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The partition of hydrogen into diffusible and residual parts was realized by pulse NMR spectroscopy, by gas chromatography and by prompt gamma activation analysis (PGAA). The total hydrogen content was determined by the two non-NMR methods and the diffusible (mobile) component by CPMG NMR pulse sequence. Results on amorphous Ni(Cu)–Zr–H systems of different compositions are shown. Partially crystallized samples were also studied as an extension. A method proposed by us directly gives the fractional population of hydrogen atoms in the free (mobile) state on the spin–spin relaxation time scale. On the other hand the least values of the residual hydrogen content correlate surprisingly well with the numbers of filled four Zr-type H-sites calculated by Batalla et al. [NATO ASI Ser. 136 (1985) 203] for 0.21-nm exclusion distance.

The paper presents the results of an experimental investigation of rigid-lattice proton magnetic resonance (PMR) spectra and second moments in Ni 0.67 Zr 0.33 –H, Ni 0.50 Zr 0.50 –H, Ni 0.33 Zr 0.67 –H binary glassy alloy–hydrogen systems in the range of hydrogen-per-metal ( H / M ) ratio of 0.14≤ H / M ≤1.9. The line shape can be described by the empirical Harper-Barnes function with exponent values ranging from 1.45 to 2.95 in the whole hydrogen concentration range. The generally assumed Gaussian form is valid in a narrow H / M interval only. The second moment as a function of H / M can be fitted by a power function of an exponent 3/4. The exponent is independent of the composition of the alloy. We found that a simple lattice gas model based on a homogeneous hydrogen distribution contradicts the experimental results. Instead, a short-range order model has been proposed in which the hydrogen atoms are located in the centres of distorted tetrahedra of metal atoms, that is in the basic building blocks of the amorphous alloys. The Switendick criterion was also taken into consideration. We have shown that few proton first neighbours (0–2) and a small number of second neighbours (1–8), that is, a cluster of hydrogen is sufficient to account for the measured value of the second moment. Ternary Zr 0.5 Ni 0.5− x Cu x –H alloys have been investigated, too. The addition of Cu nuclei did not lead to the second moment enhancement expected for a homogeneous distribution of components.

1 H spin–spin relaxation time ( T 2 ) and complementary hydrogen content, PMR spectrum width and spin–lattice relaxation time ( T 1 ) have been measured in Zr y (Ni 1− x Cu x ) 1− y –H ternary amorphous alloys of different hydrogen content at 0≤ x ≤33 at.% Cu and y =33, 50 and 67 at.% Zr concentrations using Carr–Purcell–Meiboom–Gill (CPMG), solid-echo and saturation recovery pulse sequences, respectively. At high hydrogen contents the T 2 measured by the slope of the CPMG echo train depends on both the Zr and Cu content, but is independent of the hydrogen content. The differences in the spin–spin relaxation behaviours can be attributed to the substantial change of correlation time and not to the change of activation energy or local fields. The measurements were made in the “motional narrowing” state, consequently our E a and τ ∞ quantities are averaged to the diffusion motion of protons taking part in this process. At small hydrogen contents T 2 depends on hydrogen content and the T 2 vs. 1/ T curves cannot be fitted by single Arrhenius plots. The hydrogen content measured by echo train has turned out to be systematically smaller than that measured by weight increase, demonstrating that not all the hydrogen takes part in the diffusion process.

Equilibrium pressure and potential measurements at room temperature as a function of hydrogen concentration are reported for Ni 1− x Zr x amorphous alloys with 0.33 ⩽ x ⩽ 0.45. The full range of charge of the samples was achieved by taking into account the hydrogen gas evolved in the closed electrochemical cell. The change in slope of the equilibrium potential with the state of charge shows that different types of site are filled. On the basis of the pressure-composition (P-C) diagrams, the samples with x = 0.33, 0.36 and 0.39 were selected for further electrochemical investigations.

The aim of this paper is to reinvestigate the proton magnetic resonance spectra in Zr 0.5 Ni 0.5− y Cu y H x metallic glasses. Solid-echo pulse sequences were used to analyze the line shape. The measurements were made in the temperature range 2.2–300 K and at a frequency of 87.6 MHz. The reinvestigation of the line shape mostly at low temperatures was initiated after having realized that the splitting reported earlier on our samples was a consequence of the relatively long recovery time of our spectrometer. The present solid-echo measurements yielded simple spectra describable by a Harper-Barnes line shape close to gaussian.

The proton NMR line shift with respect to water, the bulk susceptibility and in a few cases the Korringa contribution to the spin lattice relaxation time were measured in Zr0.33Ni0.67 Hx amorphous alloys with hydrogen concentration 0.1 ⩽ x ⩽ 0.7and at 343 K. All the parameters, including the hydrogen content and the bulk susceptibility, were measured simultaneously in situ, and in the shift measurements a resolution of ±1 ppm was attained. The residual Knight shift depends on the hydrogen content and is positive relative to water. Preliminary low temperature spin lattice relaxation time measurements indicate that the positive shift is the consequence of the balance of s- and d-contributions.

The splat-quenched Ni50Zr50 alloy has a rosette-shaped phase with tenfold symmetry. The structure of this phase has been interpreted (Yang, 1985) as “tenfold twins” of the orthorhombic NiZr phase. The formation and the feature of the phase with tenfold symmetry have been investigated in Ni50Zr50, Ni50−xCuxZr50 and Ni50−xCoxZr50 amorphous alloys. It was found that this phase forms first during the crystallization process. The structure comes nearer to the structure of a quasi-crystal through the influence of Cu and Co atoms.

The time evolution of the hydrogen absorption of melt-quenched Zr50Ni50 amorphous alloy ribbons was investigated for the as-quenched state and after a relaxation heat treatment. Hydriding was performed from the gas phase at 200 °C and 35 atm H2 gas pressure for charging times up to t = 48 h. The absorption process was monitored by measuring the mass increase, the thermoelectric power and the magnetization of the hydrided ribbons. For both the as-quenched and relaxed state, homogeneously hydrided ribbons could only be obtained at small ( H M ) and high ( H M ≈ 1 ) hydrogen contents. The maximum amount of absorbed hydrogen was found to be the same for both states; however, the hydrogen absorption process in the relaxed ribbons required considerably longer times than for the as-quenched state. As in our previous study of a Zr47.5Ni52.5 metallic glass, the magnetization measurements indicated also for the present alloy the occurrence of a phase separation process leading to the development of strongly magnetic nickel-rich clusters for long charging times.

The influence of hydrogen on some physical properties and on the micro-structure of a nearly equiatomic, melt-quenched NiZr amorphous alloy was investigated. Hydrogen absorption from the gas phase at 190 °C and 35–40 atm pressure was measured by weight as a function of the charging time. Considerable hydrogen absorption occurred only for charging times around 10 h and was completed within a few hours. The hydrogen content remained constant for a hydrogen-to-metal ratio of about one for prolonged charging. The room-temperature thermopower changed considerably upon hydriding and a local thermopower probe revealed that the activation time varies considerably along the ribbon length. It was found that, during further heat treatment in a hydrogen gas atmosphere after a hydrogen-to-metal ratio of approximately one was reached, the magnetic state of the amorphous NiZr samples changed progressively from paramagnetic to superparamagnetic. The density and size of the magnetic clusters, which were nickel-rich segregations induced by the hydriding process, were determined by magnetic and scanning transmission electron microscopic measurements. After desorbing hydrogen at elevated temperatures, magnetic measurements indicated the disappearance of the superparamagnetic clusters.

The proton rotating-frame spin lattice relaxation time T1r has been measured in (Ni0.5Zr0.5)0.95P0.05H0.54 and (Ni0.5Zr0.5)Po0.07H0.58 amorphous alloys in the temperature range 140–370 K. A single-exponential relaxation decay was obtained from 200 to 370 K only. The experimental data above 200 K were interpreted on the basis of a model involving diffusion of the hydrogen atoms. It is demonstrated that, by using a gaussian distribution of diffusion activation energies about a temperature independent mean energy E a = 0.32 eV atom−1 and a full width at half maximum ΔE = 0.07 eV, the temperature dependence of T1r can be well fitted in the 200–370 K range. These values are compared with relevant hydrogen diffusion data from the literature on other amorphous alloys

The proton content in Zr 0.33 Ni 0.67 H x amorphous alloy was monitored by changes in electrical resistivity and with the extraplated spin echo amplitude measured by the Carr-Purcell-Meiboom-Gill (CPMG) nuclear magnetic resonance pulse sequence in the temperature interval 300 to 450 K. Both methods show that the hydrogen desorption processes can be approximately divided into two ranges. The first is a fast process which is at present not interpretable. In the second stage, the process is thermally activated, and the activation energy calcualted from the resistivity changes is equal to 0.32 ± 0.04 eV. The CPMG spin echo measurements also give the spin-spin relaxation time of diffusing protons and the activation energy of this process, 0.34 ± 0.02 eV, is exactly the same as extracted from the resistivity measurements.

For determination of the hydrogen content in metallic samples the gravimetric method is generally used, but the large change of the electrical resistivity observed on H-absorption can also be used. The latter method is very effective if the time dependence of the process is important. The resistivity change of the sample can easily be used for monitoring the H-absorption in a gas atmosphere and with some caution for the determination of the H content in galvanic doping as well. Results are presented for the Zr33Ni67 amorphous alloy with both methods of H charging.

We studied the nuclear magnetic resonance (NMR) spin-lattice relaxation time T 1 for hydrogen in amorphous metal hydrides of the form (Ni 0.5 Zr 0.5 ) 1−x P x H y as a function of both hydrogen and phosphorus concentration. We found that the hydrogen diffusion contribution dominates T 1 over most of the temperature range from 500 K down to 150 K. The diffusion activation energy is of the order of 0.39 eV, but has a wide distribution and, in particular, low energy contributions are present which are appreciable down to the lowest temperatures studied. The Korringa relaxation time T 1e controls T 1 at the lowest temperatures and highest frequencies used. The system shows single-phase behavior above room temperature but two-phase behavior at 150 K.

The field-independent 31P NMR linewidth, δHo, is measured in nonmagnetic amorphous Ni-based alloys. In addition, the second moment contribution M originating from direct nuclear dipole–dipole interaction is calculated using Van Vleck's theory based on a computer generated DRPHS amorphous model cluster. The calculated second moment M and the experimental second moment M obtained from δHo by Gaussian line shape approximation (i.e., M = (δHo)2/4) agree fairly well for a (Ni0.27Cu0.73)82P18 metallic glass. In the case of amorphous NiP and NiPB alloys M exceeds M by a factor of two or three. This excess second moment seems to indicate the presence of some indirect indirect interactions between nuclear spins. [Russian Text Ignored].

Ni75-TM5-P20 dilute alloys were investigated by 31P NMR spectroscopy. The Knight shift and the second moment of the NMR line and the longitudinal relaxation time were measured for TM = Cu, Fe, Co, Mn, Cr, V by c.w. and pulsed NMR techniques. The influence of the 3d alloying element on the electronic structure of amorphous metal will be discussed.

The electronic structure of amorphous ZrNiP and ZrNiPH alloys was studied by means of ultraviolet photoemission spectroscopy. It was established that new states were induced around 5.7 eV binding energy by hydrogen and, at the same time, the density of states (DOS) at the Fermi level decreased. The Ni peaks below the Fermi level are shifted to higher binding energies upon hydrogenation whereas the position of the Zr peak remains unchanged but its intensity is reduced due to the presence of hydrogen. The decrease of the DOS at the Fermi level indicates that H atoms interact with Zr atoms only. On the other hand, the clear shift in the Ni d-states shows that the Ni states are affected by hydrogen via changes in the ZrNi bonding.

The thermoelectric power and resistance of (Zr48.5Ni51.5)99.3P0.7-H metallic glasses were measured. The thermoelectric power decreases from S ≈ 2 μV K−1 at zero hydrogen-to-metal ratio (HM = 0) to a negative value (S ≈ −2 μV K−1) at a hydrogen-to-metal ratio of 0.7 (HM = 0.7). These results show the high sensitivity of the thermoelectric power to hydrogen concentration and are consistent with the Mott model.

A magic-angle spinning nuclear magnetic resonance (NMR) study of the Knight shift effects in rapidly quenched alloys is presented. The 31P NMR of the melt-quenched crystalline Ni3P alloy shows that the average Knight shift and the distribution of isotropic shifts are significantly different from the corresponding values for normal crystals. The results are explained as off-stoichiometry and grain size effects on the electronic structure respectively. The NMR of hydrogen in a ZrNiP-type melt-quenched amorphous alloy shows a dependence of the average Knight shift and isotropic Knight shift distribution on the hydrogen content. These results can be explained by assuming a dilatation of the metallic matrix and by specific hydrogen dynamics respectively.

Conductance noise measurements done on (melt-quenched) glassy metal point contacts are reported. The lower limit of the noise factors obtained was stronger by 3–5 orders of magnitude than that usual in ordinary metals. That result supports well the view about the role of defects in generating the 1/f noise, but there are some doubts, whether the relevant defects are necessarily mobile.

Room temperature measurements are presented of the 31P NMR Knight shift and the T1 and T2 relaxation times for several frequencies in Ni100−xPx (17.1 ≦ x ≦ 26.8) and Cu60Ni22P18 amorphous alloys. The experimental results are analysed in terms or the Korringa relation and of the possible electronic structure of these metallic glasses.

Conductance noise measurements done on point contacts of (melt-quenched) glassy metal ribbons are reported. The lower limit of the 1/f noise factor obtained was stronger by 3-5 orders of magnitude than that usual in ordinary metals. That result supports the "two potential well tunelling" model of 1/f noise in glassy metals. The conductance fluctuations measured in hydrogenized glassy metals proved to be also 1/f noise. Diffusion noise due to hydrogen has not been found.