Metamagnetic transition in EuSe{sub 2}: A new, metastable binary rare-earth polychalcogenide
- Michigan State Univ., East Lansing, MI (United States)
The reaction of Eu with molten lithium polyselenide produced a new rare-earth dichalcogenide, EuSe{sub 2}. This compound cannot be obtained via direct combination of the elements and is therefore an example of how alkali metal chalcogenide fluxes can access metastable or kinetically stable phases. The crystals of EuSe{sub 2} are very dark red and air stable for several months. The structure was determined with single-crystal X-ray diffraction. The compound crystallizes in the tetragonal space group, I4/mcm ({number_sign} 140) with a = 6.391(1) {angstrom} and c = 7.848(1) {angstrom}, Z = 4, R1 = 3.9%, and wR2 = 10.0%. It adopts the CuAl{sub 2} structure type, and contains rows of staggered diselenide dumbbells running parallel to the c-axis, separated by rows of square antiprismatically coordinated Eu atoms. EuSe{sub 2} is a semiconductor with a band gap of 1.43 eV and decomposes at 569 C to the more stable cubic EuSe. EuSe{sub 2} displays metamagnetic behavior below 8 K. Variable temperature magnetic susceptibility and magnetization measurements were performed on single-crystal samples to study this phenomenon. A model is proposed in which all Eu spins in the ab-plane are coupled ferromagnetically, whereas alternate sheets are coupled antiferromagnetically to form bulk antiferromagnet. The Se-Se bond stretch exhibits a Raman shift of 256 cm{sup {minus}1}.
- OSTI ID:
- 328233
- Journal Information:
- Chemistry of Materials, Vol. 10, Issue 12; Other Information: PBD: Dec 1998
- Country of Publication:
- United States
- Language:
- English
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