MOSSBAUER-SPECTROSCOPY AND NEUTRON-DIFFRACTION STUDIES OF THE COMPOUND YSRCUFEO5+Y

We have studied the crystal structure and the magnetic properties of t he oxygen-deficient perovskite YSrCuFeO5+y using x-ray and neutron pow der diffraction, and Fe-57 Mossbauer spectroscopy. The neutron diffrac tion data have shown antiferromagnetic long-range order described with two propagation vectors k(1) = (1/2, 1/2, 1/2) and k(2) = 1/2, 1/2, 1 ). Mossbauer spectroscopy for T > T-N (T-N = 397 +/- 5 K) revealed the existence of two Fe local environments. The first one (85% of the spe ctral area) was attributed to fivefold-oxygen-coordinated Fe3+ (S = 5/ 2) and the second to octahedrally coordinated Fe3+ (S = 5/2). For T < T-N the spectra are magnetically split and can be analysed with a dist ribution of H-eff. The relation of the second Mossbauer site to the se cond propagation vector k(2) and to the amount of additional oxygen in the (1/2, 1/2, 1/2) position is examined.