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Title: Synthesis, structure refinement and characterisation of a new oxyphosphate Mg{sub 0.50}TiO(PO{sub 4})

Abstract

A new titanium oxyphosphate Mg{sub 0.50}TiO(PO{sub 4}) has been synthesized and characterized by several physical techniques: X-ray diffraction, {sup 31}P MAS-NMR, Raman diffusion, infrared absorption and diffuse reflectance spectroscopy. It crystallizes in the monoclinic system with unit cell parameters: a = 7.367(9), b = 7.385(8), c = 7.373(9) A, {beta} = 120.23(1), with the space group P2{sub 1}/c (no. 14), Z = 4. The crystal structure has been refined by the Rietveld method using X-ray powder diffraction. The conventional R indices obtained are R {sub wp} = 0.138, R {sub p} = 0.096 and R {sub B} = 0.0459. The structure of Mg{sub 0.50}TiO(PO{sub 4}) consists of infinite chains of corner-shared [TiO{sub 6}] octahedra parallel to the c-axis, crosslinked by corner-shared [PO{sub 4}] tetrahedra. These infinite chains have alternating short (1.74 A) and long (2.26 A) Ti-O bonds and are similar to those found in titanium oxyphosphate M{sup II} {sub 0.50}TiO(PO{sub 4}) (M{sup 2+} = Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}). The magnesium atom is located in an antiprism between two [TiO{sub 6}] octahedra. {sup 31}P MAS NMR showed only a single {sup 31}P resonance line, in a good agreement with the crystal structure. Raman andmore » IR spectra show strong bands respectively at 765 and 815 cm{sup -1}, attributed to the vibration of -Ti-O-Ti-O- bonds in the infinite chains. The gap due to the Oxygen-Titanium(IV) charge transfer is 3.37 eV.« less

Authors:
 [1];  [2];  [3];  [4];  [4];  [4];  [5]
  1. LCMS, UFR Sciences des Materiaux Solides, Faculte des Sciences Ben M' Sik, Casablanca (Morocco). E-mail: s.benmokhtar@univh2m.ac.ma
  2. LCMS, UFR Sciences des Materiaux Solides, Faculte des Sciences Ben M' Sik, Casablanca (Morocco)
  3. Departement de Chimie, Faculte des Sciences, Ain Chock, Casablanca (Morocco)
  4. Institut de chimie de la matiere condensee de Bordeaux (ICMCB-CNRS UPR 9048), 87, av. du Dr. A. Schweitzer, 33608 Pessac (France)
  5. Department of Chemistry, University of Pretoria, 0002 Pretoria (South Africa)
Publication Date:
OSTI Identifier:
21000637
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 42; Journal Issue: 5; Other Information: DOI: 10.1016/j.materresbull.2006.08.020; PII: S0025-5408(06)00346-1; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHEMICAL PREPARATION; COBALT IONS; COPPER IONS; CROSS-LINKING; INFRARED SPECTRA; IRON IONS; MAGNESIUM; MONOCLINIC LATTICES; NICKEL IONS; NUCLEAR MAGNETIC RESONANCE; PHOSPHATES; PHOSPHORUS 31; SPACE GROUPS; SPECTROSCOPY; TITANIUM; X-RAY DIFFRACTION; ZINC IONS

Citation Formats

Benmokhtar, S., El Jazouli, A., Krimi, S., Chaminade, J.P., Gravereau, P., Menetrier, M., and Waal, D. de. Synthesis, structure refinement and characterisation of a new oxyphosphate Mg{sub 0.50}TiO(PO{sub 4}). United States: N. p., 2007. Web. doi:10.1016/j.materresbull.2006.08.020.
Benmokhtar, S., El Jazouli, A., Krimi, S., Chaminade, J.P., Gravereau, P., Menetrier, M., & Waal, D. de. Synthesis, structure refinement and characterisation of a new oxyphosphate Mg{sub 0.50}TiO(PO{sub 4}). United States. doi:10.1016/j.materresbull.2006.08.020.
Benmokhtar, S., El Jazouli, A., Krimi, S., Chaminade, J.P., Gravereau, P., Menetrier, M., and Waal, D. de. Thu . "Synthesis, structure refinement and characterisation of a new oxyphosphate Mg{sub 0.50}TiO(PO{sub 4})". United States. doi:10.1016/j.materresbull.2006.08.020.
@article{osti_21000637,
title = {Synthesis, structure refinement and characterisation of a new oxyphosphate Mg{sub 0.50}TiO(PO{sub 4})},
author = {Benmokhtar, S. and El Jazouli, A. and Krimi, S. and Chaminade, J.P. and Gravereau, P. and Menetrier, M. and Waal, D. de},
abstractNote = {A new titanium oxyphosphate Mg{sub 0.50}TiO(PO{sub 4}) has been synthesized and characterized by several physical techniques: X-ray diffraction, {sup 31}P MAS-NMR, Raman diffusion, infrared absorption and diffuse reflectance spectroscopy. It crystallizes in the monoclinic system with unit cell parameters: a = 7.367(9), b = 7.385(8), c = 7.373(9) A, {beta} = 120.23(1), with the space group P2{sub 1}/c (no. 14), Z = 4. The crystal structure has been refined by the Rietveld method using X-ray powder diffraction. The conventional R indices obtained are R {sub wp} = 0.138, R {sub p} = 0.096 and R {sub B} = 0.0459. The structure of Mg{sub 0.50}TiO(PO{sub 4}) consists of infinite chains of corner-shared [TiO{sub 6}] octahedra parallel to the c-axis, crosslinked by corner-shared [PO{sub 4}] tetrahedra. These infinite chains have alternating short (1.74 A) and long (2.26 A) Ti-O bonds and are similar to those found in titanium oxyphosphate M{sup II} {sub 0.50}TiO(PO{sub 4}) (M{sup 2+} = Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}). The magnesium atom is located in an antiprism between two [TiO{sub 6}] octahedra. {sup 31}P MAS NMR showed only a single {sup 31}P resonance line, in a good agreement with the crystal structure. Raman and IR spectra show strong bands respectively at 765 and 815 cm{sup -1}, attributed to the vibration of -Ti-O-Ti-O- bonds in the infinite chains. The gap due to the Oxygen-Titanium(IV) charge transfer is 3.37 eV.},
doi = {10.1016/j.materresbull.2006.08.020},
journal = {Materials Research Bulletin},
number = 5,
volume = 42,
place = {United States},
year = {Thu May 03 00:00:00 EDT 2007},
month = {Thu May 03 00:00:00 EDT 2007}
}
  • A new iron titanyl oxyphosphate Fe{sub 0.50}TiO(PO{sub 4}) was synthesized by both solid-state reaction and Cu{sup 2+}-Fe{sup 2+} ion exchange method. The material was then characterized by X-ray diffraction, Mossbauer spectroscopy, magnetic susceptibility measurements and Raman spectroscopy. The crystal structure of the compound was refined, using X-ray powder diffraction data, by Rietveld profile method; it crytallizes in the monoclinic system, space group P2{sub 1}/c (No.14), with a=7.4039(3)A, b=7.3838(3)A, c=7.4083(3)A, {beta}=120.36{sup o}(1), V=349.44(2)A{sup 3} and Z=4. The volume of the title compound is comparable to those of the M{sub 0.50}{sup II}TiO(PO{sub 4}) series, where M{sup II}=Mg, Co, Ni and Zn. Themore » framework is built up from [TiO{sub 6}] octahedra and [PO{sub 4}] tetrahedra. [TiO{sub 6}] octahedra are linked together by corners and form infinite chains along the c-axis. Ti atoms are displaced from the center of octahedral units showing an alternating short distance (1.73A) and a long one (2.22A). These chains are linked together by [PO{sub 4}] tetrahedra. Fe{sup 2+} cations occupy a triangle-based antiprism sharing two faces with two [TiO{sub 6}] octahedra. Mossbauer and magnetic measurements show the existence of iron only in divalent state, located exclusively in octahedral sites with high spin confition (t{sub 2g}{sup 4}e{sub g}{sup 2}). Raman study confirms the existence of Ti-O-Ti chains.« less
  • The room-temperature crystal structure of a new Cu(II) oxyphosphate-{alpha} Cu{sub 0.50} {sup II}TiO(PO{sub 4})-was determined from X-ray single crystals diffraction data, in the monoclinic system, space group P2{sub 1}/c. The refinement from 5561 independent reflections lead to the following parameters: a=7.5612(4)A, b=7.0919(4)A, c=7.4874(4)A, {beta}=122.25(1){sup o}, Z=4, with the final R=0.0198, wR=0.0510. The structure of {alpha} Cu{sub 0.50} {sup II}TiO(PO{sub 4}) can be described as a TiOPO{sub 4} framework constituted by chains of tilted corner-sharing [TiO{sub 6}] octahedra running parallel to the c-axis and cross linked by phosphate [PO{sub 4}] tetrahedra, where one-half of octahedral cavities created are occupied by Cumore » atoms. Ti atoms are displaced from the center of octahedra units in alternating long (2.308 A) and short (1.722 A) Ti-O(1) bonds along chains. Such O(1) atoms not linked to P atoms justify the oxyphosphate formulation {alpha} Cu{sub 0.50}TiO(PO{sub 4}). The divalent cations Cu{sup 2+} occupy a Jahn-Teller distorted octahedron sharing two faces with two [TiO{sub 6}] octahedra. EPR and optical measurements are in good agreement with structural data. The X-ray diffraction results are supported by Raman and infrared spectroscopy studies that confirmed the existence of the infinite chains -Ti-O-Ti-O-Ti-. {alpha} Cu{sub 0.50}TiO(PO{sub 4}) shows a Curie-Weiss paramagnetic behavior in the temperature range 4-80 K. - Graphical abstract: Projection of the structure of {alpha} Cu{sub 0.50}TiO(PO{sub 4}) along the a-axis.« less
  • A new iron titanyl phosphate Fe{sub 0.50}Ti{sub 2}(PO{sub 4}){sub 3} was synthesized by both solid-state reaction and Cu{sup 2+}-Fe{sup 2+} ion exchange method. The material was then characterized by X-ray diffraction, Mossbauer, magnetic susceptibility measurements and optical absorption. The crystal structure of the compound was refined, using X-ray powder diffraction data, by the Rietveld profile method; it crystallizes in the rhombohedral system, space group R3-bar, with a=8.511(1)A and c=20.985(3)A, V=1316.45(3)A{sup 3} and Z=6. The structure, which is compared to that of Mn{sub 0.50}Ti{sub 2}(PO{sub 4}){sub 3} is built up from [TiO{sub 6}] octahedra and [PO{sub 4}] tetrahedra which are linkedmore » by corner sharing along the c-axis. Fe{sup 2+} cations are located in half of the antiprism M{sub I} sites and are orderly distributed with vacancies within the two possible positions of the M{sub I} sites of R3-bar. These results were supported by the Mossbauer studies that showed the presence of one Fe{sup 2+} site in the high spin state (t{sub 2g}{sup 4}e{sub g}{sup 2}). The Curie-Weiss-type behavior is observed in the magnetic susceptibility. Diffuse reflectance spectrum indicates the presence of octahedrally coordinated Fe{sup 2+} ions.« less
  • This work is part of a continued program of exploring copper ion conductivity in solid phosphates. The first example of a phase in the copper-iron-phosphorous-oxygen quanternary system (Cu[sup 1]Cu[sup 11])[sub 1.35] (Fe[sup II],Fe[sup III])[sub 3](PO[sub 4])[sub 3], has been prepared by a high temperature synthesis technique. The crystal structure was determined from single-crystal data and shown to be of the alluaudite type, but with differences in copper coordination and occupancy compared to the alkali and alkaline earth metal analogues. It crystallizes in the monoclinic space group C2/c with lattice constants a = 11.894(4) [angstrom], b = 12.629(4) [angstrom], c =more » 6.440(1) [angstrom], [beta] = 115.24(2)[degrees], Z = 4. the structure contains chains of edge sharing FeO[sub 6] octahedra linked together via the common corners of PO[sub 4] tetrahedra, yielding two distinct one-dimensional channels for copper ion occupation. The compound exhibits both copper and iron mixed valency. The copper-magnesium phosphate analogue Cu[sup I]Cu[sup II]Mg[sub 3](PO[sub 4])[sub 3] has been prepared and is shown to be of the same structure type, a = 11.85(2) [angstrom], b = 12.55(2) [angstrom], c = 6.38(1) [angstrom], [beta] = 115.9(2)[degrees]. Magnetic susceptibility measurements confirm the presence of one Cu[sup 2+] (d[sup 9]) ion per unit formula with [mu][sub eff] = 1.78 [mu]B (>50 K).« less
  • From the refined atomic positions obtained by Belmal et al. (2004) using X-ray diffraction for Li{sub 0.50}Co{sub 0.25}TiO(PO{sub 4}), we have performed a structural optimization by minimizing the forces acting on the atoms keeping the lattice parameters fixed at the experimental values. With this relaxed (optimized) geometry we have performed a comprehensive theoretical study of electronic properties and dispersion of the linear optical susceptibilities using the full potential linear augmented plane wave (FP-LAPW) method. The generalized gradient approximation (GGA) exchange-correlation potential was applied. In addition, the Engel-Vosko generalized gradient approximation (EVGGA) was used for comparison with GGA because it ismore » known that EVGGA approach yields better band splitting compared to the GGA. We have calculated the band structure, and the total and partial densities of states. The electron charge densities and the bonding properties were analyzed and discussed. The complex dielectric optical susceptibilities were discussed in detail. - Graphical abstract: It is shown that P is tetrahedrally coordinated by four O ions. Highlights: > Comprehensive theoretical study of electronic and optical properties was performed. > Using X-ray diffraction data we have performed a structural optimization. > The electron charge densities and the bonding properties were analyzed and discussed. > Fermi surface was analyzed since it is useful for predicting thermal, magnetic, and optical properties. > The density of states at E{sub F} and the electronic specific heat coefficient were calculated.« less