Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods
At the present study the possibility of obtaining two compositions of Ca₁₀(PO₄)₆F₂ and Ca₉Sr(PO₄)₆F₂ fluoroapatites by both chemical deposition from solutions of the initial components and reaction in the solid phase was investigated. Using X-ray diffraction (XRD) method was shown that the fluor...
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Науковий фізико-технологічний центр МОН та НАН України
2013
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nasplib_isofts_kiev_ua-123456789-1003132025-02-09T14:49:59Z Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods Анализ фторапатита, полученного методами химического осаждения и твердофазной реакции Аналіз фторапатиту, отриманого методами хімічного осадження та твердофазної реакції Sayenko, S.Yu. Shkuropatenko, V.А. Tarasov, R.V. Prudyvus, K.А. Savina, S.А. Zykova, A.V. At the present study the possibility of obtaining two compositions of Ca₁₀(PO₄)₆F₂ and Ca₉Sr(PO₄)₆F₂ fluoroapatites by both chemical deposition from solutions of the initial components and reaction in the solid phase was investigated. Using X-ray diffraction (XRD) method was shown that the fluorapatite synthesis based on calcium pyrophosphate with the addition of strontium takes place at lower temperatures. Fluoroapatite formation obtained by precipitation process is the result of the reaction between initial component solutions. At the process of heat treatment of obtained powders by XRD method was found that compared with fluorapatite obtained by solid phase reaction, fluorapatite obtained by precipitation method include less content of TCP phase. Maximum density (~92 % of the theoretical value) is reached for the sample heat treated at 1250 °C with the exposure time up to 6 hours for fluorapatite obtained by precipitation and at a temperature 1200 °C with the exposure time up to 10 hours for fluorapatite prepared by reaction in the solid phase. данной работе исследовалась возможность получения фторапатита двух составов Ca₁₀(PO₄)₆F₂ и Ca₉Sr(PO₄)₆F₂ методом химического осаждения растворов исходных компонентов и реакцией в твердой фазе. С помощью рентгенофазового анализа (РФА) показано, что с добавлением стронция синтез фторапатита на основе пирофосфата кальция проходит при более низких температурах. Образование фторапатита, полученного осаждением происходит в результате реакции между растворами исходных компонентов. При термообработке полученных порошков методом РФА установлено, что по сравнению с фторапатитом, полученным с помощью твердофазной реакции, фторапатит, полученный осаждением содержит меньшее количество ТКФ. Максимальное значение плотности (~92% от теоретической) достигнуто для образцов термообработанных при температуре 1250 °С и времени выдержки 6 часов дляфторапатита, полученного осаждениеми при температуре 1200 °С и времени выдержки 10 часов для фторапатита, полученного реакцией в твердой фазе. У даній роботі досліджувалася можливість отримання фторапатиту двох складів Ca₁₀(PO₄)₆F₂ та Ca₉Sr(PO₄)₆F₂ методом хімічного осадження розчинів вихідних компонентів і реакцією в твердій фазі. За допомогою рентгенофазового аналізу (РФА) показано, що з додаванням стронцію синтез фторапатиту на основі пірофосфата кальцію проходить при нижчих температурах. Утворення фторапатиту, отриманого осадження відбувається в результаті реакції міжрозчинами вихідних компонентів. При термообробці отриманих порошків методом РФА встановлено, що у порівнянніз фторапатитом, отриманим реакцією в твердій фазі, фторапатит, отриманий осадженням містить меншу кількість ТКФ. Максимальне значення щільності (~92% від теоретичної) досягнуте для зразків термооброблених при температурі 1250 °С і часі витримки 6 годин для фторапатиту, отриманого осадженням і при температурі 1200 °С і часі витримки 10 годин для фторапатиту, отриманого реакцією в твердій фазі. 2013 Article Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods / S.Yu. Sayenko, V.А. Shkuropatenko, R.V. Tarasov, K.А. Prudyvus, S.А. Savina, A.V. Zykova // Физическая инженерия поверхности. — 2013. — Т. 11, № 3. — С. 279–284. — Бібліогр.: 11 назв. — англ. 1999-8074 https://nasplib.isofts.kiev.ua/handle/123456789/100313 621.039.736 en Физическая инженерия поверхности application/pdf Науковий фізико-технологічний центр МОН та НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
At the present study the possibility of obtaining two compositions of Ca₁₀(PO₄)₆F₂ and Ca₉Sr(PO₄)₆F₂
fluoroapatites by both chemical deposition from solutions of the initial components and reaction in the
solid phase was investigated. Using X-ray diffraction (XRD) method was shown that the fluorapatite
synthesis based on calcium pyrophosphate with the addition of strontium takes place at lower temperatures.
Fluoroapatite formation obtained by precipitation process is the result of the reaction between
initial component solutions. At the process of heat treatment of obtained powders by XRD method
was found that compared with fluorapatite obtained by solid phase reaction, fluorapatite obtained by
precipitation method include less content of TCP phase. Maximum density (~92 % of the theoretical
value) is reached for the sample heat treated at 1250 °C with the exposure time up to 6 hours for
fluorapatite obtained by precipitation and at a temperature 1200 °C with the exposure time up to 10
hours for fluorapatite prepared by reaction in the solid phase. |
| format |
Article |
| author |
Sayenko, S.Yu. Shkuropatenko, V.А. Tarasov, R.V. Prudyvus, K.А. Savina, S.А. Zykova, A.V. |
| spellingShingle |
Sayenko, S.Yu. Shkuropatenko, V.А. Tarasov, R.V. Prudyvus, K.А. Savina, S.А. Zykova, A.V. Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods Физическая инженерия поверхности |
| author_facet |
Sayenko, S.Yu. Shkuropatenko, V.А. Tarasov, R.V. Prudyvus, K.А. Savina, S.А. Zykova, A.V. |
| author_sort |
Sayenko, S.Yu. |
| title |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| title_short |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| title_full |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| title_fullStr |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| title_full_unstemmed |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| title_sort |
analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods |
| publisher |
Науковий фізико-технологічний центр МОН та НАН України |
| publishDate |
2013 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/100313 |
| citation_txt |
Analyses of fluorapatite prepared by both chemical precipitation and solid phase reaction methods / S.Yu. Sayenko, V.А. Shkuropatenko, R.V. Tarasov, K.А. Prudyvus, S.А. Savina, A.V. Zykova // Физическая инженерия поверхности. — 2013. — Т. 11, № 3. — С. 279–284. — Бібліогр.: 11 назв. — англ. |
| series |
Физическая инженерия поверхности |
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279
UDC: 621.039.736
ANALYSES OF FLUORAPATITE PREPARED BY BOTH CHEMICAL
PRECIPITATION AND SOLID PHASE REACTION METHODS
S.Yu. Sayenko, V.А. Shkuropatenko, R.V. Тarasov, K.А. Prudyvus,
S.А. Savina, A.V. Zykova
NSC “Kharkov Institute of Physics and Technology”
Ukraine
Received 05.09.2013
At the present study the possibility of obtaining two compositions of Ca10(PO4)6F2 and Ca9Sr(PO4)6F2
fluoroapatites by both chemical deposition from solutions of the initial components and reaction in the
solid phase was investigated. Using X-ray diffraction (XRD) method was shown that the fluorapatite
synthesis based on calcium pyrophosphate with the addition of strontium takes place at lower tem-
peratures. Fluoroapatite formation obtained by precipitation process is the result of the reaction between
initial component solutions. At the process of heat treatment of obtained powders by XRD method
was found that compared with fluorapatite obtained by solid phase reaction, fluorapatite obtained by
precipitation method include less content of TCP phase. Maximum density (∼ 92 % of the theoretical
value) is reached for the sample heat treated at 1250 °C with the exposure time up to 6 hours for
fluorapatite obtained by precipitation and at a temperature 1200 °C with the exposure time up to 10
hours for fluorapatite prepared by reaction in the solid phase.
Keywords: structure modification, fluorapatite, X-ray diffraction, differential thermal analysis,
radioactive wastes immobilization
АНАЛИЗ ФТОРАПАТИТА, ПОЛУЧЕННОГО МЕТОДАМИ ХИМИЧЕСКОГО
ОСАЖДЕНИЯ И ТВЕРДОФАЗНОЙ РЕАКЦИИ
С.Ю. Саенко, В.А. Шкуропатенко, Р.В. Тарасов, Е.А. Прудывус,
С.А. Савина, А.В. Зыкова
В данной работе исследовалась возможность получения фторапатита двух составов
Ca10(PO4)6F2 и Ca9Sr(PO4)6F2 методом химического осаждения растворов исходных компо-
нентов и реакцией в твердой фазе. С помощью рентгенофазового анализа (РФА) показано,
что с добавлением стронция синтез фторапатита на основе пирофосфата кальция проходит
при более низких температурах. Образование фторапатита, полученного осаждением происхо-
дит в результате реакции между растворами исходных компонентов. При термообработке
полученных порошков методом РФА установлено, что по сравнению с фторапатитом, полу-
ченным с помощью твердофазной реакции, фторапатит, полученный осаждением содержит
меньшее количество ТКФ. Максимальное значение плотности (∼ 92% от теоретической)
достигнуто для образцов термообработанных при температуре 1250 °С и времени выдержки
6 часов для фторапатита, полученного осаждением и при температуре 1200 °С и времени выдержки
10 часов для фторапатита, полученного реакцией в твердой фазе.
Ключевые слова: радиоактивные отходы, иммобилизация, фторапатит, рентгенофазовый
анализ, дифференциально-термический анализ.
АНАЛІЗ ФТОРАПАТИТУ, ОТРИМАНОГО МЕТОДАМИ ХІМІЧНОГО
ОСАДЖЕННЯ ТА ТВЕРДОФАЗНОЇ РЕАКЦІЇ
С.Ю. Саєнко, В.А. Шкуропатенко, Р.В. Тарасов, С.О. Савіна,
К.А. Прудивус, А.В. Зикова
У даній роботі досліджувалася можливість отримання фторапатиту двох складів Ca10(PO4)6F2
та Ca9Sr(PO4)6F2 методом хімічного осадження розчинів вихідних компонентів і реакцією в
твердій фазі. За допомогою рентгенофазового аналізу (РФА) показано, що з додаванням строн-
цію синтез фторапатиту на основі пірофосфата кальцію проходить при нижчих температурах.
Утворення фторапатиту, отриманого осадження відбувається в результаті реакції між розчинами
вихідних компонентів. При термообробці отриманих порошків методом РФА встановлено, що
у порівнянні з фторапатитом, отриманим реакцією в твердій фазі, фторапатит, отриманий осад-
женням містить меншу кількість ТКФ. Максимальне значення щільності (∼ 92% від теоретичної)
досягнуте для зразків термооброблених при температурі 1250 °С і часі витримки 6 годин для
фторапатиту, отриманого осадженням і при температурі 1200 °С і часі витримки 10 годин для
фторапатиту, отриманого реакцією в твердій фазі.
Ключові слова: радіоактивні відходи, іммобілізація, фторапатит, рентгенофазовий аналіз,
диференціально-термічний аналіз.
Sayenko S.Yu., Shkuropatenko V.А., Тarasov R.V., Prudyvus K.А., Savina S.А., Zykova A.V., 2013
ФІП ФИП PSE, 2013, т. 11, № 3, vol. 11, No. 3280
INTRODUCTION
The surface and bulk material structure modifications
are effective methods of modern innovative material
development. Various technologies such as sintering,
hot pressing, chemical precipitation and others are
used for obtaining new materials with tailored
properties.
The problem of radioactive waste accumulation
is one of the long-term and hazardous consequences
of nuclear programs. The most dangerous for the
biosphere are high-level wastes (HLW). The concept
of fractionation of HLW is developed according to
the fact that the half-life, biological hazards and
chemical properties of the HLW components vary
greatly. The concept of radioactive waste
immobilization into the crystalline matrices is based
on a matrices using such as mineral phases, which
have a natural analogs stable over long geological
time.
Recently experts from different countries carried
out multidisciplinary research of more than 30 such
crystalline compounds for immobilization of HLW.
There are durable and chemical stable minerals such
as zircon, pyrochlore, magnesium-aluminum spinel,
rare earth garnets, zirconolite, apatite, monazite, etc.
[1]. In different countries, the application of a variety
of rocks for geological disposal of the immobilized
HLW is expected, so often, for the same radionuc-
lides different waste forms were used for next com-
patibility with the disposal mineral phases and the
immobilization matrices.
The immobilization waste forms based on apatite
ceramic are considered as promising materials for
the immobilization of high-level waste due to a wide
range of iso- and heterovalent substitutions, high che-
mical and radiation resistance. Minerals and synthetic
compounds with apatite structure type form a large
family: A10(BO4)6X2 (A – Ca, Sr, Ba, Pb, Na, Cd,
Fe, K, Li, rare earth elements; B – P, Si, As, Cr , V,
S; X – F, Cl, OH, O, Br, CO3) [2].
One of the famous examples showing the che-
mical and radiation resistance of apatite in nature is
uranium deposit in Oklo (Gabon, Africa). The chain
reaction of uranium fission in the mineral formation
took place some two billion years ago. The crystals
of apatite are located in this place, characterized by
abnormal enrichment of 235U and fission products.
Consequently, the apatite-like compounds can
maintain the crystalline structure within a very long
time.
Apatite materials have also found an application
in many other fields, including biology, medicine,
electronics, etc. There are various technologies of
fluorapatite synthesis such as solid phase reactions,
precipitation from solution, sol-gel, hydrothermal
methods, and others. The aim of the present study
was to obtain calcium fluorapatite and fluorapatite
with strontium content by means of the solid phase
reaction and the precipitation of initial components
solutions
MATERIALS AND METHODS
For fluoroapatite Ca10(PO4)6F2 preparation by
means of the solid phase reaction the following com-
ponents such as calcium pyrophosphate Ca2P2O7,
calcium fluoride, CaF2, calcium carbonate CaCO3,
phosphoric acid H3PO4 were taken in the required
stoichiometry. Process of preparation of fluorapatite
was made by the following reaction [3]:
2Ca2P2O7 + CaF2 + 2H3PO4 + 3SaSO3 →
→ Ca10(PO4)6F2 + 3H2O + 5SO2↑ . (1)
To obtain fine powder of calcium pyrophosphate
grinding carried out in a planetary mill Mono
“Pulverisette 6” with isopropyl alcohol.
Calcium pyrophosphate, calcium carbonate and
calcium fluoride were mixed in a mill environment in
isopropyl alcohol and dried at a temperature of
100 °C to a residual moisture content 3 – 5%. Fluo-
roapatite dried mixture was screened through a sieve
with a mesh size of 100 microns. For strontium
adding in the fluorapatite mixture the strontium nitrate
Sr(NO3)2 as an aqueous solution was used. Thus,
an uniform distribution of strontium nitrate in the
fluorapatite mixture was provided. Strontium
fluorapatite Ca9Sr(PO4)6F2 was obtained by
reaction:
2Ca2P2O7 + CaF2 + 2H3PO4 + 4CaCO3 +
+Sr(NO3)2→ Ca9Sr(PO4)6F2+3CO2↑+ 4H2O +
+ 2NO2 + (1/2)O2. (2)
For fluorapatite preparation by solutions pre-
cipitation method the following components such
as calcium nitrate Ca(NO3)2·4H2O, disodium hyd-
rogen phosphate (NH4)2HPO4, ammonium fluoride
NH4F were taken in the required stoichiometry. The
preparation of Ca10(PO4)6F2 was performed accor-
ding to the following reaction:
10Ca(NO3)2 + 6(NH4)2HPO4 + 2NH4F +
NH4OH + (1/2)O2→ Ca10(PO4)6F2 +
+ 14NN4NO3 + +5,5H2O + 7NO2↑ . (3)
ANALYSES OF FLUORAPATITE PREPARED BY BOTH CHEMICAL PRECIPITATION AND SOLID PHASE REACTION METHODS
281
The process of calcium fluoroapatite preparation
by chemical precipitation method comprises the
following steps [4]:
− Preparing of the aqueous solutions of the initial
components required concentration. A sample of
Ca(NO3)2⋅4H2O in distilled water was dissolved.
Separately, the samples of (NH4) 2HPO4 and NH4F
in distilled water were dissolved.
− Mixing the initial solutions. A solution of
(NH4)2HPO4 (0.3 M) and NH4F by drops, with
constant stirring, was poured in warm
Ca(NO3)2⋅4H2O (0,5 M) (50 °C) solution with
pH = 9 – 9.5 adjusted by adding ammonium
hydroxide NH4OH.
− Preparing of a calcium fluorapatite powder.
Flushing the precipitate, drying in air, grinding and
heat-treating of the obtained powder was carried
out in the temperature range 900 – 1250 °C for
1 hour.
The strontium incorporation into fluorapatite
structure was made by strontium nitrate Sr(NO3)2
adding to a solution of Ca(NO3)2·4H2O. The prepa-
ration of strontium containing fluorapatite was carried
out analogously to the preparation of calcium fluo-
rapatite:
9Ca(NO3)2 + Sr(NO3)2 + 6(NH4)2HPO4 +
+ 2NH4F + NH4OH + (1/2)O2 →
→ Ca9Sr(PO4)6F2 + 14NN4NO3 + 5.5 H2O +
+ 7NO2↑ . (4)
The heat treatment of the powders was made in
air furnaces SUOL–0.25.1/12 – M1 and MP – 2U.
Thermogravimetric and differential thermal analysis
(TGA/DTA) was performed on derivatograph
Q – D 1500 at a temperature range 20 – 1000 °C,
with heating rate about 12 °C/min and termoana-
lizatore SDT Q600 V20.9 Build 20 in the tempe-
rature range 50 – 1300 °C, with heating rate about
10 °C/min. The phase analysis was made by the
phase X-ray diffraction method (XRD) (DRON –
1.5 with Cu radiation using a nickel selective filter).
Samples were prepared in the form of tablets with
diameter of 14 mm and height of 5 – 7 mm by doub-
le-side axial fluorapatite powder cold pressing
method in a hydraulic press. Pressing was carried
out in the pressure range 124 – 247 MPa.
The sintering of synthesized fluorapatite samples
in air was performed in the temperature range 900
– 1250 °C. The apparent bulk density (ρap) of the
samples after sintering was determined by hydrostatic
GOST 2409 – 95.
RESULTS AND DISCUSSION
Fluoroapatite obtained by solid phase reacti-
on.According to results of XRD analysis, only lines
of calcium pyrophosphate Ca2P2O7 after mixing of
the initial components were found (fig. 1a).
The results of thermal analysis of the fluoroapatite
Ca10 (PO4)6F2 mixture are shown in fig. 2.
Heat treatment of the original mixture up to
500 °C, according to X-ray studies, does not chan-
ge the phase composition. According to TG/DTA
analysis in the temperature range 120 – 280 °C there
a)
b)
Fig. 1. Diffraction peaks of Ca10(PO4)6F2 obtained by solid
phase reaction: а) – initial mixture; b) – termal treatment
at: Т = 1000 °С, τ = 1 hour.
Fig. 2. TG/DTA analysis of Ca10(PO4)6F2.
S.YU. SAENKO, V.А. SHKUROPATENKO, R.V. ТARASOV, K.А. PRUDYVUS, S.А. SAVINA, A.V. ZYKOVA
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is a strong endothermic effect, which is associated
with the removal of adsorbed water and evidenced
by weight loss in the TG curves, and also lack of
visible change in the phase composition. Second
small endothermic peak in the DTA curve in the
temperature range 440 – 520 °C, apparently
associated with the start of decomposition of calcium
carbonate which is in a small amount in the mixture.
At the difractogram of the powder, which was heat-
treated at 600 °C, there is the appearance of lines
fluorapatite. At temperature about 700 °C, there is
a significant number of lines of fluorapatite, and
reducing the intensity of the lines Ca2P2O7. Total
synthesis of the fluorapatite with Ca2P2O7
destruction proceeds in the temperature range 900
– 1000 °C (fig. 1b). On the DTA curve at such
temperature range there is a fairly strong endothermic
effect. Furthermore the line of tricalcium phosphate
Ca3(PO4)2 (TCP) appears in addition to the lines of
the synthesized fluorapatite in the diffraction peaks.
The research of phase formation of fluorapatite
with strontium content demonstrate that heat
treatment of fluorapatite mixture up to 500 °C similar
to the case of the calcium fluoroapatite, does not
affect on the mixture phase composition. Also, similar
to the case of calcium fluoroapatite, on the DTA
curve endothermic peaks were observed, which
associated with removal of adsorbed water and the
start of decomposition of calcium carbonate.
Intensive synthesis of fluorapatite runs at 600 °C.
Total synthesis of fluorapatite with the initial phases
destruction occurs in the temperature range 800 –
900 °C (fig. 4) and is accompanied by the endother-
mic effect at the DTA curve. Similar to the calcium
fluoroapatite case the diffraction lines of TCP appear,
and its intensity decreases with increasing tempe-
rature up to 1000 °C (fig. 3).
The sintering in air at the temperature range 1100
– 1200 °C for 600 minutes residence time is
performed. The data of the relative density
measurements of the sintered samples in air are
shown in fig. 4.
The results demonstrate that the sintering
temperature increasing in air leads to increase in
density and there is the maximum value of relative
density for all investigated fluorapatite compositions
at the temperature 1200 °C.
Fluoroapatite obtained by chemical precipita-
tions method. Fig. 5 shows XRD data of powders
obtained by co-precipitation of solutions of the ini-
tial components, Ca10(PO4)6F2 calcium and
Ca9Sr(PO4)6F2 with strontium content fluorapatites.
At all diffraction lines are present only one phase –
Ca10(PO4)6F2 (fig. 1a) and Ca9Sr(PO4)6F2 (fig. 1b),
respectively. Previously the necessity of heat
treatment of resulting powder at 800 – 1000 °C for
1 hour for fluorapatite solid-phase synthesis by
calcium pyrophosphate Ca2P2O7 using, as a main
component, was shown. In contrast to fluorapatite,
obtained by reaction in the solid phase, the formation
Fig. 3. Diffraction peaks of Ca9Sr(PO4)6F2 obtained by solid
phase reaction Т = 1000 °С, τ = 1 hour.
Fig. 4. The dependence of relative density of fluorapatite
samples obtained by solid phase reaction on sintering
temperature (τ = 600 min).
Fig. 5. Diffraction peaks of initial powders Ca10(PO4)6F2 (а)
and Ca9Sr(PO4)6F2 (b) obtained by chemical precipitation
method.
ANALYSES OF FLUORAPATITE PREPARED BY BOTH CHEMICAL PRECIPITATION AND SOLID PHASE REACTION METHODS
283
of fluorapatite by chemical precipitation is directly
resulting of the reaction of the initial component
solutions.
The only endothermic peaks with minimum at
100 °C which correspond to remove adsorbed wa-
ter was observed at the DTA curve obtained by
chemical precipitation of powders Ca10(PO4)6F2
and Ca9Sr(PO4)6F2.
A small endothermic peak at the temperature
range 900 – 1000 °C in fig. 6 is observed and pro-
bably associated with the start of thermal decom-
position reaction for fluoroapatite [5]:
Ca10(PO4)6F2 → 3Ca3(PO4)2 + CaF2. (5)
DTA data are confirmed by XRD data of fluo-
rapatite heat-treated powders obtained by chemical
precipitation from solutions The line of tricalcium
phosphate with low intensity was observed after heat
treatment of the powder of calcium fluoroapatite at
900 °C.
The increasing of the thermal treatment tem-
perature up to 1150 °C does not affect on the phase
composition of calcium fluoroapatite. In contrast to
the diffractogram of strontium containing fluorapatite
which has demonstrated the increasing of the
Ca3(PO4)2 lines number as compared to
Ca9Sr(PO4)6F2, heat-treated at 900 °C. The next
temperature increasing up to 1250 °C leads to the
disappearance of the tricalcium phosphate lines in
the diffraction pattern of calcium fluorapatite and the
reducing of intensity and number of lines in the
diffraction pattern of strontium containing fluorapatite
(fig. 7). It is known that chemical durability of phos-
phate materials decreases during process of fluo-
roapatite → hydroxyapatite → tricalcium phosp-
hate transformation [6].
Therefore, the content of TCP in the fluorapatite
matrices materials for next HLW immobilization
should be minimal. The samples were sintered in
the temperature range 1000 – 1250 °C for 6 hours
in air. Fig. 8 shows the relative density fluoroapatite
Ca10(PO4)6F2 (a) and Ca9Sr(PO4)6F2 depending on
the sintering temperature.
The density measurement results found that at
the temperature 1250 °C the maximum value of the
relative density (90 – 92%) was observed both for
calcium fluoroapatite and fluorapatite containing
strontium.
a)
b)
Fig. 6. TG/DTA analysis of Ca10(PO4)6F2 (а) and
Ca9Sr(PO4)6F2 (b).
Fig. 7. Diffraction peaks of Ca10(PO4)6F2 (а) and
Ca9Sr(PO4)6F2 (b) T = 1250 °С, τ = 1 hour.
S.YU. SAENKO, V.А. SHKUROPATENKO, R.V. ТARASOV, K.А. PRUDYVUS, S.А. SAVINA, A.V. ZYKOVA
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CONCLUSIONS
1. The fluoroapatite compositions Ca10(PO4)6F2
and Ca9Sr(PO4)6F2 were prepared by both the
reaction in the solid phase and chemical pre-
cipitation methods.
2. Found that in contrast to solid phase synthesis,
the formation of fluorapatite by chemical pre-
cipitation method is directly resulted on the initial
component solutions reaction.
3. According to XRD and DTA/TG analysis using
was shown that heat treatment of obtained by
precipitation from solutions fluorapatite at a tem-
perature above 900 °C leads to formation of a
small amount of TCP.
4. By sintering in air at temperatures of 1200 –
1250 °C the samples of calcium fluoroapatite
and strontium containing fluoroapatite with low
content of TCP and acceptable relative density
of 90 – 92% both in the case of solid phase
reaction and chemical precipitation were
prepared.
5. The resulting material based on fluoroapatite
structures may be used as effective matrices for
strontium radionuclide immobilization.
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Fig. 8. The dependence of relative density of Ca10(PO4)6F2
(а) and Ca9Sr(PO4)6F2 on the sintering temperature.
ANALYSES OF FLUORAPATITE PREPARED BY BOTH CHEMICAL PRECIPITATION AND SOLID PHASE REACTION METHODS
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