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Multidisciplinary Materials Chronicles

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Received: Feb. 15, 2024; Accepted: Mar. 31, 2024; Published Online: Apr. 22, 2024


Evaluating the Effectiveness of Tellurium-Molybdenum Oxide Glass Systems for Radiation Shielding Protection

Shams A. M Issa1,2, Antoaneta Ene3, Hesham M. H. Zakaly2,4*

1 Department of Physics, Faculty of Science, University of Tabuk, Tabuk, Saudi Arabia

Physics Department, Faculty of Science, Al-Azhar University, Assiut, 71452, Egypt

INPOLDE Research Center, Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, Dunarea de Jos University of Galati,  47 Domneasca Street, 800008 Galati, Romania

Institute of Physics and Technology, Ural Federal University, 19 Mira St, 620002, Yekaterinurg, Russia

https://doi.org/10.62184/mmc.jmmc110020242

https://creativecommons.org/licenses/by/4.0/



Keywords

Tellurium; molybdenum; Gamma ray shielding; PHY-X; FLUKA.


Abstract

    The present investigation examined TeO2–MeO3 glasses with different compositions for their ability to absorb γ-rays using the Phy-X and FLUKA Code, respectively. The study covered energies ranging from 0.015 to 15 MeV, where several parameters such as effective atomic number (Zeff), free path mean (GMFP), mass attenuation coefficient (GMAC), macroscopic cross-section (GLAC), and half-value levels were analyzed (GHVL). Glass composite composed of 80% TeO2 and 20% MoO3 was found to have the lowest GLAC content among the tested samples. GHVL = 0.055 cm was the half-value of the 80TeO2–20MoO3 glasses when they were subjected to 80 keV gamma-rays. It is anticipated that the GMFP of the investigated materials ranges from 0.004 to 0.005 cm when subjected to 100 keV gamma-rays. It was said that the increase in Zeff may be attributed to an increased quantity of electrons that were accessible for interaction with photons, resulting in a decreased probability of gamma rays passing through the shielding material. The cumulative impact of these findings demonstrates that specific glass compositions, particularly those that include Tellurium, have the potential to be used as excellent radiation shielding materials. These materials are becoming more important for providing efficient radiation protection in various industries and applications, including medical imaging, nuclear power, and space exploration.



To cite this article

A. M Issa, S., Ene, A., & M. H. Zakaly, H. (2024). Evaluating the Effectiveness of Tellurium-Molybdenum Oxide Glass Systems for Radiation Shielding Protection. Multidisciplinary Materials Chronicles, 1(1), 19–29. https://doi.org/10.62184/mmc.jmmc110020242




1. Introduction

    Nuclear technology has ushered in a new era of innovation, profoundly influencing human activities across multiple sectors, including medical therapeutics, agricultural practices, research diagnostics, industrial applications, and sustainable energy generation through nuclear reactors. The advent of such diverse applications has underscored the criticality of identifying and utilizing suitable shielding materials to safely contain the various forms of radiation emanating from these technologies. In particular, within the operational environments of nuclear reactors, there is an essential need for materials that can effectively insulate against both gamma rays and neutrons [1–3]. Concrete has been the material of choice for radiation shielding due to its widespread availability and relative effectiveness. However, the protective quality of concrete is inherently limited by its hydrophilic nature. Fluctuations in moisture content can compromise its structural integrity, leading to variations in strength and density that diminish its shielding capacity [4]. Despite offering reasonable levels of protection, traditional shielding materials, such as concrete, metals, polymers, and even lead, encounter limitations due to thermal instability, susceptibility to compositional changes, lack of transparency, and a constrained scope of utility.

In the quest for more versatile shielding solutions, the industry focuses on developing transparent materials that can offer robust defense against gamma and X-rays. Such materials are in high demand within nuclear medicine and diagnostic imaging [5–7]. Addressing this need, the production process has been geared towards glass systems that integrate high levels of transparency with efficient absorption of radiation gases [8]. Glasses enriched with heavy metal oxides, notably lead oxide (PbO), are increasingly favored for such applications. This preference is attributed to their inherent properties, such as high polarizability, lower melting points, and superior refractive indices, in addition to their transparency, and chemical and thermal robustness [9].

In pursuing advancing radiation protection technologies, this investigation employs FLUKA simulation and Phy-x/PSD simulation software to meticulously evaluate the radiation shielding characteristics of newly developed glass models. The study focuses on determining the glass models' performance in several key shielding capacities, including gamma mass attenuation coefficient (GMAC), linear attenuation coefficient (GLAC), half-value layer (GHVL), mean free path (GMFP), tenth value layer (GTVL), and effective atomic number (Zeff) [10–12]. The spotlight of current research interest is on the Tellurium–Molybdenum Oxide Glass (Te-Mo glass) systems, which are being examined for their potential as superior radiation shields. This burgeoning interest is propelled by the urgent necessity for effective radiation protection materials that are not only technologically adept in providing exceptional shielding against harmful radiation but also maintain their beneficial attributes amidst the escalating advancements in medical imaging, energy production, and aerospace exploration.

2. Materials and Method

2.1. Materials

The study conducted a theoretical examination of the gamma-ray (γ-ray) shielding capabilities of four different glass materials. These materials are identified by their chemical compositions: 50% tellurium dioxide (TeO2) and 50% molybdenum trioxide (MoO3), 60% TeO2 and 40% MoO3, 70% TeO2 and 30% MoO3, and 80% TeO2 and 20% MoO3 [13]. For convenience, these compositions are abbreviated as 50Te, 60Te, 70Te, and 80Te, respectively. Computational analyses were performed on these materials to evaluate various γ-ray shielding characteristics. Details about these glass samples, including their assigned codes, densities, and molar volumes, are provided in Table 1.

The table describes a study focusing on the efficiency of certain glass materials in shielding against γ-rays. The materials are mixtures of tellurium dioxide and molybdenum trioxide in varying proportions. Each material's effectiveness in γ-ray shielding could be influenced by its composition, as the density and molar volume of the glass are likely to impact its shielding performance. The density of the materials appears to increase as the proportion of TeO2 increases, suggesting that a higher concentration of TeO2 in the glass composition results in a denser material. This trend could be relevant for γ-ray shielding since denser materials generally provide better attenuation of high-energy photons like γ-rays.

Conversely, the molar volume decreases as the TeO2 content increases, which correlates with the increasing density – as density increases, molar volume typically decreases, given that molar volume is a measure of the volume occupied by one mole of a substance. The incremental changes in the glass composition reflected by the glass code from 50Te to 80Te indicate a systematic variation in the materials' properties, which are likely being studied to understand how these variations affect γ-ray shielding efficiency. The research might be looking to optimize glass compositions for the most effective γ-ray shielding, balancing between density, molar volume, and potentially other factors like cost, durability, and ease of manufacture.

Table 1. The Chemical Composition and Density(g/cm3) of Investigated Glass Samples.

 

No.

Glasses composition

Glass code

Density (g/cm3)

Molar Volume (cm3/mol)

1.

50TeO2-50MoO3

50Te

4.858

31.24

2.

60TeO2-40MoO3

60Te

5.018

30.56

3.

70TeO2-30MoO3

70Te

5.176

29.93

4.

80TeO2-20MoO3

80Te

5.251

29.80

2.2. Shielding Simulation

The assessment of glass compositions infused with tellurium and molybdenum oxides for radiation protection necessitates rigorous simulation analysis due to the hazardous nature of empirical γ-ray interaction studies. FLUKA simulation software, collaboratively developed by CERN along with various other research entities, is at the forefront of this analysis, providing a virtual environment for particle interaction and propagation in matter [14–16]. These simulations serve an essential role in high-energy physics, radiation protection, engineering, and medical physics, with their reliability bolstered by comprehensive validations against a broad spectrum of experimental data.

FLUKA is a particle physics Monte Carlo simulation package, integral for simulating complex interactions of particles with matter. The software's robustness is evidenced through numerous validations across diverse energies and materials, as explored in seminal reviews and in-depth discussions concerning its underpinning physical models [15,17]. The precision with which FLUKA models the interactions between γ-rays and shielding materials is of particular relevance to the study of Tellurium-Molybdenum Oxide Glass Systems.

Figure 1 demonstrates the sophisticated simulation setup employed to evaluate the efficacy of various glass compositions in attenuating γ-rays. Utilizing the FLUKA Code, lauded for its advanced computational capabilities in particle physics simulations, alongside Phy-X software, this approach facilitates a granular and comprehensive analysis of γ-ray interactions. The simulation's framework managed through the FLAIR interface, depicts the spatial arrangement and geometrical specifics of the glass samples according to the detection apparatus. As an intuitive graphical user interface, FLAIR significantly streamlines the preparatory and analytical phases of simulation processes.

Despite the demonstrable precision of FLUKA simulations, it is imperative to recognize the intrinsic limitations and assumptions that accompany any simulated model. The veracity of simulations is contingent upon the model's adherence to physical reality and the precision of the defined input parameters. Variabilities inherent to real-world conditions, such as fluctuations in material properties or inconsistencies in manufacturing practices, may not be entirely captured within the simulation's parameters, thus necessitating the need for empirical validation. The definitive verification of simulation accuracy lies in experimental comparison, which is instrumental in augmenting the robustness of the computational findings, particularly within the domain of radiation shielding materials. FLUKA simulations provide a substantial foundation for theoretical inquiry and preclinical investigation, offering intricate insights into the interaction dynamics of γ-rays with potential shielding materials.


Figure 1. Simulation process geometry setup using FLAIR interface.

3. Results and Discussions

3.1.  Physical Properties

Figure 2 illustrates the variation in density and molar volume for glass compositions ranging from 50Te to 80Te. As depicted in Figure 2a, there is an upward trend in density for the glass samples from 50Te to 80Te, with values ascending from 4.858 to 5.251 g/cm3. Conversely, Figure 2b demonstrates a downward trajectory in molar volume for the same range of glass samples, decreasing from 31.24 cm3/mol to 29.80 cm3/mol. The increase in density is likely a consequence of the augmented Tellurium content, which escalates from 50 to 80 mol%. A reduction in molar volume is observed due to the inverse relationship between density and molar volume expressed by the equation ρ = M/V. This correlation implies that with the increment in glass density, there is a corresponding enhancement in material compactness, culminating in a diminished molar volume for the glass samples.

3.2. Shielding Properties

3.2.1. Macroscopic Cross-section

    Following the Beer-Lambert law, which is represented by the equation (1), the rate at which the intensity of radiation scattering and absorption that is transmitted via shielding materials (mixtures, alloys, and compounds) is measured expressed by [18]:


where Io represents the intensity of incident photons, and I stands for the intensity of transmitted photons. With the help of Phy-X programs and the FLUKA Code, Table 2 illustrates the parameters that were determined by GLAC and how they changed in response to the energy of the incoming photon. It can be seen from Table 2 that the results of the FLUKA simulations and the Phy-X analysis were in agreement for each sample. Additionally, the findings demonstrate that the GLAC decreases as the amount of energy increases, which is a consequence of the high penetrating strength of radiation [19]. At the energy levels of 40 keV, sharp absorption edges were seen in Table 2 for all samples. This indicates the existence of Te elements, which are represented by the K-edge.


Figure 2. (a) Density and (b) molar volume change with sample concentration.

Table 2. Linear attenuation coefficient (GLAC, cm-1) of the glass samples.

E

50Te

60Te

70Te

80Te

(MeV)

Phy-X

FLUKA

Phy-X

FLUKA

Phy-X

FLUKA

Phy-X

FLUKA

0.015

149.861

150.460

165.363

166.025

181.249

181.974

194.493

195.271

0.020

171.060

171.744

159.645

160.283

147.441

148.031

132.447

132.977

0.030

59.717

59.955

55.502

55.724

51.002

51.206

45.530

45.712

0.040

62.362

62.611

68.303

68.577

74.383

74.681

79.367

79.684

0.050

34.465

34.603

37.796

37.947

41.206

41.370

44.009

44.185

0.060

21.184

21.269

23.246

23.339

25.357

25.459

27.096

27.204

0.080

9.875

9.914

10.830

10.874

11.808

11.855

12.612

12.663

0.100

5.559

5.581

6.083

6.108

6.620

6.646

7.058

7.087

0.150

2.147

2.155

2.327

2.336

2.510

2.520

2.656

2.667

0.200

1.231

1.236

1.319

1.324

1.408

1.414

1.477

1.483

0.300

0.691

0.694

0.728

0.731

0.765

0.768

0.790

0.793

0.400

0.521

0.523

0.543

0.545

0.566

0.568

0.579

0.581

0.500

0.438

0.440

0.455

0.456

0.471

0.473

0.480

0.482

0.600

0.388

0.389

0.401

0.403

0.414

0.416

0.421

0.422

0.800

0.326

0.327

0.336

0.337

0.346

0.347

0.350

0.352

1.000

0.287

0.288

0.295

0.297

0.304

0.305

0.307

0.308

1.500

0.231

0.232

0.238

0.239

0.244

0.245

0.246

0.247

2.000

0.203

0.204

0.209

0.210

0.215

0.215

0.217

0.218

3.000

0.176

0.177

0.182

0.182

0.187

0.188

0.190

0.190

4.000

0.165

0.165

0.170

0.171

0.176

0.177

0.179

0.180

5.000

0.160

0.160

0.166

0.166

0.171

0.172

0.175

0.175

6.000

0.158

0.158

0.164

0.164

0.170

0.171

0.173

0.174

8.000

0.158

0.159

0.165

0.166

0.172

0.172

0.176

0.176

10.000

0.162

0.162

0.169

0.169

0.176

0.177

0.180

0.181

15.000

0.173

0.173

0.181

0.182

0.189

0.190

0.195

0.195


The results of a comparative study of GLAC vs. energy for each of the samples are shown in Table 2. Since GLAC is based on density, 80Te demonstrates the most outstanding GLAC value due to its greater density. Table 2 also indicates that 50Te has the lowest GLAC, another point of interest. According to the theory that the GLAC lowers as density falls, this is compatible with the above idea.

3.2.2.  Mass Attenuation Coefficient

    To evaluate the mass-attenuation parameter (GMAC), which is the ratio between the GLAC and the density of the samples, equation (2) is used:

Figure 3 illustrates the GMAC value calculated using FLUKA at several different energies. As a result of the fact that the mass attenuation coefficient is independent of density and is reliant on both the elemental composition and the atomic number of the element, it offers crucial insights into how the shielding qualities of a material may be adjusted by adjusting the nuclear configuration of a component. In addition, Figure 3 presents the calculated GMAC values over a range of photon energies, as determined using the FLUKA simulation software. GMAC, independent of material density, is a fundamental property that reveals the intrinsic ability of a substance to attenuate gamma radiation. It primarily depends on the elemental composition and the atomic number of the constituents within the material.

GMAC is an invaluable metric for assessing how modifications in a material's elemental makeup can enhance its protective qualities in radiation shielding. The plot shows that the GMAC decreases with increasing photon energy, which is consistent with the general behavior of photon attenuation in the matter. This trend reflects the dominant interaction mechanisms at different energy levels: the photoelectric effect at low energies, Compton scattering at intermediate energies, and pair production at high energies. The figure shows that the sample labeled as 80Te exhibits the highest GMAC values across the studied energy spectrum. This suggests that the 80Te sample, with its higher proportion of Tellurium (which has a more significant atomic number than Molybdenum), presents a more effective gamma shielding material. The higher atomic number correlates with greater photon interaction cross-sections, thereby providing superior attenuation due to increased photoelectric absorption and other mechanisms. Such insights are crucial for designing materials for radiation shielding applications, particularly in fields where precise control over radiation exposure is necessary, such as nuclear medicine and diagnostics. By understanding the relationship between GMAC and photon energy, researchers and engineers can better select and design materials that balance transparency with effective radiation absorption, ultimately leading to safer and more efficient use of nuclear technology.

Figure 3. Analysis of GMAC for all samples versus photon energy.

3.2.3.  Half-Value-Layer (GHVL)

When referring to the thickness of shielding materials capable of lowering radioactive quantities, the term GHVL is used, expressed by equation (3) [20].