当前位置: X-MOL 学术Bull. Mater. Sci. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases
Bulletin of Materials Science ( IF 1.8 ) Pub Date : 2020-06-15 , DOI: 10.1007/s12034-020-02126-2
Latha Pachayappan , P Vishnu Kamath

Imbibition of lithium sulphate into aluminium hydroxide is known to result in a sulphate-intercalated layered double hydroxide (LDH) of Li and Al. The perchlorate ion has the same size and molecular symmetry as the sulphate ion, but only half its charge. Consequently, twice the number of $$\hbox {ClO}_{4}^{-}$$ ClO 4 - ions is needed to balance LDHs the charge on the metal hydroxide layer, compared to the $$\hbox {SO}_{4}^{2-}$$ SO 4 2 - ions. In this work, the $$\hbox {ClO}_{4}^{-}$$ ClO 4 - -intercalated LDHs were obtained from both the bayerite and gibbsite precursors. Inclusion of the hydration sphere along with the $$\hbox {ClO}_{4}^{-}$$ ClO 4 - anion, induced turbostratic disorder in the stacking of the metal hydroxide layers. Temperature-induced dehydration ( $$T \sim 100$$ T ∼ 100 – $$140{^{\circ }}\hbox {C}$$ 140 ∘ C ) brought about a partial ordering in the interlayer region and the $$\hbox {ClO}_{{4}}^{{-}}$$ ClO 4 - ion oriented itself with one of its $$C_{{2}}$$ C 2 -axes parallel to the metal hydroxide layer. The close packing of $$\hbox {ClO}_{4}^{-}$$ ClO 4 - ions could be realized by the complete dehydration of LDH and the distribution of the $$\hbox {ClO}_{4}^{-}$$ ClO 4 - ions in all the available interlayer sites. In contrast, within the crystal of the sulphate analogue, the sulphate ions occupy only half the number of interlayer sites. The other half is occupied by the residual water molecules, as the sulphate analogue does not fully dehydrate even at elevated temperatures. This difference in the behaviour of the two LDHs has its origin in the large difference in the hydration enthalpies of the two anions.

中文翻译:

Li和Al的高氯酸盐插层层状双氢氧化物的可逆水合:脱水相的结构模型

已知将硫酸锂吸入氢氧化铝会导致锂和铝的硫酸盐插入层状双氢氧化物 (LDH)。高氯酸根离子与硫酸根离子具有相同的大小和分子对称性,但电荷仅为其一半。因此,与 $$\hbox {SO} 相比,需要两倍数量的 $$\hbox {ClO}_{4}^{-}$$ ClO 4 - 离子来平衡 LDHs 和金属氢氧化物层上的电荷_{4}^{2-}$$ SO 4 2 - 离子。在这项工作中,$$\hbox {ClO}_{4}^{-}$$ ClO 4 - - 插入的 LDH 是从三羟铝石和三水铝石前体中获得的。将水合球体与 $$\hbox {ClO}_{4}^{-}$$ ClO 4 - 阴离子一起包含在金属氢氧化物层的堆叠中会引起湍流紊乱。温度引起的脱水( $$T \sim 100$$ T ∼ 100 – $$140{^{\circ }}\hbox {C}$$ 140 ∘ C )导致层间区域的偏序和 $$ \hbox {ClO}_{{4}}^{{-}}$$ ClO 4 - 离子以其 $$C_{{2}}$$ C 2 - 轴之一平行于金属氢氧化物层而定向自身。$$\hbox {ClO}_{4}^{-}$$ ClO 4 - 离子的密堆积可以通过LDH的完全脱水和$$\hbox {ClO}_{4}的分布来实现^{-}$$ ClO 4 - 所有可用层间位点中的离子。相反,在硫酸盐类似物的晶体中,硫酸根离子仅占据层间位点数量的一半。另一半被残留的水分子占据,因为硫酸盐类似物即使在升高的温度下也不会完全脱水。
更新日期:2020-06-15
down
wechat
bug