Is a strain an order parameter in the α-β phase transition of solid oxygen?

✍ Scribed by Bogdan Kuchta

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 268 KB
• Volume: 113
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(85)80260-8

✦ Synopsis

TheoreWzal arguments have been presented supporting an eIastic strain as an order parameter of the m-8 phase trantiti~n. Slmple numerical calculations have been made to illustrate such a model. The monoclinic ~2 phase of solid oxygen (T < 23 9 K, space group C2/m) is antiferromagnetic. The rhombobedral B phare (23.9 < T< 43.8 K, space group R3m) exhibits only short-range antiferromagnetic ordering [ 11 _ The cujp phase transition involves two crucial effects (fig 1): (i) the change in the magnetic ordering from a three-sublattice short-mge order in the fl phase to a two-sublattice antiferromagnetic structure in the c Phase, (ii) the deformation of the rhombohedral p unit cell into a monochnic (Y structure_ Using numerical arguments based on symrnew, one can easily prove that the two-sublattice antiferromagnetic structure of the Q phase (fig. la) is less stable than the three-sublattice ordering (fig. lb) unless there has been a structural deformation of the rhombohedral * Supported by a grant from the Polish Academy of Science within project MR_J.9_