Nuclear Magnetic Resonance Investigations in Liquid In-Ni Alloys

Abstract

Measurements of the ll5In Knight shift and the NMR linewidth in liquid In-Ni have been carried out over the concentration range (0-50) at.% Ni at high temperatures. With changes of the Ni concentration important changes occur in the hyperfine interactions referring to 115In. The experimental results for higher Ni concentrations are in good agreement with a model involving a significant d-d exchange interaction.In liquid alloys of simple metals with 3 d elements (magnetic impurities) the polarization of the surrounding electrons, caused by the magnetic moment of the impuri ties, influences both the Knight shift of the solvent nucleus and the relaxation time of the NMR process.Recent NMR studies on liquid Bi-Mn [1] show that the Mn impurities possess a local magnetic moment. The im purities affect very strongly the -() Bi-Knight shift Kim^. A concentration of 3 at% Mn causes a relative change AK^Bl/ K to»B i = 33%, which is indeed a very strong effect.In this work we present measurements concerning the concentration dependence of the "-In-Knight shift and the NMR linewidth in liquid In-Ni for concentrations up to 50 at% Ni at high temperatures. To our knowledge this is the first investigation of the ll5In-Knight shift in the liquid In-Ni system.For the relatively difficult sample preparation we used metals with a purity of 99.999% (Ventron Corporation). Alloys of the required composition, particularly those with higher Ni concentration, were left several hours at 1850 A T in an A120 3 container sealed under vacuum, to get a uniform distribution of the components. The measure ments were carried out using a high temperature NMR spectrometer, of which details are given elsewhere [2. 3], Figure 1 shows our experimental results. We plotted the relative change of K,v,in defined as AK/K0 = (K(c) -K0)/ K0, where K(c) and K0 are the ll5In-Knight shifts in the alloy and in pure Indium at the melting point, respectively.The function AK(c)/K0 shows a pronounced maximum at c = 20 at% Ni and becomes negative at c = 50 at% Ni. In this respect it is interesting to consider earlier NMR in vestigations on binary liquid alloys of simple with transi tion metals [1.4-6]. In most of these systems the transition metal concentration was about 6 at% and the relative Knight shift of the simple metal was found to increase linearly with the concentration of the transition metal. NMR investigations of liquid systems with higher transi

Effects of magnetic impurity plus association on the Knight shifts in liquid Bi-In-Ni alloys

“…Several studies, in particular on Mn, Fe and CO concentrations of a few atomic per cent in liquid Al, Au, Bi, Cu, Ga and Sb [l] have shown that these 3d atoms essentially retain a localised magnetic moment, in accordance with for example susceptibility and Kondo effect behaviour. For the 3d9 atom Ni, however, in liquid In [2] or Bi [3], no local moment survives, again in accordance with susceptibility [4,5] and the solid alloy properties of Al-Ni, Au-Ni and Cu-Ni (see e.g., [6]). Moreover, the 3d band is close to being filled.…”

“…Thus the Friedel picture should apply. Filling At higher Ni concentrations in In-Ni, dK/dc turns negative [2], leading to the peculiar behaviour of K('151n) in the alloy In70Ni30 (inset in figure l(a)). When the alloy is heated, the observed NMR signal corresponds to the composition and temperature of the liquidus line.…”

“…The latter can be varied by using an alloy as the matrix. Differences between Ni-In and Ni-Bi, for example, are obvious [2,3].…”

“…0953-89841891264223 + 12 $02.50 @ 1989 IOP Publishing Ltd added Ni has been thoroughly studied [2,3], and Bi-In shows definite effects of bonding in the liquid state [9], it was interesting to determine experimentally the changes in K for Bi and In in Bi-In liquid alloys on the addition of Ni.…”

Temperatur- und Konzentrationsabhängigkeit der 115In-Knightshift im flüssigen In-Mn-System

“…B. CuMn, CuNi [22], AlMn [23], InNi [24], BiNi [6], CuGaMn [25], SbFe, SbCo, SbNi [26], CuAlMn, AuAlMn [27], Die Ergebnisse dieser Arbeiten zeigen, daß Mn und Fe als Verunreinigung in einfachen Metallen aufgelöst, im wesentlichen ihren magnetischen Charakter in der Legierung beibehalten und ein von der Elektronenstruktur des Wirtsmetalls abhängiges lokalisiertes magnetisches Moment bilden [4] mit Curie-Temperaturabhängigkeit.…”