CC BY
3
i l St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.2 Научно-технические ведомости СПбГПУ. Физико-математические науки. 15 (3.2) 2022
Conference materials UDC 539.18
DOI: https://doi.org/10.18721/JPM.153.207
X-ray spectral studies of doped bismuth-magnesium and bismuth-zinc tantalates
K. A. Bakina ,e, N. A. Zhuk 2, V. N. Sivkov \ S. V. Nekipelov 12 1 FRC Komi SC UB RAS, Syktyvkar, Russia; 2 Pitirim Sorokin Syktyvkar State University, Syktyvkar, Russia H tylxen@gmail.com
Abstract. Solid solutions of bismuth-magnesium tantalates and bismuth-zinc tantalates doped with 3d-metal atoms were studied by XPS and NEXAFS. It was shown that atoms of bismuth, magnesium and zinc in all the compounds under consideration have the charge states Bi3+, Mg2+ and Zn2+, respectively, and the tantalum atoms, in turn, have an effective charge of +(5-5).
Keywords: bismuth-magnesium, bismuth-zinc, tantalates
Funding: The study was funded by the Grant of the President of the Russian Federation (MK 3796.2021.1.2), the RFBR and the Komi Republic within the framework of research projects number 19-32-60018 and 20-42-110002 r-a. The study was supported by the Ministry of Science and Higher Education of Russia under Agreement No. 075-15-2021-1351 in part of research on NEXAFS spectroscopy.
Citation: Bakina K. A., Zhuk N. A., Sivkov V. N., Nekipelov S. V., X-ray spectral studies of doped bismuth-magnesium and bismuth-zinc tantalates, St. Petersburg State Polytechnical University Journal. Physics and Mathematics. 15 (3.2) (2022) 41-44. DOI: https://doi. org/10.18721/JPM.153.207
This is an open access article under the CC BY-NC 4.0 license (https://creativecommons. org/licenses/by-nc/4.0/)
Материалы конференции УДК 539.18
DOI: https://doi.org/10.18721/JPM.153.207
Рентгеноспектральные исследования допированных танталатов висмута-магния и висмута-цинка
К.А. Бакина 1Н, Н.А. Жук 2, В.Н. Сивков 1, С.В. Некипелов 12 1 ФИЦ Коми научный центр УрО РАН, Сыктывкар, Россия;
2 СГУ им. Питирима Сорокина, Сыктывкар, Россия н tylxen@gmail.com
Аннотация. На основе данных XPS- и NEXAFS-спектроскопии твёрдых растворов танталатов висмута-магния и висмута-цинка, допированных атомами меди и никеля, показано, что атомы висмута, магния и цинка во всех исследуемых соединениях обладают зарядовым состоянием Bi3+, Mg2+ и Zn2+, соответственно, а атомы тантала имеют эффективный заряд +(5-5).
Ключевые слова: висмут-магний, висмут-цинк, танталаты
Финансирование: Работа выполнена при финансовой поддержке Гранта Президента РФ (МК 3796.2021.1.2), РФФИ и Республики Коми в рамках научных проектов № 1932-60018 и 20-42-110002 р-а и Министерства науки и высшего образования РФ в рамках соглашения № 075-15-2021-1351 в части NEXAFS-спектроскопии.
Ссылка при цитировании: Бакина К. А., Жук Н. А., Сивков В. Н., Некипелов С. В. Рентгеноспектральные исследования допированных танталатов висмута-магния и висмута-цинка // Научно-технические ведомости СПбГПУ. Физико-математические науки. 2022. Т. 15. № 3.2. С. 41-44. DOI: https://doi.org/10.18721/ JPM.153.207
© Bakina K. A., Zhuk N. A., Sivkov V. N., Nekipelov S. V., 2022. Published by Peter the Great St.Petersburg Polytechnic University.
^St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.2
Статья открытого доступа, распространяемая по лицензии CC BY-NC 4.0 (https:// creativecommons.org/licenses/by-nc/4.0/)
Introduction
Doping of bismuth tantalates with atoms of various metals can lead to a significant change in their electrophysical properties, which can depend both on the type of doped atoms and on the degree of doping [1—4]. This work shows the results of NEXAFS and XPS studies of the electronic state and nature of interatomic interactions of 3d-metal atoms in bismuth-magnesium and bismuth-zinc tantalates doped with copper and nickel atoms at different degrees of doping Bi2Ta2Mg(Zn)1xCu(Ni)xO9 (x = 0.1—0.9). The experimental particularities and the used equipment characteristics are described in detail elsewhere [4].
Results and Discussion
Let us consider the results of spectral studies of bismuth-magnesium tantalates. Figure 1 shows the XPS spectra of bismuth-magnesium tantalates without doping and nickel-doped ones. It is clear that doping with nickel atoms slightly changes the spectral characteristics of bismuth, tantalum, and magnesium atoms. This indicates that the charge state of these atoms in the compounds under consideration is conserved.
Comparison of the XPS Bi 4f and Bi 5d spectra of the samples and Bi2O3 oxide (Fig. 1 a, b) shows that the energy position and width of the peaks in the spectra of all samples almost completely coincide and correlate well with the spectra of Bi2O3 oxide. Therefore, the bismuth atom in this compound has the Bi3+ charge state. In the case of tantalum atoms (Fig. 1 a, c), the absence of peak splitting and distortion clearly indicates that all tantalum atoms are in the same charge state. The energy position of the peaks has a shift towards lower energies compared to the binding energy in oxide Ta2O5, which is typical for a decrease in the effective positive charge. This evidence may be taken to mean that tantalum atoms have the same effective charge +(5-5). The energy position of the peaks in the XPS Mg 1s spectra (Fig. 1 d) is characteristic of a divalent magnesium atom [5]. Thus, the charge state of these atoms here is Mg2+.
HIjMg. jTa.O,
20 25 3D 35 Binding Energy, cV
150 155 160 (65 170 175 Binding Energy, eV
BiIHglliNi,,T«J0„
d)
I' ;MlJ.
210 220 230 240 250 260 Binding Energy, cV
1239 1302 1305 1303 Binding Energy, eV
Fig. 1. XPS spectra of bismuth-magnesium tantalates without doping and XPS spectra of bismuth-magnesium tantalates, doped with nickel atoms
Comparison of the XPS and NEXAFS Ni 2p spectra of the samples with the ones of nickel oxide NiO (Fig. 2) shows that nickel atoms have the same charge state, since there is no splitting and distortion of the peaks. The energy positions of the peaks in XPS spectra (Fig. 2 a) is shifted
© Бакина К. А., Жук Н. А., Сивков В. Н., Некипелов С. В., 2022. Издатель: Санкт-Петербургский политехнический университет Петра Великого.
4
Condensed matter physics
towards higher energies compared to the binding energies for the given levels in NiO oxide, which is characteristic of an increase in the effective positive charge. This suggests that nickel atoms have the same effective charge +(2+5). NEXAFS spectra (Fig. 2 b) reflects that the charge state of nickel atoms is preserved when the degree of doping is changed.
343 BSE 864 872 330 388 Binding Energy, eV
> UJ
850
852 854 858 858 Photon energy, eV
860
Fig. 2. XPS (a) and NEXAFS (b) Ni 2p spectra of Ni-doped bismuth-magnesium tantalates
Similar to samples doped with nickel atoms, in the case of doping with copper atoms, the shape of the spectra of bismuth, tantalum, and magnesium atoms remains almost unchanged. Consequently, the charge state of these atoms (Bi3+, Ta(5-5)+ and Mg2+) in the presented compounds is preserved. In this case, the behaviour of the introduced copper atoms is fundamentally different. Figure 3 shows the XPS and NEXAFS spectra of copper atoms in the samples at various degrees of doping. A comparison of the spectra shows that the samples contain Cu(I) and Cu(II) atoms.
a)
Cu IPm
Cll2psal
Uif i' i* LLLjJ , Hi/
BjzM0B.iCuB.ÏTaT°fl
Bi.Mgj.CujjTsjDj LJ
V—/ \ CtlO Cu20
CuO
Bi:TajMg„ ,Cu„ ,0,
El.TajMa.jCujjO, '¡¡Ta,Hg,,Cuns0B
CiuO
930 940 850 960 970 Binding Energy, eV
c)
CuîP),:
510
tn
J soo
c
S 490 480
HS,,Cun!
eeo
« 630 £
I 600
u
570
927 930 933 936 939 942 Photon energy, cV
d)
Cu2Ps,
MBjjCU,
927 930 933 935 928 930 932 934 935
Binding Energy, eV Binding Energy, eV
Fig. 3. XPS (a) and NEXAFS (b) Cu 2p spectra of Cu-doped bismuth-magnesium tantalates and decomposition of XPS Cu 2p spectra at x = 0.3 (c), at x = 0.7 (d)
From the analysis of XPS Cu 2p spectra (Fig. 3 c, d), it is possible to determine the contribution of Cu(I) and Cu(II) atoms to the corresponding spectra. The ratio of integral intensities Cu(I)/Cu(II) is 1.43 at x = 0.3 and 2.08 at x = 0.7. Thus, the relative contribution of Cu(I) increases with increasing degree of doping with copper atoms, which indicates a change in the position of copper atoms in the structure of pyrochlores. Perhaps, at a low concentration, copper atoms are introduced into the positions of tantalum atoms, and with an increase in their concentration, they are partially introduced into the positions of bismuth atoms. A similar behaviour of all atoms is also observed in the samples of Ni- and Cu-doped bismuth-zinc tantalates.
Conclusions
Thermally stable solid solutions of bismuth-magnesium (zinc) tantalates doped with nickel and copper atoms were obtained in a wide range of compositions. It follows from the NEXAFS and
^St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.2 ^
XPS spectra that the bismuth, magnesium, and zinc atoms in all compounds have the Bi3+, Mg2+, and Zn2+ charge state, while the tantalum atoms have an effective charge of +(5-5). The doped nickel atoms have an effective charge of +(2+5), and the copper atoms have the charge state Cu+
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2. Giampaoli G., Siritanon T., Day B., Li J., Subramanian M.A., Temperature in-dependent low loss dielectrics based on quaternary pyrochlore oxides, Prog. Solid. State Ch. 50 (2018) 16-23.
3. Zhuk N.A., Krzhizhanovskaya M.G., Koroleva A.V., Nekipelov S.V., Sivkov D.V., Sivkov V.N., Lebedev A.M., Chumakov R.G., Makeev B.A., Kharton V.V., Panova V.V., Korolev R.I., Spectroscopic characterization of cobalt doped bismuth tantalate pyrochlore. Solid State Sciences. 125 (2022) 106820.
4. Zhuk N.A., Krzhizhanovskaya M.G., Koroleva A.V., Reveguk A.A., Sivkov D.V., Nekipelov S.V., Thermal expansion, crystal structure, XPS and NEXAFS spectra of Fe-doped bismuth tantalate pyrochlore, Ceramics International. 48 (2022) 14849-14855.
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and Cu2+.
REFERENCES
THE AUTHORS
BAKINA Ksenia A.
tylxen@gmail.com ORCID: 0000-0002-6687-6908
SIVKOV Victor N.
sivkovvn@mail.ru
ORCID: 0000-0001-9916-1514
ZHUK Nadezhda A.
nzhuck@mail.ru
ORCID: 0000-0002-9907-0898
NEKIPELOV Sergey V.
nekipelovsv@mail.ru ORCID: 0000-0001-6749-738X
Received 14.08.2022. Approved after reviewing 21.08.2022. Accepted 23.08.2022.
© Peter the Great St. Petersburg Polytechnic University, 2022
