Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-17T21:21:48.376Z Has data issue: false hasContentIssue false
  • English
  • Français

Thermochemistry of Rare Earth Perovskites

Published online by Cambridge University Press:  30 June 2016

Dawei Feng  and
Alexandra Navrotsky
Dawei Feng
Affiliation:
Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
Alexandra Navrotsky*
Affiliation:
Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
*
*Corresponding author email address: [email protected] (A. Navrotsky). Tel.: (530) 752-3292; fax: (530) 752-9307
Get access

Abstract

The rare earth (RE) mineral loparite with the chemical composition (RE, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light rare earth elements (LREE) as well as niobium and tantalum. The enthalpies of formation of RE0.67-xNa3xTiO3 (RE = La, Ce) and Ca1-2xNaxLaxTiO3 from oxides and elements of lanthanum and cerium perovskites and their solid solutions have been obtained using high temperature oxide melt solution calorimetry. RE0.67-xNa3xTiO3 (RE = La, Ce) perovskites become more stable relative to oxide components as sodium content increases. Na0.5Ce0.5TiO3 and Na0.5La0.5TiO3 can be considered stable endmembers in natural loparite minerals. For perovskite solid solutions Ca1-2xNaxLaxTiO3, the enthalpies of formation from the constituent oxides $\Delta {\rm{H}}_{{\rm{f}},\,{\rm{ox}}}^^\circ$ become more exothermic with increasing Na+La content, suggesting a stabilizing effect of the substitution 2Ca2+ → Na+ + La3+ on the perovskite structure. The trend of increasing thermodynamic stability with decreasing structural distortion is similar to that seen in many other ABO3 perovskites.

Keywords

calorimetrychemical substitutioncrystallographic structure
Type
Articles
Information
MRS Advances , Volume 1 , Issue 38: Materials Design , 2016 , pp. 2695 - 2700
Copyright
Copyright © Materials Research Society 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Hurd, A.J., Kelley, R.L., Eggert, R.G., Lee, M.H.: Energy-critical elements for sustainable development. MRS Bull, 37 (2012) 405–410.CrossRefGoogle Scholar
Feng, D. W., Radha, S., Navrotsky, A.: Rare Earth Perovskites along the CaTiO3 - Na0.5La0.5TiO3 join: Phase Transitions, Formation Enthalpies, and Implications for Loparite Minerals. Am Mineral, in press 2016.CrossRefGoogle Scholar
Mitchell, R.H., Chakhmouradian, A.R.: Compositional variation of loparite from the Lovozero alkaline complex, Can Mineral, 34 (1996) 977–990.Google Scholar
Takayamamuromachi, E., Navrotsky, A.: Energetics of Compounds (A2+B4+O3) with the Perovskite Structure. J Solid State Chem, 72 (1988) 244–256.CrossRefGoogle Scholar
Kanke, Y., Navrotsky, A.: A calorimetric study of the lanthanide aluminum oxides and the lanthanide gallium oxides: Stability of the perovskites and the garnets. J Solid State Chem, 141 (1998) 424–436.CrossRefGoogle Scholar
Laberty, C., Navrotsky, A., Rao, C.N.R., Alphonse, P.: Energetics of rare earth manganese perovskites A1-xA 'xMnO3 (A = La, Nd, Y and A' = Sr, La) systems. J Solid State Chem, 145 (1999) 77–87.CrossRefGoogle Scholar
Cheng, J.H., Navrotsky, A.: Energetics of La(1-x)A(x)CrO(3-delta) perovskites (A = Ca or Sr). J Solid State Chem, 178 (2005) 234–244.CrossRefGoogle Scholar
Mocala, K., Navrotsky, A., Bringley, J.F., Scott, B.A., Frisch, M., Shaw, T.: Energetics of T, T', and T-Asterisk Phases in Some Rare-Earth Cuprates. J Solid State Chem, 104 (1993) 181–192.CrossRefGoogle Scholar
Ushakov, S.V., Cheng, J., Navrotsky, A., Wu, J.R., Haile, S.M.: Formation enthalpies of tetravalent lanthanide perovskites by high temperature oxide melt solution calorimetry. Perovskite Materials, 718 (2002) 71–76.Google Scholar
Navi, N.U., Kimmel, G., Zabicky, J., Ushakov, S.V., Shneck, R.Z., Mintz, M.H., Navrotsky, A.: Yttrium Substitution in MTiO3 (M=Ca, Sr, Ba and Ca plus Sr plus Ba) Perovskites and Implication for Incorporation of Fission Products into Ceramic Waste Forms. J Am Ceram Soc, 94 (2011) 3112–3116.CrossRefGoogle Scholar
Navi, N.U., Shneck, R.Z., Shvareva, T.Y., Kimmel, G., Zabicky, J., Mintz, M.H., Navrotsky, A.: Thermochemistry of (CaxSr1-x)TiO3 , (BaxSr1-x)TiO3, and (BaxCa1-x)TiO3 Perovskite Solid Solutions. J Am Ceram Soc, 95 (2012) 1717–1726.CrossRefGoogle Scholar
Xu, H.W., Navrotsky, A., Balmer, M.L., Su, Y.L.: Thermochemistry of substituted perovskites in the NaTi(x)Nb(1-x)O(3-0.5x) system. Perovskite Materials, 718 (2002) 65–70.Google Scholar
Xu, H.W., Su, Y.L., Balmer, M.L., Navrotsky, A.: A., A new series of oxygen-deficient perovskites in the NaTi(x)Nb(1-x)O(3-0.5x) system: Synthesis, crystal chemistry, and energetics. Chem Mater, 15 (2003) 1872–1878.CrossRefGoogle Scholar
Xu, H.W., Navrotsky, A., Su, Y.L., Balmer, M.L.: Perovskite solid solutions along the NaNbO(3)-SrTiO(3) join: Phase transitions, formation enthalpies, and implications for general perovskite energetics. Chem Mater, 17 (2005) 1880–1886.CrossRefGoogle Scholar
Davies, P.K., Navrotsky, A.: Quantitative Correlations of Deviations from Ideality in Binary and Pseudobinary Solid-Solutions. J Solid State Chem, 46 (1983) 1–22.CrossRefGoogle Scholar
Cheng, H.H., Navrotsky, A.: Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites. J Solid State Chem, 177 (2004) 126–133.CrossRefGoogle Scholar
Shannon, R.D.: Revised Effective Ionic-Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides. Acta Crystallogr A, 32 (1976) 751–767.CrossRefGoogle Scholar
Feng, D. W., Maram, P. S., Mielewczyk-Gryn, A., Navrotsky, A.: Thermochemistry of rare earth perovskites Na3x RE0.67−x TiO3 (RE = La, Ce). Am Mineral 2016, 101(7), 1125-1128.CrossRefGoogle Scholar
Chakhmouradian, A. R.; Mitchell, R. H., A structural study of the perovskite series CaTi1-2xFexNbxO3 . J Solid State Chem 1998, 138 (2), 272–277.CrossRefGoogle Scholar