A Co-Precipitated α-Alumina (Al2O3) used as a TL-Micro Dosimeter

Article abstract of DOI:10.1002/zaac.202100141

This study describes the preparation method of alumina (Al₂O₃) as a type of thermoluminescence dosimeter (TLD) to monitor gamma photons (γ-rays) in abroad band of radioactive doses (0.5 : 2000 Gy). Alumina is selected in this study because it has a relatively low cost TL material and can be easily prepared. Aluminum oxide (Al₂O₃) was chemically prepared using two different methods which are the Sol-Gel and Co-precipitation methods. For each method, the produced alumina (Al₂O₃) was divided into 4 groups which was thermally treated at (400, 600, 800, 1100 °C) respectively for 6 hours for each group. The crystalline features, morphology and sample composition of the prepared samples were chemically characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). Al₂O₃ prepared by the Co-precipitation method which was treated at 1100 °C (P4) was found to exhibit the highest gamma ray response compared to other samples. The deconvolution analysis showed that the main TL glow curve consisted of (5) overlapped peaks corresponding to number of traps. The linearity of the gamma response for this sample appeared in doses ranging from 1 Gy up to 200 Gy. The minimum detectable dose that can be detected by precipitated-alumina sample (P1) was calculated mathematically to be 3.653 mGy. The fading was found to be 45.6 % after being stored for 45 days at room temperature and approximately 65 % after 90 days. This sample was reproducible according to the repeated TL results for the same sample for 5 times as their values were very close from one other with standard deviation (±σ) 0.96 %. Henceforth, Co-precipitated α-alumina can be used as a TL-Micro dosimeter.

Full text of DOI:10.1002/zaac.202100141

Title: A Co-Precipitated α-Alumina (Al2O3) used as a TL-Micro
Dosimeter
Authors: Fouad Said, Hesham Tantawy, Nabil El-Faramawy, and
Mohamed A.E. Abdel-Rahman
This manuscript has been accepted after peer review and appears as an
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To be cited as: Z. anorg. allg. Chem. 10.1002/zaac.202100141
Link to VoR: https://doi.org/10.1002/zaac.202100141

10.1002/zaac.202100141
Zeitschrift für anorganische und allgemeine Chemie
A Co-Precipitated α-Alumina (Al2O3) used as
a TL-Micro Dosimeter
*
Fouad Said[1], Hesham Tantawy[2], Nabil El-Faramawy[3], and Mohamed A.E. Abdel-Rahman[1] 1
1 Nuclear Engineering Department, Military Technical College, Cairo, Egypt
2 Chemical Engineering Department, Military Technical College, Cairo, Egypt
3 Physics Department, Faculty of Science, Ain Shams University,11566 Abbassia, Cairo, Egypt
Abstract
This study describes the preparation method of alumina (Al2O3) as a type of thermoluminescence
dosimeter (TLD) to monitor gamma photons (γ-rays) in abroad band of radioactive doses (0.5:2000 Gy).
Alumina is selected in this study because it has a relatively low cost TL material and can be easily
prepared. Aluminum oxide (Al2O3) was chemically prepared using two different methods which are the
Sol-Gel and Co-precipitation methods. For each method, the produced alumina (Al2O3) was divided into 4
groups which was thermally treated at (400, 600, 800, 1100°C) respectively for 6 hours for each group.
The crystalline features, morphology and sample composition of the prepared samples were chemically
characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive
X-ray (EDX). Al2O3 prepared by the Co-precipitation method which was treated at 1100°C (P4) was
found to exhibit the highest gamma ray response compared to other samples. The deconvolution analysis
showed that the main TL glow curve consisted of (5) overlapped peaks corresponding to number of traps.
The linearity of the gamma response for this sample appeared in doses ranging from 1 Gy up to 200 Gy.
The minimum detectable dose that can be detected by precipitated-alumina sample (P1) was calculated
mathematically to be 3.653 mGy. The fading was found to be 45.6% after being stored for 45 days at
room temperature and approximately 65% after 90 days. This sample was reproducible according to the
repeated TL results for the same sample for 5 times as their values were very close from one other with
standard deviation (±σ) 0.96%. Henceforth, Co-precipitated α-alumina can be used as a TL-Micro
dosimeter.
Keywords: Thermoluminescence, Alumina, Co-precipitation, Sol-Gel, TLD, Dosimetric.
1. Introduction
Radiation dosimetry has played a crucial role within the field of personnel radiation protection
from exposure to hazardous ionizing radiation as electromagnetic radiation (γ-rays and X-rays),
beta particles (β), and neutrons [1]. The Thermoluminescence dosimetry (TLDs) is a widely used
dosimetric technique in medical physics staff radiation detection, radiological monitoring of the
environment [2] and as a measurement mean for attenuation of ionizing radiation occurred by
radioactive shelters as in the measurement of concrete capability to attenuate γ-rays during
passing through it [3-5]. Thermoluminescence (TL) phenomenon is the emission of light during
the thermal stimulation of the investigated insulator or semiconductor following a previous
absorption of energy from an ionizing radiation in the form of trapped charges [6]. The
photocurrent created induced by the PMT affected by annealing process before the readout
process [7]. There are many materials that can behave using the TL phenomenon such as lithium
fluoride (LiF) [8], lithium borate (Li2B4O7) [9], alumina (Al2O3) [10] and other materials [11].
These materials’ domestic characteristics can be enhanced by doping with some metals or other
elements such as (Dy, Mg, Cr, C,….) which increased structure defects (Traps) in the lattice. The
graph of the intensity of the emitted light against the applied heat is called a glow curve which
*
Corresponding author: Assoc. Prof. Mohamed A.E Abdel-Rahman , e-mail: mabdelrahman@mtc.edu.eg
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describes the TL behavior of material. Counting on the nature of the TL material and its structure,
including intrinsic defects in the lattice and those caused by impurities, various mechanisms of
energy transfer and energy losses maintained causing the luminescence creation. The preparation
method has an important role in the lattice structure and number of defects. It is also important to
evaluate the reactivity of Al2O3 prepared from aluminum nitrate, chloride and sulfate precursors
by co-precipitation methods and from organometallic precursors by Sol-Gel methods through
strict composition, surface area, porosity and surface acidity control. Thermal treatment of
alumina creates more than one phase; with the most stable phases formed are γ-phase and α-
phase which were mainly formed at a temperature (600-800) °C and at a temperature above
1000°C, respectively for sufficient heating time (36 h). The corundum or α-alumina has excellent
mechanical, electrical, thermal and optical properties due to hexagonal close packing of oxygen
ions [12]. The dosimetric characteristics (Response, Linearity, sensitivity, Fading, Minimum
Detectable Dose, Reproducibility, Energy independence) are the physical properties which assess
if this material can be used as a TLD or not so, it is necessary to be studied.
2. Materials and methods
In this study, Aluminum Oxide (Al2O3) is prepared by two different methods which are Co-
precipitation method and Sol-Gel method to compare between the dosimetric characteristics of
the Aluminum Oxide (Al2O3) in each method to be used as a thermoluminescence (TL) material.
2.1. Co-Precipitation Method
Anhydrous aluminum chloride (AlCl3) with purity 99.7% and Ammonium Carbonate (NH4CO3)
with purity 99.8% were used in preparation because they are more soluble in water relative to
other salts of Aluminum and Ammonium [13]. A homogeneous solution of Aluminum Chloride
was prepared by dissolving 39g of Aluminum Chloride (AlCl3) in 400 ml of distilled water and
stirred for 15 min then filtrated to remove the residual insoluble AlCl3. Afterwards, the cleared
solution is placed in a beaker with a volume of 5000 ml then is diluted by adding distilled water
until it reaches the graduation 4500 ml of the beaker. 45g of Ammonium Carbonate (NH4CO3) is
dissolved in 300 ml of distilled water and stirred for 15 min then made a filtration to obtain a
clear solution of Ammonium Carbonate. The Ammonium Carbonate solution is added to the
diluted Aluminum Chloride solution then stired the mixture for 15 min with heating at 70°C. a
white suspended particles of Aluminum Oxide (Al2O3) is formed. The solution is left until the
white precipitate settles in the bottom of the beaker. The product is washed several times with
distilled water at room temperature before being washed with ethanol for the final time to remove
the undesired impurities. Then, the product is dried in the oven at 80°C for 36h. After completely
drying the product, it is grinded. The product is heated in oven at 350°C for 2h to ensure that all
Ammonium Chloride (NH4Cl) is sublimated as it is the undesired side product of the chemical
reaction [14].
2.2. Sol-Gel Method
As an aluminum precursor, aluminum iso-propoxide alkoxide Al(OCH(CH3)CH3)3 is used to
produce alumina powder with a greater specific surface area [15]. Compared to other alkoxides
like tri-sec-butoxide aluminum, this precursor is less costly and more readily available. Acetic
acid is used to regulate the rate of hydrolysis and and 2-propanol as solvent, during the
preparation procedure. Firstly, a solution of aluminum isopropoxide was prepared by dissolving
3g of aluminum precursor in 230 ml Iso-propanol, then the solution is stirred continuously and
vigorously for 4h till all aluminum isopropoxide was completely soluble in the solution at room
temperature. after ensure that the solution of aluminum isopropoxide became clear and no
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particles were suspended or precipitate dropped wisely drops of mixture of acetic acid (0.1 ml)
dissolved in (3 ml) distilled water and stirred magnetically for 5h until hydrolysis completely
occurred and Aluminum Oxide (Al2O3) was formed. the hydrolysis began after 30 min from
dropping the mixture prepared of acetic acid on solution of aluminum isopropoxide. During the
stirring process, a white gel starts to form. The final mixture os left for 24h at room temperature.
Finally, it is dried in oven at 120 °C for 6h. The weight of the final product (Al2O3) is
approximately (1.3g).
2.3. Thermal Treatments
Two products of aluminum oxide (Al2O3) were prepared either by Co-Precipitation Method or by
Sol-Gel Method were thermally treated at four different temperatures which are 400, 600, 800
and 1100°C at roasting oven with heating rate of 20°C /min for 5h. The four thermal treatments
were numbered 4, 3, 2 and 1 respectively.
2.4. Chemical Characterization
The phase identification and crystallinity of prepared powders were determined using PhilipsX´
PERT MPD diffractometer at room temperature with a copper X-Ray tube CuKα (λ=1.5405 Å)
as a radiation source that operated at 30 kV and 40 mA anode current throughout the
measurement. XRD patterns were carried out in the range of 2θ = 20◦–80◦ with a step size of
0.02. In addition, the particle size was calculated using the Scherer equation [16]. The Scherer
equation which is included in the XRD software of the device used in the investigation of the
samples can be represented by the following formula: L = Kλ/ β.cosθ
where: L refers to the nano crystallite size, λ is the wavelength of radiation (X-ray) in nanometer
and β is the measuring full width at half maximum of peaks in radian located at any 2θ in the
XRD pattern. Comparisons with the corresponding JCPDS diffraction data cards were used to
identify the various crystalline phases. For prepared powders, the morphology of the samples
were investigated using Scanning Electron Microscopy (SEM, FEI Inspect S, Oxford USA) with
an acceleration beam (25-30) kV with vacuum pressure 60 pa and spot size (5-6). Energy
dispersive X-Ray spectroscopy (EDX) which when equipped to SEM was used to evaluate the
chemical composition of prepared samples [17].
3.
Result and Discussion
3.1. X-Ray diffraction
Due to applied heat treatments of samples, a noticeable transition in phase of produced (Al2O3)
occurred. Firstly, the product was in the form of amorphous alumina (boehmite) before the
heating process carried out then it converted to γ- Al2O3 then a mixed phases of γ-α Al2O3 until it
finally reached the most stable phase, α- Al2O3 [18, 19]. As the annealing temperature was raised,
the percentage of α - Al2O3 formed increased; eventually reaching 100% at 1100 °C for 1h
investigated by Naoufal et al [20]. So in this study, the maximum temperature maintained was
1100 °C and increasing the time for 5h to ensure that there all samples completely converted to
the α – phase at this temperature. The XRD patterns of prepared samples of Al2O3 either by Co-
precipitation method or by Sol-Gel method explain the influence of the heat on the phase
transmission. Fig.1 investigates the X-Ray diffraction patterns of the Co-precipitation samples of
thermally treated alumina P1, P2, P3 and P4 at 1100°C, 800°C, 600°C and 400°C, respectively,
which indicates that the product was clearly alumina in an amorphous state and all impurities
and side products created during chemical preparation such as NH4Cl were sublimated at 400°C.
All impurities and side products during chemical preparation such as NH4Cl volatilized and the
formed alumina was in the amorphous state. γ-alumina phase was clearly observed at a
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temperature of 600 °C because the three main peaks of γ- phase were noticed at 2θ angles = 37°,
46°, and 66° respectively. When the temperature was raised to 800°C, still almost alumina in γ-
phase and α-phase began to be appear. When the sample reached 1100°C, the γ- Al2O3 phase
disappeared and all samples were completely converted to the α-Al2O3 phase. Also Fig.2 shows
the X-Ray diffraction patterns of the Sol-Gel alumina powder S1, S2, S3 and S4 which thermally
treated at 1100°C, 800°C, 600°C and 400°C respectively. The same phase transitions that
occurred in case of Co-precipitation samples maintained in the case of Sol-Gel samples with
different of intensity of peaks which indicate that there was a difference of crystallinity. It should
be noted that in the case of the organic precursor, a crystalline dried powder was formed and as
the heat treatment temperature was risen too. Also, the crystallinity in case of using inorganic
precursor such as (AlCl3) used in Co-precipitation preparation was better than its organic
o
precursor such as the aluminum iso-propoxide, at a temperature of 1000 C, investigated in the
Sol-Gel preparation [21].
Fig.1: XRD patterns of alumina samples P1, P2, P3 and P4 prepared by Co-precipitation method
annealed at different temperatures 1100°C, 800°C, 600°C and 400°C respectively for 5h.
Fig.2: XRD patterns of alumina samples S1, S2, S3 and S4 prepared by Co-precipitation method
annealed at different temperatures 1100°C, 800°C, 600°C and 400°C respectively for 5h.
3.2. Scanning Electron Microscope (SEM)
The morphology and textural characteristics of the alumina powders were prepared by Co-
Precipitation and sol-gel methods were made by scanning electron microscopy analysis (SEM).
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Fig.3 (a, b) and Fig.3 (c, d) depict the SEM images of Co- Precipitation alumina and Sol alumina
calcinated at 400°C and 1100°C, respectively, for 5h. The SEM micrographs revealed that
samples thermally treated at higher temperatures had a high relative density and homogeneous
microstructure, as well as low residual porosity. While crystals have a non-uniform shape, their
surface appears to be smooth. The particle size and shape of the alumina was determined by the
crystal structure of the original hydroxide and the series of phase transformations which occur
during calcinations [22].
(a)
(b)
(c)
(d)
Fig.3: SEM images of Co- Precipitation alumina at (a) 400°C and (b) 1100 °C and Sol alumina calcinated
at (c) 400°C and (d) 1100 °C, respectively.
3.3. Energy dispersive X-Ray spectroscopy (EDX)
Fig.4 and Fig.5 show the chemical composition of prepared samples of alumina (Al2O3) by two
different methods. EDX diagram ensure that all samples composed of two elements only which
are aluminum (Al) and oxygen (O) with different percentages. It is observed that the percentage
of oxygen (O %) in the composition decreased by increasing the temperature until it reached the
minimum value at the highest temperature (1100°C). By contrast, the percentage of aluminum
increased by increasing the temperature.
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Fig.4: EDX diagram of alumina (Al2O3) prepared by Co-Precipitation method (a) P4 thermally treated at
400°C and (b) P1 thermally treated at 1100°C.
Fig.5: EDX diagram of alumina (Al2O3) prepared by Sol-Gel method (c) S4 thermally treated at 400°C
and (d) S1 thermally treated at 1100°C.
3.4. Dosimetric Characteristics
The thermoluminescence properties of the prepared samples were investigated by using a
Harshaw model 3500 TLD reader, which was operated by a Win-REMS operating system on a
computer and connected to the reader through a serial port. The reader was cooled by nitrogen
supply which connected to the device directly by rubber hose. The γ-rays used in the irradiation
process was emitted from 60Co γ-source, with an activity of 610 Ci (at the time of measurements).
The optimum parameters of the time temperature profile (TTP) were preheat temperature 50°C,
the maximum temperature 400°C and the heating rate 8 °C/s and from those parameters the
required time was (45 s) which be calculated as:
(1)
All TL measurements were taken after 24 hours from irradiation.
3.4.1. Response
There were a total of 24 samples consisting of 12 Co-precipitation alumina samples and 12 Sol-
Gel alumina samples divided to 8 groups each group had 3 samples of the same type treated at
the same temperature. All groups were irradiated to the same radioactive dose (10 Gy) in the
irradiation station then measured by TL reader to evaluate the TL response mean for each group
to minimize the percentage of error. From Table 1, it can be noticed that the preferred result of
TL responses was (8.929±0.12 µc) of sample (P1) treated at 1100°C. Also, the preferred glow
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curve shape was had by the same sample so this sample was chosen to continue the residual
dosimetric properties such as linearity, sensitivity, fading and reproducibility.
Table 1: TL responses of prepared samples by two different methods thermally treated
at different temperatures and irradiated to the same dose (10 Gy).
Temperature of thermal
Powder samples of Al2O3
TL Response mean (µc)
treatment (°C)
CO-precipitation sample (P1)
CO-precipitation sample (P2)
CO-precipitation sample (P3)
CO-precipitation sample (P4)
Sol-Gel sample (S1)
1100
800
600
400
1100
800
600
400
8.929±0.12
5.370±0.31
1.696±0.20
0.1249±0.42
8.287±0.13
8.362±0.12
6.012±0.22
0.650±0.32
Sol-Gel sample (S2)
Sol-Gel sample (S3)
Sol-Gel sample (S4)
3.4.2. Kinetic analysis of TL glow curve
The glow curve data deconvoluted by using the TL analysis software (TL anal software) which
split the main glow curve to peaks to be analyzed and each peak represents trap in the lattice [23].
Fig. 6 describes the deconvolution analysis of TL glow curve of α-alumina sample (P1) irradiated
with dose 50 Gy which indicates that the fitted glow curve consisted mainly of (5) overlapped
peaks. The first peak was at T = 520 ±3 K, the maximum peak was the 2nd one at T = 550 ±2.6 K,
the 3rd at T = 460 ±4.1 K, the 4th at T = 430 ±2.8 K [24]. The number of traps was validated
experimentally by using repeated initial rise method (RIR) which gave five values for activation
energy (0.947, 0.64, 0.46, 0.5 and 0.54 eV) represented for each trap. The thermal stability
analysis showed that the first peak was the most unstable peak which disappeared through less
than 24 hours from irradiation process so to detect this peak the irradiated sample should be read
out immediately after irradiation. The parameter that assesses the quality of fitting is the figure of
merit (FOM). It was calculated from equation (2) formulated by Balian and Eddy [25] which
included in the software to be (1.423%). the value of FOM > 2.5% which gave a good indication
that the deviation between the experimental data and the fitted data was very small.
[ ]
∑
(2)
Where ji is the start point and jf is the end point of the area under the glow curve, yj represents
real data obtained experimentally, y (kf) represents the value of the function of fitting and A is
the value of integration of the area under the fitted glow curve. All peaks were deconvoluted by
software in form of general order evaluated by equation (3) [26].
[ ]
(
(
)) [
]
.
(3)
(
)
where IM is the intensity at the maximum point of the main TL glow curve and TM is the
temperature at the maximum intensity, and the two sub-parameters F(T,E) and F(TM,E) can be
evaluated from the equations (4),(5) as following:
( ) * ( )+.
(4)
(
) * (
)+
(5)
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Fig.6: Deconvolution module of TL glow curve of irradiated α-alumina sample (P1) at dose 50 Gy.
3.4.3. Linearity
The Tl materials' linearity is one of the most important dosimetric characteristics which defined
as the dose range over which TL intensity behaves linearly to absorbed dose, it is necessary for
calibration, allowing the TL material to be used as dosimeter [27]. The contribution of different
traps inside the material to the emitted TL light determines the linearity behavior. Approximately
equal-weighted Co-precipitated Alumina samples (5-7 mg) were irradiated with various gamma
doses ranging from 10 mGy to 2 kGy to investigate dose–response linearity. The TL responses of
low doses irradiated samples in range from 10 mGy to > 0.5 Gy were very close to the
background mean and, henceforth, it was be neglected. Fig.7 shows the behavior of normalized
reported TL glow curves (TL intensity/ sample mass) at various doses ranging from 0.5 Gy to 2
kGy. By plotting the integrated area under each glow curve against the different doses, the dose-
response of alumina samples were assessed as shown in Fig. 8. In the dose range of 0.5 Gy to 1
Gy, a sub-linear behavior was observed, whereas in the dose range of 1 Gy to 200 Gy, a linear
dose–response was obtained and supra-linear region appeared in range from 200 Gy to 2 kGy
[28] .
Fig.7: Normalized reported TL glow curves (TL intensity/ sample mass) of alumina (P1) at various
doses ranging from 0.5 Gy to 2 kGy.
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Fig.8: Linearity of TL responses of Co-precipitated alumina (P1) treated at 1100°C
with respect to abroad band of absorbed doses
3.4.4. Sensitivity
The sensitivity of a sample is known as the measurement of relative TL signal intensities at the
same applied dose [29]. The Co-precipitation alumina powder thermally treated at 1100°C and
commercial LiF-100 were both irradiated with a 10 Gy dose and measured to determine the
relative TL signal strength of the powder samples compared to that of a standard dosimeter (LiF-
100). The TL glow curves were then registered as soon as the irradiation process was completed.
By substitution of the values included in table 2 in the ratio equation (6), the TL signal intensity
of commercial LiF-100 related to the absorbed dose was 1.4 times higher than that of the treated
alumina powder.
Table 2: Normalized TL intensities of irradiated samples at dose (10 Gy)
Irradiated samples at Mean of TL intensities
Mass of
sample/chip (mg)
Normalized TL
intensity
Ratio
1.4
1 Gy
(nc)
Al2O3 powder
treated at 1100°C
0.9774±0.63
6
0.15745
0.222
Commercial
LiF-100 chips
21.11±0.2
95
(6)
3.4.5. Minimum detectable dose (M.D.D.)
It was necessary to evaluate the minimum detectable dose (MDD) which was considered as one
of the most important dosimetric characteristics to be studied [30, 31]. It can be defined as the
threshold value of sensed dose by prepared TL material or the lowest radiation detection level of
produced dosimeter. The value of MDD is very close to the background signals. An empirical
formula suggested by Shrouk et al [32] was used to determine the MDD of the prepared α-
alumina sample (P1) as following:
(7)
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Where, B* is the mean of TL intensities of un-irradiated Co-precipitated alumina samples after
being annealed at 400°C for 30 min, (σB) is the standard deviation of intensities and F is the
calibration factor which can be estimated by F = calibration dose (mGy)/A(nC). The background
of un-irradiated samples was measured for (4) times and the mean of the (4) readings (B*) was
(226.025) with standard deviation (σB) = (47.204). Samples were irradiated with calibration dose
(5 Gy) so, the calibration factor (F) was calculated at this calibration dose from the previous
equation and was (0.0114). By substitution in eqn (7) the MDD was 3.653 mGy.
3.4.6. Fading
Fading is characterized as the stability of stored TL signals under the influence of some physical
quantity such as storage time and the effect of lab light. The fading samples were kept in dark
boxes after being irradiated to dose (10 Gy) at ambient temperature to decrease the loss of
trapped charges along the period of measurement. All measurements were maintained in the
laboratory with no light to ensure that the only parameter affecting results was time. The TL
results were obtained at 0, 1, 7, 14, 21, 30, 45, 60 and 90 days at 12:00 PM. All results were
normalized to the first reading (i.e. result at 0 days) by dividing them on the value of it to appear
in form of percentage %. Fig. 9 represents the normalized TL readings against storage time which
indicated that approximately 45.6% of the original signal of first reading lost after 1 day from
irradiation that referred to fading shallow peaks which disappeared immediately after irradiation
due to the thermal instability at room temperature [27]. It was observed that no change in the
results in period (1:45) days then a slight change occurred after 45 days. So the first and second
traps which represent fading shallow peaks was very weak in contrast the residual TL signal
(54.4% of the original signal) which represents other traps in the prepared samples were more
stable in the room temperature.
Fig.9: TL signal of irradiated (P1) sample with dose (10 Gy) as a
function of storage time at room temperature
3.4.7. Reproducibility
Generally, "reproducibility" refers to the ability to determine the TL glow curve response after
repeatedly using the same dosimeter at the same applied dosage. It is necessary to investigate the
reproducibility properties of Al2O3 powder used as gamma dosimeters in order to determine their
reliability. The dose measurement's reproducibility was tested using three Al2O3 samples, and
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five radiation–readout cycles were performed for each sample with 50 Gy exposure during the
annealing process (400°C in 30 minutes). After five cycles, the repeating process shows strong
reproducibility of Al2O3 samples [33]. The normalized TL responses obtained from glow curves
with five readout times as shown in Fig. 10. The results all over the cycles reflected that they
were similar with calculated standard deviation (±σ) was 0.96%. These measurements meant that
there was very slight change in sensitivity which can be neglected so, this powder can be used as
a reusable TLD for γ-rays.
Fig.10: Reproducibility of normalized area under the glow curve of
irradiated sample (P1) after readout 5 times
4. Conclusion
The experimental results proved that the increasing of temperature during heat treatment
improved the crystalline structure of alumina particles. Additionally, the crystallinity of micro-
alumina (Al2O3) sample chemically prepared by using inorganic precursor (AlCl3) in Co-
precipitation method is better than the produced nano-alumina by using organic precursors
(Aluminum iso-propoxide). The best alumina sample with respect to the TL response to γ-
radiation was the sample prepared by Co-precipitation which thermally treated at 1100°C
symbolled by (P1) because it has the best crystallinity comparing with other samples.
Consequently, The TL dosimetric characteristics (linearity, sensitivity, fading, reproducibility)
were studied for (P1). The deconvolution maintained by TL analysis software proved that the
glow curve contained (5) overlapped peaks which represents the charge traps in the aluminum
oxide lattice. In doses ranging from 1 Gy to 200 Gy, the response of gamma radiation was linear,
sublinear in doses from 0.5 Gy to 1 Gy and supralinear in dose range from 200 Gy to 2 kGy. The
sensitivity of sample (P1) to γ-rays compared with the standard commercial TLD-100 (LiF-100)
showed that TL signal intensity of LiF-100 was higher than 1.4 times that of prepared sample
(P1). The minimum detectable dose (MDD) calculated to be 3.653 mGy. The fading of sample
(P1) was relatively high (45.6%) in the 45 days of storage time compared with the TL signal of
first reading (0 days) so, it must be taken into consideration to make the TL measurements after
24 h from irradiation. The reproducibility of the sample (P1) was good after repeated (4) cycles
with standard deviation (±σ) 0.96%. The studied TL characteristics of the prepared α-micro
alumina sample (P1) proved that it can be used as a TL-micro dosimeter. The dosimetric
properties of alumina can be improved by adding some dopants as (C, Cr, Dy, …) which creates
new traps in the lattice.
11
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10.1002/zaac.202100141
Zeitschrift für anorganische und allgemeine Chemie
5. References
1. Mukherjee, B., Woda, C., Mares, V., A TLD-Microdosimeter for aerospace usage: Results relevant
to airline pilots undertook long-haul intercontinental flights during March–May 2017. Acta
Astronautica, 2020. 166: p. 444-449.
2. Azorin, J., Preparation methods of thermoluminescent materials for dosimetric applications: An
overview. Applied Radiation and Isotopes, 2014. 83: p. 187-191.
3. Abdel‐Rahman, M.A.E., Fouda, A. A., El‐Mongy, S. A., Study of γ‐Fast Neutron Attenuation and
Mechanical Characteristics of Modified Concretes for Shielding and Sheltering Purposes. Zeitschrift
für anorganische und allgemeine Chemie, 2019. 645(8): p. 649-655.
4. Abdel-Rahman, M.A.E., Ali, M. A. E. M., El-Mongy, S. A., Penetrability of γ/n and Static Behavior
of Newly Developed Concrete Using Different Passive Assay Techniques. Nuclear Technology, 2020.
206(5): p. 766-778.
5. El-Samrah, M., Abdel-Rahman, M.A.E., El Shazly, R.M., Effect of heating on physical, mechanical,
and nuclear radiation shielding properties of modified concrete mixes. Radiation Physics and
Chemistry, 2018. 153: p. 104-110.
6. Ahmed, M., et al., Dosimetric properties of Cr doped Al2O3 nanophosphors. Journal of
Luminescence, 2018. 196: p. 449-454.
7. Abdel‐Rahman, M.A.E., Lohstroh, A., Sellin, P. J., The effect of annealing on the X‐ray induced
photocurrent characteristics of CVD diamond radiation detectors with different electrical contacts.
physica status solidi (a), 2011. 208(9): p. 2079-2086.
8. Abd El-Hafez, A., Rawash, S., Diab, N., El-Faramawy , N., Improvement the dose-response range in
the assessment of therapeutic doses. Radiation Effects and Defects in Solids, 2020. 175(9/10): p.
853–862.
9. N.A. El-Faramawy, S.U.E.-K., A.I. Abd-Elhafez, M.A. Hosein, G.E. Metwally Study of thermal
treatment and kinetic parameters of prepared Li2B4O7: Cu thermoluminescence dosimeter. Egyp. J.
Solids, 2000. 23(1): p. 103-111.
10. Ahmed, M., Salah, A., Ashour, A., Hafez, H., El-Faramawy, N., Dosimetric properties of Cr doped
Al2O3 nanophosphors. Journal of Luminescence, 2018. 196: p. 449-454.
11. El-Kheshen, A., Woda, C., Discher, M., El-Faramawy, N., Investigation of phosphate glass doped
lanthanum as beta dosimeter. Journal of Luminescence, 2018. 200: p. 254-259.
12. Wang, Y., Pan, Z.Y., Ho, Y.K., Xu, Y., Du, A.J., Nuclear instruments and methods in physics
research section B: beam interactions with materials and atoms. Nuclear Instruments and Methods in
Physics Research B, 2001. 180(1-4): p. 251-256.
13. Rogers, K., The chemical reactions of life: from metabolism to photosynthesis. 2010: Britannica
Educational Publishing.
14. Chaiken, R.F., Sibbett, D.J., Sutherland, J.E., Van de Mark, D.K., Wheeler, A., Rate of sublimation of
ammonium halides. The Journal of Chemical Physics, 1962. 37(10): p. 2311-2318.
15. Siahpoosh, S.M., Salahi, E., Hessari, F.A., Mobasherpour, I., FACILE SYNTHESIS OF γ-ALUMINA
NANOPARTICLES VIA THE SOL-GEL METHOD IN PRESENCE OF VARIOUS SOLVENTS.
Sigma: Journal of Engineering & Natural Sciences/Mühendislik ve Fen Bilimleri Dergisi, 2017.
35(3).
16. Monshi, A., M.R. Foroughi, and M.R. Monshi, Modified Scherrer equation to estimate more
accurately nano-crystallite size using XRD. World journal of nano science and engineering, 2012.
2(3): p. 154-160.
17. Sadabadi, H., Aftabtalab, A., Zafarian, S., Shaker, S., Ahmadipour, M., Rao, K.V., High purity Alpha
Alumina nanoparticle: Synthesis and characterization. Int. J. Sci. Eng. Res, 2013. 4(4): p. 1593-
1596.
12
This article is protected by copyright. All rights reserved.

10.1002/zaac.202100141
Zeitschrift für anorganische und allgemeine Chemie
18. Boumaza, A., Favaro, L., Lédion, J., Sattonnay, G., Brubach, J.B., Berthet, P., Huntz, A.M., Roy, P.,
Tétot, R., Transition alumina phases induced by heat treatment of boehmite: an X-ray diffraction and
infrared spectroscopy study. Journal of solid state chemistry, 2009. 182(5): p. 1171-1176.
19. McQuaig, M.K., Toro, A., Van Geertruyden, W., Misiolek, W.Z., The effect of high temperature heat
treatment on the structure and properties of anodic aluminum oxide. Journal of Materials Science,
2011. 46(1): p. 243-253.
20. Bahlawane, N., Watanabe, T., New Sol–Gel Route for the Preparation of Pure α‐Alumina at 950° C.
Journal of the American Ceramic Society, 2000. 83(9): p. 2324-2326.
21. Rogojan, R., Andronescu, E., Ghitulica, C., Vasile, B.S., Synthesis and characterization of alumina
nano-powder obtained by sol-gel method. UPB Buletin Stiintific, Series B: Chemistry and Materials
Science, 2011. 73(2): p. 67-76.
22. Mirjalili, F., Hasmaliza, M., Abdullah, L.C., Size-controlled synthesis of nano α-alumina particles
through the sol–gel method. Ceramics International, 2010. 36(4): p. 1253-1257.
23. Chung, K.S., Lee, J.I., Kim, J.L., A computer program for the deconvolution of the
thermoluminescence glow curves by employing the interactive trap model. Radiation measurements,
2012. 47(9): p. 766-769.
24. Reddy, S.S., Chauhan, N., Nagabhushana, K.R., Singh, F., TL/OSL properties of beta irradiated
Al2O3: Tm3+ phosphor synthesized by microwave combustion method. Materials Research Bulletin,
2018. 104: p. 236-243.
25. Balian, H.G., Eddy, N. W., Figure-of-merit (FOM), an improved criterion over the normalized chi-
squared test for assessing goodness-of-fit of gamma-ray spectral peaks. Nuclear Instruments and
Methods, 1977. 145(2): p. 389-395.
26. El‐Faramawy, N., El‐Naggar, A., Woda, C., and M. El‐Kinawy, Dosimetric properties of lithium
borate glass doped with dysprosium. Luminescence, 2021. 36(1): p. 210-214.
27. Fontainha, C.C.P., Alves, N., Ferraz, W.B., de Faria, L.O., Very sensitive α-Al2O3: C polycrystals for
thermoluminescent dosimetry. Applied Radiation and Isotopes, 2018. 141: p. 234-240.
28. Sun, T., Tang, K., Cui, H., Zhu, H., Fan, H, Optically stimulated luminescence of α-Al2O3: C by the
vertical gradient freezing (VGF) method. Journal of Luminescence, 2019. 205: p. 568-571.
29. Johnson, P.D., Williams, F.E., The interpretation of the dependence of luminescent efficiency on
activator concentration. The Journal of Chemical Physics, 1950. 18(11): p. 1477-1483.
30. Omar Abo-Bakr, O., Abdel-Rahman, M.A.E., El-Mongy, S.A., Validation and Correction for 208Tl
Activity to Assay 232Th in Equilibrium with Its Daughters. Physics of Particles and Nuclei Letters,
2019. 16(6): p. 835-841.
31. Abdel-Rahman, M.A.E., Abu Shady, H., El-Mongy, S.A., Analysis of Ores and its Purified
Constituents by γ-Spectrometry with Calculation of Uranium Isotopic Atom, Mass, and Activity
Ratios. Zeitschrift für anorganische und allgemeine Chemie, 2018. 644(10): p. 477-482.
32. Farouk, S., El‐Azab, H., Gad, A., El‐Nashar, H.,El‐Faramawy, N., Investigation of
thermoluminescence glow curves in quartz extracted from the Central Eastern Desert, Egypt.
Luminescence, 2020. 35(4): p. 586-593.
33. Wesolowska, P.E., Cole, A., Santos, T., Bokulic, T., Kazantsev, P., Izewska, J., Characterization of
three solid state dosimetry systems for use in high energy photon dosimetry audits in radiotherapy.
Radiation Measurements, 2017. 106: p. 556-562.
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