NEW POLYMORPH OF CaHPO4 (MONETITE): SYNTHESIS AND CRYSTAL STRUCTURE

calcium hydrogenphosphate polymorphs synthesis single crystal X-ray diffraction monetite crystal structure.

СТРУКТУРА И СВОЙСТВА КРИСТАЛЛОВ LI2-2xМg2+x(Мо04)з АКТИВИРОВАННЫХ ИОНАМИ МЕДИ, DESIGN OF A NEW ROTARY MOLECULAR MACHINE BASED ON NITROGEN INVERSION: A DFT INVESTIGATION, ...

2016. 57, 3 - – - UDC 548.73:546.18:546.21 NEW POLYMORPH OF CaHPO4 (MONETITE): SYNTHESIS AND CRYSTAL STRUCTURE N. Ouerfelli1, 2, M.F. Zid 1 1Laboratoire de Matйriaux et Cristallochimie, Facultй des Sciences de Tunis, Universitй de Tunis El Manar, El Manar II, Tunis, Tunisia E-mail: najouerf@yahoo.fr 2Université de Tunis Carthage, Institue Préparatoire aux Etudes d'Ingénieur de Bizerte BP 64-7021 - Zarzouna (Bizerte), Tunisia Received February, 25, 2015 A novel form of anhydrous dicalcium phosphate CaHPO4 (monetite) is synthesized hydrothermally and characterized by single crystal X-ray diffraction. <...> A threedimensional crystal structure can be described by {HPO4}n infinite zigzag chains linked by Ca—O bonds. <...> The comparison to the crystal structures of other polymorphs is given. <...> The chemistry and crystal structure of calcium phosphates is an interesting field of study for a long time. <...> The synthesis and structural characterization of anhydrous calcium hydrogen phosphates have been well known for a long time [5 ]. <...> In this work we focus on the crystal structure of new polymorph monetite. <...> They were identified using single crystal diffraction analyses as and orthorhombic polymorph CaHPO4 and Ca0.5Fe(HP3O10) respectively. <...> It was found that the new compound crystallized in the orthorhombic system, space group Ccm21. <...> Anisotropic thermal parameters were assigned to all non-hydrogen atoms. <...> To the best of our knowledge, the structure of the title compound is the new polymorph monetite CaHPO4. <...> It crystallizes in the orthorhombic space group Ccm21, two others have triclinic forms; low-temperature (LT) and room-temperature (RT) polymorphs crystallize in P1 [ 12 ] and P-1 [ 13 ] spaces groups respectively. <...> Fig. 1 shows that these PO4 tetrahedra are linked together by O1—H1 O3 hydrogen bonds to form {HPO4}n infinite zigzag chains lying parallel to the (010) plane and running along the c axis. <...> The Ca—O bonds link these chains to form a three-dimensional network structure. <...> The comparison of the title compound with other monetite polymorphs indicates that the most evident difference between the orthorhombic phase (Ccm21) and triclinic CaHPO4 (P1 [12 <...>

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