Anisotropic phonon DOS: the application of Rietveld and Mossbauer texture analysis in aligned powders

Abstract

While synthesizing the single crystals of novel materials is not always feasible, orienting the layered polycrystals becomes an attractive method in the studies of angular dependencies of inelastic scattering of x-rays or neutrons. Putting in use the Rietveld analysis of layered structures in novel manganites and cuprates we develop the studies of their anisotropic properties with oriented powders instead of single crystals. Densities of phonon states (DOS) and atomic thermal displacememts (ATD) are anisotropic in the A-site ordered manganites LnBaMn2Oy of both y=5 and y=6 series (Ln=Y, La, Sm, Gd). We establish the angular dependence of DOS on textures of arbitrary strengths, link the textures observed by x-ray and gamma-ray techniques, and solve the problem of disentanglement of Goldanskii-Karyagin effect (GKE) and texture in Moessbauer spectra.

6 pages; 5 figures, revised

Cited by in corpus (2)

• Condensation of a tetrahedra rigid-body libration mode in HoBaCo4O7 : the origin of phase transition at 355 K
• Vibrational abisotropy and quadrupole interactions of Fe substituted into Mn site of the charge and orbitally ordered and disordered layered manganites LnBaMn1.96Fe0.04O5 and LnBaMn1.96Fe0.04O6 (Ln=Y,Gd,Sm,La)