characterization by AES of Niobium Diselenide Single Crystals

✍ Scribed by A. Rolland; G. Vacquier; A. Casalot

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 400 KB
• Volume: 106
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1294

✦ Synopsis

Niobium diselenide powder, (\mathrm{NbSe}{2}), was prepared by direct synthesis from pure elements. Single crystals were obtained by chemical vapor transport (CVT) using iodine as a gas vector in a threezone thermal profile and analyzed by Auger electron spectroscopy (AES). The bulk composition of deep-seated cleaved single crystals corresponds to the stoichiometric composition given by the (\mathrm{NbSe}{2}) formula. The crystal surface is strongly reactive: superficial carbon adsorption occurs even in an ultravacuum atmosphere. In ambient air a thick superficial altered film is formed: the surface is oxide-coated and nitrogen is dissolved between the layers. Under iodine atmosphere, a simultaneous superficial adsorption of iodine, nitrogen, and carbon is observed, but the superficial layers are easily removed by argon sputtering. 1993 Academic Press, lnc.