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【答案】应助回帖
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爱与雨下: 金币+1 2013-03-25 19:22:52
X1213655221: 金币+50, 翻译EPI+1, ★★★很有帮助 2013-03-26 09:31:50
ref. only.
As shown in Fig. 2, the sample shows strong absorption peaks only at 712 cm- and 876 cm-1, which is in accordance with the characteristic peaks of calcite ((712 cm-1 and 876 cm-1). Comparison with the PDF standard card (card number: 05-0586) indicates that the diffraction peaks appeared in Fig. 3 (2θ=23.0°、29.4°、39.4°、47.5°) can be assigned to (012), (104), (113) and (018) facet of the calcite. This further demonstrates the product is pure calcite, consistent with the results of the FTIR. Fig. 4 shows that CaCO3 agglomerates in regular layer structure in pure water system, homogeneously distributed as cubic shape with grain size of ca. 3-6 nm. In summary, calcium carbonate forms pure calcite in pure water system.
Fig. 5 shows peaks at 712 cm-1, 745 cm-1, and 876 cm-1, which is consistent with the absorption peaks of calcite and vaterite ((745 cm-1、876 cm-1). The intensity difference of these peaks might be due to the content of the vaterite synthesized at different pH conditions. This demonstrates that the calcium carbonate synthesized at different pH conditions has both calcite and vaterite crystal forms , but the content of the latter might be different. |
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