| With the acceleration of the life level, the incidence of oral diseaseincreased. Oral care products with antibacterial have emerged. Currently theantibacterial agent added into the oral care products is mainly antibiotics，whichcan cause drug resistance and raise the threat of having cancer when longtimeused. Therefore，preparing a material that can release inorganic antibacterial ionas antimicrobial agent that used in oral health care product is an urgent issue.Hydroxyapatite has excellent biological activity, it can dissolve out dentalmineralization ions can be blocked to the damage of teeth when used, that canreduce sensitivity of the teeth. Tin element used in oral care products has a longhistory，mainly in SnF2as an additive. Hydroxyapatite contents Tin (II) materialcan both reduce tooth sensitivity and inhibit oral bacteria during usage.Three kinds of probably structural model of Hydroxyapatite contained Sn(II)was speculated depending on the chemical and structure property of Sn andHydroxyapatite. And defect formation energy of each model was calculated byABINIT code. Synthesis process was determined by the model which has lowerdefect formation energy. Then relation of lattice parameter, phase purity andprocess values was studied. Last, atom occupancy was solved by using Rietveldrefinement. The main contents and results are as follows:Three possible type of Sn(II) contained Hydroxyapatite model, Cal sitesubstituted，Ca2site substituted and P site substituted，was determinedaccording to the valence characteristics of Sn and the atom size inHydroxyapatite crystal. The final lattice parameter and defect formation energywas calculated by using ABINIT code with cell optimization option checked.And the final result shows that there is a high possibility that Cal site substituteand Ca2site substitute occurs in Sn(II) contained Hydroxyapatite.According to the characteristics of Cal site substitute model and Ca2sitesubstitute model，substitute type was determined as cat ionic substitution.Synthesis process was designed according to the structure of cat ionic substitute Hydroxy apatite. The relation between products and process parameter wasstudied by adjusting process parameter, the study results shows that:the processpH values has significant effect on phase purity and the best process pH values isshown as10; higher aging temperature can both lead to good crystalline powderand raise the possibility of the transform from Sn (II) to Sn (IV) and Sn(IV) isdifficult to enter the cell to substitute，the aging temperature set at20。C to80。Cis good to produce a higher substitute ratio product; the addition of Sn is helpto improve substitute ratio, Although Ca ion has a larger radius against Sn ion, ithas small electro negativity which cause Sn-0bond has an longer bond lengthagainst Ca-0bond. That is the reason why cell volume is increase when moreSn substitutes into cell.Finally, Rietveld refinement is conduct to refine the occupancy of Sn atom.By using whole pattern fitting method fit the XRD pattern of one sample, theinput model is designed to show the Sn atom occupancy against Cal site atom,Ca2site atom and P site atom. The refinement result suggest that Sn atomsubstitution occurs in Cal site (Sn atom occupancy is11.6%) and Ca2site (Snatom occupancy is7.4%). The result is matched the DFT calculation result andthe selected model. Therefore, The main substitution type of Sn(II) containedHydroxyapatite is metal cat ion substitution, the substitution occurs in both Calsite and Ca2site. |
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