Guo Linghong, Huang Mei, Zhang Xingdong
Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China.
J Mater Sci Mater Med. 2003 Sep;14(9):817-22. doi: 10.1023/a:1025048724330.
It is obvious that the sintering temperature of hydroxyapatite (HA) ceramics significantly affects their biological responses in vitro or in vivo. The HA ceramics sintered at different temperatures exhibit a wide variation of biological response, but the correlation of this variation with the parameters of HA crystalline structure is not fully investigated. In present study, the crystalline structure of HA powders sintered at different temperatures at 600, 800, 1000, 1200 degrees C, was characterized using X-ray diffraction (XRD), and then refined with Rietveld method. A series of structure parameters, such as, cell lattice parameters (a and c) and bond length, distances of special atoms on surface to nearest atom, a numerical index of distortion for PO(4) tetrahedron, as well as internal energy and density of HA cell, were calculated to characterize the crystalline structure of HA at atom level. The broadening effect of XRD reflections was also separated to calculate the micro-strain/crystalline size, respectively. These parameters of HA crystalline structure and cell demonstrated that with rising of the sintered temperature, the internal energy and micro-strain of HA cell decreased, but the crystalline size increased. The regularity of PO(4) tetrahedron and distance between Ca(1) and O(3) in HA cell showed the same tendency as the internal energy and micro-strain with sintering temperature. All of these parameters indicated that HA became more stable with the rising of sintering temperature.
显然，羟基磷灰石（HA）陶瓷的烧结温度会显著影响其在体外或体内的生物学反应。在不同温度下烧结的HA陶瓷表现出广泛的生物学反应差异，但这种差异与HA晶体结构参数之间的相关性尚未得到充分研究。在本研究中，使用X射线衍射（XRD）对在600、800、1000、1200℃不同温度下烧结的HA粉末的晶体结构进行了表征，然后用Rietveld方法进行了精修。计算了一系列结构参数，如晶胞参数（a和c）、键长、表面特殊原子到最近原子的距离、PO(4)四面体的畸变数值指数，以及HA晶胞的内能和密度，以在原子水平上表征HA的晶体结构。XRD反射的展宽效应也被分离出来分别计算微观应变/晶体尺寸。HA晶体结构和晶胞的这些参数表明，随着烧结温度的升高，HA晶胞的内能和微观应变降低，但晶体尺寸增大。HA晶胞中PO(4)四面体的规则性以及Ca(1)和O(3)之间的距离与烧结温度下的内能和微观应变表现出相同的趋势。所有这些参数表明，随着烧结温度的升高，HA变得更加稳定。
