Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation
There were provided the comparative investigations of the efficiency of optical absorption centers formation in magnesium aluminates spinel (single crystals and ceramics) at the influence of high energy gamma or electron beams. It was revealed that at gamma irradiation in the single crystals and c...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation / S.P. Gokov, V.T. Gritsyna, V.I. Kasilov, S.S. Kochetov, Yu.G. Kazarinov // Вопросы атомной науки и техники. — 2009. — № 5. — С. 81-84. — Бібліогр.: 14 назв. — англ. |
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Gokov, S.P. Gritsyna, V.T. Kasilov, V.I. Kochetov, S.S. Kazarinov, Yu.G. 2016-03-17T20:34:29Z 2016-03-17T20:34:29Z 2009 Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation / S.P. Gokov, V.T. Gritsyna, V.I. Kasilov, S.S. Kochetov, Yu.G. Kazarinov // Вопросы атомной науки и техники. — 2009. — № 5. — С. 81-84. — Бібліогр.: 14 назв. — англ. 1562-6016 PACS: 61. 80. https://nasplib.isofts.kiev.ua/handle/123456789/96511 There were provided the comparative investigations of the efficiency of optical absorption centers formation in magnesium aluminates spinel (single crystals and ceramics) at the influence of high energy gamma or electron beams. It was revealed that at gamma irradiation in the single crystals and ceramics the most probably the hole centers are formed which were created primarily at growth defects: cationic vacancies and anti-site defects. After electron irradiation of different fluences in absorption spectra there were observed bands related to hole centers (defects in the cationic sub-lattice) which practically does not change, while the concentration of electron centers (defects in the anion sub-lattice) grows proportionally to the electron fluence. Виконано порiвняльнi дослiдження ефективностi створення оптичних центрiв поглинання в магнiй- алюмiнiєвiй шпiнелi (монокристалiв та керамiки) пiд дiєю високоенергетичних гама-квантiв та електронiв. Показано, що гама-опромiнення монокристалiв та керамiки призводить переважно до створення дiркових центрiв, якi формуються на ростових дефектах: катiонних вакансiях та дефектах анти-структури. Пiсля електронного опромiнення рiзними флюенсами в спектрах поглинання спостерiгаються смуги, зумовленi дiрковими центрами (дефекти в катiоннiй пiдгратцi), концентрацiя яких практично не змiнилась, в той час як концентрацiя електронних центрiв (дефекти в анiоннiй пiдгратцi) росте пропорцiйно флюєнсу електронiв. Проведены сравнительные исследования эффективности образования оптических центров поглощения в магний-алюминиевой шпинели (монокристаллов и керамики) при воздействии высокоэнергетических гамма-квантов и электронов. Установлено, что гамма облучение монокристаллов и керамики приводит преимущественно к образованию дырочных центров, которые формируются на ростовых дефектах: катионных вакансиях и дефектах антиструктуры. После электронного облучения до различных флюенсов в спектрах поглощения наблюдаются полосы, обусловленные дырочными центрами (дефекты в катионной подрешетке), концентрация которых практически не изменилась, в то время как концентрация электронных центров (дефектов в анионной подрешетке) растет пропорционально флюенсу электронов. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Ядернo-физические методы и обработка данных Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation Ефективнiсть утворення дефектiв в шпiнелi пiд дiєю високоенергетичних електронiв та гама-квантiв Эффективность образования дефектов в шпинели под воздействием высокоэнергетичных электронов и гамма-квантов Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| spellingShingle |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation Gokov, S.P. Gritsyna, V.T. Kasilov, V.I. Kochetov, S.S. Kazarinov, Yu.G. Ядернo-физические методы и обработка данных |
| title_short |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| title_full |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| title_fullStr |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| title_full_unstemmed |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| title_sort |
efficiency of defects formation in spinel under high energy electron and gamma beam irradiation |
| author |
Gokov, S.P. Gritsyna, V.T. Kasilov, V.I. Kochetov, S.S. Kazarinov, Yu.G. |
| author_facet |
Gokov, S.P. Gritsyna, V.T. Kasilov, V.I. Kochetov, S.S. Kazarinov, Yu.G. |
| topic |
Ядернo-физические методы и обработка данных |
| topic_facet |
Ядернo-физические методы и обработка данных |
| publishDate |
2009 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Ефективнiсть утворення дефектiв в шпiнелi пiд дiєю високоенергетичних електронiв та гама-квантiв Эффективность образования дефектов в шпинели под воздействием высокоэнергетичных электронов и гамма-квантов |
| description |
There were provided the comparative investigations of the efficiency of optical absorption centers formation in magnesium
aluminates spinel (single crystals and ceramics) at the influence of high energy gamma or electron beams.
It was revealed that at gamma irradiation in the single crystals and ceramics the most probably the hole centers
are formed which were created primarily at growth defects: cationic vacancies and anti-site defects. After electron
irradiation of different fluences in absorption spectra there were observed bands related to hole centers (defects in
the cationic sub-lattice) which practically does not change, while the concentration of electron centers (defects in the
anion sub-lattice) grows proportionally to the electron fluence.
Виконано порiвняльнi дослiдження ефективностi створення оптичних центрiв поглинання в магнiй-
алюмiнiєвiй шпiнелi (монокристалiв та керамiки) пiд дiєю високоенергетичних гама-квантiв та електронiв. Показано, що гама-опромiнення монокристалiв та керамiки призводить переважно до створення дiркових центрiв, якi формуються на ростових дефектах: катiонних вакансiях та дефектах анти-структури. Пiсля електронного опромiнення рiзними флюенсами в спектрах поглинання спостерiгаються смуги, зумовленi дiрковими центрами (дефекти в катiоннiй пiдгратцi), концентрацiя яких практично не змiнилась, в той час як концентрацiя електронних центрiв (дефекти в анiоннiй пiдгратцi)
росте пропорцiйно флюєнсу електронiв.
Проведены сравнительные исследования эффективности образования оптических центров поглощения
в магний-алюминиевой шпинели (монокристаллов и керамики) при воздействии высокоэнергетических
гамма-квантов и электронов. Установлено, что гамма облучение монокристаллов и керамики приводит
преимущественно к образованию дырочных центров, которые формируются на ростовых дефектах:
катионных вакансиях и дефектах антиструктуры. После электронного облучения до различных флюенсов в спектрах поглощения наблюдаются полосы, обусловленные дырочными центрами (дефекты в
катионной подрешетке), концентрация которых практически не изменилась, в то время как концентрация электронных центров (дефектов в анионной подрешетке) растет пропорционально флюенсу
электронов.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/96511 |
| citation_txt |
Efficiency of defects formation in spinel under high energy electron and gamma beam irradiation / S.P. Gokov, V.T. Gritsyna, V.I. Kasilov, S.S. Kochetov, Yu.G. Kazarinov // Вопросы атомной науки и техники. — 2009. — № 5. — С. 81-84. — Бібліогр.: 14 назв. — англ. |
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| fulltext |
EFFICIENCY OF DEFECTS FORMATION IN SPINEL
UNDER HIGH ENERGY ELECTRON AND GAMMA BEAM
IRRADIATION
S.P. Gokov1∗, V.T. Gritsyna2, V.I. Kasilov1 S.S. Kochetov1, Yu.G. Kazarinov 2
1National Science Center ”Kharkov Institute of Physics and Technology”, 61108, Kharkov, Ukraine
2V.N. Karazin Kharkiv National University, 61077, Kharkiv, Ukraine
(Received July 16, 2009)
There were provided the comparative investigations of the efficiency of optical absorption centers formation in mag-
nesium aluminates spinel (single crystals and ceramics) at the influence of high energy gamma or electron beams.
It was revealed that at gamma irradiation in the single crystals and ceramics the most probably the hole centers
are formed which were created primarily at growth defects: cationic vacancies and anti-site defects. After electron
irradiation of different fluences in absorption spectra there were observed bands related to hole centers (defects in
the cationic sub-lattice) which practically does not change, while the concentration of electron centers (defects in the
anion sub-lattice) grows proportionally to the electron fluence.
PACS: 61. 80.
1. INTRODUCTION
Magnesium aluminates spinel, MgAl2O4, (hereafter
termed ”spinel”) is highly radiation resistant material
and is prospective for use in nuclear reactors as fuel
forms, as inert matrix for transmutation of actinides,
in fusion reactors as insulators for magnetic coils and
windows for radiofrequency plasma heating [1, 2]. In
all indicated cases this material w frequently will un-
dergo to irradiation of different nature and intensity.
Because single crystals are restricted in size and pro-
duction is very expensive the development of ceramic
technology of this material is now in progress [3, 4].
Therefore, the comparison of influence of irradiation
on the properties of single crystals and ceramics is
issue of the day. One of the most successful processes
for producing optical quality spinel ceramics is hot-
pressing technique of spinel powder doped with LiF
[5, 6]. The variations of processing condition were
applied to change of microstructure, porosity, optical
and mechanical properties of spinel ceramics. Thus
initial properties of ceramics and single crystals, ba-
sically degree of crystalline perfection, may influence
on the sensitivity of this material to different types
of irradiation. Under high energy ionizing irradiation
such as gamma-rays or fast electrons the process of
optical center formation goes through creation of free
charge carriers with subsequent trapping by growth
or radiation induced defects and impurity ions. In
this paper we describe the results of comparative in-
vestigations of radiation induced defects in spinel sin-
gle crystals and ceramics after irradiation with high
energy electrons and gamma quanta.
2. EXPERIMENTAL PROCEDURE
Irradiation of spinel samples with electron or gamma
beam was provided at linear accelerator LUE − 300
with nominal electron energy of 30MeV . There was
used deflected output which allows to decrease the
energy spread of electron beam and contribution of
bremsstrahlung gamma-rays at irradiation. The en-
ergy of electron was 16 MeV , the beam current about
2.5 and 10 µA/cm2 , and different fluences was ac-
cessed by variation of irradiation time. The irradia-
tion with gamma beam was provided at strait output
to increase the irradiation dose. Gamma-rays were
generated by conversion of electrons with energy of
7 MeV in tantalum target with thickness of 2.0 mm.
Using deflecting magnet the gamma component was
separated from electrons. Gamma-beam was formed
using collimator and was directed to samples. Elec-
tron fluence on conversion target was 3.4× 1017 elec-
trons, which corresponds to 1016 gamma quant/cm2
on samples under investigation. Stoichiometric spinel
crystals were grown by Verneuil methods. From
grown boule the slices of 12×10×0.7 mm were cut and
polished to optical finish. Stoichiometric spinel ce-
ramics were obtained by ordinary hot-pressing tech-
nique of spinel powder containing 1 % of lithium flu-
oride to get optically transparent material. Slices of
12×7×0.7 mm were cut and also polished to optical
finish.
3. RESULTS AND DISCUSSION
The absorption spectra of pristine crys-
tals have no definite bands indicating the
∗Corresponding author E-mail address: gokovsp@kipt.kharkov.ua
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2009, N5.
Series: Nuclear Physics Investigations (52), p.81-84.
81
absence of impurities. In the gamma-ray-
irradiated samples the absorption spectra con-
tains several overlapping bands which form max-
ima at approximately 3.1 and 5.0 eV (Fig.1).
Fig.1. Optical absorption spectra of gamma- and
electron-irradiated spinel single crystals
Previous investigations of radiation induced opti-
cal centers gave a possibility to identify the ab-
sorption bands with corresponding lattice defects:
5.3 eV absorption band is related to F -centers,
i.e. anion vacancies captured two electrons [7, 8];
4.75 eV absorption related to F+ - centers, also
cation vacancies but captured one electron [9, 10];
4.2 eV absorption band was tentatively identified
with electron centers formed at defects of positively
charged anti-site defects. Absorption of photons
of energy lower 4 eV contains many overlapping
bands which were identified with different types
of hole centers, i.e. cationic vacancies and nega-
tively charged anti-site defects captured one or more
holes [11, 12]. Therefore we conclude that under
gamma irradiation both hole and electron centers
of different concentration are formed. It should
be noted that absorption in high energy photon
range very often caused by uncontrolled impuri-
ties which change under irradiation charging states.
Fig.2. Radiation induced optical absorption spectra
in gamma- and electron-irradiated spinel single
crystals
Electron irradiation to fluence of 3.0× 1016el/cm2 at
the currant density of 10 µA/cm2 leads to formation
only one weak absorption band at 4.75 eV . To de-
convolute the spectra into specific bands we subtract
from spectra of irradiated sample the initial spectra.
Such difference absorption spectra are shown in Fig.2.
Evidently we can distinguish main band at 3.2 and
4.75 eV with some contribution of bands at 3.8 eV
(as a peak) and 5.3 eV (as a hole) [13]. Therefore,
we may conclude that under gamma irradiation the
main process of optical centers formation is charge
exchange between cationic and anionic vacancies.
The irradiation with high energy electrons at high
flux the temperature of sample was raise up to 200◦C,
which leads to annealing of hole centers, also the ra-
diation created anionic vacancies capture electrons
forming F+ centers, which are stable up to 200◦C
[14]. Absorption spectra of gamma irradiated spinel
ceramics very similar to that of single crystals, which
are shown in Fig.3. Absorption spectra of electron ir-
radiated ceramics at low electron flux 2.5 µA/cm2 to
Fig.3. Optical absorption spectra of gamma- and
electron-irradiated spinel ceramics
different fuences demonstrate the formation of two
wide spectral regions: in the visible range of photon
energy 2...4 eV which does not depend on fluence,
and UV-range of photon energy 4...6 eV growing
with increase of fluence. By subtracting of initial
spectra we obtained radiation induced optical spec-
tra, which are shown in Fig.4. By deconvolution
of these spectra into Gaussians we obtained bands
at 2.8, 3.2 and 3.8 eV which were identified with
hole centers at cationic defects, including empty
cationic vacancy, complex defects of lithium ions
in cation vacancy, and anti-site defects (Mg2+
Al )0, re-
spectively. In the second spectral region the bands
at 4.15, 4.75 and 5.3 eV are found which were iden-
tified with electron centers at anion defects, related
to anti-site defects (Al3+Mg)0, anion vacancies cap-
tured one electron (F+-centers) or two electrons (F -
centers), respectively. In the indicated range of flu-
ences the concentration of hole centers practically
does not change (defects in cationic sub-lattice), at
the same time the concentration of electron centers
82
Fig.4. Radiation induced optical absorption spectra
in gamma- and electron-irradiated spinel ceramics
(defects in anion sub-lattice) growths propor-
tionally to electron fluence. Using semi empir-
ical Smakula formula we calculated the maxi-
mal concentration of F -type centers which reaches
1.1× 1017 defects/cm3. I.e., the efficiency of cre-
ation of stable defects at irradiation with 16MeV
electrons equals 0.33 defects/electron.
4. CONCLUSION
There were provided the comparative investigations
of the efficiency of optical absorption centers forma-
tion in magnesium aluminates spinel (single crystals
and ceramics) at the action of high energy gamma or
electron beams. It was revealed that at gamma irra-
diation of single crystals the most probably the hole
centers are formed which were created primarily at
growth defects: cationic vacancies and anti-site de-
fects. At the irradiation with electrons at beam cur-
rent density of 10 µA/cm2 the temperature of sample
was raised which leads to partly thermal annealing
of unstable radiation-induced centers and absorption
spectra demonstrate the weak bands related of F -
type centers which are formed at radiation induced
anionic vacancies. After gamma irradiation of spinel
ceramics also mainly hole centers are formed at ini-
tial defects. After electron irradiation of ceramics
at beam current density of 2.5 µA/cm2 in absorp-
tion spectra there were observed bands related to hole
and electron centers. At the investigation of the dose
dependences of the efficiency of defects formation it
was found that the concentration of hole centers (de-
fects in the cationic sub-lattice) practically does not
change, while the concentration of electron centers
(defects in the anion sub-lattice) grows proportion-
ally to the fluence of irradiation. There was defined
the efficiency of defect formation in anionic vacancies
in complex oxide of magnesium aluminates spinel at
the irradiation with 16 MeV electrons.
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stoichiometric spinel crystals // Nucl. Instr. and
Meth. 2006, v.B250, p.349-353.
ЭФФЕКТИВНОСТЬ ОБРАЗОВАНИЯ ДЕФЕКТОВ В ШПИНЕЛИ ПОД
ВОЗДЕЙСТВИЕМ ВЫСОКОЭНЕРГЕТИЧНЫХ ЭЛЕКТРОНОВ И
ГАММА-КВАНТОВ
С.П. Гоков, В.Т. Грицына, В.И. Касилов, С.С. Кочетов, Ю.Г. Казаринов
Проведены сравнительные исследования эффективности образования оптических центров поглощения
в магний-алюминиевой шпинели (монокристаллов и керамики) при воздействии высокоэнергетических
гамма-квантов и электронов. Установлено, что гамма облучение монокристаллов и керамики приводит
преимущественно к образованию дырочных центров, которые формируются на ростовых дефектах:
катионных вакансиях и дефектах антиструктуры. После электронного облучения до различных флю-
енсов в спектрах поглощения наблюдаются полосы, обусловленные дырочными центрами (дефекты в
катионной подрешетке), концентрация которых практически не изменилась, в то время как концен-
трация электронных центров (дефектов в анионной подрешетке) растет пропорционально флюенсу
электронов.
ЕФЕКТИВНIСТЬ УТВОРЕННЯ ДЕФЕКТIВ В ШПIНЕЛI ПIД ДIЄЮ
ВИСОКОЕНЕРГЕТИЧНИХ ЕЛЕКТРОНIВ ТА ГАМА-КВАНТIВ
С.П. Гоков, В.Т. Грицина, В.Й. Касiлов, С.С. Кочетов, Ю.Г. Казаринов
Виконано порiвняльнi дослiдження ефективностi створення оптичних центрiв поглинання в магнiй-
алюмiнiєвiй шпiнелi (монокристалiв та керамiки) пiд дiєю високоенергетичних гама-квантiв та елек-
тронiв. Показано, що гама-опромiнення монокристалiв та керамiки призводить переважно до створен-
ня дiркових центрiв, якi формуються на ростових дефектах: катiонних вакансiях та дефектах анти-
структури. Пiсля електронного опромiнення рiзними флюенсами в спектрах поглинання спостерiга-
ються смуги, зумовленi дiрковими центрами (дефекти в катiоннiй пiдгратцi), концентрацiя яких прак-
тично не змiнилась, в той час як концентрацiя електронних центрiв (дефекти в анiоннiй пiдгратцi)
росте пропорцiйно флюєнсу електронiв.
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