Effects of size on mass density and its influence on mechanical and thermal properties of ZrO2 nanoparticles in different structures

This study investigates the effect of size on mass density and its subsequent influence on the other physical parameters of zirconia nanoparticles in the structural forms of cubic, tetragonal and monoclinic. The general equations for these calculations are established based on the variation of lattice parameter model and surface internal atoms ratio. The mass density of nanoparticles differs from the bulk value when particle size decreases. At a diameter of 4 nm, the mass density values of zirconia nanoparticles are 3.898, 3.626 and 3.488 g ⋅ cm−3 compared to 6.25, 6.1 and 5.87 g⋅ cm−3 for bulk cubic, tetragonal and monoclinic forms, respectively. These results indicate that the variation in mass density is largely due to the differences on their boundaries and the variation in lattice parameters. The calculated results agree well with the available experimental data for the monoclinic form structure of ZrO 2 nanoparticles. The relationship between mass density and melting temperature; and Debye temperature and cohesive energy are proposed. All these parameters have the same nanosize dependence in this regard.