Tin-doped LuCrO₃: A new type of material allowing the location of a ¹¹⁹Sn Mössbauer spectroscopic probe on the gas–solid interface

M. I. Afanasov (1) , Alain Wattiaux (2) , Christine Labrugère (2) , P. Fabritchnyi (1) , Claude Delmas (2)

1 Department of Chemistry, Lomonosov Moscow State University
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

In situ 119Sn Mössbauer measurements show that annealing in hydrogen atmosphere of co-precipitated chromium and lutetium hydroxides, doped with 0.2 at.% Sn⁴⁺, results in the formation of Sn²⁺ cations on the surface sites of LuCrO₃ microcrystals. Such a distribution of dopant cations is consistent with the anomalously high concentration of tin revealed by X-ray photoelectron spectroscopy (XPS). The 19Sn spectrum recorded above the Néel point of LuCrO₃ attests to the distribution of Sn²⁺ ions over two kinds of site. For both of them, the isomer shift and quadrupole splitting values agree with those previously reported for 119Sn²⁺ on surface sites of several oxides other than the perovskite-type one. The instantaneous oxidation of tin upon contact with ambient air did not allow us to characterize the cationic surrounding of Sn²⁺ by measurements involving sample transfer into a liquid-helium cryostat. Relevant information is obtained for the Sn^2+→4+ oxidized species located on the sites with unchanged cationic surroundings. The spectrum recorded at 4.2 K shows that nearly two-thirds of the Sn^2+→4+ species are spin-polarized to different extents. Comparison with Mössbauer parameters reported for 119Sn ions sitting in the regular Cr-substitution site in the bulk of LuCrO₃ allows us to ascribe the diffuse magnetic contribution to a distribution of Sn^2+→4+ species over Cr-substitution sites with lower (than in the bulk) number of neighboring Cr³⁺ ions. The presence of an additional non-magnetic component in the spectrum of Sn^2+→4+ ions points to the location of the remaining Sn⁴⁺ ions and, very likely, the predecessor Sn²⁺ ones, on Lu-substitution sites with magnetically compensated (2Cr↑+2Cr↓) surroundings.

Mots clés: Magnetically ordered materials; Chemical synthesis; Point defects; Nuclear resonances

Domaines: Matériaux

M. I. Afanasov, Alain Wattiaux, Christine Labrugère, P. Fabritchnyi, Claude Delmas. Tin-doped LuCrO₃: A new type of material allowing the location of a ¹¹⁹Sn Mössbauer spectroscopic probe on the gas–solid interface. Solid State Communications, 2009, 149 (33-34), pp.1333-1336. ⟨10.1016/j.ssc.2009.05.030⟩. ⟨hal-00420693⟩