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Octahedral microporous phases Na2Nb2−xTixO6−x(OH)x·H2O and their related perovskites: Crystal chemistry, energetics, and stability relations

Published online by Cambridge University Press:  01 March 2005

Hongwu Xu ,
Alexandra Navrotsky ,
May D. Nyman  and
Tina M. Nenoff
Hongwu Xu*
Affiliation:
Thermochemistry Facility and Nanomaterials in the Environment, Agriculture, and Technology (NEAT) Organized Research Unit (ORU), University of California at Davis, Davis, California 95616
Alexandra Navrotsky
Affiliation:
Thermochemistry Facility and Nanomaterials in the Environment, Agriculture, and Technology (NEAT) Organized Research Unit (ORU), University of California at Davis, Davis, California 95616
May D. Nyman
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
Tina M. Nenoff
Affiliation:
Sandia National Laboratories, Albuquerque, New Mexico 87185
*
a)Address all correspondence to this author. Present address: Los Alamos Neutron Science Center, LANSCE-12, MS-H805, Los Alamos National Laboratory, Los Alamos, NM 87545. e-mail: hxu@lanl.gov
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Abstract

A family of microporous phases with compositions Na2Nb2−xTixO6−x(OH)x⋅H2O (0 ≤ x ≤ 0.4) transform to Na2Nb2−xTixO6−0.5x perovskites upon heating. In this study, we have measured the enthalpies of formation of the microporous phases and their corresponding perovskites from the constituent oxides and from the elements by drop solution calorimetry in 3Na2O·4MoO3 solvent at 974 K. As Ti/Nb increases, the enthalpies of formation for the microporous phases become less exothermic up to x = ∼0.2 but then more exothermic thereafter. In contrast, the formation enthalpies for the corresponding perovskites become less exothermic across the series. The energetic disparity between the two series can be attributed to their different mechanisms of ionic substitutions: Nb5+ + O2− → Ti4+ + OH− for the microporous phases and Nb5+ → Ti4+ + 0.5VO.. for the perovskites. From the calorimetric data for the two series, the enthalpies of the dehydration reaction, Na2Nb2−xTixO6−x(OH)x⋅H2O → Na2Nb2−xTixO6−0.5x + H2O, have been derived, and their implications for phase stability at the synthesis conditions are discussed.

Keywords

CalorimetryStabilityX-ray diffraction (XRD)
Type
Articles
Information
Journal of Materials Research , Volume 20 , Issue 3 , March 2005 , pp. 618 - 627
Copyright
Copyright © Materials Research Society 2005

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References

REFERENCES

1.Breck, D.W.: Zeolite Molecular Sieves: Structure, Chemistry and Use (Wiley, New York, NY, 1974), p. 771.Google Scholar
2.Anderson, M.W., Terasaki, O., Ohsuna, T., Malley, P.J.O., Philippou, A., MacKay, S.P., Ferreira, A., Rocha, J. and Lidin, S.: Microporous titanosilicate ETS-10: A structural survey. Philos. Mag. B 71, 813 (1995).CrossRefGoogle Scholar
3.Clearfield, A.: Structure and ion exchange properties of tunnel type titanium silicates. Solid State Sci. 3, 103 (2001).CrossRefGoogle Scholar
4.Behrens, E.A., Poojary, D.M. and Clearfield, A.: Syntheses, crystal structures, and ion-exchange properties of porous titanosilicates, HM3Ti4O4(SiO4)3·4H2O (M = H+, K+, Cs+), structural analogues of the mineral pharmacosiderite. Chem. Mater. 8, 1236 (1996).CrossRefGoogle Scholar
5.Behrens, E.A., Poojary, D.M. and Clearfield, A.: Syntheses, x-ray powder structures, and preliminary ion-exchange properties of germanium-substituted titanosilicate pharmacosiderites: HM3(AO)4(BO4)3·4H2O (M = K, Rb, Cs; A = Ti, Ge; B = Si, Ge). Chem. Mater. 10, 959 (1998).CrossRefGoogle Scholar
6.Dyer, A., Pillinger, M. and Amin, S.: Ion exchange of caesium and strontium on a titanosilicate analogue of the mineral pharmacosiderite. J. Mater. Chem. 9, 2481 (1999).CrossRefGoogle Scholar
7.Anthony, R.G., Philip, C.V. and Dosch, R.G.: Selective adsorption and ion exchange of metal cations and anions with silico-titanates and layered titanates. Waste Manage. 13, 503 (1993).CrossRefGoogle Scholar
8.Nyman, M., Tripathi, A., Parise, J.B., Maxwell, R.S., Harrison, W.T.A. and Nenoff, T.M.: A new family of octahedral molecular sieves: Sodium Ti/Zr-IV niobates. J. Am. Chem. Soc. 123, 1529 (2001).CrossRefGoogle Scholar
9.Nyman, M., Tripathi, A., Parise, J.B., Maxwell, R.S. and Nenoff, T.M.: Sandia octahedral molecular sieves (SOMS): Structural and property effects of charge-balancing the M-IV-substituted (M = Ti, Zr) niobate framework. J. Am. Chem. Soc. 124, 1704 (2002).CrossRefGoogle ScholarPubMed
10.Nenoff, T. and Nyman, M., New, A Class of Inorganic Molecular Sieves: Sodium Niobium Metal Oxides, U.S. Patent No. 6 596 254 (22 July 2003).Google Scholar
11.Xu, H., Nyman, M., Nenoff, T.M. and Navrotsky, A.: Prototype sandia octahedral molecular sieve (SOMS) Na2Nb2O6⋅H2O: Synthesis, structure and thermodynamic stability. Chem. Mater. 16, 2034 (2004).CrossRefGoogle Scholar
12.Park, S.H., Parise, J.B., Gies, H., Liu, H., Grey, C.P. and Toby, B.H.: A new porous lithosilicate with a high ionic conductivity and ion-exchange capacity. J. Am. Chem. Soc. 122, 11023 (2000).CrossRefGoogle Scholar
13.Ringwood, A.E., Kesson, S.E., Ware, N.G., Hibberson, W. and Major, A.: Immobilisation of high level nuclear reactor wastes in SYNROC. Nature 278, 219 (1979).CrossRefGoogle Scholar
14.Larson, A.C. and Von Dreele, R.B.: GSAS, General Structure Analysis System, Los Alamos National Laboratory, Report No. LAUR 86–748 (Los Alamos, NM, 2000).Google Scholar
15.Sakowski-Cowley, A.C., Lukaszewicz, K. and Megaw, H.D.: The structure of sodium niobate at room temperature, and the problem of reliability in pseudosymmetric structures. Acta Crystallogr. B 25, 851 (1969).CrossRefGoogle Scholar
16.Navrotsky, A.: Progress and new directions in high temperature calorimetry revisited. Phys. Chem. Miner. 24, 222 (1997).CrossRefGoogle Scholar
17.Navrotsky, A., Rapp, R.P., Smelik, E., Burnly, P., Circone, S., Chai, L., Bose, K. and Westrich, H.R.: The behavior of H2O and CO2 in high-temperature lead borate solution calorimetry of volatile-bearing phases. Am. Mineral. 79, 1099 (1994).Google Scholar
18.Xu, H., Su, Y., Balmer, M.L. and Navrotsky, A.: A new series of oxygen-deficient perovskites in the NaTixNb1−xO3−0.5x system: Synthesis, crystal chemistry, and energetics. Chem. Mater. 15, 1872 (2003).CrossRefGoogle Scholar
19.Shannon, R.D.: Revised effective ionic-radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr. A 32, 751 (1976).CrossRefGoogle Scholar
20.Armstrong, T.R., Stevenson, J.W., Pederson, L.R. and Raney, P.E.: Dimensional instability of doped lanthanum chromite. J. Electrochem. Soc. 143, 2919 (1996).CrossRefGoogle Scholar
21.Yang, J.B., Yelon, W.B., James, W.J., Chu, Z., Kornecki, M., Xie, Y.X., Zhou, X.D., Anderson, H.U., Joshi, A.G. and Malik, S.K.: Crystal structure, magnetic properties, and Mossbauer studies of La0.6Sr0.4FeO3−δ prepared by quenching in different atmospheres. Phys. Rev. B: Condens. Matter Mater. Phys. 66, 184415 (2002).CrossRefGoogle Scholar
22.Ullmann, H. and Trofimenko, N.: Estimation of effective ionic radii in highly defective perovskite-type oxides from experimental data. J. Alloys Compd. 316, 153 (2001).CrossRefGoogle Scholar
23.Tessier, F., Navrotsky, A., Sauze, A. Le and Marchand, R.: Thermochemistry of phosphorus oxynitrides: PON and LiNaPON glasses. Chem. Mater. 12, 148 (2000).CrossRefGoogle Scholar
24.Pozdnyakova, I., Navrotsky, A., Shilkina, L. and Reznichenko, L.: Thermodynamic and structural properties of sodium lithium niobate solid solutions. J. Am. Ceram. Soc. 85, 379 (2002).CrossRefGoogle Scholar
25.Putnam, R.L., Navrotsky, A., Woodfield, B.F., Boerio-Goates, J. and Shapiro, J.L.: Thermodynamics of formation for zirconolite (CaZrTi2O7) from T = 298.15 K to T = 1500 K. J. Chem. Thermodyn. 31, 229 (1999).CrossRefGoogle Scholar
26.Robie, R.A. and Hemingway, B.S.: Thermodynamic Properties of Minerals and Related Substances at 298.15 K and 1 Bar (105 Pascals) Pressure and at Higher Temperatures, Geological Survey Bulletin No. 2131 (1995).Google Scholar
27.Chase, M.W. Jr.: NIST-JANAF. Thermochemical Tables, 4th ed., J. Phys. Chem. Ref. Data Monograph No. 9 (1998).Google Scholar
28.Kunz, M. and Brown, I.D.: Out-of-center distortions around octahedrally coordinated d0 transition metals. J. Solid State Chem. 115, 395 (1995).CrossRefGoogle Scholar
29.Nyman, M., Criscenti, L.J., Bonhomme, F., Rodriguez, M.A. and Cygan, R.T.: Synthesis, structure, and molecular modeling of a titanoniobate isopolyanion. J. Solid State Chem. 176, 111 (2003).CrossRefGoogle Scholar
30.Cheng, J. and Navrotsky, A.: Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites. J. Solid State Chem. 177, 126 (2004).CrossRefGoogle Scholar