The technique for compressing macroscopic volumes 0.f hydrogen to record pressures of tens of kilobars, developed in the Institute of Solid State Physics of the USSR Academy of Sciences, has permitted the ,first syntheses of the hydrides o,f a number of metals namely: manganese, iron, cobalt, molybdenum, technetium, rhenium and gold. This paper presents the results of the application of the technique ,for the hydrogenation of the platinum metals. The data obtained on hydrogen solubility at high pressures are used to estimate its equilibrium solubility at atmospheric pressure.The first metal hydride investigated was that of palladium (I), but more than 120 years passed before the synthesis of a hydride of a second platinum metal, rhodium, occurred (2).To date hydrides of all the transition metals have been synthesised except those of the remaining four platinum metals and tungsten As far as the platinum metals are concerned, this situation has not resulted from any lack of attempts to synthesise platinum, iridium, osmium and ruthenium hydrides, but is due to their low levels of acceptability of hydrogen into their lattices. This inertness or resistance to hydrogen absorption is characterised by the fact that although the chemical potential of hydrogen dissolved in the metal can be very high, solubilities of hydrogen corresponding to equivalent high external pressures of hydrogen gas, are generally very low.Even the development of very high chemical potentials within the above metals by traditional non-equilibrium methods (for example, by electrolysis) has not previously been successful in introducing very high hydrogen contents.The most direct way to increase the chemical potential of the hydrogen is to compress the hydrogen to high pressures. By this means we (3-5).have synthesised rhodium hydride (2) by using molecular hydrogen compressed to P H~ 250 kbar, and recently the range of investigation has been extended to P H~Z Z 90 kbar. In this paper we will summarise observations made on platinum metals under such record hydrogen pressures.The specimens were of 99.99 per cent purity. Palladium, rhodium, iridium and platinum specimens were cut from polycrystalline foils approximately 0. I mm thick, while the ruthenium and osmium specimens with a thickness of about 0. I 5mm were cut from single crystals. Hydrogen compression was carried out by a method which has been outlined (6) and later described in detail (4).Hydrogen significantly alters the electrical resistance of a metal in which it is dissolved. Thus changes in the electrical resistance of specimens can serve as a conveniently measurable indicator of processes occurring in metalhydrogen systems at high pressures. Some forms of electrical resistance-pressure isotherms measured in the present work are shown in Figures I and 2. The measurements were obtained as the pressure was altered in steps, each pressure being maintained until any observed drift in resistance had stopped, and the pressure simultaneously became constant. It

Hi& molution neutmn scattering studies of vibrationel spectra (2-800 meV) were carried out on the e-, 6'and 6-phof titanium hydride, obtained after high pressure treatment. The observed splitting of the fundamental optic peak in the &-phase spectrum can be explained by a strong H-H interaction along the D axis. Well pronounced features are seen on the low energy side of the tw-and three phonon optic bands. Thex are assigned to bound bi-and tri-phonon excitations. This is the first observation of biand tri-phonons in metal hydrides.

We review the development trends in microwave magnetism and superconductivity over the last five decades. The review contains the key results of recent studies related to the promising areas of modern magnetism and applied physics – spintronics, magnonics, magnon caloritronics, physics of magnonic crystals, spin-wave logic, and the development of novel micro- and nano-scale magnetic devices. The main achievements in these fields of physics are summarized and generalized.

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