Issue 23, 2002

Neutron-diffraction study of the Jahn–Teller transition in PrMnO3

Abstract

The stoichiometric perovskites RMnO3 (R = rare earth) experience Jahn–Teller (JT) transitions as a function of temperature and R size similar to that recently described for LaMnO3. We have investigated the JT transition for R = Pr by ATD techniques and neutron powder diffraction. This transition takes place at approximately 1050 K, and it is characterized by a strong reduction of the MnO6 octahedra and sudden changes in the unit cell parameters and Mn–O bond distances. For T < TJT, PrMnO3 perovskite exhibits the so-called O′ orthorhombic structure, characterized by c/√2 < a < b and a strong distortion of the MnO6 octahedra. Also Mn–O distances lying in the basal plane are drastically different, reflecting the orbital ordering due to the JT effect. For T > TJT, we observe an orthorhombic O-type structure, with much less distorted MnO6 octahedra and a < c/√2 < b. In contrast to LaMnO3, the lattice parameters do not converge to give a metrically cubic unit cell above the transition, probably due to the higher mismatch between ionic radii (steric effect)

Graphical abstract: Neutron-diffraction study of the Jahn–Teller transition in PrMnO3

Article information

Article type
Paper
Submitted
27 Aug 2002
Accepted
03 Oct 2002
First published
01 Nov 2002

J. Chem. Soc., Dalton Trans., 2002, 4422-4425

Neutron-diffraction study of the Jahn–Teller transition in PrMnO3

D. Sánchez, J. A. Alonso and M. J. Martínez-Lope, J. Chem. Soc., Dalton Trans., 2002, 4422 DOI: 10.1039/B208660N

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