Consani Sirio, Balić-Žunić Tonci, Cardinale Anna Maria, Sgroi Walter, Giuli Gabriele, Carbone Cristina
Dipartimento di Scienze della Terra dell'Ambiente e della Vita (DISTAV), University of Genova, Corso Europa 26, Genova 16132, Italy.
Department of Geosciences and Natural Resource Management, Copenhagen University, Øster Voldgade 10, Copenhagen K 1350, Denmark.
Materials (Basel). 2018 Jan 14;11(1):130. doi: 10.3390/ma11010130.
A synthetic Cu-Al-SO₄ layered double hydroxide (LDH), analogue to the mineral woodwardite [CuAl(SO₄)(OH)₂·nH₂O], with x < 0.5 and n ≤ 3x/2, was synthesised by adding a solution of Cu and Al sulphates to a solution with NaOH. The pH values were kept constant at 8.0 and 10.0 by a continuous addition of NaOH. The material obtained had poor crystallinity, turbostratic structure, and consisted of nanoscopic crystallites. The analyses performed in order to characterise the obtained materials (X-ray diffraction (XRD), thermogravimetry (TG), and Fourier Transform Infra-Red (FTIR) spectroscopy) showed that the Cu-Al-SO₄ LDH is very similar to woodwardite, although it has a smaller layer spacing, presumably due to a lesser water content than in natural samples. The synthesis was performed by adding light rare earth elements (LREEs) (La, Ce, and Nd) and heavy rare earth elements (HREEs) (Gd and Y) in order to test the affinity of the Cu-Al-SO₄ LDH to the incorporation of REEs. The concentration of rare earth elements (REEs) in the solid fraction was in the range of 3.5-8 wt %. The results showed a good affinity for HREE and Nd, especially for materials synthesised at pH 10.0, whereas the affinities for Ce and La were much lower or non-existent. The thermal decomposition of the REE-doped materials generates a mixture of Cu, Al, and REE oxides, making them interesting as precursors in REE oxide synthesis.
一种合成的铜铝硫酸根层状双氢氧化物（LDH），类似于矿物羟铜铝矾[CuAl(SO₄)(OH)₂·nH₂O]，其中x < 0.5且n ≤ 3x/2，通过将硫酸铜和硫酸铝溶液加入到氢氧化钠溶液中合成。通过持续加入氢氧化钠将pH值保持在8.0和10.0不变。所得材料结晶度差，具有乱层结构，由纳米微晶组成。为表征所得材料进行的分析（X射线衍射（XRD）、热重分析（TG）和傅里叶变换红外（FTIR）光谱）表明，铜铝硫酸根LDH与羟铜铝矾非常相似，尽管其层间距较小，推测是由于水含量低于天然样品。通过添加轻稀土元素（LREEs）（La、Ce和Nd）和重稀土元素（HREEs）（Gd和Y）进行合成，以测试铜铝硫酸根LDH对稀土元素掺入的亲和力。固体部分中稀土元素（REEs）的浓度在3.5 - 8 wt%范围内。结果表明对重稀土元素和Nd具有良好的亲和力，特别是对于在pH 10.0合成的材料，而对Ce和La的亲和力则低得多或不存在。掺杂稀土元素的材料的热分解产生铜、铝和稀土氧化物的混合物，使其成为稀土氧化物合成中有趣的前驱体。
