abstract
The compressibilities of the cobaltates YBaCo4O7, YBaCo4O7+delta, YBaCoZn3O7 and BaCoO3-x, were investigated by in situ powder X-ray diffraction experiments up to 30 GPa using diamond anvil cells. Pressure-induced phase transitions and amorphization were observed in all the samples. The onset of the pressure-induced phase transition and the onset of the amorphization were observed at similar to 11.7 and 12.2 GPa (YBaCo4O7), at similar to 14.2 and 16.1 GPa (YBaCo4O7+delta), and at similar to 16.7 and 18.7 GPa (YBaCoZn3O7). respectively. An attempt to laser anneal at high-pressure failed as it led to a decomposition of the YBaCo4O7 phase into a mixture of phases. Fits of second- and third-order Birch-Murnaghan equations-of-state to the p-V data result in B-0 = 109(3) GPa for YBaCo4O7: B-0 = 186(4) GPa and B' = 1.5 for YBaCo4O7+delta; and B-0 = 117(1) GPa for YBaCoZn3O7. The high-pressure behavior of the studied compounds was compared with isostructural compounds and it is shown that the oxygen-content has a very large effect on the high-pressure behavior of this class of materials. (C) 2012 Elsevier Inc. All rights reserved.
keywords
NEUTRON POWDER DIFFRACTION; CRYSTAL-STRUCTURE; OXONITRIDOALUMINOSILICATES
subject category
Chemistry
authors
Juarez-Arellano, EA; Avdeev, M; Yakovlev, S; Lopez-de-la-Torre, L; Bayarjargal, L; Winkler, B; Friedrich, A; Kharton, VV
our authors
Vladislav Kharton
Invited Principal ResearcherGroups
acknowledgements
The authors are grateful to the ESRF (Grenoble, France) for beam time and financial support and to the ALS (Berkeley, USA) for beam time. We are grateful for the assistance of the beam line scientists (Michael Hanfland and Simon Clark, respectively). The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Science, of the U.S. Department of Energy under contract DE-AC02-05CH11231. Financial support from the DFG, Germany, within SPP1236 (Projects Wi-1232, Fr-2491) and DFG grant Wi-1232/35-1 are gratefully acknowledged. EAJA gratefully acknowledges financial support from SEP (project PROMEP/103.5/10/5489) and CONACYT (project CB-2009-01-129934); he also acknowledges Los Alamos National Laboratory (Lujan Neutron Scattering Center) for all the facilities given. AF and LB thank the Goethe university for funding via the young researcher FOKUS program. LLT thanks DAAD for the postdoctoral scholarship.