We demonstrate that the incompressibility of spinel Ge3N 4 nanocrystals decreases when the pressure is elevated above ∼20 GPa. Ge3N4 nanocrystals initially exhibit a higher bulk modulus of 381(2) GPa. But, above 20 GPa, the bulk modulus is apparently reduced to 268(4) GPa, which is similar to the reported bulk modulus of 208-296 GPa for the bulk Ge3N4. Thus, a threshold pressure of ∼20 GPa was determined that signifies the onset of size-induced disappearance of elastic stiffness in nanocrystalline Ge3N 4. Enhanced surface energy contributions to the shell layers of nanoparticles and resulting effect on the corresponding large d spacing planes are used to elucidate the observed phenomenon. This study provides a reasonable explanation for the different compressibility properties of numerous nanocrystals.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry