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The Study On Crystal Growth Kinetics Based On Optical Interferometry

Posted on:2013-05-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:J ZhaoFull Text:PDF
GTID:1221330377451850Subject:Solid mechanics
Abstract/Summary:PDF Full Text Request
Crystal growth is a complex physicochemical process. The quality and morphology of crystal have direct relationships with crystal growth kinetics parameters, such as the concentration gradient near growth interface, supersaturation, crystal growth rate, and so on. Recently, some real-time measurement techniques have been proposed to monitor the crystal growth process. As a high sensitive, non-contact and quantitative measurement method, optical interferometry has become an important means in the research of crystal growth kinetics and crystal phase diagram. For the process of crystal growth from solution, especially for protein crystallization, current measurement methods are still unable to obtain the accurate absolute concentration, real-time supersaturation and other time dependent parameters.In this paper, a real-time monitoring system based on optical interferometry, phase-shift technique and temporal phase analysis method was proposed and developed. Using the system, the crystal growth processes of inorganic salt and protein have been investigated, and the main achievements are listed as follows.1) An experimental system to real-time monitor and control crystal growth process has been designed and established for quantitative measurement of crystal growth kinetics parameters, which consists of an optical monitoring system, a temperature control module and crystal growth cells. The phase retrieval methods were introduced into the system to monitor the x-y-t3D concentration distribution during the crystal growth process, including the phase shifting technique and the temporal phase analysis method. The analysis process, the measurement accuracy and the application field of temporal phase analysis method were also discussed.2) The concentration boundary around crystals, the convection phenomenon and the mass transfer process have been studied experimentally during the dissolution and crystallization processes of NaCl. The temporal phase analysis method was firstly employed in the crystal growth process experiments to extract the x-y-t3D absolute concentration distribution and the real-time supersaturation evolution. Based on the evaporation rate and the absolution concentration, a new method to study mass transfer process during the crystal growth without the knowledge of the mass transfer coefficient is proposed, and then the crystal growth rate can also be retrieved under the hypothesis of cubic crystals. The limiting supersaturation and the metastable zone width can also been obtained by the temporal phase analysis method, which would provide quantitative data for optimizing the crystal growth process.3) The final aim of real-time monitoring the crystal growth kinetics parameters is to optimize crystallization process and obtain crystals with good quality. Based on the experimental system, the effects of different evaporation rates and temperatures on the crystal growth and the quality of crystals were also investigated.4) The optical monitoring system was further improved to obtain several crystal growth kinetics parameters more precisely and quantitatively in ONE experiment, according to the characters of protein crystallization, such as long experiment period, weak effective signal, multi-concentration coupling and so on. The Lysozyme crystallization process with higher initial supersaturation was also studied and optimized in the last part of this thesis.
Keywords/Search Tags:crystal growth, temporal phase analysis, phase retrieval, phase shifting, protein crystallization
PDF Full Text Request
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