Micro/Nanoscale Research On Crystallization Behaviors Of Copper Compounds

As one kind of inorganic functional materials,copper-based micro/nanomaterials present some novel properties and wide applications.In this dissertation,copper compounds (i.e.,cuprous oxide,copper hydroxyphosphate,malachite,lindgrenite,cuprous thiocyanate, and ammonium copper molybdate) were investigated.The aim is to explore the synthesis of complex micro/nanostructure copper compounds by solution routes.Their growth mechanisms and crystal shapes were investigated.Cuprous oxide(Cu₂O) was selected in this study to elucidate the shape evolution in the cubic crystal system.A wide range of novel cuprous oxide microcrystals(based on the five branching growth patterns) has been prepared through an EDTA reduction route by employing EDTA molecule as chelating reagent,reductant,and sorbent.The morphology of these microcrystals has a strong dependence on the reaction conditions,which implies vast possibilities of designing new crystal morphologies.Copper hydroxyphosphate(Cu₂(OH)PO₄) with complex architectures has been successfully synthesized through a hydrothermal route. Single-crystals,twinned-crystals,and various novel architectures of copper hydroxyphosphate were constructed through a careful control of synthetic parameters.Copper hydroxyphosphate crystals tend to grow along the c-axis and have a rotation twinned growth habit,which is essential for the formation of various complex architectures.Malachite(Cu₂(OH)₂CO₃) with a hierarchical sphere-like architecture has been successfully synthesized via a hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates.The hierarchical malachite particles are comprised of numerous two-dimensional micro-platelets paralleling to the sphere surface. The growth of the hierarchical architecture is believed to be a layer-by-layer growth process. Copper oxide with the similar morphology can be easily obtained from the as-prepared malachite.Lindgrenite(Cu₃(OH)₂(MoO₄)₂) with a hollow and prickly sphere-like architecture has been synthesized via the same hydrothermal route.The hierarchical lindgrenite particles are hollow and prickly spheres,which are comprised of numerous small crystal strips that are aligned perpendicularly to the spherical surface.Ostwald ripening in solution is responsible for the hollow structure.Furthermore,Cu₃Mo₂O₉ with the similar size and morphology can be easily obtained by a thermal treatment of the as-prepared lindgrenite in air atmosphere. A novel strategy has been designed to form upended taper-shaped cuprous thiocyanate (β-CuSCN) arrays and curved ammonium copper molybdate((NH₄)₂Cu(MoO₄)₂) nanoflakes on a copper substrate using a solution-phase method at room temperature.This method consists in a liquid-solid reaction between a solution of thiocyanate ammonium and the copper substrate itself in the assistance of fonnamide.Novel cuprous thiocyanate arrays are approximately perpendicular to copper substrate surfaces.Every single crystal shows an upended taper-like morphology.Cuprous thiocyanate crystals tend to grow along the c-axis, which is essential for the formation of cuprous thiocyanate arrays on a copper substrate.The lamellar ammonium copper molybdate are approximately perpendicular to the copper substrate surface and are intermeshed with each other to form nanogroove structures. Formamide molecules can not only promote the oxidation of copper substrate and the formation of copper-complex,but also act as NH₄⁺ source in the final products.Furthermore, the selective adsorption of formamide molecules on different crystallographic planes of ammonium copper molybdate plays the major role in determining the curved morphology.