Gevers Bianca R, Naseem Sajid, Leuteritz Andreas, Labuschagné Frederick J W J
University of Pretoria Lynnwood Road, 0002 Pretoria South Africa
Leibniz-Institut für Polymerforschung Dresden e. V. Hohe Straße 6 01069 Dresden Germany.
RSC Adv. 2019 Sep 9;9(48):28262-28275. doi: 10.1039/c9ra05452a. eCollection 2019 Sep 3.
Comparison of layered double hydroxides (LDHs) synthesised using different methods, conditions and post-treatment is difficult to achieve because these greatly modify their material properties. This paper aims to provide a comparison of material properties for modified quintinite, where all LDHs were synthesised at the same conditions - thus allowing for direct comparison of the material properties obtained. Nano-structured materials were formed in all cases. The nano-structured transition metal (TM) MgMAl-LDHs were synthesised using constant pH co-precipitation. Five TMs (M = Fe, Co, Ni, Cu, Zn) were included in the LDH layers with molar substitutions of 0.5%, 1%, 5%, 10%, and 25% based on Mg-replacement for divalent TM cations and Al-replacement for trivalent TM cations. The materials were characterised using powder X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared analysis (ATR-FTIR), thermogravimetric analysis (TGA) and particle size analysis (PSA). The modified LDHs were synthesised free of major by-products and with similar morphologies. It could be shown that the crystallite dimensions varied between the different TM substitutions, that morphological changes were visible for some of the TMs used, that the processability depended on the TMs substituted, and that the substitution of TMs influenced the thermal stability of the LDHs.
由于不同的合成方法、条件和后处理会极大地改变层状双氢氧化物（LDHs）的材料特性，因此很难对使用这些方法合成的LDHs进行比较。本文旨在对改性水滑石的材料特性进行比较，所有的LDHs都是在相同条件下合成的，从而可以直接比较所获得的材料特性。在所有情况下都形成了纳米结构材料。采用恒pH共沉淀法合成了纳米结构过渡金属（TM）MgMAl-LDHs。在LDH层中包含了五种过渡金属（M = Fe、Co、Ni、Cu、Zn），基于二价TM阳离子的Mg替代和三价TM阳离子的Al替代，其摩尔取代率分别为0.5%、1%、5%、10%和25%。使用粉末X射线衍射（XRD）、X射线荧光光谱（XRF）、扫描电子显微镜（SEM）、衰减全反射傅里叶变换红外分析（ATR-FTIR）、热重分析（TGA）和粒度分析（PSA）对材料进行了表征。合成的改性LDHs不含主要副产物，且具有相似的形态。结果表明，不同TM取代之间的微晶尺寸不同，使用的一些TM存在明显的形态变化，可加工性取决于所取代的TM，并且TM的取代会影响LDHs的热稳定性。
