1. Introduction
The multitude of physical, thermal, optical, and structural properties of glasses make them far better than other goods. They are manufactured easily at different temperatures, which led to the increase in studies where they were used in optoelectronic devices and in other industries. A large number of these experiments are dedicated to glasses comprising rare earth metal oxides [
1,
2,
3]. These low-cost glasses are ideal hosts for rare earth elements and are excellent materials for optoelectronics. Tellurium oxide (TeO
2), the source material for tellurite glasses, acts as the network former in the matrix as it is combined with alkali metals, alkaline earth metals, intermediate metals, or other glass formers to form the glass [
4]. Tellurium glasses exhibit low melting temperatures, high transmittance, high refractive indices, and chemical and mechanical tolerance.
In comparison, tellurium oxide glasses are equivalent to others in electrical conductivity, and have strong dielectric constants [
5,
6]. In addition to basic studies in which crystallization of binary and pure tellurite glasses were conducted, there are also important dielectric, structural, and radiation shielding studies reported. People expect glasses that involve transition metal oxides to be semiconducting [
7]. In experiments, added metallic oxides produce a promising performance. Adding such insoluble metals to tellurium-based glasses greatly drives the creation of semiconducting materials. Vanadium pentoxide occurs as a glassmaker with semiconducting properties in the glasses, making it a reasonable option for a wide variety of applications [
7,
8]. It was recently shown that these glasses could have a high degree of radiation protection [
9,
10,
11,
12]. Previously, Elmahroug et al. investigated the radiation shielding properties for a Bi
2O
3–V
2O
5–TeO
2 glass system in the energy range of 0.356–1.33 MeV. Their results showed that increasing Bi
2O
3 in a V
2O
5–TeO
2 glass system leads to an increment in shielding competencies [
13]. In fact, the use of glass materials for radiation shielding is not limited to this type of glass, but the frequency of research has been increasing day by day as a hot subject emphasized in many similar studies in recent years [
14,
15,
16,
17,
18].
Some of the reasons for this situation are that some traditional materials such as lead and concrete used in radiation fields do not have superior material properties and have some characteristics that threaten health. Of course, although this does not show that they are an inadequate radiation shielding material, some international institutions and organizations have direct incentives for researchers to study new generation shielding materials that can be an alternative to these materials with their eco-friendly and promising properties. In this case, glasses can be considered as a strong candidate for these types of utilizations. In this study, a group of glasses encoded VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 based on a TeO
2–V
2O
5–(B
2O
3/Nd
2O
3) glass composition were extensively investigated in terms of their gamma and neutron radiation attenuation competencies [
1]. To the best of our knowledge, no extensive gamma-ray shielding characterization has been done using advanced simulation methods and numerical comparison TeO
2–V
2O
5–(B
2O
3/Nd
2O
3). Therefore, this study aimed to perform a detailed characterization on the aforementioned glass composition, which could be very useful to understand the competencies of studied glass samples in medical and industrial radiation facilities. Moreover, this study aimed to discuss the potential effects of B
2O
3/Nd
2O
3 substitution on nuclear radiation shielding properties. Therefore, another important point to highlight is the concept of investigation that additive replacement effects will be evaluated with details. Some of the investigated parameters can be listed as linear attenuation coefficients (LAC), mass attenuation coefficients (MAC), Effective electron density (N
eff), Half value layer (T
1/2), Exposure buildup factor (EBF) and energy absorption buildup factor (EABF), tenth value layer (TVL), mean free path (λ), and effective atomic number (Z
eff). The obtained outcomes from the current investigation would be useful to understand the direct impact of the glass structure and density as well as the replacement type on radiation shielding properties of a TeO
2–V
2O
5–(B
2O
3/Nd
2O
3) system.
3. Results
In this study, four different glass samples encoded VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 based on 74.75TeO
2–0.25V
2O
5–(25 − x)B
2O
3–xNd
2O
3 (x = 0, 0.5, 1, 1.5 mol%) systems were tested for their feasibility for nuclear radiation shielding utilizations. The experiments on optical and structural properties were widely reported, which included alloys of different composition. In a previous paper, Kilic [
1] discussed the effect of B
2O
3 and Nd
2O
3 substitution on the optical, structural, and thermal properties of these glass samples. He discovered a personal association between Nd
2O
3 reinforcement and the optical properties and thermal and structural properties of 74.75TeO
2–0.25V
2O
5–(25 − x)B
2O
3–xNd
2O
3 (x = 0, 0.5, 1, 1.5 mol%) oxide glasses. To fulfil the demands of IAEA and WHO organizations, the importance of alternative shielding materials is rising. This study attempted to investigate the connection between the intriguing results in the Nd
2O
3 reinforced oxide glasses and their nuclear radiation shielding properties. A first move was made in evaluating availability concentrations for alloys in a 0.015–15 MeV range, using a general-purpose Monte Carlo method and Phy-X software. The selected energy range is a standard energy range of theoretical gamma ray shielding calculations, where the critical behaviors at the low, middle, and high energy region depending on dominant interaction processes such as photoelectric effect, Compton scattering, and pair production can be observed. The word ‘LAC’ (µ) is used to measure the shielding efficacy of glass samples. Density relies on the effectiveness of shielding compounds and the energy of the gamma rays.
Figure 2 shows the interaction between the photon energy of VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples. In
Figure 2, the energy zone’s effect on the variance of the LAC value was affected by the photoelectric effect, Compton scattering, and pair production mechanisms. This result occurs due to the nature of radiation’s interaction with matter. At low energies, the LAC value is decreased because of photo adsorption. In the mid-energy region, Compton scattering was the dominant interaction in the measurement pattern. However, the highest LAC amount was calculated in the VTBNd1.5 sample, which has the highest concentration of Nd
2O
3. The mass attenuation coefficient (MAC) of the specified substance is density-independent and unique.
Figure 3 displays the variation of obtained MAC values against photon energy (E). A variety of gamma-ray radiation and chemical compositions of attenuator glass have changed the rate of difference of MAC values. The landscape of the MAC data reveals noticeable trends in distinct areas. In the low energy area where the photoelectric effect determines how much gamma ray is absorbed, the absorption decreased significantly. Compton scattering dominance showed statistically substantial declines from MAC values. It appears that the VTBNd1.5 sample has higher MAC values at all incident photon energies. In particular, the findings for VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples were reported as 0.4926, 0.4977, 0.5027, and 0.5075 at 0.15 MeV photon energy, respectively. Moreover, MAC values were reported as 0.0353, 0.0355, 0.0356, and 0.0358 at 15 MeV photon energy for the studied glass samples in the same order. The condition obtained in both low and high energy areas can be explained by the inclusion of the largest amount of Nd
2O
3 in the glass composition because of its high atomic number. Similar results were reported by Elmahroug et al. [
13]. Their results showed that Bi
2O
3 reinforcement in the V
2O
5–TeO
2 glass system directly increased the mass attenuation coefficients of the studied glasses. Similar to our results, an increasing reinforcement amount with higher atomic number resulted in an increment in the V
2O
5–TeO
2 glass system. The term HVL factor is a useful quantity to evaluate the required thickness of a shield, which can reduce the intensity of the incident gamma ray by half. Therefore, a smaller HVL can be considered as a supremacy indicator in shielding materials. In this study, HVL values of the studied glasses were determined.
Figure 4 shows a variation of the half value layer (T
1/2) against photon energy for all glasses. In the lower energies, HVL values were reported as small. This is an expected situation for any type of shielding material as low energy gamma rays can be attenuated in low material thicknesses. However, it can be seen from
Figure 4 that HVL values are higher in the high energy zone.
It can be explained by the penetration property of gamma rays and its dependence on energy. For example, the HVL values of the VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples at different energies were found to be 0.0041 cm HVL
VTBNd0.
0 > 0.0039 cm HVL
VTBNd0.
5 > 0.0038 HVL
VTBNd1.
0 > 0.0037 cm HVL
VTBNd1.
5 at 0.015 MeV. Moreover, HVL values were reported as 0.2992 cm HVL
VTBNd0.
0 > 0.2840 cm HVL
VTBNd0.
5 > 0.2806 HVL
VTBNd1.
0 > 0.2760 cm HVL
VTBNd1.
5 at 0.15 MeV. Finally, HVL values were reported as 4.1660 cm HVL
VTBNd0.
0 > 3.9777 cm HVL
VTBNd0.
5 > 3.9533 HVL
VTBNd1.
0 > 3.9106 cm HVL
VTBNd1.
5 at 15 MeV, respectively. As shown from this ranking, the minimum HVL values were reported for the VTBNd1.5 sample, which has the highest amount of Nd
2O
3 additive in its glass structure. Therefore, one can say that VTBNd1.5 requires the smallest thickness to reduce incident gamma rays by half (T
1/2). The importance of the mean free path (λ) is a consideration in the gamma-protection abilities of shielding materials. The glass samples were examined, and the results are detailed in
Figure 5.
The λ values will differ similarly to the evolving pattern of HVL. The minimum λ values were recorded for the VTBNd1.5 sample. Another important shielding parameter is the tenth value layer (TVL). The term TVL factor is another essential evaluation criterion for the required thickness of a shield, reducing the intensity of an incident gamma ray to one-tenth (1/10). TVL vales of the studied glasses were determined and the results presented in
Figure 6 as a function of the incident photon energy for all glasses. In the lower energies, TVL values were reported as small. A similar variation trend of HVL was also reported for the TVL values of the VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples. For example, TVL values were reported as 0.9941 cm TVL
VTBNd0.
0 > 0.9435 cm TVL
VTBNd0.
5 > 0.9323 TVL
VTBNd1.
0 > 0.9170 cm HVL
VTBNd1.
5 at 0.15 MeV. Overall, the minimum TVL values were reported for the VTBNd1.5 sample, which has the highest amount of Nd
2O
3 additive. The required atomic number for measuring the material’s appropriateness for gamma applications is tied to the proper photon control stage. The Z
eff values of the glass samples measured are shown in
Figure 7.
Thanks to its high-quality shading properties, Z
eff values were greatest for the VTBNd1.5 glass sample. For example, Z
eff values for VTBNd1.5 were 34.80, 35.13, 35.46, and 35.78 for the VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples at 0.15 MeV, respectively. However, the highest Z
eff values were reported at 0.04 MeV as 50.44, 50.48, 50.52, and 50.55 for the VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples. The particle concentration in the medium is calculated, and then a radiation density correction is used in the equation to account for scattered radiation. Secondary ionizing radiation must be included in the overall calculation of buildup. The buildup factor is a multiplier compounded by the photon’s attenuation rate to calculate the photon’s total attenuation. The moderator allows for the disparity in the numbers of photons between the sources that makes up for their different intensities. Using the two sub terms of energy absorption, it can be classified into two forms of energy absorption factor, energy absorption buildup factor (EABF) and exposure buildup factor (EBF). In this study, EBF and EABF values were measured using a G-P fit approach from 0.5 to 40 mfp. The obtained fitting parameters along with their numerical values can be seen in
Table 3,
Table 4,
Table 5 and
Table 6.
Figure 8a–e or
Figure 9a–e display the calculated EBF and EABF values against photon energy for the VTBNd0.0, VTBNd0.5, VTBNd1.0, and VTBNd1.5 samples.
Figure 8a–e or
Figure 9a–e illustrate the concentration of the three distinct constituent layers of EBF and EABF due to photon radiation. Areas affected by gamma rays are important to the connections between radiation and matter. Since the photoelectric effect can be ignored near the binding energy of high atomic numbers, peaks can be observed in the first region. On the other side, though, the third segment of the sample is the most interesting during pair growth, with the value declining due to absorption processes.
Figure 10 and
Figure 11 display the changes in EBF and EABF values of studied glass samples at 10, 20, 30, and 40 mfp. These figures can also be considered as the dependency function of EBF and EABF values against glass structure.
Figure 10 shows that VTBNd1.5 has the lowest EBF and EABF values with its superior shielding properties among the investigated glasses. The same pattern was also seen for the EABF value. The minimum EABF values recorded for sample VPBCd8 were found at all mfp values. Analysis was conducted to compare the EBF and EABF values for a set of glass formulations based on mfp values such as 10, 20, 30, and 40 mfp.
Figure 12 shows variation of energy absorption buildup factor (EABF) and exposure buildup factor (EBF) against effective atomic number (Z
eff) at 1 MeV and 5 mfp for all glasses. It can be clearly seen from
Figure 12 that the EBF and EABF is higher for glasses with high Z
eff than for glasses with low atomic Z
eff. It can be easily shown that there is a strict relationship between EBF values and the efficient atomic number.
4. Conclusions
Nd2O3-doped glasses, among the technologically important lanthanide-doped glasses, are studied frequently due to their luminescence and optical properties. Moreover, among these studies, TeO2 glasses are mostly preferred due to their excellent optical properties. Being synthesized at low temperatures is one of the many advantages of these glasses. On the other hand, vanadium-doped tellurium glasses with semiconducting properties are considered valuable materials for semiconductor technology and optoelectronic materials such as lasers with the addition of Nd2O3. Apart from these advantageous properties, these glasses’ radiation properties were investigated in detail in this study. We aimed to perform a sizeable simulated characterization on a different type of Nd2O3, reinforced glasses and their nuclear radiation shielding properties regarding an ideal shield’s essential needs. The effect of varying the ratio of boron (III) oxide and neodymium (III) oxide concentrations on the radiation shielding properties of TeO2–V2O5–(B2O3/Nd2O3) were illustrated. The attenuation properties computed at expansive energies within the range of (0.015–15) × 10+3 keV. Some critical properties, such as T1/2, λ, TVL, µ, µm, Zeff, EBF, and EABF were determined. Simulated and theoretical µm values were obtained using the MXNPX code and the Phy-X PSD database. Good agreement was observed between the simulated and theoretical results. Generally, the VTBNd1.5 sample (1.5 mol%) Nd2O3 had the lowest T1/2, λ, and TVL values and the highest µ, µm, and Zeff values. That means that the VTBNd1.5 sample (with 1.5mol% Nd2O3) offers superior shielding against gamma radiation compared to the other samples. The results showed that radiation shielding properties increase according to the doping ratio. As a result of this study, it can be concluded that continuous research is needed in terms of glass sciences and material development studies. The effect of reinforcement was apparent. However, different types of comprehensive investigations with varying additive amounts can be considered as the continuous research of our project on eco-friendly novel shields.