Isotope effect in manganites and hydrogenated palladium

A theory of the isotopic dependence of the hydrogen content in palladium an d the excess oxygen content in manganites is formulated. The theoretical re sults for the first system are obtained without any fitting parameters and reproduce the experimental data within 2-3% error limits in the temperature range from 170 K to 1450 K. An exact expression for the magnitude of the e ffect is also obtained for the second system, but owing to the lack of nece ssary experimental data, it can only be estimated in order of magnitude. (C ) 1999 American Institute of Physics. [S1063-7834(99)00312-3].