TY - JOUR
T1 - Thermopower across the insulator-metal divide in NiCr2-xVxS4 (0 2)
AU - Powell, A V
AU - Vaqueiro, P
AU - Ohtani, T
PY - 2005/3/15
Y1 - 2005/3/15
N2 - Measurements of the Seebeck coefficient of phases in the series NiCr 2-xVxS4 have been carried out over the temperature range 90=T/K=700. The data demonstrate that with increasing levels of vanadium incorporation, there is a change from semiconducting to metallic behavior at a critical composition 0.4=xc=0.5. This change in the nature of the electronic states is coincident with a structural distortion, previously identified by powder neutron diffraction, involving the formation of zigzag cation chains within a dichalcogenide slab. Analysis of the temperature dependence of the thermopower in the semiconducting and metallic regions suggests that the transport properties are strongly affected by electron-phonon coupling, which for x=0.2 leads to a small-polaron hopping conduction mechanism. Analysis of the conductivity data yields activation energies of 28.1(1) and 60.3(3) meV for x=0.0 and 0.2, respectively. ©2005 The American Physical Society.
AB - Measurements of the Seebeck coefficient of phases in the series NiCr 2-xVxS4 have been carried out over the temperature range 90=T/K=700. The data demonstrate that with increasing levels of vanadium incorporation, there is a change from semiconducting to metallic behavior at a critical composition 0.4=xc=0.5. This change in the nature of the electronic states is coincident with a structural distortion, previously identified by powder neutron diffraction, involving the formation of zigzag cation chains within a dichalcogenide slab. Analysis of the temperature dependence of the thermopower in the semiconducting and metallic regions suggests that the transport properties are strongly affected by electron-phonon coupling, which for x=0.2 leads to a small-polaron hopping conduction mechanism. Analysis of the conductivity data yields activation energies of 28.1(1) and 60.3(3) meV for x=0.0 and 0.2, respectively. ©2005 The American Physical Society.
UR - http://www.scopus.com/inward/record.url?scp=20044369998&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.71.125120
DO - 10.1103/PhysRevB.71.125120
M3 - Article
SN - 1098-0121
VL - 71
SP - 1
EP - 6
JO - Physical Review B: Condensed Matter and Materials Physics
JF - Physical Review B: Condensed Matter and Materials Physics
IS - 12
M1 - 125120
ER -