TY - JOUR

T1 - Specific structural features of LnZrOx (Ln

T2 - La, Sm) mixed oxides prepared by different methods

AU - Kuznetsova, Tatyana

AU - Kriger, Tamara

AU - Chesalov, Yurii

AU - Boronin, Andrey

AU - Ishchenko, Arcadii

AU - Pandis, Pavlos K.

AU - Krivensov, Vladimir

AU - Litvak, Galina

AU - Larina, Tatyana

AU - Sadykov, Vladislav

AU - Stathopoulos, Vassilis N.

N1 - Publisher Copyright: © 2018 Chinese Materials Research Society

PY - 2018/8/1

Y1 - 2018/8/1

N2 - LnZrOx (Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods (complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction, Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy. The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation.

AB - LnZrOx (Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods (complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction, Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy. The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation.

KW - Fluorites

KW - Powders

KW - Pyrochlores

KW - Structure

KW - Synthesis

KW - ZIRCONIA

KW - NONSTOICHIOMETRY

KW - MECHANICAL-PROPERTIES

KW - CO OXIDATION

KW - SMFE1-XALXO3 X=0.00

KW - TEMPERATURE

KW - THERMAL BARRIER COATINGS

KW - LN(2)ZR(2)O(7) LN

KW - GD

KW - CERAMICS

UR - http://www.scopus.com/inward/record.url?scp=85050966763&partnerID=8YFLogxK

U2 - 10.1016/j.pnsc.2018.07.007

DO - 10.1016/j.pnsc.2018.07.007

M3 - Article

AN - SCOPUS:85050966763

VL - 28

SP - 437

EP - 446

JO - Progress in Natural Science: Materials International

JF - Progress in Natural Science: Materials International

SN - 1002-0071

IS - 4

ER -