The first attempt was made to determine the grain-boundary enthalpy and its grain-size dependence in an elemental nanocrystalline material. The nanocrystallization of amorphous Se was carried out by means of isothermal annealing. Calorimetric measurements showed that the grain-boundary enthalpy decreased with decreasing grain size of the samples. This behavior was consistent with other related measurements, and with computer-simulation results, and implied that the intrinsic nature of a grain boundary in a polycrystal varied with crystallite dimensions in the nanometre regime.

K.Lu, N.X.Sun: Philosophical Magazine Letters, 1997, 75[6], 389-95