Formation of MoO₃ crystals in electric arc plasma source
Formation of molybdenum trioxide crystals by electric arc discharge between molybdenum electrodes is considered. Molybdenum oxide crystals were deposited on side surface of anode. Observation of crystals formation zone was used for determination of main formations stages. Plasma temperature was esti...
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| Zitieren: | Formation of MoO₃ crystals in electric arc plasma source / A.V. Lebid, A.N. Veklich, V.F. Boretskij, O.G. Kolesnyk, S.P. Savenok, O.V. Andreev // Вопросы атомной науки и техники. — 2014. — № 6. — С. 141-144. — Бібліогр.: 11 назв. — англ. |
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irk-123456789-819472015-05-23T03:02:05Z Formation of MoO₃ crystals in electric arc plasma source Lebid, A.V. Veklich, A.N. Boretskij, V.F. Kolesnyk, O.G. Savenok, S.P. Andreev, O.V. Низкотемпературная плазма и плазменные технологии Formation of molybdenum trioxide crystals by electric arc discharge between molybdenum electrodes is considered. Molybdenum oxide crystals were deposited on side surface of anode. Observation of crystals formation zone was used for determination of main formations stages. Plasma temperature was estimated by optical emission spectroscopy method. The resulting products were studied by X-rays diffraction, time-of-flight laser mass-spectrometry and optical microscopy methods. It was found, that self-organizing vapor-deposition process of MoO₃ crystals formation has place. The resulting product is colorless sparkling prisms and platelets, which are mainly consist of orthorhombic α-MoO₃ phase. Optical microscopy indicates the formation of closely packed feather-like pin structures by vapor-solid process. Рассматривается формирование кристаллов триоксида молибдена при помощи электродугового разряда между молибденовыми электродами. Кристаллы формировались на боковой поверхности анода во время горения дуги. Эти кристаллы представляют собой прозрачные блестящие призмы и пластинки, состоящие, главным образом, из орторомбической фазы MoO₃. Для определения основных этапов формирования кристаллов, их химического состава и структуры применялись наблюдение зоны роста, рентгеноструктурный анализ, времяпролетная масс-спектрометрия и микроскопические исследования. Розглянуто формування кристалів триоксиду молібдену за допомогою електродугового розряду між молібденовими електродами. Кристали формувались на боковій поверхні анода під час горіння вільноіснуючої електричної дуги. Ці кристали являли собою прозорі блискучі призми та пластинки, які складались, головним чином, із орторомбічної фази MoO₃. Для визначення основних етапів формування кристалів, їх хімічного складу та структури застосовувались спостереження зони росту, 2014 Article Formation of MoO₃ crystals in electric arc plasma source / A.V. Lebid, A.N. Veklich, V.F. Boretskij, O.G. Kolesnyk, S.P. Savenok, O.V. Andreev // Вопросы атомной науки и техники. — 2014. — № 6. — С. 141-144. — Бібліогр.: 11 назв. — англ. 1562-6016 PACS: 52.50.Dg, 52.77.-j, 81.15.Gh http://dspace.nbuv.gov.ua/handle/123456789/81947 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Низкотемпературная плазма и плазменные технологии Низкотемпературная плазма и плазменные технологии |
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Низкотемпературная плазма и плазменные технологии Низкотемпературная плазма и плазменные технологии Lebid, A.V. Veklich, A.N. Boretskij, V.F. Kolesnyk, O.G. Savenok, S.P. Andreev, O.V. Formation of MoO₃ crystals in electric arc plasma source Вопросы атомной науки и техники |
| description |
Formation of molybdenum trioxide crystals by electric arc discharge between molybdenum electrodes is considered. Molybdenum oxide crystals were deposited on side surface of anode. Observation of crystals formation zone was used for determination of main formations stages. Plasma temperature was estimated by optical emission spectroscopy method. The resulting products were studied by X-rays diffraction, time-of-flight laser mass-spectrometry and optical microscopy methods. It was found, that self-organizing vapor-deposition process of MoO₃ crystals formation has place. The resulting product is colorless sparkling prisms and platelets, which are mainly consist of orthorhombic α-MoO₃ phase. Optical microscopy indicates the formation of closely packed feather-like pin structures by vapor-solid process. |
| format |
Article |
| author |
Lebid, A.V. Veklich, A.N. Boretskij, V.F. Kolesnyk, O.G. Savenok, S.P. Andreev, O.V. |
| author_facet |
Lebid, A.V. Veklich, A.N. Boretskij, V.F. Kolesnyk, O.G. Savenok, S.P. Andreev, O.V. |
| author_sort |
Lebid, A.V. |
| title |
Formation of MoO₃ crystals in electric arc plasma source |
| title_short |
Formation of MoO₃ crystals in electric arc plasma source |
| title_full |
Formation of MoO₃ crystals in electric arc plasma source |
| title_fullStr |
Formation of MoO₃ crystals in electric arc plasma source |
| title_full_unstemmed |
Formation of MoO₃ crystals in electric arc plasma source |
| title_sort |
formation of moo₃ crystals in electric arc plasma source |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2014 |
| topic_facet |
Низкотемпературная плазма и плазменные технологии |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/81947 |
| citation_txt |
Formation of MoO₃ crystals in electric arc plasma source / A.V. Lebid, A.N. Veklich, V.F. Boretskij, O.G. Kolesnyk, S.P. Savenok, O.V. Andreev // Вопросы атомной науки и техники. — 2014. — № 6. — С. 141-144. — Бібліогр.: 11 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT lebidav formationofmoo3crystalsinelectricarcplasmasource AT veklichan formationofmoo3crystalsinelectricarcplasmasource AT boretskijvf formationofmoo3crystalsinelectricarcplasmasource AT kolesnykog formationofmoo3crystalsinelectricarcplasmasource AT savenoksp formationofmoo3crystalsinelectricarcplasmasource AT andreevov formationofmoo3crystalsinelectricarcplasmasource |
| first_indexed |
2025-07-06T07:43:45Z |
| last_indexed |
2025-07-06T07:43:45Z |
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1836882678398320640 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2014. №6(94)
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2014, №6. Series: Plasma Physics (20), p. 141-144. 141
FORMATION OF MoO3 CRYSTALS IN ELECTRIC ARC PLASMA
SOURCE
A.V. Lebid, A.N. Veklich, V.F. Boretskij, O.G. Kolesnyk, S.P. Savenok, O.V. Andreev
Taras Shevchenko National University of Kyiv, Ukraine
E-mail: tgctg@yandex.ru, van@univ.kiev.ua
Formation of molybdenum trioxide crystals by electric arc discharge between molybdenum electrodes is
considered. Molybdenum oxide crystals were deposited on side surface of anode. Observation of crystals formation
zone was used for determination of main formations stages. Plasma temperature was estimated by optical emission
spectroscopy method. The resulting products were studied by X-rays diffraction, time-of-flight laser mass-
spectrometry and optical microscopy methods. It was found, that self-organizing vapor-deposition process of MoO3
crystals formation has place. The resulting product is colorless sparkling prisms and platelets, which are mainly
consist of orthorhombic α-MoO3 phase. Optical microscopy indicates the formation of closely packed feather-like
pin structures by vapor-solid process.
PACS: 52.50.Dg, 52.77.-j, 81.15.Gh
INTRODUCTION
Molybdenum trioxide MoO3 has some unique
physicochemical properties. It can be used as
perspective material for lithium-ion batteries [1,2]; as
highly field emission cathode for display devices [3]; as
catalyst for hydrocarbons transformation reactions [4]
and as material for thin film gas sensors [5].
Fabrication of MoO3 usually is performed by
chemical or physical methods. The physical methods
allow to obtain micro- and nano- structured materials,
particularly crystals. These methods are mainly based
on vapor-deposition processes. Such kind of processes
are organized by evaporation of molybdenum or
molybdenum oxide powders in special furnace [1,6],
evaporation of molybdenum foil by infra-red heating
[3], atmospheric plasma processes based on UHF
discharge [2, 7].
The aim of this work is determination of
peculiarities of crystal formation in the electric arc
plasma source.
1. EXPERIMENTAL TECHNIQUES
The vertically oriented free-burning arc was ignited
in air between the end surfaces of metallic molybdenum
non-cooled electrodes (Fig. 1,a). The diameter of the
rod electrodes was 6 mm, the discharge gap was 8 mm
and DC current was 3.5 A. Molybdenum oxide appears
on side surface of anode (Fig. 1,b) during arcing. It must
be noted, that zone of crystals formation has place at
3...5 mm below the end surface of electrode.
The middle cross-section of electric arc discharge
plasma was studied by optical emission spectroscopy
technique [8]. The realized configuration of
experimental setup with diffraction grating 600 g/mm
permits simultaneous registration of spatial intensity
distribution in spectral range 400…660 nm.
Video registration of crystal formation zone was
used for determination of main process stages.
Peculiarities of crystal structure were studied by optical
microscopy method with using of MBI-1 microscope.
a b
Fig. 1. Experimental scheme (a) and general view of anode with deposited MoO3-crystals (b)
mailto:tgctg@yandex.ru
142 ISSN 1562-6016. ВАНТ. 2014. №6(94)
Chemical composition and structure of obtained
crystals and evaporation products were determined by
X-rays diffraction method and time-of-flight laser mass-
spectrometry.
2. RESULTS AND DISCUSSIONS
2.1. PLASMA SPECTROSCOPY
Optical emission spectroscopy and Boltzmann plot
method was used for determination of plasma
temperature. MoI spectral lines 473.1, 476.0, 550.6,
553.3, 557.0 and 603.0 nm (Fig. 2) and preliminary
selected spectroscopic data [9] were used. The
temperature in the middle cross-section of plasma was
estimated as 8000 K.
2.2. CRYSTAL FORMATION
The process of crystals formation during arc
discharge can be separated on specific sequential stages.
Immediately after arc ignition there wasn’t evaporation
due to relatively low temperature of anode surface
(Fig. 3,a).
After few seconds a white fume was observed
around the electrode (Fig. 3, b). This stage was
explained by oxidation of metallic molybdenum and
volatilization of oxides at increasing electrode
temperature. Really, oxidation of metallic molybdenum
surface and volatilization of oxide layer were observed
during heating in the furnance [1, 6]. It was mentioned
in work [6] that oxide layer completely evaporates from
molybdenum surface at temperature above 1150 C. So,
this assumption explains the absence of crystals near the
end surface of electrode (see Fig. 1,b) where surface
temperature was obviously more higher.
The MoO3-crystallites on electrode surface appeared
at the next process phase (Fig. 3,c). Crystals start
growing from white fume evaporations, which are
transported by convectional air flow. Probably, initial
crystallization starts on surface defects or on greyish-
black particles, which can be Mo2O3. Friable layer
around electrode (see Fig. 1,b), which consists of
irregular oriented transparent prisms and platelets, was
formed by vapor deposition.
Re-evaporation of deposited crystals is avoided by
two reasons. The first one is low thermal conductivity
between electrode and crystallites due to their irregular
orientation. The crystallites are weakly connected to
electrode surface but have numerous connection with
440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600 610
0
50
100
150
Wavelength, nm
MoI 476.0MoI 473.1 MoI 550,6 MoI 553,3
MoI 557,0
MoI 603,0
Intensity, a.u
Fig. 2. Registered spectrum and it’s interpretation
a b c
Fig. 3. View of anode at different process stages. Initial view – 7 s after arc ignition (a),
appearance of white fume at 17 s (b), formation of MoO3-crystallites at 25 s (c)
ISSN 1562-6016. ВАНТ. 2014. №6(94) 143
others. The second reason is cooling of crystallites by
convectional flows.
Therefore, in proposed plasma source self-
organizing vapor-deposition process of MoO3-crystals
formation has place. The process consists of
molybdenum surface oxidation, evaporation of oxide
layers, vapour transportation by convectional air flow
and crystal growth.
Usually formation of crystals is terminated after
2 min after arc ignition. It can be explained by
overlapping of molybdenum surface by crystals, which
complicates following evaporation and transportation of
building material.
2.3. CHEMICAL COMPOSITION AND
STRUCTURE
Chemical composition and structure of produced
crystals were determined by time-of-flight laser mass-
spectrometry (Fig. 4) and X-rays diffraction method
(Fig. 5, a,b). Obtained crystals were detached from
electrode surface and milled before the investigations.
X-ray diffraction (XRD) study indicates that resulting
crystals consist of orthorhombic α-MoO3 phase
(see Fig. 5, a). Positions of diffraction peaks are in good
agreement with reference data [10]. High intensity of
some diffraction peaks can be explained by orientation
effects in structure of obtained crystalline material. Only
slight admixture of monoclinic β-MoO3 phase was
detected.
Two forms of deposited crystals has place. The
prismatic transparent crystallites with longitudinal
dimension up to 3 mm and flat platelets (Fig. 6) with
dimensions up to 3x3 mm are obtained.
20 30 40 50
0
200
400
600
800
1000
1200
I
detector
, a.u.
I
detector
- detector signal,
2
o
І -MoO
3
, a.u.
0
50
100
I -MoO
3
- reference data [10]
a b
Fig. 5. XRD diagrams for MoO3-crystals (a) and evaporation products deposited on nickel foil (b)
100 μm
a b
Fig. 6. Optical microscopy of crystals growth structures
0 20 40 60 80 100 120
200
400
600
O
+
O
++
Mo
+
Signal Intensity, a.u.
Mass to charge ratio, m/z
Mo
++
Fig. 4. Time of flight mass-spectrometry diagram for
obtained crystals
142 ISSN 1562-6016. ВАНТ. 2014. №6(94)
Optical microscopy indicates formation of closely
packed feather-like structures (see Fig. 6 a,b). Every
“feather” consists of closely packed parallel needles,
which are unfinished structures of directional crystal
growth. Probably, attaching of building material on these
pins has place during vapor deposition process and
supports further translation of crystal structure.
Additionally evaporation products were collected on
mounted above the cathode nickel foil (see Fig. 1,b). The
deposited material also consists of MoO3, but the content
of β-MoO3 in powder is significantly higher than in
crystals. The ratio α-MoO3 / β-MoO3 can be estimated
from XRD peak intensities (Fig. 5, b).
CONCLUSIONS
The temperature of plasma in the middle cross-section
of electric arc discharge source was estimated as 8000 K.
The following stages of crystal formation were found:
molybdenum surface oxidation, evaporation of oxide
layer, vapour transportation by convectional air flow and
crystal growth.
The crystals are prismatic transparent prisms and flat
platelets with dimensions up to 3 mm. The peculiarity of
crystal was closely packed feather-like structures. Every
“feather” consists of parallel needles–unfinished
structures of directional crystal growth.
XRD analysis indicates that resulting crystals mainly
consist of orthorhombic α-MoO3 phase and only slight
admixture of monoclinic β-MoO3 phase was detected. But
the content of β-MoO3 in deposited evaporation products
(powder) is significantly higher than in crystals.
REFERENCES
1. W. Li, F. Cheng, Z. Tao, J. Chen. Vapor-transportation
preparation and reversible lithium intercalation /
deintercalation of α-MoO3 microrods // J. Phys. Chem. B.
2006, v. 110, p. 119-124.
2. D. Mariotti, H. Lindstrom, A. Chandra Bose,
K Ostrikov. Monoclinic β-MoO3 nanosheets produced by
atmospheric microplasma: application to lithium-ion
batteries // Nanotechnology. 2008, № 19, p. 495302.
3. Y.B. Li, Y. Bando, D. Golberg and K. Kurashima.
Field emission from MoO3 nanobelts // Appl. Phys. Lett.
2002, № 81, p. 5048-5050.
4. K.T. Queeney, C.M. Friend. Site-Selective Surface
Reactions: Hydrocarbon Oxidation Processes on Oxidized
Mo (110) // J. Phys. Chem. B. 2000, v. 104, № 3, p. 409-415.
5. E. Comini , G. Faglia, G. Sberveglieri, C. Cantlini,
M. Passacantando , S. Santucci,Y. Li, W. Wlodarski,
W. Qu. Carbon monoxide response of molybdenum oxide
thin films deposited by different techniques //
Sensors and Actuators. 2000, v. 68, p. 168-174.
6. F.W. Vahldiek. Growth and microstructure of
molybdenum oxide // Journal of the Less-Common
Metals. 1968, № 16, p. 351-359.
7. A. Chandra Bose, Y. Shimizu, D. Mariotti, T. Sasaki,
K. Terashima, N. Koshizaki. Flow rate effect on the
structure and morphology of molybdenum oxide
nanoparticles deposited by atmospheric-pressure
microplasma processing // Nanotechnology. 2006, v. 17,
№ 24, p. 5976-5982.
8. A. Veklich, A. Lebid. Technique of electric arc
discharge plasma diagnostic: peculiarities of registration
and treatment of spectra // Bulletin of Taras Shevchenko
National University of Kyiv. Radiophysics and
electronics, 2012, № 18. p. 6-9.
9. A.N. Veklich, A.V. Lebid, T.A. Tmenova,
V.F. Boretskij. Spectroscopic investigations of electric arc
plasma with additions of copper and molybdenum //
Bulletin of Taras Shevchenko National University of Kyiv
Series Physics & Mathematics. 2013, № 1, p. 251-256.
10. Powder diffraction files. Pdf-2. The International
Centre for Diffraction Data 2013 (Available from:
http://www.icdd.com/products/pdf2.htm).
11. I. Juarez Ramirez, A. Martinez-de la Cruz. Synthesis
of β-MoO3 by vacuum drying and its structural and
electrochemical characterisation // Materials Letters.
2003, v. 57, p. 1034-1039.
Article received 30.09.2014
ФОРМИРОВАНИЕ КРИСТАЛЛОВ MoO3 В ЭЛЕКТРОДУГОВОМ ИСТОЧНИКЕ ПЛАЗМЫ
А.В. Лебедь, А.Н. Веклич, В.Ф. Борецкий, О.Г. Колесник, С.П. Савенок, А.В. Андреев
Рассматривается формирование кристаллов триоксида молибдена при помощи электродугового разряда
между молибденовыми электродами. Кристаллы формировались на боковой поверхности анода во время
горения дуги. Эти кристаллы представляют собой прозрачные блестящие призмы и пластинки, состоящие,
главным образом, из орторомбической фазы MoO3. Для определения основных этапов формирования
кристаллов, их химического состава и структуры применялись наблюдение зоны роста, рентгеноструктурный
анализ, времяпролетная масс-спектрометрия и микроскопические исследования.
ФОРМУВАННЯ КРИСТАЛІВ MoO3 В ЕЛЕКТРОДУГОВОМУ ДЖЕРЕЛІ ПЛАЗМИ
А.В. Лебідь, А.М. Веклич, В.Ф. Борецький, О.Г. Колесник, С.П. Савенок, О.В. Андрєєв
Розглянуто формування кристалів триоксиду молібдену за допомогою електродугового розряду між
молібденовими електродами. Кристали формувались на боковій поверхні анода під час горіння вільноіснуючої
електричної дуги. Ці кристали являли собою прозорі блискучі призми та пластинки, які складались, головним
чином, із орторомбічної фази MoO3. Для визначення основних етапів формування кристалів, їх хімічного
складу та структури застосовувались спостереження зони росту, рентгеноструктурний аналіз, часопролітна
лазерна мас-спектрометрія та мікроскопічні дослідження.
144
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