skip to main content

SciTech ConnectSciTech Connect

Title: High-pressure transformation in the cobalt spinel ferrites

We report high pressure angle-dispersive x-ray diffraction measurements on Co{sub x}Fe{sub 3−x}O{sub 4} (x=1, 1.5, 1.75) spinels at room temperature up to 34 GPa. The three samples show a similar structural phase transformation from the cubic spinel structure to an analogous post-spinel phase at around 20 GPa. Spinel and post-spinel phases coexist in a wide pressure range (∼20–25 GPa) and the transformation is irreversible. The equation of state of the three cubic spinel ferrites was determined and our results agree with the data obtained in related oxide spinels showing the role of the pressure-transmitting medium for the accurate determination of the equation of state. Measurements releasing pressure revealed that the post-spinel phase is stable down to 4 GPa when it decomposes yielding a new phase with poor crystallinity. Later compression does not recover either the spinel or the post-spinel phases. This phase transformation induced by pressure explains the irreversible lost of the ferrimagnetic behavior reported in these spinels. - Graphical abstract: Pressure dependence of the unit cell volume per formula unit for Co{sub 1.5}Fe{sub 1.5}O{sub 4} spinel. Circles and squares stand for spinel and postspinel phases, respectively. Dark (open) symbols: determination upon compression (decompression). - Highlights: • The pressure inducesmore » similar phase transformation in Co{sub 3−x}Fe{sub x}O{sub 4} spinels (1≤x≤2). • The postspinel phases decompose after releasing pressure. • The irreversibility of this phase transformation explains the disappearance of magnetism in these spinels after applying pressure. • Accurate equation of state can be obtained up to 10 GPa using an alcohol mixture as pressure transmitting medium. • The equation of state suggests similar elastic properties for these spinels in this composition range.« less
Authors:
 [1] ; ;  [1] ;  [2] ;  [3]
  1. Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, Consejo Superior de Investigaciones Científicas y Universidad de Zaragoza, 50009 Zaragoza (Spain)
  2. CELLS-ALBA Synchrotron Light Facility, Ctra. BP1413 km 3.3, 08290 Cerdanyola del Vallès, Barcelona (Spain)
  3. European Synchrotron Radiation Facility, F-38043 Grenoble Cedex 9 (France)
Publication Date:
OSTI Identifier:
22443493
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 221; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBONATES; COBALT; COMPRESSION; ELASTICITY; EQUATIONS OF STATE; FERRITE; FERRITES; MAGNETISM; MIXTURES; OXIDES; PHASE TRANSFORMATIONS; PRESSURE DEPENDENCE; SPINELS; TRANSFORMATIONS; X-RAY DIFFRACTION