Consequences of pressure-instigated spin crossover in R perovskites; a volume collapse with no symmetry modificationG. Kh. Rozenberg1, M. P. Pasternak1, W. M. Xu1, L. S. Dubrovinsky2, S. Carlson3 and R. D. Taylor4
1 School of Physics and Astronomy, Tel-Aviv University - Tel-Aviv, Israel
2 Bayerisches Geoinstitut, University Bayreuth - Bayreuth, Germany
3 European Synchrotron Radiation Facility - Grenoble, France
4 MST-10, Los Alamos National Laboratory - Los Alamos, NM 87545, USA
received 3 March 2005; accepted in final form 11 May 2005
published online 8 June 2005
High-pressure X-ray diffraction, Mössbauer, and Raman studies in the antiferromagnetic insulators R orthorhombic perovskites ( , , ) disclose an unusual phenomena of a reversible first-order isostructural phase transition around 50 concurring with an abrupt volume decrease. It is shown experimentally that this transformation concurs with, and is driven by, a high-to-low-spin transition taking place in ; a manifestation of a new kind of isostructural phase transition. These studies suggest that the R perovskite is a rather sturdy oxide-structure, maintaining its original structural symmetry beyond 125.
61.10.-i - X-ray diffraction and scattering.
62.50.+p - High-pressure and shock wave effects in solids and liquids.
76.80.+y - Mössbauer effect; other -ray spectroscopy.
© EDP Sciences 2005