Mat. Res. Bull., Vol. 18, pp. 173-180, 1983. Printed in the USA. 0025-5408/83/020173-08503.00/0 Copyright (c) 1983 Pergamon Press Ltd. AMINE INTERCALATES OF LAMELLAR COMPOUNDS NiPS 3 AND CdPS 3 P.J.S. Foot and N.G. Shaker School of Chemistry, Brighton Polytechnic, Brighton BN2 4GJ, England (Received November 30, 1982; Communicated by J. B. Goodenough) ABSTRACT Layered compounds CdPS 3 and NiPS 3 were reacted with a variety of am- ines, of which only short-chain linear alkylamines gave stable inter- calation products. NiPS 3 and CdPS 3 reacted by quite distinct mechan- isms. The inserted amines were partly ionised, and there was a large transfer of electrons into the host crystal in the case of NIPS3, but the material remained a semiconductor. Introduction NiPS 3 and CdPS 3 are wide-gap semiconductors with optical absorption edges at 1.6 and 3.5 eV (1,2), and have layered structures related to CdCl 2 . (3) The former is important as a potential high-energy battery material, by virtue of an energetic and reversible inclusion reaction (intercalation) with lith- ium, which does not occur for CdPS 3 (4). Lithium exists as mobile interlayer cations in the intercalate LixNiPS 3 , and the host lattice receives the concomitant electrons with resulting in- crease in its conductivity (i). The lack of reaction for CdPS 3 has been ascri- bed (4) to its much wider band-gap,preventing electron transfer. Nonetheless, both NiPS 3 (5,6) and CdPS 3 (7) have been intercalated by organometallics of low ionisation-energy. Lewis-bases such as alkylamines have been intercalated into layered metal dichalcogenides, lowering the superconducting transition temperatures in many cases, by donating electronic charge to the host compounds (8). A few metal phosphorus trichalcogenides have been shown to intercalate amines (9,10), and the conductivity of MnPSe 3 was found to increase by 10 3 times on absorption of pyridine into the interlamellar van der Waals region (i0). To obtain more information on intercalation mechanisms for NiPS 3 and to in- vestigate the possible effect of Lewis-base insertion on the performance of NiPS 3 in a lithium battery, we have studied the reactions of a variety of amines with NiPS 3 (and for comparison, with CdPS3). 173