(中南大學(xué) 化學(xué)化工學(xué)院，長沙 410083)
摘 要: 用劍橋連續(xù)總能量軟件包(CASTEP)程序，對氫氧化鋁的各個經(jīng)常顯露面族的(001)、(100)、(010)、(011)、(110)、(101)和(112)面進(jìn)行理論計算，分析氫氧化鋁晶體的晶面顯露特征與表面化學(xué)鍵力的關(guān)系。對氫氧化鋁晶體的徑向長大、附聚長大的機制和晶體生長中晶面疊合方式以及同類面族、非同類面族間的疊合進(jìn)行研究。計算結(jié)果表明，對于長大后的氫氧化鋁晶體，當(dāng)(001)，(101)和(100)面為主要顯露面時，能量狀態(tài)較為穩(wěn)定；若(010)面顯露較多，長大后的晶體的能量穩(wěn)定性較差。氫氧化鋁的(001)面的前線價電子較為活躍，其晶面可能存在與鋁酸鈉溶液中不同形態(tài)的鋁酸根離子或者是晶體生長基元發(fā)生鍵合的“活性點”。鍵布居分析結(jié)果表明，整體上氫氧化鋁的(001)面的Al—O鍵的結(jié)合力不強，(011)和(110)面的Al—O鍵的平均鍵布居數(shù)較高，結(jié)合力較強；若小幅度降低(001)面的顯露比例，并使(110)和(011)面較多顯露，就有可能提高氫氧化鋁表面的Al—O鍵的結(jié)合力。
關(guān)鍵字: 氫氧化鋁；表面性質(zhì)；晶面疊合；機制
crystal surface combination
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:Based on the theoretic calculation of crystal faces (001), (100), (010), (011), (110), (101) and (112) of gibbsite by CASTEP program, the relationship between unfold character of crystal face and chemical bond strength of surface of gibbsite was investigated. The mechanism of precipitation and growth of sodium aluminate solution and crystal surface combination mode were studied. The combinations of same faces and different faces of gibbsite were investigated. The results show that the energy state of gibbsite is more stable when faces (001), (101) and (100) are mainly unfold faces, while the energy state would be instable when face (010) is mainly unfolded. Whereas the calculation result of electric structure shows that the front valence electron of face (001) of gibbsite is active correspondingly. That is there may be some activity points on this face. It is found that from bond population calculation results, the bonding strength of Al—O bond of faces (011) and (011) of gibbsite are stronger than that of face (001). If the proportion of unfold of (001) surface is decreased and the proportion of unfold of (011) and (011) surfaces is increased to same possible extend, the bonding strength of Al—O bond of gibbsite would be more strong.
Key words: gibbsite; surface property; crystal surface combination; mechanism
