The Solution-Based Synthesis And Morphology Control Of Inorganic Particle Materials

The controlled synthesis of inorganic nano- or micro-scale materials with specific size and morphology has been a key issue in modern synthesis of materials and fabrication of nano-diveces.This paper aimed to explore new chemical routes for the synthesis of inorganic particle materials.Several easy,facile solution-synthesis techniques have been developed.By systematical adjusting the crucial factors in the reaction system,SnS,MnS,PbWO₄ and CaCO₃ micro-particles with controllable morphology and size have been successfully synthesized and the possible formation mechanisms for these materials have also been discussed.The results can be summarized as follows:1.Novel dendrite-like SnS micro-crystals have been successfully synthesized by a solvothermal reaction of SnCl₂.2H₂O and thiourea at 200℃in a mixed solvent of ethylenediamin(En)and dodecanethiol(De)for 24 h.The concentration of SnCl₂.2H₂O and volume ratio of En to De in the mixed solvent in the reaction system will remarkably affect the morphologies of the products.A series of SnS crystals with distinctive structures have been obtained by systematical adjusting these factors and primary formation mechanism have also been studied.2.Novel flower-likeα-manganese sulfide(MnS)particles were solvothermally synthesized via a precipitation of MnCl₂.4H₂O and thiourea(Tu)in ethylene glycol solvent at 180℃.The influence of experimental parameters,including reaction temperatures and time,molar ratio of MnCl₂.4H₂O to Tu,and solvents on the morphologies of the products were investigated.A possible formation mechanism was proposed to explain the formation of flower-like MnS particles.3.PbWO₄ particles with different morphologies,such as dendrite,needle, polyhedron and fishbone,were prepared in O/W microemulsion containing surfactant SDBS,chloroform,n-pentanol and aqueous solution.It was found that the presence of single surfactant SDBS or chloroform,could alter the morphology of the products. The influence of the amounts of SDBS,pH value and temperature on the morphologies of the products was studied. 4.Novel calcite hollow microspheres attached bundles of aragonite needles have been successfully synthesized via a simple precipitation reaction of aqueous solutions of CaCl₂ and Na₂CO₃ in the presence of Mg²⁺ions at room temperature.The experimental results revealed that an appropriate molar ratio of[Mg²⁺]/[Ca²⁺](R),pH value of the solution and aging time are crucial for the formation of the unusual hierarchical CaCO₃ superstructure.A possible growth mechanism was proposed.5.Peanut-shaped CaCO₃ aggregates,featured of two dandelion-like heads built up from rod-like subunits,have been synthesized via a facile precipitation reaction between Na₂CO₃ and CaCl₂ at ambient temperature in the presence of magnesium ions and ethanol solvent.It was found that a high magnesium concentration and ethanol solvent are necessary for the formation of the unusual peanut-like aggregates. A possible mechanism for the formation of the unusual peanut-shape aggregates has been proposed and discussed.6.The morphogenesis and phase changes of calcium carbonate in an ethanol/water mixed solvent in the presence of polyelectrolyte poly-(sodium 4-styrene-sulfate) (PSSS)were carefully investigated.The influence of the experimental parameters including the ethanol volume content in the mixed solvent,temperature,the molar ratio of[CO₃^2-]/[Ca²⁺](R),and the concentrations of PSSS and CaCO₃ on morphologies and polymorphs of CaCO₃ were studied.The lower R was beneficial to the formation of vaterite crystal,while higher R promoted the formation of the mixture calcite and vaterite crystal.It is believed that such multi-additives systems may offer a new way to control the morphology and polymorph of inorganic materials and could be also extended to other systems.7.Calcium carbonate particles with different surface structures were successfully prepared by the precipitation of sodium carbonate with calcium chloride in the presence of polyelectrolyte poly-(sodium 4-styrene-sulfate)(PSSS).The surface morphology or texture of CaCO₃ microspheres can easily be adjusted by varying the concentration of PSSS.The formation mechanisms of CaCO₃ particles with different morphologies were discussed.