ISSN:
0009-2940
Keywords:
Barium
;
Copper
;
Arsenate
;
Magnetic susceptibility
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Two new compounds Cu4(AsO4)2O (1) and Ba2Cu7As6O24 (2) were obtained from a mixture of CuO and As2O5 · xH2O heated to 1090°C for 72 h in a BaCO3 flux. Compound 1 was obtained as dark green crystals, belonging to the orthorhombic crystal system. Compound 2 was obtained as light gray to colorless crystals belonging to the triclinic crystal system. The structure of 1 contains two copper ions with distorted trigonal bipyramidal geometries and a third with a distorted square pyramidal geometry. One ‚oxide‘ ion is surrounded by four copper ions in a distorted tetrahedral arrangement. Compounds 2 consists of two chains with alternating units of trigonal bipyramidal CuO5 and square planar CuO4 units, with the oxygen atoms derived from the AsO4 groups. Magnetic susceptibility measurements of 1 and 2 both show effective magnetic moments, μeff=1.90-1.95 B.M./Cu at 25°C, which is consistent with Cu2+ ions having one unpaired electron. Significant antiferromagnetic coupling was revealed by variable temperature measurements. At very low temperatures (15-25 K) samples of both 1 and 2 undergo a transition to a weak ferromagnetic state.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19971300110
