Structural phase transition in polyphenyls. VII. A neutron diffraction study of the structural phase transition in biphenyl-d10

摘要: Recently a soft mode has been observed in biphenylhl0 (hydrogenated) by Raman spectroscopy below T c = 40 K. The structural phase transition biphenyld l0 (deuterated) investigated neutron diffraction. Surprisingly, superlattice reflections appeared K, corresponding to doubling of the b parameter only, and not b, as was found for p-terphenyl p-quaterphenyl. torsion angle between planes phenyl groups is about 10 °, opposite directions two neighbouring molecules along b. intensity shows linear behaviour with temperature, agreement Landau theory.