A Research On Solid-liquid Equilibrium And Crystal Morphology Of Solid Solutions

Solid solution is a solid-state mixture with the molecules or atoms of solutes mixted in the crystal structure of solvent,which is a widespread phenomenon both in organic and inorganic fields,and has been widely researched in industrial crystallization and functional materials in the past decases.The formation of solid solutions may cause severe problems in the process of separation and purification,where the product purity is one of the most important attributes.Meanwhile,by adjusting the molecular of materials and the spatial arrangement or filling mode of molecules in crystals,we can obtain functional materials with specific properties.Therefore,both from the perspective of crystallization separation of solid solution and the preparation of solid solution functional materials,this work can provide a theoretical and practical guidance for the study of phase equilibrium relationship,crystallization kinetics,crystal microstructure and morphology of solid solution system.In this paper,In this paper,in order to research the separation of solid solution system and optimizing material by forming solid solution,anthracene,phenanthrene,carbazole and halogenated salicylideneaniline were seclected as model system.The phase equilibrium relationship and crystal behavior of discontinuous solid solution system and continuous solid solution have been researched comprehensively:(1)By analyzing the crystal structure of anthracene,phenanthrene and carbazole analysis,they have the potential for formation solid solution.By studying the thermodynamic properties and heating process of the solid solutions,it was found that they could form binary discontinuious solid solution.The lattice energies of the solid solution were calculated in simulation software,and the types of solid solutions were illustrated from the aspect of energy.(2)With scanning electron microscopy(SEM)and microscopy,the crystal morphology of solid solution were measured,it was found that there were two kinds of solid solutions in each binary solid solution system,whose crystal morphology was similar to the major components and changing with the concentration of minor component.Scanned by powdered X-ray diffraction,the result revealed that the crystal structure of solid solution changes continuously with the variation of composition,and crystal expansion wese observed.By using population balance model,the crystallization kinetics of binary solid solution of anthracene-phenanthrene and anthracene-carbazole were investigated.(3)Based on above research the crystallization behavior of solid solution,the solvents suitable for separation and purification of anthracene and carbazole from coal tar were selected.And the ability of separation was evaluated.An effective purification process of anthracene and carbazole by crystallization was developed and industrialized successfully.(4)Based on the analyzing the crystal structure of halogenated salicylaniline,it was found that these compounds likely to form continuous solid solutions.The thermodynamic properties and heating process were studied,the feasibility of forming continuous solid solution was verified.The crystal structure of solid solution with different mole fraction were analyzed by single crystal X-ray diffraction and powder X-ray diffraction.The randomly distribution of the molecules in solid solution was observed,and the crystal structure changed continuously with the composition was confirmed,accompanyied by crystal expansion.(5)The chromism properties of the model compounds and the solid solution were studied by the measurement of UV absorption.It was found that the absorbance intensity of solid solutions changed continuously with the composition,which can be explained from the aspect of crystal structure.