Advertisement

Investigation of modified zinc borate glasses doped with BaO as a nuclear radiation-shielding material

  • H. A. Saudi
  • S. U. El-Kameesy
Original Paper
  • 142 Downloads

Abstract

Background

Radiation protection and detection have been a main interest for researchers. The prepared glass samples were subjected to experimental investigations to evaluate their mechanical and attenuation properties. As a consequence, the values of the mass attenuation coefficient, total electronic cross section, the effective atomic number and an effective electron number were determined and utilized to assess the shielding effectiveness of the investigated glass samples. The mass attenuation coefficients of these samples were calculated theoretically using WinXcom program.

Purpose

Preparation of glass of borate with zinc and barium can withstand shock, heat and corrosion to be used as a radiation shield.

Methods

Glass samples were prepared by melt quenching technique. Density and molar volume measurements were obtained by applying the Archimedes principle. The hardness was measured by using a microhardness tester (Leco AMH 100, USA) for sample indentation. The thermal behavior of the glass samples was investigated by differential scanning calorimetry (DSC). Also, by using a scintillator detector (1.5″ × 1.5″ NaI (Tl)) exposed to 232Th, 137Cs and 60Co gamma ray sources with accuracy range 0.12%.

Results

The investigated glasses have relatively good gamma ray attenuation properties, water resistance ability and thermal stability with increasing barium oxide. So, they can be used in containers for keeping radioactive waste and radioactive sources.

Conclusion

The changes in the molar volume and density show approximately opposite linear trends. Also, μm is dependent on the chemical compositions of glass samples and energy of gamma rays. Good agreement between the experimentally obtained mass attenuation coefficient values and the corresponding theoretical predictions based on the known WinXcom program was observed. Additionally, the effect of gamma irradiation on this glass is minor because its impact on the hardness values and dissolution rate is extremely small.

Keywords

Borate glasses Shielding properties Hardness Durability 

Introduction

Today, developing materials which might be employed in the environment of high radiation exposure has become one among the foremost vital analysis areas. These materials will play a good role in industrial, medical, engineering and lots of different scientific applications. There is invariably a requirement to develop material, which might be used under laborious conditions of nuclear radiation exposure and may act as a shielding material. Additions of high-atomic-number components with the acknowledged quantitative relation of the amorphous mixture fashioned glass produce an honest shielding properties material. Glassy materials, which might be modified through their chemical composition additionally to their high optical transmission, became appropriate to be used as shielding materials for nuclear radiation [1]. Borate glass may be a form of glass with the most glass-forming constituent that is an elemental chemical compound that is one among the foremost vital glass formers that acknowledged for having an occasional temperature, improved chemical strength, reduced liquid temperature preventing crystallization and conjointly improved visible properties. In an exceedingly previous study the lead part was the essential one within the glassy systems; however, owing to the difficulties that arise from its use in glass composition as a high value and hepatic toxic material [2], the recent studies are a unit targeted on substitution lead by another part that met the necessities of the protecting material from nuclear radiation and reducing the aforesaid issues. Barium is enjoying a homogenous role in radiation shielding by substituting the lead. It is one among the metallic element metals that have a desirable property as a network modifier that represents an honest candidate in radiation-shielding domain [3]. Moreover, it is a robust absorption of quick nucleon and gamma rays, high density, comparatively smart hardness and also the most significant proven fact that metal is non-toxic [4]. The role of Li2O is to cut back the temperature of melting, whereas the role of ZnO is to extend the transparency of the glass matrix [5]. The mass attenuation coefficient is important for determining the penetration of gamma-ray photons within the matter; it is useful in etymologizing many varieties of different photon interaction parameters like 0.5 price layer (HVL), mean free path (MFP) and effective number (Zeff). Boron is a good nucleon-shielding material, and chemical element acid is additionally employed in nuclear reactors as nucleon poisoning [6, 7].

In this paper, we are interested on detailed analysis of radiation-shielding properties of (70-x) B2O3–20ZnO–10Li2O–xBaO‏ where (0 ≤ x ≤ 40 mol%) glasses, where x = 0, 10, 20, 35 and 40 mol%. The gamma rays-shielding properties such as the mass attenuation coefficients and half-value layer (HVL) of glass samples have been experimentally determined, and a comparison with a theoretical approach making use of the WinXCom program has been performed. Moreover, the chemical durability and the effect of gamma irradiation dose on hardness are determined.

Materials and methods

Glass samples of the composition of (70-x) B2O3–20ZnO–10Li2O–xBaO where (0 ≤ x ≤ 40 mol%) were prepared by melt quenching technique at 1200 °C in a porcelain crucible by an electrical furnace. Dry oxygen was bubbled thoroughly for 1 h. These melts were quenched at room temperature in the air by pouring between stainless steel plates forming a circular shape. The quench glasses were annealed at 300 °C for 3 h to reduce thermal stress before cooling down to room temperature.

Density and molar volume measurements were obtained by applying the Archimedes principle, and the weights of the prepared glass samples were measured in air and in toluene (ρliq = 0.866 gm/cm3 at room temperature) using 4-digit sensitive microbalance.

The hardness is defined as the ratio of the applied test load to the projected area of the resultant intentional impression [8]. Vickers hardness, Hv, was measured by using a microhardness tester (Leco AMH 100, USA) for sample indentation. Microhardness can be calculated from Hv = 1.8 p/d2 [9], where p is the indentation load and d is the diagonal length impression.

The surfaces of specimens were ground using 240-grit SiC paper and then placed in distilled water at 90 °C for 15 and 30 days; then, the weight loss was measured at each time interval. The dissolution rate (DR) was calculated from the expression DR = Δw/(A·t), where Δw is the weight loss (g), A is the sample area (cm2), and t is the immersion time.

The thermal behavior of the glass samples was investigated by differential scanning calorimetry (DSC). The tests were carried out with glass powders and prepared by grinding the glass into a manual agate mortar, and all samples were heated in air at a constant heating rate 5 °C/min from room temperature up to 600 °C. The samples were heated in an alumina crucible, and as a reference, a blank alumina crucible was used.

The average linear thermal expansion coefficients (α) of the glass were calculated based on the measurement of the slope of each curve within a specified temperature range according to the following equation: α = ΔL/L0 ΔT where ΔL, L0 and ΔT are the linear expansion, the sample initial length and the specified temperature interval, respectively. In the present study, the value of α was calculated in the temperature range 25–400 °C.

The study of gamma-ray attenuation properties of the investigated glass samples was performed experimentally at 238, 662, 911, 1173, 1333 and 2614 keV gamma-ray energy lines emitted from 232Th, 137Cs and 60Co radioactive sources using a 1.5″ × 1.5″ Na I (Tl) detector.

The linear attenuation coefficient (μ) describes the fraction of a beam of γ-rays that is absorbed or scattered per unit thickness of the absorber, and it can be given by Lambert–Beer law [10].

The mass attenuation coefficient μm of elements that is defined as the probability of radiation interaction with a material per unit length [11] can be evaluated using the relation: \( \mu_{\text{m}} = \mu /\rho = \frac{1}{\rho t} \ln ( I_{o} /I) \), where I0 and I are the incidents and transmitted intensities, and t is the thickness of the absorbing medium and is the density of the absorbing material (g/cm3).

The theoretical values of the mass attenuation coefficient of the prepared glass samples were evaluated by the WinXCom program (version 3.1) developed by NIST [12].

The effective atomic number (Zeff) of the material can be evaluated [13] by using the relation: Zeff = σt,a/σt,e, where (σt,a) is the total atomic cross sections and (σt,e) is the total electronic cross section.

The total atomic cross sections (σt) for materials can be obtained from the measured mass attenuation coefficient μm values according to σt,a = μm M/NA, where \( M = \sum n_{i} A_{i} \) is the molar mass of materials, NA is the Avogadro’s number, and ni and Ai are the number of formula units and atomic weight, respectively.

The removal cross section or the neutron attenuation coefficient \( \sum_{\text{R}} \) for homogenous mixture may be calculated from the value \( \sum_{{{\text{R}}/\rho }} \) or \( \sum_{\text{R}} \) for various elements in the compounds or mixtures using the following formula [14]
$$ \frac{{\varSigma_{\text{R}} }}{\rho } = \varSigma_{i} W_{i} (\varSigma_{\text{R}} /\rho )_{i} $$
where Wi is the weight percentage, and ρi and (ΣR/ρ)i are the partial density and the fast neutron mass attenuation coefficient of the ith constituent, respectively.

Results and discussion

Density and molar volume

The density and molar volume of the prepared glass systems were measured. The values of densities and molar volume for the barium, zinc borate glass system as a function of BaO content are shown in Fig. 1. It can be observed from Fig. 1 that the densities increase steeply from 3.05 to 4.36 g cm−3 with the increase in x value which can be attributed to the replacement of a low-density B2O3 with the high-density BaO. Ionic radii and bond length of BaO are large compared to B2O3 leading to large excess in molar volume that increases the general of molar volume values from 23.70 to 24.3 cm3 mol−1 with the increase in x value, implying the glasses amendment toward the additional open structure with the substitution of borate by barium [15, 16].
Fig. 1

The density and molar volume versus BaO content

Gamma-ray and neutron-shielding properties

Gamma-ray-shielding properties of barium, zinc borate glasses are studied on paper theoretically and experimentally at different energies, 238, 662, 911, 1173, 1333 and 2614 keV. The essential quantities that confirm the penetration of gamma-ray photons in the matter are linear attenuation and the mass attenuation coefficients. As shown in Fig. 2, the fraction of photons removed from gamma rays per unit thickness of BaO-free glass material is displayed in that figure as an example. From that figure, it is clearly shown that the attenuation coefficients increase with the increase in the weight fraction of BaO which may be attributed to the increase in the weight fraction of the higher atomic number constituent (Ba) as compared to other elements (B).
Fig. 2

Linear attenuation coefficient µ for BaO % with different energies as in the example

In Fig. 3 the theoretical and experimental values of mass attenuation coefficients µm were plotted against barium oxide concentration (BaO %) at different γ-ray energies (238, 662, 911, 1173, 1333 and 2614 keV). It is observed that for these chosen samples, µm remains in sensible agreement with the theoretical values and increases with the increase in BaO concentration in all glass systems. This is often chiefly owing to the rise of interactions via photoelectric absorption and Compton effect.
Fig. 3

Experimental and theoretical values of µm of different energies for different concentrations of BaO

HVL values are always used to describe the effectiveness of γ-ray shielding. As shown in Fig. 4, the HVL values decrease with the increase in the weight fraction of barium oxide and increase with increasing energy, which is certainly attributed to the increase in the mass attenuation coefficients and densities of the glass samples. It is recommended that higher contents of BaO within the glass system improve the radiation-shielding properties in terms of the mass attenuation coefficient and HVL parameters. Figure 5 illustrates that the behavior of the total electronic cross sections σe with energy is the identical to that of µm.
Fig. 4

Variation of HVL as a function of different concentrations of BaO at different energies

Fig. 5

Variation of electronic cross section (σe) as a function of different concentrations of BaO at different energies

Trends of Zeff values as a function of BaO concentrations at different energies are shown graphically in Fig. 6. It is clearly observed from the figure that the values of Zeff are obsessed on the composition of glass system and vary with the atomic number. Moreover, the values of the Zeff decrease as the photon energy increases and nearly have constant values for various concentrations of BaO at a similar energy. This is often in the main as a result of the doable increase in photoelectric absorption process. The photoelectric absorption depends on the atomic number, whereas the Compton scattering tends to rely on density [17].
Fig. 6

Variations of effective atomic number (Zeff) as a function of different concentrations of BaO at different energies

The effective electron number Nel results of the investigated glass samples within the photon energy 238–2614 keV are computed consistent with (µm/σe). It is found that there are slight variations in Nel results for various glass samples wherever a higher result of Nel would indicate an increased probability of photon-electron energy transfer and energy deposition into the glass. The results of Nel in Fig. 7 prove that there is an identical photon energy dependence to what was determined for Zeff [18].
Fig. 7

Variation of effective electron number (Nel) as a function of different concentrations of BaO at different energies

Fast neutron attenuation is delineated by a parameter referred to as the “removal cross section,” denoted by ΣR (cm−1). The removal cross section represents the chance that a fast or fission-energetic neutron undergoes a primary collision that removes it from the cluster of penetrating un-collided neutrons [19, 20]. Indeed, within the MeV-energy region, the absorption cross section of neutrons is extremely low compared to the scattering cross section. In fact, the fast neutrons are not directly absorbed throughout their passage through the shielding hydrogenated material; however, they slow primarily by sequent elastic collisions with the nuclei of light elements and once their energy is within the order of the thermal energy (0.025 eV), they are absorbed by the nuclei of heavy elements via interaction radiative capture [7, 16]. Generally, shielding materials are chemical compounds or mixtures, and their macroscopic removal cross sections will be obtained by calculating (ΣR) of their constituent elements.

Figure 8 shows the trend of the calculated mass removal cross sections of the whole glass system (ΣR)c as a function of BaO concentration. The calculated values of removal cross sections (ΣR)C show that the sample contained 0% BaO has the most important removal cross section. Therefore, the addition of BaO does not improve the removal cross-sectional values of those glasses.
Fig. 8

Removal cross sections (ΣR)C as a function of BaO concentration

Microhardness before and after gamma irradiation

Hardness is the material’s resistance to penetration or surface indentation [21]. The variation of the hardness number (Hv) as a function of different concentrations of BaO at load 200 g is shown in Fig. 9. From this figure, it is clear to us that (Hv) increases with the increase in BaO content and as a result microhardness involves the creation of a compression once the indenter is pushed down into the glass with the load applied. During the removal of the indenter, obviously, there is a retrievable elastic compression. Also, the addition of BaO reinforced the bond energy between B–O and Zn–O that will rise to the surface of this glass and that results in a rise within the values of microhardness that depend upon the structure of surface [21].
Fig. 9

Variation of Hv with different γ-ray doses for glass samples at 200 gm

The microhardness of the prepared glasses when exposed to gamma irradiation at two different gamma doses (10 and 50 KGy/s) at load = 200 g was measured. The obtained results reveal that the microhardness decreases slightly with irradiation doses as compared with original samples; this suggests that the impact of gamma irradiation on the investigated glasses chiefly depends on strictly electronic processes [22, 23]. These effects occur from radiation, and as a result, the electrons are excited and leave their positions and travel through the glass network. These phenomena clearly were delineated antecedently in another glass system [21].

Chemical durability before and after irradiation

The presence of barium within the prepared glasses causes an enhancement in the internal network glass structure and additionally a amendment within the action against the offensive water. Table 1 indicates that dissolution rates (DR) tend to decrease with the increase in BaO content. Low DR means the glass includes a high chemical durability. Also, from Table 1, it can be observed that there is no vital amendment in DR with the increase in the immersions periods. The DR values for prepared glass samples decrease slightly with exposure to radiation and also, decrease with increased doses of radiation. So, these glass samples will be thought about as chemical durable glasses. Gamma irradiation effects on interstitial compounds [21] are clearly tiny, and as a result, Ba and boron (BO3) network groups have the flexibility to resist irradiation.
Table 1

Variation of dissolution rates DR with different immersion periods and different doses

Time

0 days

15 days

30 days

X (wt%)

Dr (0 KGy/s)

Dr (10 KGy/s)

Dr (50 KGy/s)

Dr (0 KGy/s)

Dr (10 KGy/s)

Dr (50 KGy/s)

Dr (0 KGy/s)

Dr (10 KGy/s)

Dr (50 KGy/s)

0

4.6 × 10−5

4.3 × 10−5

4.3 × 10−5

4.2 × 10−5

4.1 × 10−5

4.1 × 10−5

4.4 × 10−5

4.2 × 10−5

4.1 × 10−5

10

3.7 × 10−5

3.5 × 10−5

3.4 × 10−5

3.4 × 10−5

3.3 × 10−5

3.2 × 10−5

3.1 × 10−5

3.010−5

2.9 × 10−5

20

1.9 × 10−5

1.7 × 10−5

1.5 × 10−5

1.7 × 10−5

1.5 × 10−5

1.3 × 10−5

1.2 × 10−5

1.1 × 10−5

1.1 × 10−5

30

1.41 × 10−5

1.3 × 10−5

1.1 × 10−5

1.11 × 10−5

1.1 × 10−5

0.9 × 10−5

0.9 × 10−5

0.8 × 10−5

0.7 × 10−5

40

0.9 × 10−5

0.8 × 10−5

0.8 × 10−5

0.8 × 10−5

0.7 × 10−5

0.6 × 10−5

0.6 × 10−5

0.5 × 10−5

0.4 × 10−5

Linear thermal expansion behavior

The addition of Ba oxide leads to a remarkable decrease in all characteristic temperatures with 30–35 °C as a result of the associated modifications within the glass structure and will result in the rise within the number of Ba–O linkage that is weaker than B–O linkage.

Figures 10 and 11 show the thermal expansion behavior (L/Lo as a function of temperature and BaO content, respectively) for all glass samples. Figure 11 shows that the average thermal expansion coefficient (α) is very small and has a value of about 3 * 10−6. The small dependence of α on BaO content provides an additional support for these investigated glasses to be thought about as correct radiation-shielding materials.
Fig. 10

Thermal expansion curves of the glass samples as a function of temperature

Fig. 11

Variation of the average thermal expansion coefficient with BaO content

Conclusion

In the present work concerning the investigation of modified zinc borate glasses doped with different Ba oxide concentrations, it is found that the changes in the molar volume and density show approximately opposite linear trends. Also, the obtained results show that µm is dependent on the chemical compositions of glass samples and energy of gamma rays. Good agreement between the experimentally obtained mass attenuation coefficient values and the corresponding theoretical predictions based on the known WinXCom program was observed. Additionally, the effect of gamma irradiation on the glass containing BaO is minor because its impact on the hardness values and dissolution rate is extremely small.

It can be concluded that the investigated glasses have relatively good gamma-ray attenuation properties, water resistance ability and thermal stability with the increase in barium oxide. So, it can be used as a container for keeping radioactive waste and radioactive sources.

References

  1. 1.
    S. Kaur, K.J. Singh, Int. J. Innov. Technol. Explor. Eng. (IJITEE) 2(5), 2278–3075 (2013)Google Scholar
  2. 2.
    S. Gupta, S.G. Singh, Int. J. Sci. Res. Publ. 1(2), 59–70 (2012)Google Scholar
  3. 3.
    S. Singh, A. Kumar, D. Singh, K.S. Thind, G.S. Mudahar, Nucl. Instrum. Methods Phys. B 266(1), 140–146 (2008)ADSCrossRefGoogle Scholar
  4. 4.
    N. Chanthima, J. Kaewkhao, P. Limkitjaroenporn, S. Tuscharoen, S. Kothan, M. Tungjai, S. Kaewjaeng, S. Sarachai, P. Limsuwan, Radiat. Phys. Chem. 137, 72–77 (2017)ADSCrossRefGoogle Scholar
  5. 5.
    S.U. El-Kameesy, H.A. Saudi, G. Mahmoud, R. Saeed, J. Adv. Phys. 11, 4 (2015)Google Scholar
  6. 6.
    J. Mauro, Report from: Glass Laboratory, college of Ceramics (Alfred University. Private communication through the internet, Alfred, 2000)Google Scholar
  7. 7.
    T. Özdemir, İ.K. Akbay, H. Uzun, İ.A. Reyhancan, Prog. Nucl. Energy 89, 102–109 (2016)CrossRefGoogle Scholar
  8. 8.
    J.H. Gong, W.J. Si, Z.D. Guan, Effect of load-dependence of hardness on indentation toughness determination for soda-lime glass. J. Non-Cryst. Solids 282, 325–328 (2001)ADSCrossRefGoogle Scholar
  9. 9.
    A. Tawansi, E. Ahmed, D. Holland, I.A. GohAar, N.A. El-Shishtawi, J. Non-Cryst. Solids 105(1–2), 78–90 (1988)ADSCrossRefGoogle Scholar
  10. 10.
    H.A. Saudi, A.G. Mostafa, N. Sheta, S.U. ElKameesy, H.A. Sallam, Phys. B Phys. Condens. Matter 406, 4001–4006 (2011)ADSCrossRefGoogle Scholar
  11. 11.
    J. Wood, Computational methods in reactor shielding (Pergamon, New York, 1982)Google Scholar
  12. 12.
    L. Gerward, N. Guilbert, K.B. Jensen, H. Levring, Radiat. Phys. Chem. 60, 23–24 (2001)ADSCrossRefGoogle Scholar
  13. 13.
    Sukhpal Singh, Ashok Kumar, Devinder Singh, K. Singh, T. Mudahar, S. Gurmel, Nucl. Instrum. Methods Phys. Res. Sect. B 266(1), 140–146 (2008)ADSCrossRefGoogle Scholar
  14. 14.
    H.A. Sallam, H.A. Saudy, World J. Condens. Matter Phys. 3, 62–66 (2013)ADSCrossRefGoogle Scholar
  15. 15.
    A.S. Makarious, I.I. Bashter, Abdo AEl. Sayad, A.M. Sameer Abdul, W.A. Kansouh, Ann. Nucl. Energy. 23, 195 (1996)CrossRefGoogle Scholar
  16. 16.
    H.A. Saudi, Appl. Math. Phys. 1(4), 143–146 (2013)Google Scholar
  17. 17.
    H.A. Saudy, S. El Mosallamy, S.U. El Kameesy, N. Sheta, A.G. Mostafa, H.A. Sallam, World J. Condens. Matter Phys. 3, 9–13 (2013)ADSCrossRefGoogle Scholar
  18. 18.
    V.P. Singh, N.M. Badiger, N. Chanthima, J. Kaewkhao, Phys. Chem. 98, 14–21 (2014)ADSGoogle Scholar
  19. 19.
    J.H. Hubbell, J. Phys. Med. Biol. 44, 1 (1999)CrossRefGoogle Scholar
  20. 20.
    H.A. Saudi, SOP Trans. Appl. Phys. Phys. Chem. 1(1), 29–32 (2014)Google Scholar
  21. 21.
    H.A. Saudi, Am. J. Phys. Appl. 4(6), 140–144 (2016)Google Scholar
  22. 22.
    M.A. Marzouk et al., J. Non-Cryst. Solids 387, 155–160 (2014)ADSCrossRefGoogle Scholar
  23. 23.
    E. J. Friebele, Radiation effects, in Optical Properties of Glass, ed. by D. R. Uhlmann, N. J. Kreidl (American Ceramic Society, Westerville, 1991)Google Scholar

Copyright information

© Institute of High Energy Physics, Chinese Academy of Sciences; Nuclear Electronics and Nuclear Detection Society and Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Department of Physics, Faculty of Science (Girls’ Branch)Al-Azhar UniversityCairoEgypt
  2. 2.Department of Physics, Faculty of ScienceAin Shams UniversityCairoEgypt

Personalised recommendations