Novel measurement of proton distribution and site energies in metal hydrides

The low temperature electron spin resonance (ESR) spectrum of dilute Er in ScH/sub x/ and YH/sub x/ powders contains distinct signals which are due to the presence of octahedral as well as tetrahedral protons in the vicinity of the Er ions. The occupation probability for the octahedral protons is determined from the ESR signal intensities, and its variation with hydrogen-to-metal ratio x is explained by a lattice-gas calculation, yielding information about bulk proton distribution and relative site energies in these materials