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Crystal Growth of Smectite: A Study Based on the Change in Crystal Chemistry and Morphology of Saponites with Synthesis Time
ACS Earth and Space Chemistry ( IF 3.4 ) Pub Date : 2019-12-11 , DOI: 10.1021/acsearthspacechem.9b00194 Chaoqun Zhang 1, 2, 3, 4 , Sabine Petit 2 , Hongping He 1, 4 , Frédéric Villiéras 5 , Angelina Razafitianamaharavo 5 , Fabien Baron 2 , Qi Tao 1, 4 , Jianxi Zhu 1, 4
ACS Earth and Space Chemistry ( IF 3.4 ) Pub Date : 2019-12-11 , DOI: 10.1021/acsearthspacechem.9b00194 Chaoqun Zhang 1, 2, 3, 4 , Sabine Petit 2 , Hongping He 1, 4 , Frédéric Villiéras 5 , Angelina Razafitianamaharavo 5 , Fabien Baron 2 , Qi Tao 1, 4 , Jianxi Zhu 1, 4
Affiliation
Smectites are 2:1 type swelling clay minerals widely distributed in the earth’s crust. The unique structures and properties endow them with various applications in many fields. However, their growth process and mechanism are still not completely understood. In this study, we tried to understand this growth process and pattern from the perspective of crystal chemistry and morphology. Smectites were synthesized by the hydrothermal treatment of starting materials at 220 °C under autogenous pressure from 0.25 to 30 days. The starting materials were obtained from the mixtures of Mg- and Ni-smectite precursors synthesized at 150 °C for 1 day with identical molar weights. The starting materials, as well as further synthesized samples, are identified as smectites, saponite-type, by X-ray diffraction analysis and Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra of the starting materials exhibited the νMg3OH and νNi3OH bands only. After the hydrothermal treatment (220 °C) of the starting materials, the νMg2NiOH and νNi2MgOH bands appear and relatively increase with the prolonged treatment, indicating the appearance of neighboring Mg–Ni in the octahedral sheet of saponite and thus the crystallization of the newly formed saponite with a mixed composition. Argon adsorption and scanning transmission electron microscopy (STEM) results are consistent and indicate that the mean particle size of the synthesized saponites increases for a short duration and tends to remain stagnant from 14 to 30 days. The evolution of Mg and Ni distribution and of the particle size from argon adsorption and STEM imply the following: (i) the distribution of the octahedral cations tends to be random; (ii) the combination of argon adsorption and STEM offers a powerful evidence for the increase of particle size; and (iii) crystal growth proceeds via a lateral extension of the layers by surface-controlled growth. The experimental results indicate the viability and effectiveness of coupling FTIR, argon adsorption, and STEM in illuminating the crystal chemistry and morphology at the early stage of the crystal growth process of smectite.
中文翻译:
蒙脱石的晶体生长:基于合成时间对皂石的晶体化学和形态变化的研究
蒙脱石是广泛分布在地壳中的2:1型溶胀粘土矿物。独特的结构和属性使它们在许多领域中具有各种应用。但是,它们的生长过程和机制仍不完全清楚。在这项研究中,我们试图从晶体化学和形态学的角度理解这种生长过程和模式。蒙脱石是通过在起始温度为0.25至30天,在220°C的条件下对原材料进行水热处理而合成的。原料是从Mg和Ni蒙脱石前体的混合物中获得的,该混合物在150°C下合成1天,具有相同的分子量。起始原料以及进一步合成的样品被鉴定为蒙皂石,皂石型,通过X射线衍射分析和傅立叶变换红外(FTIR)光谱。原材料的FTIR光谱显示νMg3 OH和νNi 3只OH频带。起始原料,νMg的水热处理(220℃)后2化NiOH和νNi 2随着处理时间的延长,MgOH谱带出现并相对增加,表明在皂角石的八面体片中出现了相邻的Mg-Ni,从而表明新形成的具有混合成分的皂石的结晶。氩气吸附和扫描透射电子显微镜(STEM)结果一致,表明合成皂苷的平均粒径在短时间内增加,并在14至30天趋于停滞。Mg和Ni分布的变化以及氩气吸附和STEM产生的粒度表明:(i)八面体阳离子的分布趋于无规;(ii)氩气吸附和STEM的结合为颗粒尺寸的增加提供了有力的证据;(iii)晶体生长是通过表面受控生长通过各层的横向延伸而进行的。实验结果表明,在蒙脱石晶体生长早期,FTIR,氩气吸附和STEM耦合在阐明晶体化学和形态方面的可行性和有效性。
更新日期:2019-12-13
中文翻译:
蒙脱石的晶体生长:基于合成时间对皂石的晶体化学和形态变化的研究
蒙脱石是广泛分布在地壳中的2:1型溶胀粘土矿物。独特的结构和属性使它们在许多领域中具有各种应用。但是,它们的生长过程和机制仍不完全清楚。在这项研究中,我们试图从晶体化学和形态学的角度理解这种生长过程和模式。蒙脱石是通过在起始温度为0.25至30天,在220°C的条件下对原材料进行水热处理而合成的。原料是从Mg和Ni蒙脱石前体的混合物中获得的,该混合物在150°C下合成1天,具有相同的分子量。起始原料以及进一步合成的样品被鉴定为蒙皂石,皂石型,通过X射线衍射分析和傅立叶变换红外(FTIR)光谱。原材料的FTIR光谱显示νMg3 OH和νNi 3只OH频带。起始原料,νMg的水热处理(220℃)后2化NiOH和νNi 2随着处理时间的延长,MgOH谱带出现并相对增加,表明在皂角石的八面体片中出现了相邻的Mg-Ni,从而表明新形成的具有混合成分的皂石的结晶。氩气吸附和扫描透射电子显微镜(STEM)结果一致,表明合成皂苷的平均粒径在短时间内增加,并在14至30天趋于停滞。Mg和Ni分布的变化以及氩气吸附和STEM产生的粒度表明:(i)八面体阳离子的分布趋于无规;(ii)氩气吸附和STEM的结合为颗粒尺寸的增加提供了有力的证据;(iii)晶体生长是通过表面受控生长通过各层的横向延伸而进行的。实验结果表明,在蒙脱石晶体生长早期,FTIR,氩气吸附和STEM耦合在阐明晶体化学和形态方面的可行性和有效性。