Magnetic and Crystal Structure Determination of K2UBr5

✍ Scribed by Karl Krämer; Lukas Keller; Peter Fischer; Bernd Jung; Norman N. Edelstein; Hans-U Güdel; Gerd Meyer

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 235 KB
• Volume: 103
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1087

✦ Synopsis

Magnetic susceptibility measurements show an antiferromagnetic ordering phenomenon for (\mathrm{K}{2} \mathrm{UBr}{5}). There is a broad maximum in the (\chi) versus (T) curve al about (10 \mathrm{~K}). Aiming at the determination of the magnetic structure of (\mathrm{K}{1} \mathrm{UBr}), powder neutron diffration investigations were performed. The nuclear structure of (\mathrm{K}{2} \mathrm{JBr}) ( (\mathrm{K}{2} \mathrm{P}^{2 \mathrm{C}} \mathrm{Cl}{1}) ype of structure) was refined at (1.5 \mathrm{~K}) in the paramagnetic state. The magnetic structure, whicle wits determined from a measurement at (1.5 \mathrm{~K}) in the magnetically ordered state. belongs to the Shubnikov space group (P^{\prime} n^{\prime} m^{\prime} a^{\prime}) with (\mathbf{k}=0). In the uranium chains along (\left.\mid 010\right]) there is an antiferromagnelic ordering of the magnetic moments with components in the (010) plane only. The magnetic moments of neighboring chains are perpendicular to each other within the error limit. Each (\mathrm{U}^{3+}) has an ordered magnetic moment of (2.31(4) \mu_{\mathrm{B}}). According to the temperature dependence of the intensity of the 010 and 111 magnetic peaks the Néel temperature is (2.8(3) \mathrm{K}). Presumably, there is a short-range magnetic ordering along the (\left[\mathrm{UBr}{3} \mathrm{Br}{4 i}\right]^{2-}) chains giving rise to the maximum of (\chi) at (7=10 \mathrm{~K}), followed by long-range (three-dimensional) ordering at (2.8 \mathrm{~K}). 1993 Academic Press. Inc.