Advances in Applied NanoBio-Technologies 2021, Volume 2, Issue 2, Pages: 49-52 49 Adv. Appl. NanoBio Tech. ISSN:2710-4001 Influence of phosphor precursors on the morphology and purity of sol–gel-derived hydroxyapatite nanoparticles Kh.Yousefi 1* , A.R.Khalifeh 2 1 Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran. 2 Department of Inspection, Shiraz Petrochemical Complex, Shiraz, Iran. Abstract In this study nano crystalline hydroxyapatite (HA) particles were produced by both sol-gel and precipitation methods. For this purpose calcium nitrate tetra hydrate (Ca(NO3)2·4H2O) was selected as calcium precursors and three types of phosphorus precursors such as acid phosphoric (H3PO4) , triethyl phosphate (C2H5O)3PO and pentad oxide phosphorus (P2O5) were chosen. The produced powders were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that although hydroxyapatite can be produced by all phosphorus precursors used in the current research, the purity of HA obtained from penta oxide phosphorus and phosphoric acid is higher than that of triethyl phosphate. The SEM micrographs prove that the morphology of nano-HAP depends on the type of phosphorus precursor .The HAP prepared from acid phosphoric was spherically shaped whereas the one from triethyl phosphate is needle like and from penta oxide phosphorus was found to be Pyramidal in shape. Keywords: Hydroxyapatite, Sol-gel, Precipitation, Phosphor preceusor. 1 Introduction Hydroxyapatite is a ceramic which most important feature is the bioactive, so it can establish chemical bond with tissue and therefore it has a wide application in medicine and dentistry [1, 2]. It has been used for the construction of orthopedic implants, porous scaffold, filling bone defects, making dental implants, dental fillings, and etc [3, 4]. Several different HA synthesis techniques have been developed in recent years. To obtain HA with good morphology, nano particle size, and high purity, efficient production methods should be considered [5-7]. These techniques include mechanochemical synthesis [5, 8, 9], various type of wet chemistry techniques such as direct precipitation from aqueous solutions [6], electrochemical deposition [10], sol–gel [11],and hydrothermal synthesis [12]. Among these methods, sol– gel synthesis of HA ceramics has recently attracted much attention, due to its many advantages which include high product purity, homogeneous composition, and low synthesis temperature [13]. But in sol-gel method many parameters affect properties of product. These parameters are hydrolyzing time, aging time, temperature reaction, types of precursor and so on [14, 15]. Researchers have been carried out many investigations to improve the sol-gel method. Effects of parameter changes such as hydrolyzing time [16, 17], aging time [18, 19], temperature reaction [20], calcium precursor [21]. Also in sol-gel method, different phosphor precursor are used which affect hydrolyzing and aging time. As a result, they affect HA properties but the effect of phosphor precursor not yet has been studied. Features of HA, including Biocompatibility and degradation, depend on particle morphology, purity and particle size[22, 23]. So in this study different phosphor materials were used and purity and morphology of obtained phases were compared with each other. 2 Material and methods 2.1 Material Materials that were used in three tests have been listed in Table 1. Table 1: Used materials Test No Calcium presursor Phosphor presursor Solvent Test 1 Ca(NO3)2.4H2O H3PO4 water Test 2 Ca(NO3)2.4H2O P2O5` Ethanol Test 3 Ca(NO3)2.4H2O (C2H5O)3PO Ethanol + water 2.2 Methods Three type of phosphor precursors were used in this study. In test 1, first 0.25M H3PO4 was prepared in distilled water. 0.1M calcium nitrate tetra hydrate was prepared by completely dissolving in distilled water. This calcium solution was slowly Corresponding author: Kh.Yousefi, Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran. E-mail: Khadije.yousefi@gmail.com