Many papers on NMR in alloys are addressed to NMR specialists rather than to metal or alloy specialists, and talk about the “potential” of NMR for application to alloys. This presentation emphasizes a review of some useful results of NMR experiments in alloys, including applications in diffusion, phase diagrams, magnetic materials, ordering in intermetallic compounds, liquid alloys and amorphous alloys.

Nuclear magnetic resonance (NMR) methods offer many opportunities for studying both crystal and electronic structure in hydrides, as well as the changes that occur in these at phase transitions. NMR also affords an almost uniquely powerful approach to the study of hydrogen diffusion in hydrides. The NMR of all three hydrogen isotopes can be utilized, as well as of a range of technolgically significant metals. Single crystals are not required, samples need not be single-phase, and measurements can be conveniently made over a wide range of temperatures.

The results of nuclear magnetic resonance (nmr) experiments on simple type–I superconductors were among the first and most important verifications of the BCS theory of superconductivity. In this paper, the application of nmr techniques to the study of superconducting properties in the more complex type–II superconductors will be reviewed. The discussion will include the effect of material parameters (e.g., degree of long range crystalline order, density of states at the Fermi level, effects of magnetic dopants) on the superconducting properties, including size of the superconducting gap, vortex structure, upper–critical field Hc2, and variations in Tc. Emphasis will be placed on high Tc, high Hc2 materials, i.e., A15 compounds and the ternary Chevrel phases.

A review is given of the wide range of magnetic resonance methods used to study the special properties of quasi onedimensional (1-d) conductors. Specific examples are presented which show how magnetic resonance methods have been exploited (a) to tell if the conduction is 1-d, (b) to locate the conduction electrons on a molecular distance scale, (c) to probe the unusual effects of disorder in 1-d conductors, (d) to study the charge density wave transition, and (e) to verify exotic electrical transport mechanisms, such as charged solitons in trans-(CH)x.

A survey of NMR relaxation time techniques for studying ionic diffusion in solids is presented. Particular emphasis is placed on discussing the kinds of information obtainable from T1, Tlρ, TlD, and TlD' measurements. Applications to the study of local and nonlocal diffusion, diffusion in weakly magnetic systems, and motions between unequal potential wells are described. Relaxation due to fluctuating dipolar, quadrupolar, and chemical shift anisotropy interactions is discussed.

The purpose of this paper is to demonstrate, primarily for the non-specialist and within the context of new and recent achievements, the diagnostic value of electron paramagnetic resonance (EPR) in the study of material properties and processes. I have selected three EPR studies which demonstrate the elegance and uniqueness of EPR in atomic defect studies and exemplify unusual achievements through the use of new techniques for material measurement and preparation. A brief introduction into the origin, interaction, and detection of unpaired electrons is included.

Electron spin resonance and related spin dependent measurements have been used to make key contributions to the understanding of amorphous silicon, specifically as probes of the dominant states in the gap, recombination processes and doping. In this paper we give a cursory description of the techniques as they apply to this problem. We then review what has been learned in a-Si:H usually from coupled results of spin resonance and other complementary experimental techniques. The results lead us to a surprisingly simple picture of the equilibrium and non-equilibrium behavior of defects and carriers in this prototypical amorphous semiconductor.

EPR studies of Cr impurities in GaAs and intrinsic defects in GaP are reviewed to illustrate the contributions that EPR has made to the materials science and technology of III-V semiconductors. EPR has shown how the Cr impurity acts to compensate residual shallow donors or acceptors to produce semi–insulating GaAs which is used for device substrates. EPR work has identified two intrinsic defects, the PGa antisite and the VGa vacancy, and clarified their role in electrical and stoichiometric properties of GaP.

Some applications of electron spin resonance to the study of amorphous insulators are briefly described. Specific topics addressed include radiation-induced defect centers, redox equilibria, phase separation, photochromics, and ferromagnetic precipitates.

The utility of electron spin resonance (ESR) for catalyst characterization is illustrated for the desulfurization catalysts used to remove sulfur, nitrogen, and organically bound metals from petroleum. These catalysts consist of active metals (Mo, W, Co, Ni) in mixed oxide and sulfide phases on high surface area alumina supports. Coordinated studies of unsupported sulfide and oxide model systems determine the chemical form and number of defect sites on the actual catalysts. Parallel catalysis studies correlate ESR defects and catalytic activity for many reactions.

A brief introduction to the Mössbauer effect is presented. The hyperfine interactions associated with the electric monopole, magnetic dipole and electric quadrupole moments of the nuclear states involved in the Mössbauer transition are described. Their use in materials research is illustrated through examples dealing with phase analysis, binary solubility, defect interaction and surface properties.

A review is presented of the use of Mössbauer spectroscopy to study the mechanisms responsible for the improvements in wear resistance in ferrous alloys implanted with either light or heavy ions. The phases present in the near surface layers of iron and steel samples implanted with either nitrogen, carbon or tin ions are identified using Conversion Electron Mössbauer Scattering (CEMS) spectra. Samples of wear debris from tin-implanted iron wear discs are analysed in Mössbauer absorption measurements.

Mössbauer spectroscopy as applied to the studies of amorphous metallic, and often magnetic solids will be discussed. The advantages of using this microscopic technique will be compared with others in terms of obtaining information on electronic, magnetic, hyperfine, structural and other properties. Examples of magnetic ordering structures, concentration dependence of ordering temperature, hyperfine field distribution, spin-wave excitations, crystallization behavior, quadrupole interaction, isomer shift, etc., as obtained by Mössbauer spectroscopy will be presented.

The presence of iron bearing minerals in coal makes the Moessbauer effect extremely useful as an analytical tool. In this paper we present a general review of the use of Moessbauer spectroscopy in coal research. We discuss a simple method to identify iron bearing minerals in coal. Several researchers have used the Moessbauer effect to study the transformations of iron minerals during coal processing. We have studied the stoichiometries of iron sulfides produced during coal liquefaction. We found drastic changes in the stoichiometry of the pyrrhotites as a function of the total sulfur content of the coal, and the reaction conditions. Some in situ experiments are reported in this paper. We have observed evidence of reactions between the coal components and the iron sulfides at high temperatures (400° C). The possibility of studying in situ reactions makes the Moessbauer effect a unique analytical tool.

Nuclear and electron resonance and the Mössbauer effect are techniques which observe the interaction of moments with fields directly in the energy domain. An energy splitting, however, also implies the precession of the moment in the field. When a means exists to determine the orientation of the moment then the precession can be observed in the time domain. The direction of radiation emitted in a nuclear, muonic or atomic decay is correlated to the direction of corresponding moments (spins) and can thus act as a detector of spin precession. In the language of nuclear, muonic and atomic physics, these methods are called perturbed angular correlations (PAC), muonic spin rotation, and quantum beats, respectively. Below, these methods will be illustrated by displaying some examples of the application of perturbed angular correlations to a variety of materials systems.

Helium decorated vacancies may be trapped to a high degree and with a high activation enthalpy at impurities in metals. This effect is studied by means of the hyperfine interaction of the radio-active impurities 111In → 111Cd, 119Sb → 119Sn and 129mTe → 129I, implanted into a number of f.c.c. metals and into iron and cobalt. Large changes of the magnetic hyperfine field are caused at 119Sn impurities in Ni, Co and Fe and hiqh values of the electric quadrupole interaction strength are found at 111Cd impurities in Al, Cu, Ag, Ni and Pt when helium decorated vacancies are trapped at the impurities. These effects provide a new method for studying the trapping and desorption mechanism of helium in metals.

Recent advances in the study of point defects and small defect clusters by nuclear methods will be reviewed. Suitable radioactive atoms which fulfill the requirements of spin precession techniques are introduced into solids, where they are used as microscopic probes to investigate their immediate surrounding. Trapping, detrapping or annealing of defects is reflected by changes of the hyperfine interaction between the nuclear moments of the probe atoms and the electromagnetic fields of the defects. The interaction is extracted from a time differential spin precession pattern or–more obviously–from the Fourier transform of it, which can be regarded as the resonance spectrum of the involved frequencies. It allows a distinct recognition of different defects and comprises detailed information about their structural properties. Experimental data on interstitials, vacancies and clusters in metals will be quoted as illustrations for the scope of information, which can be achieved by hyperfine interaction studies.

Contributions of the muon spin rotation technique (μSR) to metal physics problems are surveyed. The similarity between the muon and the proton constitutes μSR as a new tool to investigate the physics of H–like interstitials on an atomic scale. Experiments on the lattice location and on local properties like the Knight shift as well as diffusion measurements are reviewed. In particular the extreme sensitivity of muons toward impurities and lattice defects is emphasized. Results on the trapping of muons by substitutional impurities or vacancies in the ppm range are displayed.

We present 195Pt NMR lineshapes as well as relaxation data in three different samples of platinum metal particles (46%, 26%, and 15% dispersion) supported on alumina. We show that the electronic properties of these particles are very much different from those of bulk Pt metal. A prominent peak in the lineshape has been identified as a “surface resonance” which arises from Pt nuclei on the surface of the Pt particles. We find that these surface Pt atoms are “nonmetallic” when coated with adsorbed molecules.

Several multiple-pulse double-resonance NMR techniques have been applied to isolate and characterize the spectra of the adsorbed states of formic acid on two Y zeolites. The two surface states, bidentatT3 and ynidentate, possess different motional properties and 13C - H cross-polarization techniques may be used to separate the spectra. The 13C chemical shift anisotropy is founa to iorrelate with the symmetry of the formate species. The H spectrum of the carbonyl hydrogen, selectively observed with the dipolardifference method, indicates that this hydrogen becomes more acidic upon adsorption.