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Crystals of a new potassium cobalt(II) iron(II) triorthophosphate salt, KCo3Fe(PO4)3, as well as amorphous nanoparticles of the same material have been produced by hydrothermal reactions, under supercritical water (SCW) conditions, of equivalent quantities of aq. CoCl2·6H2O (2 mol/L) and K4P2O7 (1 mol/L) in concd. HCl in a stainless steel batch reactor at 400–450 °C and 25–32 MPa. The dark-violet crystals of the new salt have been characterized by single-crystal X-ray diffraction and IR, Raman, and Mössbauer spectroscopy. The Fe(II) in the new orthophosphate salt must derive from leaching of iron from the stainless steel walls of the reactor by concd. HCl under the SCW conditions. The salt crystallizes in the orthorhombic space group Pnnm, Z = 4, with unit cell parameters as follows: a = 9.672(1) Å, b = 16.457(2) Å, c = 6.2004(8) Å, V = 986.97 Å3. Microporous KCo3Fe(PO4)3 exhibits infinite chains of corner-sharing [PO43–], [FeO6], and [CoO5] units, which form two large rhombus tunnels, occupied by K+ ions, running parallel to [100] in the unit cell. The vibrational spectra have been interpreted partly on the basis of factor group effects and are in accord with the centrosymmetric structure of the material. The particle sizes of this new nanomaterial and their distribution have been determined by scanning electron micrography and laser scattering particle size distribution analysis, while the amorphous nanomaterial has also been characterized by X-ray powder diffraction and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Beige crystals of a new magnesium hydrogen orthophosphate salt, Mg3.5H2(PO4)3, as well as nanoparticles of an amorphous, non-Mg-containing phosphate material, Fe1−y K y PO4 (0< y <1), have been produced by hydrothermal reactions in supercritical water (SCW) of equivalent quantities of aqueous MgCl2·6H2O (2M), and K4P2O7 (1M) in concentrated HCl in a stainless-steel batch reactor at 400–450°C and 25–32MPa. The new salt has been characterized by single-crystal X-ray diffraction and IR and Raman spectroscopies. It crystallizes in the triclinic space group Pī, Z =2 with the following unit-cell parameters: a =6.438(1), b =7.856(1), c =9.438(1)Å; α =104.57(1), β =108.61(1), γ =101.28(1)°, V =739.99Å3. The effects of the SCW conditions on the nature of the products and their yields and morphologies have been studied by IR and Raman spectroscopies, X-ray powder diffraction, X-ray energy dispersive analysis, scanning electron microscopy, transmission electron microscopy and inductively coupled plasma analysis. [Copyright &y& Elsevier]