Jour nal of ELSEVIER Journal of Alloys and Compounds 232 (1996) 84-89 PMR measurements on (Ni,_,Cu,),~,Zr,~,-H, amorphous alloys K. Tompa, P. Bhki, C. Hargitai, G. Lasanda, L.K. Varga Research Institute for Solid State Physics of the Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary Received 20 January 1995; revised 20 June 1995 Abstract Spin-spin relaxation time (T,) and complementary hydrogen content (HIM), PMR spectrum width (PWHM) and spin lattice relaxation time (T,) have been measured in (Ni,_,Cu,),,,Zr,,, -H, ternary amorphous alloys at 0 c x s 29 at.% concentrations using Carr-Purcell-Meiboom-Gill (CPMG), solid-echo and saturation recovery pulse sequences respectively. The T2 relaxation time measured by the slope of the CPMG echo train depends on both the hydrogen and Cu content. The dependence can be attributed to the change of correlation time and not to the change of activation energy or local field. The measurements were made in the ‘motional narrowing’ state; consequently our E, and T, quantities are averaged to the diffusional motion of protons taking part in this process. The extrapolated amplitude of the echo train measured on the alloy-hydrogen system and normalized to the same quantity in water, gives the value of proton magnetization in thermal equilibrium, that is the hydrogen content free from any perturbing effects. The hydrogen content measured by CPMG echo train has turned out to be systematically smaller than that measured by weight increase. Keywords: PMR, (Ni,_,Cu,),,Zr,,,; Amorphous alloys; Hydrides; Relaxation 1. Introduction This paper presents a study of the proton magnetic resonance in amorphous alloys and is coherent in two respects. Firstly, the Zr-Ni-Cu ternary alloys constitute an amorphous alloy system in which the host nuclear magnetic environment can be varied over a relatively wide range and the variations can be traced by proton resonance. In the parent Zr-Ni-H system, the contri- butions to the local dipole-dipole fields at the proton sites, due to the host nuclei (Zr and Ni) are negligible compared with the contributions coming from the other protons. The addition of Cu can, however, modify the situation as all the factors influencing the local dipole field (the high abundance of Cu nuclei with non-zero magnetic moment, the gyro magnetic ratios and the spin values) give rise to a sizable local field contribution. In binary and ternary amorphous alloys the hydrogen can be located at tetrahedral sites of different composition. Energetically, these distorted tetrahedral sites are different and the occupation of the sites depends on the composition and overall hydrogen content of the sample. At low temperature, 0925-8388/96/$15.00 0 1996 Elsevier Science S.A. All rights reserved SSDZ 0925-8388(95)01959-6 the proton distribution is more or less static; at higher temperatures, the NMR characteristics, the relaxation times and the diffisional parameters, can also be influenced by both the hydrogen content and the metallic constituents. Secondly, the metallic composition including the Cu content is predetermined by the alloying; the hydrogen content is not. Therefore, the determination of the actual hydrogen content is crucial. Our aim was consequently to measure as precisely as possible the wanted NMR parameters and the hydrogen content simultaneously. Using the Carr-Pur- cell-Meiboom-Gill (CPMG) pulse sequence, the ex- trapolated amplitude of the echo train gives the overall proton magnetization in thermal equilibrium. The overall proton magnetization is, in turn, a direct measure of the hydrogen content in the alloy that is free from any field inhomogeneity, inaccurate pulse settings and after r.f.-pulse transient effects. At the same time, the slope of CPGM echo train offers a value for the spin-spin relaxation time T,. The in- vestigation of T2 was the primary goal of the present work. To discuss the methodical details, the results by