Relative recoilless F-factors in REFeO 3 (RE = rare-earth La, Pr, Nd and Sm) orthoferrites synthesized by self-combustion method

Abstract

a b s t r a c tIn this work, rare-earth orthoferrites polycrystalline compounds REFeO 3 (REFO) with RE = rare-earth La, Pr, Nd and Sm were synthesized by the self-combustion method. A direct correlation between the magnitude of the magnetic hyperfine field and the FeAO 1 AFe bond angles was observed. From transmission Mössbauer spectra recorded at room-temperature, relative recoilless F-factors for these REFO compounds were estimated. The method applied to perform this calculation was based on the determination of two subspectral areas present in a mixture of known amounts of the compound under study and a standard sample (a-Fe). For that purpose spectra were thickness-corrected and fitted using lorentzian lines. The so obtained factors were F-REFeO3 (RE = rare-earth La, Pr, Nd and Sm): 1.30 ± 0.02, 1.08 ± 0.04, 1.15 ± 0.05, 1.18 ± 0.08 respectively. The absolute recoilless factors obtained by this method had an average relative error around 11% in comparison with the values predicted by the Debye model.

Determination of Debye temperatures and Lamb–Mössbauer factors for LnFeO3orthoferrite perovskites (Ln = La, Nd, Sm, Eu, Gd)

“…These values are not relative to αFe, as is often presented, and are the recoilfree fractions of these phases alone. The recoilfree fractions of these materials have been found to be greater than that of αFe previously, by comparing the spectral areas of suitable Mössbauer absorbers [64]. An ffactor that is greater than that of αFe implies that the iron nucleus is more strongly embedded, allowing for the recoilless absorption of γrays.…”

Experimental and Theoretical Infrared Signatures of REMO3 (RE = La, Pr, Nd, Sm, and M = Co, Fe) Perovskites

“… a Lattice parameters (in Å), α mean distortion angle (in °), and extremum values of M–O distances d (M–O) (in Å). (i), (j), and (k) are reported from refs, − respectively. …”