【摘要】 在碳酸羟基磷灰石(CHA)结构分析中,对A型取代(CO32-取代OH-)和B型取代(CO32-取代PO43-)2种取代的稳定性仍存有争议。为了研究碳酸取代的可能位置和2种取代稳定性,本文利用计算机辅助手段详细研究了不同反应顺序和不同反应试剂对碳酸羟基磷灰石晶体结构的影响。本实验分别采用含Na和不含Na2种不同的反应试剂,分别在HA生成过程中和HA生成以后加入CO32-,通过离子共沉淀法制备了4种碳酸羟基磷灰石。通过X射线衍射(XRD)、红外光谱(IR)对他们的结构和基团进行了表征,并用Jade6.5,MaterialsStudio4.0以及Origin7.0进行了精修、计算和拟合。结果表明,无论工艺过程如何变化,均主要生成晶体能量较低、晶格结构稳定的B型取代碳酸羟基磷灰石;与普通磷灰石相比,由于存在晶格畸变,因此碳酸取代磷灰石的结晶度下降;碳酸根在反应溶液中的浓度影响CHA的晶格畸变程度,较高游离碳酸浓度引起的晶格畸变大;Na+的引入,可以降低碳酸羟基磷灰石中的晶格畸变,从而提高结晶度;含Na的B型取代主要是取代Ca(Ⅱ)位置的Ca离子。IR分析结果表明四种碳酸羟基磷灰石中的CO32-均以B型取代为主,通过对870cm-1附近峰的拟合,计算出材料中A型取代和B型取代的比值。更多还原

【Abstract】 There are two types of carbonate substitution in carbonated hydroxyapatite(CHA),including Type-A(OH-was substituted by CO32-)and Type-B(PO43- was substituted by CO32).But there is an uncertainty about the stability between Type-A and Type-B substitution.Four kinds of carbonated hydroxyapatites were prepared with different reagents(with and without Na salt)and methods(CO32- was added into the solution during or after the process),in order to research the possible site of carbonate substitution in CHA and the stability of both carbonate substitution.The data were refined,fitted and calculated with Jade 6.5,Materials Studio 4.0 and Origin 7.0.The results showed that lattice distortion in the structure of the carbonated hydroxyapatite has occurred,resulting in lower crystallinity.Type-B carbonate substitution had less crystal energy but better stability than Type-A.Among the type-B substituent CO32- in the crystal structure,CO3/Na processed the most stable structure,and the substituent Na took the place of Ca(Ⅱ).It was also found that the incorporation of Na+ would decrease the lattice distortion of carbonate hydroxyapatite and improve its crystallinity.Fitting spectrum of the characteristic peak of CO32- at 870cm-1 showed that more type-B CO32- substitution was present in the carbonate hydroxyapatite than Type-A CO32- substitution.The type-B substitution/Type-A substitution ratios have also been calculated according to the IR fitting spectrum.更多还原