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首页> 外文会议>NATO Advanced Research Workshop on Nanostructured Materials and Coatings for Biomedical and Sensor Applications Aug 4-8, 2002 Kyiv, Ukraine >PREPARATION OF HYDROXYAPATITE NANOPARTICLES USING A MODIFIED PRECIPITATION METHOD
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PREPARATION OF HYDROXYAPATITE NANOPARTICLES USING A MODIFIED PRECIPITATION METHOD

机译：改进的沉淀法制备羟基磷灰石纳米颗粒

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Hydroxyapatite (HAp) is the primary constituent of the human hard tissues. The preparation of fine and well sinterable HAp powder is the most important step in fabrication of bioceramics. HAp nanoparticles were prepared using rapid increase of the pH value, by adding an amount of concentrated NH_4OH solution, of a well-mixed solution of Ca(H_2PO_4)_2·H_2O and CaCl_2 with stoichiometric atomic ratio of Ca/P. This modified precipitation method is called "pH shock wave method". The XRD and FTIR analyses indicated that the precipitated powder was crystallized HAp. The HAp was stable during calcination at 550℃, while a significant amount of β-Ca_3(PO_4)_2 appear at 800℃. The TEM micrograph showed arbitrary morphology of nanoparticles, with average grain size of ～80-200 nm in length, and of ～10-30 nm in width and thickness. The adsorption isotherm of HAp was typical for nonporous particles. The specific surface area of powder was 74 m~2 · g~(-1). The chemical analysis indicates the formation of nonstoichiometric hydrated HAp with empirical formula Ca_(8.86)(HPO_4)_(1.28)(PO_4)_(4.72)(OH)·7.50H_2O and atomic ratio of Ca/P equal to 1.477. The lattice parameters were different from standard ones, due to the presence of HPO_4~(2-) groups in the powder. The sizes of the crystallites responsible for the Bragg reflection of (002) and (300) planes were 31.1 and 14.9 nm, respectively, indicating anisotropic growth with maximum along the <001> direction. The HAp particles form aggregates, which average diameter is 1-5 μm. In the interspaces between the aggregated particles, the water remained entrapped after drying. The thermogravimetric analysis confirmed the above mentioned conclusions. The formation of β-Ca_3(PO_4)_2 took place at about 780℃. Sintering of a unixially compressed cylindrical specimen, took place mainly in the temperature range from 800 to 1150 ℃.
机译：羟基磷灰石（HAp）是人类硬组织的主要成分。精细且可烧结性好的HAp粉末的制备是生物陶瓷制造中最重要的步骤。通过添加一定浓度的NH_4OH溶液，Ca（H_2PO_4）_2·H_2O和CaCl_2的化学溶液原子比为Ca / P的充分混合的溶液，通过快速增加pH值来制备HAp纳米颗粒。这种改进的沉淀法称为“ pH冲击波法”。 XRD和FTIR分析表明，沉淀的粉末结晶为HAp。在550℃煅烧过程中HAp稳定，而在800℃出现大量的β-Ca_3（PO_4）_2。 TEM显微照片显示出纳米粒子的任意形态，平均晶粒长约80-200 nm，宽度和厚度约10-30 nm。 HAp的吸附等温线是无孔颗粒的典型特征。粉末的比表面积为74m〜2·g〜（-1）。化学分析表明，形成了非化学计量水合HAp，其经验公式为Ca_（8.86）（HPO_4）_（1.28）（PO_4）_（4.72）（OH）·7.50H_2O，且Ca / P的原子比等于1.477。由于粉末中存在HPO_4〜（2-）基团，晶格参数与标准参数不同。负责（002）和（300）平面布拉格反射的微晶尺寸分别为31.1和14.9 nm，这表明各向异性生长沿<001>方向最大。 HAp颗粒形成聚集体，平均直径为1-5μm。在聚集的颗粒之间的空隙中，水在干燥后仍然被截留。热重分析证实了上述结论。 β-Ca_3（PO_4）_2的形成发生在约780℃。单轴压缩的圆柱试样的烧结主要发生在800至1150℃的温度范围内。

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