Abstract
The crystal, local and electronic structure of complex oxides Ln2Hf2O7 (Ln = Gd, Tb, Dy) formed as a result of annealing of amorphous mixed hydroxides LnHf(OH)7∙nH2O (precursors) have been studied using a set of modern local-sensitive techniques of structural analysis based on the interaction of synchrotron radiation with condensed matter (XAFS spectroscopy, PDF analysis, anomalous X-ray diffraction). It was shown that the thermal treatment of precursors in the temperature range 600-700°C/3 h induces the formation of nanocrystallites with the fluorite structure characterized by the considerable inequivalence of local surrounding of Ln3+ and Hf4+ cations. It was found that the cation ordering of the pyrochlore type takes place in nanocrystals of gadolinium hafnate Gd2Hf2O7 and terbium hafnate Tb2Hf2O7. The phase transition fluorite → pyrochlore goes through the formation of the pyrochlore nanodomains in the matrix of well-crystallized fluorite. In the case of Gd2Hf2O7 the formation of the pyrochlore local structure is completed at annealing temperature ~1000-1200°C/3 h and at ≥1300°C/3 h the pyrochlore phase is detected by the diffraction techniques. In Tb2Hf2O7 the process of the pyrochlore phase formation exhibits the more complex behavior. Nanocrystals of dysprosium hafnate Dy2Hf2O7 retain the structure of defect fluorite in the whole temperature range of the heat treatment (up to 1600°C).
Similar content being viewed by others
References
K. A. Subramanian, G. Aravamudan, and G. V. Subba Rao, Prog. Solid State Chem., 15, No. 2, 55 (1983).
W. Pan, S. R. Phillpot, C. Wan, et al., MRS Bull., 32, No. 10, 917 (2012).
A. V. Shlyakhtina and L. G. Shcherbakova, Russ. J. Electrochem., 48, No.1, 1 (2012).
V. D. Risovany, A. V. Zakharov, E. M. Muraleva, et al., J. Nucl. Mater., 355, No. 1, 163 (2006).
R. C. Ewing, W. J. Weber, and J. Lian, J. Appl. Phys., 95, No. 11, 5949 (2004).
A. R. Cleave, Atomic Scale Simulations for Waste Forms Applications, Ph. D. Thesis, Imperial College, London, UK (2006).
J. S. Gardner, M. J. P. Gingras, and J. E. Greedan, Rev. Modern Phys., 82, No. 1, 53 (2010).
E. R. Andrievskaya, J. Eur. Ceram. Soc., 28, No. 12, 2363 (2008).
P. E. R. Blanchard, R. Clements, D. J. Kennedy, et al., Inorg. Chem., 51, No. 24, 13237 (2012).
C. Karthik, T. J. Anderson, D. Gout, et al., J. Solid State Chem., 194, No. 1, 168 (2012).
M. P. Saradhi, S. V. Ushakov, and A. Navrotsky, RSC Adv., 2, No. 8, 3328 (2012).
N. A. Shabanova, V. V. Popov, and P. D. Sarkisov, Chemistry and Technology of Nanodispersed Oxides [in Russian], Akademkniga, Moscow (2006).
M. P. Moroz, Russ. Chem. Rev., 80, No. 4, 293 (2011).
V. V. Popov, Formation and Evolution of Oxide Nanosytems Obtained by Hydrolytic Polycondensation [in Russian], Doctoral (Chem.) Dissertation, MUCTR, moscow (2011).
V. V. Popov, V. F. Petrunin, S. A. Korovin, et al., Russ. J. Inorg. Chem., 56, No. 10, 1538 (2011).
V. V. Popov, Ya. V. Zubavichus, A. P. Menushenkov, et al., Russ. J. Inorg. Chem., 60, No. 1, 16 (2015).
A. P. Hammersley, S. O. Svensson, M. Hanfland, et al., High Pressure Res., 14, Nos. 4-6, 235 (1996).
V. Petricek, M. Dusek, and L. Palatinus, Z. Kristallogr., 229, No. 5, 345 (2014).
K. V. Klementev, J. Phys. D: Appl. Phys., 34, No. 2, 209 (2001).
M. P. Newville, J. Synchrotron Radiat., 8, No. 2, 322 (2001).
A. L. Ankudinov, C. Bouldin, J. J. Rehr, et al., Phys. Rev. B, 58, No. 12, 7565 (1998).
X. Qiu, J. W. Thompson, and S. J. L. Billinge, J. Appl. Crystallogr., 37, No. 4, 678 (2004).
C. L. Farrow, P. Juhas, J. W. Liu, et al., J. Phys.: Condens. Matter, 19, No. 33, 335219 (2007).
Ya. V. Zubavichus, Structural Characterization of Weakly Ordered Intercalation Compounds of Molybdenum Disulphide [in Russian], Doctoral (Chem.) Dissertation, INEOS RAS, Moscow (2001).
V. V. Popov, Ya. V. Zubavichus, V. F. Petrunin, et al., Glass Phys. Chem., 37, No. 5, 512 (2011).
V. V. Popov, A. P. Menushenkov, Ya. V. Zubavichus, et al., Russ. J. Inorg. Chem., 58, No. 12, 1400 (2013).
V. V. Popov, A. P. Menushenkov, Ya. V. Zubavichus, et al., Russ. J. Inorg. Chem., 59, No. 4, 279 (2014).
C. R. Stanek, Atomic Scale Disorder in Fluorite and Fluorite Related Oxides, Ph. D. Thesis, Imperial College, London, UK (2003).
X. T. Zu, N. Li, and F. Gao, J. Appl. Phys., 104, 043517 (2008).
K. V. Klementiev; http://www.cells.es/old/Beamlines/CLAESS/software/xanda.html.
Author information
Authors and Affiliations
Corresponding author
Additional information
Translated from Zhurnal Strukturnoi Khimii, Vol. 57, No. 7, pp. 1529-1538, September-October, 2016.
Rights and permissions
About this article
Cite this article
Menushenkov, A.P., Popov, V.V., Zubavichus, Y.V. et al. Local peculiarities of the nanocrystalline structure of ternary oxides Ln2Hf2O7 (Ln = Gd, Tb, Dy). J Struct Chem 57, 1450–1458 (2016). https://doi.org/10.1134/S0022476616070210
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0022476616070210