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Energy of vacancy formation in rubidium
The thermal volume and linear expansion, and temperature variation of electrical resistance of pure rubidium metal was measured between 200 and 300°K. A deviation of these properties from a linear dependence on temperature was observed above 250°K. Assuming that the deviation was caused by the thermal generation of vacancies in the lattice, the energy of formation of 0.42(±0. 09) eV/atom and 0. 43(±0. 04)eV/atom was deduced from the data. The simultaneous measurement of the linear and volume expansion indicated that the vacancies contributed more to the volume than to the length, therefore casting considerable doubt on the relationship t3=3«. The energy of self diffusion was determined to be 0. 8 2(±0. 08) eV/ atom from the expansion of spherical samples of the metal.