Premium
Electrical and magnetic properties of two crystallographic forms of (DEPE) 2+ (TCNQ) 4 2−
Author(s) -
Ashwell G. J.,
Eley D. D.,
Willis M. R.,
Woodward J.
Publication year - 1977
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220790229
Subject(s) - seebeck coefficient , tetracyanoquinodimethane , electrical resistivity and conductivity , singlet state , atmospheric temperature range , magnetic susceptibility , metal , paramagnetism , materials science , thermoelectric effect , condensed matter physics , crystallography , chemistry , thermodynamics , physics , organic chemistry , atomic physics , molecule , metallurgy , quantum mechanics , excited state
1,2‐di(N‐ethyl‐4‐pyridinium)ethylene 2+ (7,7,8,8‐tetracyanoquinodimethane) 4 2−crystallises in two forms: a metallic form (DEPE) 2+ (TCNQ) 4 2−I and a semiconducting form (DEPE) 2t (TCNQ) 4 2−II. On cooling from room temperature to 30 mK the electrical conductivity of I increases monotonic‐ally such that σ30mk/σRT=3.7. The thermoelectric power, in the temperature range studied, and the paramagnetic susceptibility of I, in the range of 60 to 300 K, are nearly independent of temperature, indicative of metallic behaviour. The magnetic susceptibility of II, however, exhibits singlet‐triplet behaviour with a singlet‐triplet separation of 0.029 eV. The electrical conductivity and thermoelectric power are similarly activated. The electrical and magnetic properties of both forms are discussed.