Triple Phosphates of Calcium, Sodium and Trivalent Elements With Whitlockite-Like Structure

Chemical Department, Moscow State University, 119899, GSP, Moscow, Russia
Materials Research Bulletin (Impact Factor: 2.29). 02/1996; 31(2):207-216. DOI: 10.1016/0025-5408(95)00181-6


Triple phosphates of calcium, sodium and trivalent elements (Eu, Nd, Fe) in Ca3(PO4)2-RPO4-Na3PO4 systems were predicted on the basis of crystal chemistry data and synthesized. The obtained phases were studied by XRD, IR-spectroscopy and emission spectroscopy under 90Sr-90Y and λ = 380 nm excitation. The only phosphates with the whitlockite-like structure appear within the range of Ca3(PO4)2-Ca9Na1.5R0.5(PO4)7-Ca10Na(PO4)7 compositi The emission spectra of phases with europium under 90Sr-90Y excitation consist of transition lines in Eu3+ and two broad bands of inherent luminescence of the matrix with maximums at ~ 360 and ~ 510 nm.

Download full-text


Available from: Elena Vovk,
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Structural and spectroscopic characterizations of the Ce3+/Tb3+(Mn2+) solely and Ce3+–Tb3+(Mn2+) doubly doped phosphate compound Ca9ZnLi(PO4)7 with β-Ca3(PO4)2 structure have been performed by powder X-ray diffraction and photoluminescence spectra measurements. The weak green emission from Tb3+ and red emission from Mn2+ are significantly enhanced by introduction of sensitizer Ce3+ ions due to an efficient resonant-type energy transfer from Ce3+ to activators Tb3+ or Mn2+. The energy transfer efficiency and the mechanism have been estimated based on spectroscopic data. Meanwhile, the critical distances for energy transfer between the Ce3+ and Tb3+ or Mn2+ ions are also calculated by the method of spectral overlapping.
    Applied Physics A 09/2012; 108(3). DOI:10.1007/s00339-012-6928-0 · 1.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The review deals with aspects of the modelling of the compositions and properties of inorganic compounds with tetrahedral anions on the basis of crystal-chemical information. One of the possible algorithms employing crystal-chemical data for the modelling of the compositions, structures, and properties of new compounds is proposed on the basis of the structures of six structural types (glaserite, beta-K2SO4, bredigite, palmierite, NASICON, and whitlockite). The likely usefulness of such data for the solution of various problems in materials science is demonstrated. The bibliography includes 208 references. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
    Russian Chemical Reviews 04/1996; 65(4):287-305. DOI:10.1070/RC1996v065n04ABEH000211 · 2.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: New calcium copper phosphates o-Ca19Cu2(PO4)14, r′-Ca19Cu2H1.42(PO4)14, and r″-Ca19Cu2−yH2.24(PO4)14 (0.64≤y≤0.7) were synthesized and characterized. The structures of these phosphates were refined using Rietveld analysis. The compound o-Ca19Cu2(PO4)14 has β-Ca3(PO4)2-like structure (Space Group R3c, z=3). Compounds r′-Ca19Cu2H1.42(PO4)14 and r″-Ca19Cu2−yH2.24(PO4)14 (0.64≤y≤0.7) have the whitlockite-like structure (Space Group R3c, z=3). The corresponding crystal data are (i) o-Ca19Cu2(PO4)14: a=10.3633(1) Å, c=37.242(2) Å, V=3463.8(9) Å3, Rp=4.24%, Rwp=5.75%; (ii) r′-Ca19Cu2H1.42(PO4)14: a=10.3987(1) Å, c=37.300(2) Å, V= 3493.0(9) Å3, Rp=4.89%, Rwp=6.50%; (iii) r″-Ca19 Cu2−yH2.24(PO4)14 (0.64≤y≤0.7): a=10.3975(1) Å, c= 37.274(2) Å, V=3489.7(9) Å3, Rp=4.57%, Rwp=6.04%. Redox reactions in calcium/copper double phosphates were investigated by XRD, DTA, DTG, and IR spectroscopy under hydrogen-containing and oxygen-containing atmospheres. These reactions proceed reversibly in the temperature ranges 753–825 K for the reduction process and 973–1173 K for the oxidation process. The redox cycles can be repeated continuously without destroying the crystal lattice.
    Journal of Solid State Chemistry 06/1999; 145(1):345-355. DOI:10.1006/jssc.1999.8294 · 2.13 Impact Factor
Show more