Magnetization and Mössbauer effect study of the pseudo-binary system (Ti 1- xNb x) Fe 2

Abstract

Mössbauer spectroscopy, magnetization and X-ray diffraction measurements have been done on (Ti 1- x Nb x )Fe 2 compounds in order to investigate the effect of Nb on the magnetic properties of TiFe 2. The experimental results show that Nb enters the lattice by filling Ti sites thereby forming a continuous phase over the entire range of Nb concentrations. The Mössbauer spectra at 80 K fitted with a magnetic hyperfine field distribution show a continuous decrease in the average magnetic hyperfine field with increasing Nb concentrations as well as several different magnetic configurations for x ≥ 0.3. A similar result was obtained for the spectra at 10 K when samples with x ≥ 0.5 were fitted with a magnetic hyperfine field distribution. Magnetization measurements of M versus H for constant temperature and M versus T for constant magnetic field yield the following results: the pseudoternary compounds are antiferromagnetic in the concentration range 0 ≤ x ≤ 0.5 with the Néel temperature increasing slightly with Nb content up to x = 0.3 followed by a steady decrease as x increases to 0.5. Between x = 0.5 and 0.6 a magnetic phase transition from AF to ferromagnetism occurs. The spontaneous magnetization σ 0 increases with Nb content, reaching a maximum at x = 0.8. For larger Nb contents σ 0 decreases, going to 0 for the pure NbFe 2 phase. The Curie temperature shows behavior similar to that of σ 0.