Synthesis of Pb3O4-SiO2-ZnO-WO3 Glasses and their Fundamental Properties for Gamma Shielding Applications

Zinc lead silicate glass system contains different amount of WO3 were fabricated using the classical melt-quench technique. The nature of the samples was investigated using X-ray diffraction. The ultrasonic velocities and elastic moduli were tested experimentally after that the results were compared by using the theoretical consideration. With increasing the WO3 content, decreasing the molar volume causes a decrease in the inter-ionic distance Ri. The FLUKA code were used to estimate the main attenuation considerations mass attenuation coefficients (MAC) and linear attenuation coefficients (LAC). The LAC increment from 0.728 cm-1 to 0.856 cm−1 as the WO3 concentration increment from 0 to 5 mol%, resulting in high shielding performance for G5. The dose rate at energy of 0.6 MeV with the G5 sample found to be declines from 2.35 × 107 R/h at 1 mm to 4.71 × 106 R/h at 4 mm. The values of mean free path (MFP) and the half value layer (HVL) are smaller than those of the traditional photon shields signifying that the fabricated samples (particularly G5) have interesting shielding characteristics to be used in applications involving x/gamma rays.

In the field of optoelectronic tools, screen reflection, thermal and mechanical instruments, attenuation protecting, etc., glasses based on weighty metal oxides (WMO) as Pb 3 O 4 , Bi 2 O 3 , WO 3 and Y 2 O 3 have extensive applications [18][19][20][21][22][23][24][25][26][27][28][29]. WMO glasses extremely have density therefore its superior gamma-ray shielding attributes. A great candidate for γ-ray shielding purpose has been found to be lead containing silicate glasses. Pb 3 O 4 are identified as intermediary oxides, or provisional glass network modifiers. Subsequently, the percentage of the oxide in glass play an important role, it may be act as network former or network modifier. Once its concentration higher than 30 mol%, Pb 3 O 4 acts as both network former and network modifier in some silicate glasses. As Pb 3 O 4 modifies the network of silicate glasses, the structural units of silicate may be interacted with the structural unit of lead (PbO 4 ) strongly. Tungstate glasses is classified as non-traditional glasses. In its compounds, WO 3 , can explore 6 ionization states: from zero (0) to six (+6). It is founded in form W +3 , W +4 , W +5 and W +6 at many prepared and published glasses systems. The emergence of WO 3 into the network enhanced many characteristics properties of the manufacture systems [30][31][32].
On The Other Hand, some (WMi) or (TMi) holding glasses demonstrate protecting behavior toward more successive γ-rays. Several research on radiation effect on various doped glasses with different transition metal ions (TMi) have recently been developed by El Batal et al. [33,34]. Among the disguised objectives of several researchers, the requirements of substances that can perform a dual function across the last period can be considered. Considerable numbers of glass research laboratories are increasing daily to develop superior and useful features to use in protection purpose. These glasses are applied in advanced optical tools and in radiation shielding where radiation safety is needed.
The glass under studied has grown to be preferred replacement for concrete shielding due to its extraordinary features such as stiffness, and mechanical potency, likewise these glasses, have clarity and mechanical strength. The main objective of the paper under investigation is to prepare, recognize the attenuation impact of zinc lead silicate glasses containing various quantities of W 3+ and determine of its mechanical characteristics. Table 1 explore the content of fabricated glasses [35]. SiO 2 , Pb 3 O 4 , ZnO and WO 3 are the primary raw materials for getting these samples. Original materials that were purchased from Sigma-Aldrich Company. The blend materials were grinding continually to acquire a fine powder. To evaporate H 2 O and other volatile compounds or elements, the start materials were heated to 950 K for 30 min., then raised for 90 min to 1350 K. The samples were annealed at 700 K for 3 h to reduce internal stresses.
By theoretical equation the elastic moduli of the samples were determined [36,37] depend on packing density Vi ¼ where the ionic radii of metallic and oxygen Pauling are R m and R O respectively. Longitudinal waves L Where N A is the number of Avogadro, Planck constant is h and Boltzmann constants is k.
, Thermal coefficient of expansion α P = = 23.2 (v L − 0.57457) , the molar volume Monte Carlo technique is a simulation process for a full description of any experiment in a software environment. In the present study, several Monte Carlo simulations were applied via FLUKA code which is a powerful platform to handle the propagation of radiation (e.g. photons) for a large energy range reaching several hundred MeV [38]. In fact, the FLUKA code is mainly designed to generate the events (collisions) of hadrons in high energy physics. However, since 15 years FLUKA code is used for electromagnetic interactions with high accuracy for estimating the cross sections for photons and electrons. For the present work, we used FLUKA2005.6 version that have a huge library for the photon interactions including coherent process, pair production, and photoelectric effect. Moreover, it is worth mention that different Monte Carlo platforms such as PHITS, Geant4, and MCNP approved their successes to evaluate the photon shielding parameters for several studies [39][40][41][42][43][44][45].

Results and Discussion
It is increases with tungsten ion increased this is dependent on the reduction of Vm. Computed inter-ionic distance as.
Radius was established as polaron r p and internuclear r i , was calculated as: As a result of the decrease in Vm, these have been observed that these characteristics decrease with tungsten. For BO or NBO linking verification, the average number that has been coordinated is a considerable factor and is calculated as m = ∑ n ci X i where n ci is the cation coordination. Calculating the number per unit of bonds is estimated as n b ¼ N A V m ∑n ci X i . These characteristics have been noted to be increased  with an increase in tungsten oxide concentration. All these characteristics, as shown in Table 2. Figure 3 depicts the changes in the glass system's Vm and density. The densities of these samples increased as the WO 3 content increased, while Vm reduced. Because of the variation in molecular quantities between ZnO and WO 3 [81.389 & 231.838], the density increased. With increasing tungsten concentration, decreased molar volume values are reported in the present study. The network is therefore more compact, and the glass matrices have increased connectivity. The variations in V o and OPD demonstrated in Fig. 4. The values of V o have been observed to decrease while the OPD has been enhanced. These results pointed to an increase in the number of oxygen bridges (BO) due to the decrease in Vm.
The velocity of prepared glasses with varying quantities of tungsten oxide has been exemplified in Fig. 5. As shown in Table 3, both velocities (v L and v T ) were improved with an increase in WO 3 and (v L ) values higher than (v T ). The expansion in the evaluated ultrasonic velocity may be clarified by considering the following variables:  Table 3 The values of v L, v T and elastic moduli of fabricated glasses   Fig. 7 Theoretical elastic modules of prepared glasses with varying quantities of WO 3 development of tungstate glasses rather than zincate. Elastic modules exposed in Table 4. Figure 8 illustrates a schematic representation for the wellknown experiment setup namely, the narrow beam transmission experiment. The geometry of such experiment is an essential block to study and understand the radiation interaction (especially x/gamma rays) with materials. In the present work, we draw this geometry by using FLUKA code. The main attenuation parameters: mass and linear coefficients, give a full understanding of photon propagation through mass/linear thickness of an absorbing target. Both MAC and LAC were obtained utilizing several simulations for every energy by FLUKA code. The simulations outcomes of these factors were plotted in Fig. 9. Both μ/ρ and μ have similar variation with  Gi, (kcal/kJ) photon energy, whereas the μ values are higher than those of μ/ρ values. The important difference between μ/ρ and μ is that the μ factor is very helpful to understand the chemical composition dependence of the photon attenuation for the prepared glass specimens. For example, the curve of μ shows that the highest photon attenuation occurs by using G5 glass sample and the lowest photon attenuation occurs by using G1 glass samples. This indicates that the WO 3 addition plays an important role to attenuate the photons beam and then to improve the x/gamma shielding ability of the prepared glass system. More specifically, the maximum μ occurred at 0.6 MeV with the values of 0.728, 0.747, 0.759, 0.796, and 0.856 cm −1 for the prepared glass samples of G1, G2, G3, G4, and G5, respectively. The reason of such increase is the replacement of light metal oxide (ZnO) by higher one (WO 3 ). As WO 3 additive from 0 to 5 mol%, the LAC improved from 0.728 cm −1 to 0.856 cm −1 . Therefore, it is recommended to increase the WO 3 content for getting more superior photon shielding properties of our designed glasses. Our simulation outcomes were numerically

L G K Y
The highest Dev. % was noted at 1.25, 0.6, 1.5, 1.5, and 0.6 MeV with the values of 0.727, 0.923, 0.742, 0.735, and 0.751 for the glass samplings of G1 to G5, respectively. Therefore, the highest Dev. % between FLUKA and XCOM was observed for G2 glass sample with the value of 0.923. Such agreement confirms the accuracy of our simulation outcomes for all the studied parameters in the present work.
The previous interesting observations of the attenuation factors encouraged us taking more deep step to investigate the photon shielding capability of our present glass system. The transmission factors (MFP and HVL) are very important to choose a specific thickness of a material which uses for shielding applications. Moreover, they are usually used for comparing the photon shielding efficiency of new candidates with the conventional photon shields. Figure 10 shows a description for the photon shielding ability of our prepared glass system in terms of MFP and HVL as a comparison with several photon shields namely, ordinary, hematite-serpentine, ilmenite-limonite, basalt-magnetite, ilmenite, steelscrap, and steel-magnetite concretes and commercial RS-253-G18 and RS360 glasses. Obviously, the MFP and HVL values are lower than those of traditional photon shields, indicating that our arranged glass (particularly G5) has superior shielding characteristics for x or gamma ray proposals. Another important factor in the photon attenuation studies is the effective atomic number (Z eff ) that is directly related to the partial interactions occurred at different energy regions. Furthermore, the Z eff factor is a main term to determine the effective electron density (N eff ) of an absorbing medium. The calculated Z eff & N eff values were plotted as a function of energy for all of the prepared glass specimens as shown in Fig. 11 The final task in the present work is the evaluation of the energy absorption factors for each prepared glass sample. The first factor in this task is called specific gamma constant (SGC or Γ) that describes the radioactive source and its exposure in  air. The SGC values of the present prepared glass system were calculated and drawn as a function of WO 3 content for different photon energies namely, 1, 2, 4, and 8 MeV, as shown in Fig. 12. Clearly, the SGC has no significant change by increasing the concentration of WO 3 content at a given photon energy. However, there is a remarkable increase in the values of SGC as the photon energy. Such that the SGC factor increases from the value of about 61 Rm 2 / Ci h at 4 MeV to the value of about 141 Rm 2 / Ci h at 8 MeV. The second factor in this task is called mass energy absorption coefficient (MEAC) that measures the actual absorbed energy by a material (say glass sample). The MEAC factor is of importance in dose rate calculation that is a basic quantity for radiation applications in medicine. Both SGC and MEAC factors were used to calculate the dose rate for each prepared glass sample over the entire measured energy range. Figure 13 depicts the variation of dose rate (in unit of R/h) with photon energy at several levels of distance in the range between 1 and 15 mm. The values of the dose rate vary from the highest values at the lowest distance (e.g., 1 mm) to the lowest values at the highest distance (e.g., 15 mm). Moreover, one can notice that the rate of reduction in the dose rate was very large between 1 and 5 mm. At 0.6 MeV in the case of G5 glass (as an example), we found that the dose rate decreases from 2.35 × 10 7 R/h at 1 mm to 4.71 × 10 6 R/h at 4 mm.

Conclusions
Zinc lead silicate glass system contains different amount of WO 3 were fabricated with the traditional melt-quench technique. For these glasses, the physical, mechanical, and photon shielding parameters were investigated. The higher energy formation of W-O bonds than Zn-O is the main reason behind this conclusion which promotes the development of tungstate glasses rather than zincate. XRD result confirms the fabricated samples' amorphous nature. The parameters such as density, molar volume, and velocities (v L and v T ) were measured and then used to determine the mechanical characterized of fabricated samples. Elastic moduli exhibits an increasing trend as WO 3 increases from 0 to 5 mol% and there is a good agreement between the experimental and theoretical elastic moduli. 154 for the glass samples of G1, G2, G3, G4, and G5, respectively. The WO 3 content plays an valuable role to attenuate the photons beam and then to improve the x/gamma shielding capability of the arranged glass system. The specific gamma constant (SGC) has no significant change by increasing the concentration of WO 3 content, while it swiftly increases from 61 Rm 2 / Ci h to 141 Rm 2 / Ci h as photon energy increases from 4 MeV to 8 MeV. It can be concluded that we successfully introduced a new glass system containing Pb 3 O 4 , SiO 2 , ZnO, and WO 3 with good mechanical properties and potential use in photon shielding applications.