L Journal of Alloys and Compounds 356–357 (2003) 218–222 www.elsevier.com / locate / jallcom KKR-CPA study of the electronic and magnetic structures of disordered Pd Ni alloys and their hydrides 1 2y y a,b, a a a a,c a,d * M.G. Shelyapina , D. Fruchart , E.K. Hlil , S. Miraglia , D.S. dos Santos , S.S.M. Tavares , a,e J. Tobol «a a Laboratoire de Cristallographie, CNRS, BP 166, 38042 Grenoble Cedex 9, France b Institute of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvorets, St. Petersburg 198904, Russia c COPPE / UFRJ, C.P . 68505, 21945-970 Rio de Janeiro, RJ, Brazil d Departamento de Eng. Mecanica / UFF, R. Passo da Patria 156, 24210-470 CEP , Brazil e ´ Faculty of Physics and Nuclear Techniques, AGH, Al. Mickiewicza 30, 30-059 Krakow, Poland Received 1 September 2002; accepted 15 October 2002 Abstract The electronic and magnetic structures of Pd Ni alloys were calculated using the charge and spin self-consistent Korringa–Kohn– 12y y Rostoker method combined with the coherent potential approximation (KKR-CPA). The total and atomic magnetic moments were estimated versus y, the nickel concentration. For 0.01 # y # 0.1 and 0.5 # y # 0.99, the magnetic moment of Ni does not vary, being respectively 0.44 and 0.69 m / f.u., and for intermediate compositions it increases linearly with y. For several Ni contents, the total and B atomic magnetic moments were calculated versus x for Pd Ni H and then compared with other theoretical and experimental data. 12y y x  2003 Elsevier B.V. All rights reserved. Keywords: PdNi alloys; Metal hydrides; Electronic structure calculations 1. Introduction for, using, for example, the coherent-potential-approxi- mation method. Similarly, the electronic structure of PdH x Metal–hydrogen systems have attracted much attention has been carefully investigated. The main effect of H during the last decade from both an experimental and insertion is to create bonding states below the Pd d band theoretical viewpoint. Hydrogen inserted in a metal can (see, for example, Ref. [2] and references therein). In dramatically change the fundamental properties of the host addition, Pd-based binary alloys are very interesting due to matrix. For example, Pd, a near-ferromagnetic metal, the giant magnetic moment induced by Pd at the 3d yields superconducting PdH at low temperature when transition metal impurity site [3], such as, for example, 8 x hydrogenated. The ferromagnetic properties of NiH van- m for Mn, 12.6 m for Fe, and 10.8 m for Co [4]. x B B B ish when the hydrogen concentration is increased. In this Theoretical analyses of the induced magnetization on 3d system, theoretical calculations of the electronic states transition metal impurities in Pd show that the 3d–Pd versus x(H) were performed on the basis of the linear- interaction decreases from Cr to Ni [5]. muffin-tin-orbital (LMTO) formalism (e.g. Ref. [1]). Since Therefore, it would be interesting to study the impact of it was assumed that the H vacancies are ordered, only a hydrogen insertion on the magnetization of 3d impurities limited number of x values were probed due to symmetry in Pd–3d–H systems. We present here a theoretical KKR- limits. For a more realistic approach, a random repartition CPA analysis of the electronic and magnetic structures of of H in each of the interstitial sites should be accounted disordered Pd Ni alloys and their hydrides Pd Ni H 12y y 12y y x versus the Ni and H concentrations. The total and partial densities of states (DOSs) were calculated at each atom *Corresponding author. Institute of Physics, St. Petersburg State site as well as the angular momentum decomposition and University, Ulyanovskaya 1, Petrodvorets, St. Petersburg 198904, Russia. E-mail address: phys@ms4828.spb.edu (M.G. Shelyapina). the total and atomic magnetic moments. 0925-8388 / 03 / $ – see front matter  2003 Elsevier B.V. All rights reserved. doi:10.1016 / S0925-8388(03)00169-5