| Abstract
| - To investigate surface properties of fractured silica particles, which are commonly connected to the etiologyof silica toxicity, models of low-index unrelaxed surfaces of quartz and kaolinite were constructed and analyzedusing the periodic density functional theory calculations. The models were used to investigate surface sitesthat emerge in the processes of heterolytic and homolytic cleavage of quartz. It is found that the quartzsurface is stabilized by two types of interactions. One, due to a more even charge distribution of sites, wascharacterized by surface energies of up to 0.025 eV·Å-2 and the other, due to a more even oxygen distributionbetween complementary surfaces, was up to 0.036 eV·Å-2. The total specific surface energies of unrelaxedsurfaces ranged from 0.161 to 0.200 eV·Å-2 for quartz and from 0.017 to 0.158 eV·Å-2 for kaolinite. For theconchoidal fracture of quartz an average specific surface energy of 0.187 eV·Å-2 was obtained. These resultsprovide a foundation for further characterization of the surface properties of mechanically comminuted respirablesilica particulate and for reduction of occupational health hazards due to pulverized silica.
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