Запис Детальніше

ФТОРВМІСНІ Bi-ВТНП СПОЛУКИ

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Title ФТОРВМІСНІ Bi-ВТНП СПОЛУКИ
FLUORIDE Bi-HTSC COMPOUNDS
 
Creator Зенькович, Елена Георгиевна
Недилько, Сергей Андреевич
Трачевский, Владимир Васильевич
Ашуев, Антон Андреевич
 
Subject фторид-іон
властивості
купрати
надпровідники
синтез
гетеровалентне заміщення
fluoride ion
the properties
cuprates
superconductors
synthesis
heterovalent substitution
 
Description Методом твердофазного синтезу синтезовані зразки фторвмісної Bi-2212 ВТНП
кераміки з використанням різних фторуючих агентів. Наявність фтору в одержаних зразках
підтверджена методом ЯМР-спектроскопії
The aim of the work was the synthesis of fluorinated ceramics based on Bi-2212 with cations
that occupy different crystallographic positions in the structure of Bi2Sr2CaCu2O8, namely PbF2, EuF3,
BiOF, NH4F, CaF2 and SrF2, ie obtaining samples of Bi2-xPbxSr2CaCu2O8-2xF2x, Bi2-xEuxSr2CaCu2O8-
3xF3x, Bi2Sr2CaCu2O8-xFx, Bi2Sr2CaCu2O8-xF2x, studying the phase composition and unit cell parameters
of the samples and determination of fluorine in the samples by the method of NMR spectroscopy of
solids.
All the samples of ceramics were studied by X-ray diffraction analysis. According to the X-ray
studies of crystal lattice parameters of the sampleswere calculated.
Conventional analytical methods of determination of fluoride were uncomfortable and
ineffective to confirm the replacement of oxygen atoms by fluorine in Bi-2212 due to small amount of
fluoride ions in the samples. Therefore the NMR 19F method was used in this work.
The existence of chemical shift (δ) from 0 ppm shows that the solid-phase synthesis of
samples of Bi2-xPbxSr2CaCu2O8-2x, Bi2-xEuxSr2CaCu2O8-3xF3x, Bi2Sr2CaCu2O8-xFx, Bi2Sr2CaCu2O8-xF2x
leads to entering of fluorine atoms to the structure of Bi-2212 with the replacing of oxygen atoms by
fluorine taking place. Width of lines in the spectra of samples obtained with PbF2, EuF3, NH4F and
CaF2 used as fluorinating agents may indicate a superposition of at least two signals which are not
separated due to the influence of the local magnetic field of paramagnetic copper (II)-containing
fragments. In the case of systems containing BiOF and SrF2 we obtained the other picture of character
ISSN 2074-6652
Наукові праці ДонНТУ. Серія: Хімія і хімічна технологія Випуск 1(20), 2013
 Fomina E.S., 2013 36
spectra - clearly separated signals with different chemical shifts, corresponding to fluorine atoms in
different chemical environments.
Value of integrated intensities signal gives a reason to expect that in case of strontium fluoride,
in which the Sr-F bond is more ionic than in case of other fluorinating agents, fluoride ion is a part of
copper based structure fragments. The fact of chemical shift to the strong field in the spectra of
samples indicates the increasing shielding of the 19F nuclei, accompanied by the occurrence of
fluoride ions in the extended fragments in the structure as possible bridges between copper atoms and
increase symmetry close to them.
Chemical shift at 140 ppm corresponds to fluorine atoms that are associated with atoms of
copper. This fact shows that, the fluorine atoms are situated in chains CuO2, and the substitution may
significantly affect the electrophysical parameters of the Bi-containing ceramics.
 
Date 2013-04-10T16:07:33Z
2013-04-10T16:07:33Z
2013-04-10
 
Type Article
 
Identifier 2074-6652
http://ea.donntu.edu.ua/handle/123456789/18370
 
Relation Наукові праці ДонНТУ;Серія: Хімія і хімічна технологія, 2013. - Вип.1(20). - С.30-36