An X-ray powder and electron diffraction study of reduced tantalates with perovskite structure, Na1-xSrxTaO3, 0<x<0.4

Istomin, S.Y.; Svensson, G.; Hannerz, H.; Koehler, J.

Авторы: Istomin S.Ya, Svensson G., Hannerz H., Koehler J.
Журнал: Journal of Solid State Chemistry
Том: 154
Год издания: 2000
Издательство: Elsevier B.V.
Местоположение издательства: Netherlands
Первая страница: 427
Последняя страница: 434
DOI: 10.1006/jssc.2000.8860
Аннотация: Single-phase perovskite-type reduced tantalates, Na1 �� x SrxTaO3 with 0 < x40.4, have been synthesized by heating mix- tures of NaTaO3, Sr5Ta4O15 and Ta in sealed tantalum ampules at 14003C for 20+24 h. At Sr contents of 0.54x40.8 and above 14003C, polyphasic samples were obtained. X-ray powder di4raction (XRD) and transmission electron microscopy studies (selected area (SAED) and convergent beam electron di4raction (CBED)) showed an orthorhombic distortion of the x �� 0.1 sample (GdFeO3 type, space group Pnma). The interpretation of the XRD, SAED, and CBED studies indicates the crystallites found in the x �� 0.2 and 0.3 samples to consist of domains with tetragonal and orthorhombic symmetry having the unit cell para- meters of a �� b+@2aper and c+2aper and a+b+@2aper and c+aper (aper cell axis in the ideal perovskite structure), respec- tively. The x �� 0.4 sample was cubic (space group Pm3m) with a��aper. Resistivity measurements showed that all samples are semiconducting and that the conductivity increases with Sr con- tent. Magnetic measurements of Na0.6Sr0.4TaO3 revealed a dia- magnetic behavior down to 20 K. Below this temperature a slight paramagnetism arises.
Добавил в систему: Истомин Сергей Яковлевич

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An X-ray powder and electron diffraction study of reduced tantalates with perovskite structure, Na1-xSrxTaO3, 0<x<0.4статья

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