Journal of Alloys and Compounds 482 (2009) 199–202 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Parallelogram-like microparticles of calcium dihydrogen phosphate monohydrate (Ca(H 2 PO 4 ) 2 ·H 2 O) obtained by a rapid precipitation route in aqueous and acetone media Banjong Boonchom a,b,∗ a King Mongkut’s Institute of Technology Ladkrabang, Chumphon Campus, 17/1 M. 6 Pha Thiew District, Chumphon, 86160, Thailand b Department of Chemistry, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Ladkrabang, Bangkok, 10520, Thailand article info Article history: Received 23 November 2008 Received in revised form 25 March 2009 Accepted 26 March 2009 Available online 5 April 2009 Keywords: Calcium dihydrogenphosphate monohydrate Aqueous and acetone Rapid precipitation Parallelogram-like particles abstract Calcium dihydrogenphosphate monohydrate (Ca(H 2 PO 4 ) 2 ·H 2 O) was prepared by a rapid and simple pre- cipitation method using CaCO 3 and H 3 PO 4 in aqueous and acetone media at ambient temperature. The thermal transformation of the synthesized Ca(H 2 PO 4 ) 2 ·H 2 O at 500 ◦ C was obtained to be CaP 2 O 6 occurred through the dehydration and the phosphate condensation reactions, as revealed by thermoana- lytical techniques (TG/DTG/DTA). The synthesized Ca(H 2 PO 4 ) 2 ·H 2 O and its decomposition product CaP 2 O 6 were characterized by X-ray powder diffraction (XRD), Fourier transfer infrared (FTIR) spectroscopy and scanning electron microscope (SEM). Thermal behavior and the morphology of the synthesized Ca(H 2 PO 4 ) 2 ·H 2 O in aqueous and acetone media are compared with those of other works. The SEM micro- graph of Ca(H 2 PO 4 ) 2 ·H 2 O show parallelogram-like microparticles containing small and large grain sizes. The aqueous and acetone media are proposed to play an important role in the synthetic process of calcium phosphates in exhibiting different physical properties, which are important for specific applications. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Calcium phosphate compounds have been investigated exten- sively during the past 50 years. They are primarily used as bone substitutes in the biomedical industry due to their biocompati- bility, low density, chemical stability, high wear resistance, and their compositional similarity with the mineral phase of bone [1–10]. They are composed of ions commonly found in physiolog- ical environment, which make them highly biocompatible. They exist in different forms and phases depending on temperature, partial pressure of water and the presence of impurities [7,8]. Differ- ent forms and phases are used in different applications depending upon whether a resorbable or bioactive material is desired [10]. For example, HAp, -TCP, -TCP, biphasic calcium phosphate (BCP) [9], monocalcium phosphate monohydrate (MCPM) and unsin- tered apatite (AP) are different forms of commercially available calcium phosphates currently used in the biomedical industry. In addition, they exhibit considerably improved biological affin- ity and activity compared to other bioceramics such as alumina, zirconia, coralline, ALCAP (aluminum calcium phosphate ceram- ics), ZCAP (zinc calcium phosphate oxide ceramics), ZSCAP (zinc sulphate calcium phosphate ceramics) and FECAP (ferric calcium ∗ Tel.: +66 7750 6422x4546; fax: +66 7750 6410. E-mail address: kbbanjon@kmitl.ac.th. phosphate oxide ceramics). Therefore, they are the materials of choice in both dentistry and medicine nowadays [4–6]. In another application, calcium phosphates are valuable phosphorus (P) and micronutrient (Ca) fertilizer due to their solubility in soil [11]. When calcined, they yield other forms such as calcium pyrophosphate and calcium polyphosphate, which are used as pigments, cata- lysts and fertilizers [11] For instance, an important production step of phosphate fertilizers, such as calcium polyphosphates (CaP 2 O 6 or Ca(PO 3 ) 2 ), is the acid thermal treatment of the phosphate raw materials accompanied by condensation of the intermediate acidic salts, mainly Ca(H 2 PO 4 ) 2 ·H 2 O. So far, calcium phosphates, such as Ca(H 2 PO 4 ) 2 ·H 2 O and Ca(PO 3 ) 2 , were synthesized by sev- eral methods: precipitation method [12], hydrothermal reaction [13], template method [14], sol–gel method [15], microemulsion synthesis [16], micelle synthesis [17], mechanochemical synthe- sis [18], combustion method [19] and microwave irradiation [20]. Conventional precipitation method has some drawbacks in pre- cisely controlling the stoichiometry, crystallinity, larger particle size and morphology of products, which were improved via intro- ducing surfactants as templates [14], ultrasound irradiation [20] and microwave irradiation [21], microemulsion [14] and micelle [16] as the reaction vessels. Most recently, the preparation of some transition metal phosphates by different synthesis conditions and medium agents had been reported, which give rise to final metal phosphates with cost-effective method [22–24]. The prepara- tion methods need to obtain well-defined chemical microstructure 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2009.03.157