Use of layered double hydroxides as a new route to prepare nanostructured ceramic materials.

A.V. Lukashin

In the present work the new method of synthesis functional nanostructured materials was suggested. This method is based on use anion- and cation-substituted layered double hydroxides (LDH) as a precursors with subsequent chemical modification. It combines simplicity of chemical methods of synthesis and possibility of obtainment two- and one-dimensional nanoparticles in ceramic matrixes. Layered double hydroxides is the class of layered inorganic compounds with general formula M'1-xM''x(OH)2[(anion)x/nmH2O], where M' and M'' are metals in the oxidation state +2 and +3 respectively, and anionn- is almost any anion, which does not form stable complexes with M' and M''. Their structure consists of positively charged hydroxide layers [M'1-xM''x(OH)2]x+, which are bonded by negatively charged anions placed within the interlayer space. Due to the relatively large interlayer distance, anions in LDHs are readily exchanged and it is possible to obtain species with practically stoichiometric content of an appropriate anoinn-. When anionn- undergoes some reaction, hydroxide layers of LDH restrict the reaction area. Thus, interlayer space of LDH may serve as a two-dimensional nanoreactor. The chemical modification of substituted LDH allows to obtain wide range of materials, having various functional properties. Suggested method was successfully used for prepare magnetic nanomaterials (M/matrix, MOx/matrix; M = Fe, Co, Ni; matrix = Mg1-xAlxO1+x/2) and semiconductors quantum dots (PbS/matrix, matrix = Mg1-xAlx(OH)2[(anionn-)x/n mH2O]).