Mössbauer investigation of 57Fe-doped Ni(III) perovskites ANi0.98Fe0.02O3 (A = Pr, Nd, Sm, Y, Lu, Tl) versus temperature
Language
en
Article de revue
This item was published in
Journal of Solid State Chemistry. 2002, vol. 168, n° 1, p. 126-133
Elsevier
English Abstract
Nickelates ANiO3 (A=Pr, Nd, Sm, Lu, Y, Tl) containing Mössbauer probe 57Fe atoms were synthesized. In the case of nickelates with larger rare earth (A=Pr, Nd, Sm) the Mössbauer spectra confirm that ferric ions are located ...Read more >
Nickelates ANiO3 (A=Pr, Nd, Sm, Lu, Y, Tl) containing Mössbauer probe 57Fe atoms were synthesized. In the case of nickelates with larger rare earth (A=Pr, Nd, Sm) the Mössbauer spectra confirm that ferric ions are located in single type of crystallographic positions. On the contrary, the spectra of ANi0.98Fe0.02O3 with small cations (A=Lu, Y, Tl) can be described as a superposition of two sub-spectra which indicate that 57Fe probe atoms are simultaneously stabilized in two non-equivalent crystallographic positions. These results have been interpreted in terms of partial charge disproportionation of Ni3+ cations associated with the electronic localization in monoclinic distorted Lu, Y, Tl nickelates. The modification of 57Fe spectra for TlNi0.98Fe0.02O3 as a function of temperature has shown that this charge disproportionation occurs in varying degrees, corresponding to the charge states Fe(3+σ)+ and Fe(3−σ′)+. On the contrary, the spectra for Lu and Y nickelates show that charge variation (σ,σ′) for dopant Fe(1) and Fe(2) cations does not depend on temperature.Read less <
Italian Keywords
Mössbauer spectroscopy
Perovskite
Trivalent nickel
Charge disproportionation
Origin
Hal imported