SYNTHESIS AND STRUCTURAL, MAGNETIC AND ELECTRICAL CHARACTERIZATION OF THE REDUCED OXONIOBATES BANB8O14, EUNB8O14, EU2NB5O9 AND EUXNBO3 (X=0.7, 1.0) / ZUBKOV VG,TYUTYUNNIK AP,PERELIAEV VA,SHVEIKIN GP,KOHLER J,KREMER RK,SIMON A,SVENSSON G // JOURNAL OF ALLOYS AND COMPOUNDS. - 1995. - V. 226, l. 1-2. - P. 24-30.

ISSN/EISSN:

0925-8388 / нет данных

Type:

Article

Abstract:

Powder samples of the reduced oxoniobates Eu0.7NbO3, EuNbO3, Eu2Nb5O9, EuNb8O14 and BaNb8O14 have been synthesised. EuNbO3 and Eu0.7NbO3 adopt the perovskite type structure (space group Pm3m) with unit cell parameters a = 4.021 (1) and 3.981 (3) Angstrom, respectively. Eu,Nb,Og exhibits an intergrowth structure which can be described as alternating slabs of NbO and EuNbO3. It crystallises in P4/mmm with a = 4.131(1) and c = 12.043(5) Angstrom. EuNb8O14 and the here synthesised modification of BaNb8O14 is isostructural with SrNb8O14. The structures of EuNb8O14 and BaNb8O14 have been refined from X-ray powder diffraction data with the Rietveld technique, They have the unit cell parameters a = 9.2272(1), b = 10.2647(2), c = 5.9381(1) and a = 9.3451(1), b = 10.2689(2), c = 5.9470(4) Angstrom, (space group Pbam), respectively. In all the studied compounds AO(12) cuboctahedra (A = Eu, Ba) form either chains (in ANb(8)O(14)), double layers (in Eu2Nb5O9) or three-dimensional nets (in EuNbO3 and Eu0.7NbO3). Magnetic susceptibility measurements show temperature independent paramagnetism for BaNb8O14, while the susceptibilities of the Eu niobates follow Curie-Weiss laws with effective magnetic moments in good agreement with the expected mu(eff)=7.9 mu(B) for EU(2+). Eu0.7NbO3 and Eu1.0NbO3 exhibit ferromagnetic ordering below 4 K. BaNb8O14 and EuNb8O14 are semiconductors, while Eu2Nb5O9, EuNbO3 and Eu0.7NbO3 are metallic.

Author keywords:

MAGNETIC CHARACTERIZATION; ELECTRICAL CHARACTERISTICS; REDUCED OXONIOBATES X-RAY-DIFFRACTION; SINGLE-CRYSTAL; REFINEMENT; CLUSTERS

DOI:

10.1016/0925-8388(95)01597-3

Web of Science ID:

ISI:A1995RT39300006

Соавторы в МНС:

Другие поля

Поле	Значение
Month	AUG 1
Publisher	ELSEVIER SCIENCE SA LAUSANNE
Address	PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND
Language	English
Keywords-Plus	X-RAY-DIFFRACTION; SINGLE-CRYSTAL; REFINEMENT; CLUSTERS
Research-Areas	Chemistry; Materials Science; Metallurgy \& Metallurgical Engineering
Web-of-Science-Categories	Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy \& Metallurgical Engineering
ResearcherID-Numbers	Tyutyunnik, Alexander/P-2230-2015
Number-of-Cited-References	24
Usage-Count-Last-180-days	2
Usage-Count-Since-2013	9
Journal-ISO	J. Alloy. Compd.
Doc-Delivery-Number	RT393