TY - JOUR
T1 - Cu0.66EuTe2, KCu2EuTe4, and Na0.2Ag2.8EuTe4
T2 - Compounds with modulated square Te nets
AU - Patschke, Rhonda
AU - Brazis, Paul
AU - Kannewurf, Carl R.
AU - Kanatzidis, Mcrcouri G.
PY - 1999
Y1 - 1999
N2 - Reactions of europium with copper or silver in molten alkali metal/polytelluride fluxes have produced the new polytelluride compounds, Cu0.66EuTe2, KCu2EuTe4, and Na0.2Ag2.8EuTe4. All three compounds are stable in air, and crystallize as red-brown plates in tetragonal space groups. Cu0.66EuTe2 crystallizes in the. space group P4lnmm with a=4.481(2), c= 10.260(3)Å (at 23°C), and Z=2. KCu2EuTe4, and Na0.2Ag2.8EuTe4 are isostructural, and crystallize in the space group P4mm with 0 = 4.4365(6), c= 11.365(2) Å (at 23°C) for KCu2EuTe4, and a = 4.4544(6), c= 11.106(2) A (at 23 °C) for Na0.2Ag2.8EuTe4. Cu0.66EuTe2 adopts the CaMnBi2 structure-type with square antiprismatic europium atoms sandwiched between an anti-PbO type layer of [CuTe]-, and a flat square net of tellurium. The structure of KCu2EuTe4 can be derived from that of Cu0.66EuTe2 by systematically replacing half of the europium atoms in the framework with potassium. Electron diffraction studies on KCu2EuTe4, and Na0.2Ag2.8EuTe4 suggest a la × 7b superlattice, the result of a charge density wave (CDW) distortion in the square Te net of these compounds. KCu2EuTe4 exhibits semimetallic behavior while Na0.2Ag2.8EuTe4 is a p-type semiconductor with a bandgap of 0.24 eV.
AB - Reactions of europium with copper or silver in molten alkali metal/polytelluride fluxes have produced the new polytelluride compounds, Cu0.66EuTe2, KCu2EuTe4, and Na0.2Ag2.8EuTe4. All three compounds are stable in air, and crystallize as red-brown plates in tetragonal space groups. Cu0.66EuTe2 crystallizes in the. space group P4lnmm with a=4.481(2), c= 10.260(3)Å (at 23°C), and Z=2. KCu2EuTe4, and Na0.2Ag2.8EuTe4 are isostructural, and crystallize in the space group P4mm with 0 = 4.4365(6), c= 11.365(2) Å (at 23°C) for KCu2EuTe4, and a = 4.4544(6), c= 11.106(2) A (at 23 °C) for Na0.2Ag2.8EuTe4. Cu0.66EuTe2 adopts the CaMnBi2 structure-type with square antiprismatic europium atoms sandwiched between an anti-PbO type layer of [CuTe]-, and a flat square net of tellurium. The structure of KCu2EuTe4 can be derived from that of Cu0.66EuTe2 by systematically replacing half of the europium atoms in the framework with potassium. Electron diffraction studies on KCu2EuTe4, and Na0.2Ag2.8EuTe4 suggest a la × 7b superlattice, the result of a charge density wave (CDW) distortion in the square Te net of these compounds. KCu2EuTe4 exhibits semimetallic behavior while Na0.2Ag2.8EuTe4 is a p-type semiconductor with a bandgap of 0.24 eV.
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U2 - 10.1039/a903945g
DO - 10.1039/a903945g
M3 - Article
AN - SCOPUS:0032703311
VL - 9
SP - 2293
EP - 2296
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
SN - 0959-9428
IS - 10
ER -