Pajchel Lukasz, Kolodziejski Waclaw
Department of Inorganic and Analytical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, ul. Banacha 1, 02-097 Warsaw, Poland.
J Nanopart Res. 2013;15(8):1868. doi: 10.1007/s11051-013-1868-y. Epub 2013 Jul 30.
A series of nanocrystalline calcium hydroxyapatites was prepared by dry milling and characterized using proton and P MAS NMR, TEM, and TGA methods. The samples contained stubby rod-shaped crystals, which length and width varied in the 130-30 and 95-20 nm ranges, respectively. It was confirmed that concentration of structural hydroxyl groups in nanocrystalline apatites decreases with the decreasing crystal size. In the series of the studied apatites, the decrease was from 86 to ca. 50 % in reference to stoichiometric apatite. Water was found in the surface hydrated layer and in the -axis channels, in which compartments existed as adsorbed and structural, respectively. Molecules of the adsorbed water were capable of moving from the crystal surface into the lattice -axis channels of apatite. This process introduced considerable structural disorder within and around those channels and reduced the content of the structural hydroxyl groups, particularly in the region underneath the apatite crystal surface.
通过干磨制备了一系列纳米晶羟基磷灰石，并采用质子和磷的固体核磁共振（MAS NMR）、透射电子显微镜（TEM）和热重分析（TGA）方法对其进行了表征。样品包含短棒状晶体，其长度和宽度分别在130 - 30纳米和95 - 20纳米范围内变化。已证实，纳米晶磷灰石中结构羟基的浓度随晶体尺寸减小而降低。在所研究的一系列磷灰石中，相对于化学计量比的磷灰石，该浓度从86%降至约50%。在表面水化层和c轴通道中发现了水，其中水在这些区域分别以吸附态和结构态存在。吸附水的分子能够从晶体表面移动到磷灰石的晶格c轴通道中。这一过程在这些通道内部和周围引入了相当大的结构无序，并减少了结构羟基的含量，特别是在磷灰石晶体表面下方的区域。
