Stability field and structural properties of intra-rare earth perovskites

• Published in: Journal of alloys and compounds Vol. 494; no. 1; pp. 336 - 339
• Main Authors: Artini, C., Costa, G.A., Carnasciali, M.M., Masini, R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 02-04-2010; Elsevier
• Subjects: Alloys; Condensed matter: structure, mechanical and thermal properties; Correlation; Exact sciences and technology; Inorganic compounds; Mixed oxides; Oxalates; Oxides; Physics; Rare earth metals; Rare earth perovskites; Stability; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Thermal decomposition; Thermodynamic stability; Thermogravimetric analysis; Water, oxides, hydroxides, peroxides; Rare earth perovskites; Thermodynamic stability; Mixed oxides; Rietveld method; Space groups; Lattice distortion; Thermal decomposition; Thermogravimetry; Magnetic moments; Perovskites; Ionic radius; Lanthanum Rare earths Oxides Mixed; Coprecipitation; Exchange interactions; Crystal structure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.01.030

A stability study of perovskitic LaREO
3 oxides (RE
=
Dy, Ho, Er, Tm, Yb, Lu) as a function of temperature was undertaken. A correlation between the Goldschmidt
t value and the perovskitic stability field amplitude was found: the latter widens as
t increases. Magnetic measurements, performed on all the perovskitic samples, showed that
t is also related to the exchange interactions.
LaREO
3 oxides were synthesized by thermal decomposition of the corresponding coprecipitated oxalates at temperatures ranging between 600 and 1800
°C. Simultaneous differential thermal and thermogravimetric analyses showed that all the La–RE mixed oxalates decompose similarly. All the oxides, except LaDyO
3, crystallize in the perovskitic form in a temperature range that depends on the ionic size difference between La and the smaller rare earth; above and below the perovskitic stability field, the B or C form, typical of rare earth sesquioxides, is present. Rietveld refinements, carried out on all the LaREO
3 samples synthesized at 1200
°C, showed the occurrence of an orthorhombic distorted perovskitic structure belonging to the
Pnma space group.