A series of MgAl-NO3- -LDHs compounds with different x values (x=nAl3+/(nAl3++nMg2+) were synthesized by the coprecipitation method. The influence of the x values on interlayer environment of LDHs was studied. XRD patterns showed that the degree of crystallization increased when the x value decreased from 0.6 to 0.29. And the change of basal spacing of LDHs with x values suggested that the arrangement of NO3- between the- layers was changing. For x=0.6, a "flat-lying" model that the anions were parallel with layer plates was proposed, to the contrast, a "tilt-lying" model was possibly existed for x=0.29~0.5. And lattice parameter c increased with the decrease of x values, however, lattice parameter a, the crystal size along the vertical direction of (003) crystal face(D003) and the size along the vertical direction of (110) crystal face(D110) were intricately influenced by x values. The FT-IR spectrum revealed that the infrared activity of NO3- was strengthened for the samples of x=0.4~0.6, but it was weakened for the samples of x=0.29~0.33.%采用共沉淀法制备了不同层板中Al3+摩尔分数x值(x=nAl3+/(nAl3++nMg2+),其中x值为0.29～0.6)的MgAl-NO3-LDHs化合物,研究了Al3+摩尔分数对MgAl-NO3--LDHs层间域环境的影响.XRD分析表明,当x从0.6降至0.29时,MgAl-NO3--LDHs的结晶度逐渐提高.LDHs的层间距随x值减小而增大,NO3-由x为0.6时的与层板平行排布,变为x为0.29～0.5时的与层板呈倾斜排布.晶胞参数c随着x值的减小而增大,晶胞参数α、沿(003)晶面垂直方向上的晶粒尺寸D003和沿(110)晶面垂直方向上的晶粒尺寸D110受x值变化的影响较为复杂.FT-IR分析表明,在高x值(x为0.4～0.6)时MgAl-NO3--LDHs中NO3-基团的红外活性增强,而在低x值(x为0.29～0.33)时其红外活性减弱.
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