First-Principles Calculations Of Transition Metal Ion Doped Apatites For The Potential Applications In Vivo Fluorescence Imaging

Vivo fluorescence imaging becomes an important medical technology due to its non-invasive detection character in various disease diagnoses and monitoring of therapeutic reactions.Among its various optical ranges,the second near infrared window located at the wavelength range of 1000-1350 nm has been recently paid more attention.At present,the medical materials scientists have focused on transition-metal-doped apatite materials in order to realize the near-infrared emission at1000-1500 nm,as the apatite materials are of very excellent biocompatibility and non-toxicity,and Mn⁵⁺ ions can be a good candidate for the required spectroscopic emission.Following the motivation activated by those potential applications,the present master degree thesis implemented the investigation of the structural,elastic,electronic and optical properties of transition-metal-doped apatite materials from the theoretical point of view and the results presented here are expected to be useful for the experimental studies in future.The studied objects are split into two categories: the host exploration and understanding optical impurities.In the former,we calculated 18 apatite materials A₅?BO₄?₃Z?A = Ca,Sr,Ba;B = P,V;Z = F,Cl,Br?by using density functional theory,and established the dependence of various physical properties on the host chemical components.As for the latter,Cr³⁺ and Mn⁵⁺ ions were chosen as the typical doping examples,and the doping effect on the structural and optical properties was analyzed by employing the exchange charge model.In Chapters 1 and 2,we made the reference retrieval on the previous theoretical and experimental reports of apatite luminescent materials,elaborated the research significance of transition-metal-?such as Mn5+-?doped apatite materials.Our reference retrieval cover the technique applications of new-type green lighting and vivo fluorescence imaging,the experimental analyses of transition-metal-and/or lanthanidedoped apatite materials,and understanding the calculation results of the first-principles and/or exchange charge models on the corresponding materials.The density functional theory is deemed to a good scheme for the regulation of the dependence of the host's properties on the host chemical components.On the other hand,the exchange charge model was chosen for the spectroscopic analysis of transition-metal impurities.In Chapters 3 and 4,we calculated the structural,elastic and electronic properties of 18 apatites A₅?BO₄?₃Z?A = Ca,Sr,Ba;B = P,V;Z = F,Cl,Br?in details.A high-throughput study gives the theoretical values and opens the feasibility of analyzing the component-property relationship.The dependence of the calculated physical properties on the host chemical components was briefly summarized as follows: 1)the lattice constants increase linearly with the increase of the atomic numbers of the host components;2)the elastic constants and other elastic parameters decrease linearly when the host components become heavy;3)the optical bandgap shows a linear decrease when the host components go to the bottom of the periodic table..In Chapter 5,Cr³⁺ and Mn⁵⁺ ions were selected for the purpose of demonstration,and the structural,electronic and optical properties of Al₂O₃:Cr³⁺,Be₃Al₂?Si O₃?6:Cr³⁺and Sr₅?PO₄?₃Cl:Mn⁵⁺ were calculated and compared with the experimental results given in the reference papers.It should be noticed that the exchange charge model plays an important role for understanding the optical properties of those doped materials.The energy level diagrams obtained in the present work can be a good roadmap for the spectroscopic analysis of Cr³⁺ and Mn⁵⁺-doped luminescent materials.Finally,we summarized all the results presented in the master degree thesis,and gave the prospect for the research jobs carried out in future.The present theoretical data obtained here are expected to facilitate the experimental studies of apatite luminescent materials.