The role of the thermal history of the precursor was studied for amorphous and crystalline calcium carbon- ate phases synthesized from calcium nitrate. The X-ray diffraction patterns of these phases are influenced by ...The role of the thermal history of the precursor was studied for amorphous and crystalline calcium carbon- ate phases synthesized from calcium nitrate. The X-ray diffraction patterns of these phases are influenced by their annealing temperature of 0, 300, 400, and 500 ℃. However, the effect of the precursor thermal history on the X-ray diffraction pattern of the resulting calcium carbonate phase is negligible. Transmis- sion electron microscopy indicates that materials annealed at 400 ℃ consist of amorphous aggregates, irrespective of the precursor thermal history. The crystallite size of crystalline calcium carbonate is influ- enced by the precursor thermal history, and ranges from 23 to 26 rim. Near-edge X-ray absorption fine structure measurements indicate that the annealing temperature plays an important role in determining the local electronic structure. The role of the thermal history of the precursor is also important for the resultinu electronic structure.展开更多
文摘The role of the thermal history of the precursor was studied for amorphous and crystalline calcium carbon- ate phases synthesized from calcium nitrate. The X-ray diffraction patterns of these phases are influenced by their annealing temperature of 0, 300, 400, and 500 ℃. However, the effect of the precursor thermal history on the X-ray diffraction pattern of the resulting calcium carbonate phase is negligible. Transmis- sion electron microscopy indicates that materials annealed at 400 ℃ consist of amorphous aggregates, irrespective of the precursor thermal history. The crystallite size of crystalline calcium carbonate is influ- enced by the precursor thermal history, and ranges from 23 to 26 rim. Near-edge X-ray absorption fine structure measurements indicate that the annealing temperature plays an important role in determining the local electronic structure. The role of the thermal history of the precursor is also important for the resultinu electronic structure.
