Calcium carbonate (calcite crystal form) was dry-ground with a vibration mill consisted of an alumina vessel and balls. ESR spectra and X-ray diffraction patterns of the ground samples were measured. SEM photographs of the samples were also taken. The root-mean-squared strain and crystallite sizes of the samples were determined by Stokes-corrected Fourier analysis of the X-ray peaks.
In the early stage of grinding, the amorphous calcium carbonate in the particles was deposited as aragonite crystalline on the surface of the calcite crystallite. And amorphous manganese, which was impurity for the amorphous calcium carbonate, was replaced by the position of Ca
2+ of the aragonite as Mn
2+. The aragonite was transformed to calcite in the middle stage of grin-ding. In further grinding, the amorphous calcium carbonate was deposited on the calcite crystallite surface as calcite. Then the position of Ca
2+ of the calcite was replaced by Mn
2+, and the ultrafine particles of the calcite crystallite were developed to be large mechanochemically calcined particles.
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