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. 2025 Feb 24;15:6537. doi: 10.1038/s41598-025-90902-7

Gamma-radiation insulating performance of AlON-hardened Na2O–Bi2O3–SiO2–BaO–Fe2O3–ZrO2 glasses

Jamila S Alzahrani 1,✉, Z A Alrowaili 2, I O Olarinoye 3, Chahkrit Sriwunkum 4, Imen Kebaili 5, M S Al-Buriahi 6
PMCID: PMC11850596  PMID: 39994341

Abstract

Aside high radiation cross-section, high mechanical strength is an essential quality for durable and effective glass shields. Many emerging glass shields are brittle with low strength parameters; consequently, limiting their longstanding applications. In this study, the use of AlON (aluminium oxynitride) to increase the hardness of a Zr-based glass system and the consequent effects on the glass density and gamma shielding capacity were investigated. AlON was produced from a combination of AlN and Al2O3 powders through the solid-phase reaction process at 1750 °C. The melt-and-quench process was then used to make the Zr-based (Na2O–Bi2O3–SiO2–BaO–Fe2O3–ZrO2) glass. The glass was homogeneously mixed with varying quantities (0 (GZr8), 4 (GZr8Al4), and 8% (GZr8Al8) by weight) of AlON powder. Using the FLUKA Monte Carlo code, the gamma photon interaction parameters of the AlON-doped glasses were obtained. The density of the glasses increased from 2.90 to 3.11 g/cm3 as the AlON mass proportion increased from 0 to 8%. For GZr8, GZr8Al4, and GZr8Al8, the mass attenuation coefficient had values in the range 0.0316–38.9421 cm2/g, 0.0315–38.8504 cm2/g, and 0.0311–37.0391 cm2/g, respectively. The range of the half-value layer and mean free path for 0.015–15 MeV photons is about 0.01–7.54 cm and 0.01–10.87 cm for GZr8, 0.01–7.19 cm and 0.01–10.38 cm for GZr8Al4, and 0.01–7.14 cm and 0.01–10.31 cm for GZr8Al8. The introduction of AlON into the glass matrix quenched photon buildup factors and enhanced the photon shielding ability of the GZr8 glass system. GZr8Al8 can displace many existing shielding materials, including glasses, concrete, and rocks, based on the analysis of the obtained results. Aside high gamma shielding efficiency, the mechanical strength and Pb-free nature are other attractive features that give the AlON-doped glasses an edge over many existing gamma shielding materials. The present glass system is useful for durable gamma-ray shielding of small-scale gamma sources gamma sources applied in medicine and radiation research.

Keywords: Dose-rate, Gamma-radiation, Glass-ceramics, Monte-Carlo-simulation, Radiation protection

Subject terms: Materials science, Physics

Introduction

The quantification of gamma-ray transmission level and energy deposition processes are essential in many technical and research fields. Traditionally, gamma radiation is an essential tool in the health sector for probing the health status of humans and animals, treating diseases, and sterilizing equipment1–3. Gamma radiation is also used for airport security, testing the quality of manufactured materials, food production and preservation, crop and micro-organism culturing and growth control, material characterization and property control4–10. Gamma radiation is a product of natural and technologically induced nuclear processes, therefore, it is ubiquitous in the Earth surface and environment. Based on the successes recorded in the existing applications and the availability of measures to prevent nuclear radiation accident, the scope of radiation applications can be projected to expand. Accidental exposure of gamma radiation can result in undesirable effects such as, cell mutation, disease, death, and damages to materials and gadgets, hence, the control of ionizing radiation is essential.

To mitigate the unwanted effects of uncontrolled exposure in human environments, radiation protection measures, including the use of shields have been emphasized and enforced and advised by local authorities and international organizations, respectively, in many areas where radiation are deployed for the benefits of mankind and the biota. Many materials have the potential to function as shields in radiation environments, however, different radiation application areas (such as the aerospace, health, research, manufacturing, agricultural, food and nuclear industries), require distinct qualities for effective shielding performance. In the past, Pb and Pb-based materials were preferred for gamma and x-ray shielding, because of the high photon cross-section that Pb exhibits. However, the fear of poisoning and its high density has made the use of Pb unpopular in many conventional radiation applications and in scenarios where light shields are preferred. Concrete blended from different aggregates is popular for biological shields, its opaqueness and instability also restrict its application in high temperature and extreme environments, security observatories and the airspace industries for shielding. The use of rocks and metals are also limited by their opaque nature. The limitations imposed by the inherent properties of potential shielding materials prevent their applications as radiation insulators in certain radiation environments. In addition, the unique requirements imposed by radiation environments also make it hard to have a universal shield for all radiation environments. Therefore, recent investigations11–26 have focused on finding novel materials with superior shielding and dosimetry competences and having attractive properties that delineate the environments where they are most suitable or stable, and functional as radiation protective barriers. In addition, the economics of producing novel materials from pristine raw materials have made researchers to investigate the open-loop recycling of waste materials for shielding applications20–26.

In recent times, depending on their chemical configurations, glasses have been recognized as effective and sometimes durable shields compared to traditional shields such as lead (Pb), metals and their alloys, and concrete. This is a result of some of the attributes of glasses which have attracted radiation-protection scientist and technicians. These features include, flexibility in the choice of chemical configuration, ease and low cost of production. These properties make it easy to tailor glsass properties, produce cheap, durable and effective glass shields that fits into different radiation environments. Consequently, many glass matrices have been produced and characterized for their radiation shielding parameters and other characteristics that define where they can be deployed for radiation control applications, especially in recent times27–33. Also, these previous studies have highlighted the roles of different chemical admixtures in projecting diverse aspects of the properties and functionalities of glass systems. For instance, glasses that are optically active and having high radiation absorption cross-sections are preferred as transparent shields, radiation detectors and dosimeters20–31. Also, chemically unreactive and thermally resilient glasses are preferred in harsh nuclear environments, such as space and nuclear reactors. Durable and tough glasses are also attractive for nuclear waste management and radiation control. Clearly, the thermal response, optical behavior, strength, and chemical durability of glasses are some of the factors that determine where glasses with high gamma absorption features can be used for shielding.

Glasses are generally brittle; this limits their mechanical strength and functionality. Therefore, in modern glass manufacturing, mechanical performance is a key issue of interest34. Recently, the improvement of mechanical strength, brough about by playing around the chemistry of materials, synthesis method, and post-production treatment, or a combination of the three, has allowed for a wide range of glass applications over the past 10 years. For instance, there has been tremendous improvement in damage resistance of covering glasses of handheld devices in recent times34–36. This has improved the durability and market value of the gadgets. Despite this progress, the limitations of glass brittleness and low hardness continue to constrain some glass matrices in many applications. Moreover, deliberately increasing the mechanical strength and hardness of glasses intended for radiation shields is scarce in the literature.

In this study, the use of AlON (aluminium oxynitride) to increase the hardness of a Zr-based glass system (Na2O–Bi2O3–SiO2–BaO–Fe2O3–ZrO2) and the consequent effects on the glass density and gamma shielding capacity is investigated. The glass composition is interesting and chosen to give a balance between low and high atomic number modifying oxides. The inclusion of Bi2O3, ZrO2, and BaO serves to stabilize the glass structure and increase the gamma-cross-section due to their density and affective atomic number37,38. On the other hand, Na2O is a good network stabilizer which can also help to improve the mechanical strength of glasses37. Also, AlON is known to possess high hardness, strength, and resistant to abrasion39. This study attempts to improve the mechanical aspect of the glass system without degrading its gamma radiation absorption prowess. This research produced mechanically strong and durable Zr-based glasses with good gamma radiation insulating properties for practical applications gamma-shields in medical and other radiation-based facilities. It also highlights the use of AlON as n hardening agent for shielding glasses. This study is important from material chemistry and development perspectives and useful for radiation protection of man and the environment.

Materials and method

Aluminum nitride (AlN) and Al2O3 (alumina) powders of 35.7 mol% and 64.3 mol% concentration, respectively were blended together and reacted through the solid-phase reaction process at 1750 °C to produce AlON. The obtained powder was compressed into pellets using a steel die. Then, using the cold isostatic pressing method, the pellets were densified further. The resulting pellets were sintered for 4 h at 1750 °C in a N2 environment. The high temperature reactive sintering is required to achieve homogenous and completely dense samples40. The AlON powder compacts were then ground into a powder using a vibrating disc mill.

The melt-and-quench was used to make the Zr-based (Na2O–Bi2O3–SiO2–BaO–Fe2O3–ZrO2) glass. All the chemical reagents were purchased from Merck. For 20 min, the components that made up the glass composition were melted at 1350 °C. The uniform material was placed into a mold to cool after melting. The bulk glass was heated to 250 °C for 8 h in order to anneal it. Grinded in an agate mortar, the glass was powdered to serve as a matrix for AlON doping. Ultimately, the glass was homogeneously mixed with AlON powder in varying quantities (0, 4, and 8% by weight) and pressed in the die to create an AlON-reinforced Zr-based glass–ceramic composite. To increase their density, sample composites underwent cold isostatic pressing. For ninety minutes, the resulting samples were sintered at 570 °C. The sample code and chemical makeup of the prepared sample, as determined by the X-ray fluorescence analysis are displayed in Table 1.

Table 1.

Sample code and weight fraction (wt.%) of compound present in the prepared glasses including their measured density and hardness.

Composition (wt%) Glass sample
GZr8 GZr8Al4 GZr8Al8
N 0.00000 0.24341 0.54138
O 35.30582 36.38945 36.51223
Na 7.70761 6.80527 6.95471
Al 0.00000 1.79513 3.58147
Si 12.68026 11.60243 11.30661
Fe 1.47190 1.40974 0.93701
Zr 11.34759 10.04057 9.78657
Ba 6.27548 6.29817 6.44456
Bi 25.21134 25.41582 23.93545
Density (g/cm3) 2.90 3.05 3.11
Vickers Hardness (GPa) 4.89 5.94 6.33
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The glass–ceramics samples’ physical, mechanical, and radiation response qualities were ascertained by a variety of experimental and theoretical methods. The popular Archimedes method was used to determine the densities of the samples. The mass of the glass–ceramics in air (Inline graphic) and when complete immersed in xylene (Inline graphic) was taken. Using the density of xylene (Inline graphic g/cm3), the densities of the produced glass–ceramics were determined as:

graphic file with name M4.gif 1

In addition, the effect of adding AlON on the mechanical hardness of the Zr-based glasses was determined using the micro-indentation hardness test. The test was performed by the Vickers hardness instrument using a force of 20 N for 15 s.

In conclusion, the gamma photon interaction parameters of the synthesised samples were obtained for gamma-ray energies (E) within 15 keV ≤ E ≤ 15 MeV using FLUKA simulations and computation methods. First, the mass attenuation coefficients Inline graphic of the glass ceramics were obtained using photon transmission simulations in the FLUKA Monte Carlo code environment. Figure 1 summarises the simulation arrangement in the FLUKA program. To ascertain the acceptability of the simulation arrangement, accuracy of the transmission data, and Inline graphic obtained therein, the values of Inline graphic of the samples were also computed using XCOM41 for the same energy spectrum as FLUKA simulations. FLUKA is a Monte Carlo code which can be used to perform the simulation of the interaction and transmission processes of radiation of different qualities. For gamma photon transmission simulation, the input file specifies the beam source, number of incident photons, energy, and position. Also, among the interacting material, its dimension, and geometry of the setup is described in the input file. The entire setup is surrounded by a black hole environment where all radiation is absorbed due to infinite radiation absorption cross-section. FLUKA has a friendly user interface called flair where input files are created and edited and the output files can be viewed. A card is used to define keywords and argument. The BEAM, BEAMPOS, Geometry, and Media cards were used to define the beam characteristics, position and direction of the primary beam, geometry of the setup, and define the interactive medium, respectively, while the scoring card was used to record the transmitted particles. More details of local deployment can be found in previous articles42–44. Other photon interaction parameters were computed either using the NIST database41 or direct computation from the values of the Inline graphic based on standard computation procedures as previously highlighted45–48. The computed parameters include: linear attenuation coefficient (µ), half-value layer (HVL), mean free path (Inline graphic), effective electron density (Inline graphic), effective atomic number (Inline graphic), specific gamma constant (Γ), mass energy absorption coefficient Inline graphic, dose rates (Dr) at different sample thicknesses. Expressions for evaluating these quantities can be found in11–26. The exposure (EBF) and energy absorption (EABF) buildup factors were computed based on the geometric progression fitting process30,49.

Fig. 1.

Fig. 1

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FLUKA simulation setup used for evaluating the gamma-ray transmission parameters of the prepared glasses.

Results and discussion

In Table 1, the measured density and Vickers hardness values of the prepared glasses (GZr8, GZr8Al4, and GZr8Al8) are presented. Both parameters increase with the AlON content of the glasses. While density increases from 2.90 to 3.11 ± 0.01 g/cm3, hardness increases from 4.89 to 6.33 GPa as the AlON mass proportion increases from 0 to 8%. The observed growth in the value of density could be attributed to the increase in the weight concentrations of dense metals (such as Ba and Bi) in the glasses, when AlON was introduced. This increases the weight per unit volume and the glass system become more compact. The values of the hardness reveal that AlON increases the resilience of the glasses against mechanical failure and deformation. This shows that adding AlON could enhance the toughness, compactness, and mechanical attributes of a glass matrix. This abrasive resistance nature of the AlON-rich glasses makes them useful for high strength applications such as in construction industry or nuclear waste management.

The values of Inline graphic obtained from FLUKA simulations and XCOM software and the absolute differences between both set of values are tabulated for each glass material and energy in Table 2. The values of Inline graphic computed from FLUKA Monte Carlo simulation data and direct computation using XCOM have good direct correlation, as the variations between them were less than 1%. The implication of this is that the adopted simulation geometry approximates a narrow beam photon transmission setup. The insignificant differences in the values could be attributed to error associated with counting statistics in FLUKA and slight differences in the cross-section data library in XCOM and FLUKA. Due to the insignificant differences in the obtained Inline graphic from both methods, the simulation technique could therefore be used to investigate photon interaction processes and obtain interaction parameters for other materials.

Table 2.

Mass attenuation coefficient of the prepared glasses via FLUKA and XCOM at different photon energies.

Energy (MeV) GZr8 GZr8Al4 GZr8Al8
XCOM FLUKA Dev.% XCOM FLUKA Dev.% XCOM FLUKA Dev.%
0.015 39.17242 38.94213 0.588 39.07858 38.85041 0.584 37.24691 37.03906 0.558
0.02 34.03242 33.94164 0.267 33.26612 33.20525 0.183 31.73301 31.67963 0.168
0.03 11.87849 11.87552 0.025 11.61840 11.62273 0.037 11.08293 11.08575 0.025
0.04 6.86797 6.85213 0.231 6.75545 6.74667 0.130 6.53367 6.52533 0.128
0.05 3.85943 3.84530 0.366 3.79992 3.78900 0.287 3.67769 3.66729 0.283
0.06 2.42138 2.40538 0.661 2.38633 2.37493 0.478 2.31125 2.30054 0.464
0.08 1.18988 1.17804 0.995 1.17489 1.16490 0.850 1.14008 1.13088 0.807
0.1 1.78958 1.78326 0.353 1.79066 1.78396 0.374 1.70812 1.70195 0.361
0.15 0.69672 0.69424 0.356 0.69759 0.69517 0.347 0.66882 0.66659 0.334
0.2 0.38251 0.38220 0.082 0.38308 0.38327 0.048 0.36963 0.36981 0.050
0.3 0.19284 0.19230 0.280 0.19314 0.19306 0.044 0.18854 0.18845 0.051
0.4 0.13421 0.13334 0.649 0.13441 0.13421 0.154 0.13227 0.13212 0.107
0.5 0.10744 0.10691 0.496 0.10759 0.10744 0.136 0.10641 0.10634 0.064
0.6 0.09210 0.09158 0.564 0.09222 0.09179 0.461 0.09150 0.09108 0.456
0.8 0.07469 0.07444 0.334 0.07478 0.07465 0.181 0.07447 0.07433 0.195
1.0 0.06457 0.06408 0.759 0.06464 0.06419 0.709 0.06450 0.06406 0.685
1.5 0.05097 0.05053 0.862 0.05102 0.05058 0.860 0.05099 0.05056 0.836
2 0.04436 0.04403 0.747 0.04440 0.04408 0.726 0.04435 0.04403 0.720
3 0.03782 0.03745 0.986 0.03782 0.03746 0.968 0.03771 0.03734 0.966
4 0.03475 0.03443 0.923 0.03472 0.03439 0.936 0.03453 0.03421 0.938
5 0.03314 0.03288 0.789 0.03309 0.03281 0.841 0.03284 0.03256 0.844
6 0.03229 0.03209 0.612 0.03221 0.03201 0.621 0.03191 0.03171 0.626
8 0.03171 0.03159 0.370 0.03160 0.03148 0.378 0.03121 0.03109 0.394
10 0.03186 0.03176 0.320 0.03172 0.03161 0.324 0.03126 0.03115 0.341
15 0.03322 0.03314 0.232 0.03302 0.03293 0.289 0.03243 0.03251 0.255
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Using the FLUKA-simulation-generated Inline graphic values in Table 2, it is clear that the mass attenuation coefficients of the glasses vary with gamma-ray energy (E), and AlON content. Figure 2 shows the changes in the values of Inline graphic with respect to E for Inline graphic and µ. Due to the direct mathematical relationship between µ and Inline graphic (Eq. 2), the plots of both attenuation coefficients vary in similar ways with photon energy, E.

graphic file with name M20.gif 2

Fig. 2.

Fig. 2

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(a) Linear attenuation coefficient (Inline graphic) and (b) mass attenuation coefficient (Inline graphic) of the prepared glasses with different photon energies.

The attenuation coefficients decrease with E for 15 keV ≤ E ≤ 8 MeV, but slightly increase afterwards. For GZr8, GZr8Al4, and GZr8Al8, Inline graphic had the highest values for GZr8 sample. The changes in the attenuation coefficients can be described by dividing the energy spectrum into three unique regions. Firstly, for E ≤ 60 keV, there was a rapid decay in attenuation coefficients. Second, for 60 ≤ E ≤ 8 MeV, the decay continued but at a slower pace, except at 100 keV, where a bump was observed. Lastly, the high energy region (E > 8 MeV), the values of the attenuation coefficients increase gradually. To explain these, it is important to consider how the gamma-photon interaction cross-sections for photoelectron creation (PEC), Compton scattering (CS), and pair creation (PC) behave as functions of energy. Hence,

graphic file with name M24.gif 3

where Inline graphic refers the process interaction of PEC, CS, and PC to the Inline graphic. For photons energy E, incident on an atom with Z, Inline graphic 50,51:

graphic file with name M28.gif 4
graphic file with name M29.gif 5
graphic file with name M30.gif 6

Equations 4, 5 and 6 shows that the PEC process accounts for the high but rapidly decreasing values of Inline graphic in the first energy division while the CS and PC processes dictates the trend of Inline graphic in the two latter energy divisions, respectively. The sudden rise in the attenuation coefficients at 100 keV is attributed to the K-absorption edge of Bi atoms. Due to high photoelectric absorption of photons at absorption edges, Inline graphic spectra often show high values at absorption edges of atoms.

Comparatively, the Inline graphic at each energy follows the order: Inline graphic for most of the energy spectrum. The order is reversed at 15 keV due to the proximity of the energy to absorption edges of low atomic number atoms which have higher concentrations in the AlON-deficient samples. However, the former order is consistent with the density and AlON content of the glasses. The introduction AlON increases the weight proportions of Ba, and Bi, two atoms with high Inline graphic. This ultimately increased the effective Z of the glass system, hence, the observed growth in the value of Inline graphic. AlON thus increased the gamma-interaction probabilities of the glass system.

The description of the shielding capacity of a medium is often conveniently stated in terms of linear thicknesses. Two parameters are often used for this purpose: the mean free path (λ) and the half-value layer (Inline graphic). These parameters can be evaluated directly from the values of Inline graphic according to the following equations52–56:

graphic file with name M40.gif 7
graphic file with name M41.gif 8

The former is a measure of the distance moved between interactions by photons, while the latter gives the thickness required to attenuate incident photon beams by 50%. The two quantities vary inversely as the attenuation coefficients; hence, lower λ and Inline graphic  are indications of e better attenuation prowess and thinner absorber is required to achieve a specific radiation transmission level. In Fig. 3, the spectra of Inline graphic and λ are shown for the investigated glasses. The E-variations of the two parameters are approximately the inverses of the attenuation coefficient and the order of Inline graphic at each energy is Inline graphic The trend is the same for λ. Inline graphic One can say that the thickness of AlON-rich glasses required for photon absorption is lower. It can be concluded that the addition of AlON to the glass matrix lowers the distance travelled by photons between interactions and makes the glasses less transparent to gamma radiation. Furthermore, the spectra show that the thickness of glass required to shield more energetic photons is higher due to a decrease in the interaction coefficients of high-energy photons.

Fig. 3.

Fig. 3

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Mean free path (Inline graphic, solid line) and half value layer (d1/2, dash line) variations with respect to f photon energy in the prepared glasses.

In Fig. 4, the attenuation of GZr8Al8 is placed in contrast to a wide variety of shielding materials based on the values λ for wide energy range. The compared materials include Schott glasses57–59, other glasses (PBZH360, PBCN-M461, S862, ZBP463, and BSNW464, different types of concrete compositions (ordinary (OC), hematite-serpentine (HS), ilmenite-limonite (IL), basalt-magnetite (BM), ilmenite (IN), steel-scrap (SS), and steel-magnetite (SM) concretes)65, and other composite materials including polymers (P2)66, guanine 67, rocks (VR3)68, and alloys (FBCSP1)69. The mean free path of GZr8Al8 appears lower than those of RS253 and RS253G18 but higher than those of RS253G19 and RS360 at three distinct gamma energies, as seen in Fig. 4a. This affirms the superior gamma absorption ability of GZr8Al8 compared to RS253 and RS253G18. The fact that GZr8Al8 is Pb-free adds to the comparative advantage of the glass relative to these two commercial glasses. In addition, GZr8Al8 can absorb photons better than all five different shielding glasses compared in Fig. 4b for most of the 15 keV–15 MeV energy spectrum. In Fig. 4c, the photon absorption prowess of GZr8Al8 relative to the light and dense concrete samples is superior at energies below 100 keV. Above this energy, only SS and SM could outshine GZr8Al8 in attenuating photons. Finally, in Fig. 4d, GZr8Al8 showed better gamma shielding competence compared to other composite materials, except FBCSP1. The mean free path of GZr8Al8 is comparable to that of FBCSP1 at energies below 500 keV and lower for the rest of the energy spectrum. From Fig. 4, it is clear that GZr8Al8 can displace many existing shielding materials including glasses, concrete, and rocks. The mechanical strength of the glass and Pb-free composition are other attractive features of GZr8Al8 that give it an edge over many existing gamma shielding materials. GZr8Al8 is an attractive shielding material from toxicity and mechanical strength perspectives. The glass is thus recommended for shielding of laboratory sources and other places where hard material is required.

Fig. 4.

Fig. 4

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Comparison of mean free path (Inline graphic) parameter of the prepared GZr8Al8 glass with those in (a) commercial SCHOTT’s radiation shielding glasses57–59, (b) some glass systems60–64, (c) standard shielding concretes65, and (d) polymer-composite materials66–69.

The Inline graphic and Inline graphic of a composite material are quick parameters for identifying equivalent materials for shielding applications. When it comes to photon interactions, Inline graphic is to a chemical compound or mixture what Z is to pure atoms, while Inline graphic is a measure of the average Z/A of a composite medium. The values of Inline graphic and Inline graphic for different energies are plotted for GZr8, GZr8Al4, and GZr8Al8 in Fig. 5. Both quantities vary similarly with E. The values of Inline graphic and Inline graphic vary from 14.65–55.13 and 2.92 × 1023–10.99 electrons/g for GZr8, 14.41–55.74 and 2.92 × 1023–11.17 × 1023 electrons/g for GZr8Al4, and 14.10–55.01 and 2.93 × 1023–11.18 × 1023 electrons/g for GZr8Al8. The energy variations and the order of Inline graphic is predicted by the main interaction process at a particular energy, as predicted by Eqs. (3)-(5). The order of Inline graphic and Inline graphic vary inversely from one another due to the decrease in the average Z/A value with respect to Z.

Fig. 5.

Fig. 5

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(a) Effective atomic number and (b) effective electron density of the prepared glasses with different photon energies.

For dosimetry purposes, Inline graphic, Γ, and Dr are important quantities for a medium. The mass attenuation coefficient and Inline graphic are similar, while the former gives a measure of total photon interaction in a medium, the latter quantifies the amount of photon energy absorbed from the interactions. Both quantities are directly proportional and the ratio of Inline graphic gives the ratio of the incident photon energy to that absorbed in a medium. This explains why the energy variations of Inline graphic shown in Fig. 6a is similar to that of Inline graphic. The explanation describing the energy variation of Inline graphic suffices for Inline graphic. The maximum Inline graphic values of 32.80 cm2/g, 32.6818 cm2/g, and 31.22098 cm2/g for GZr8, GZr8Al4, and GZr8Al8 was obtained at 15 keV.

Fig. 6.

Fig. 6

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(a) Mass energy-absorption coefficient and (b) specific gamma ray constant of the prepared glasses with different photon energies.

The absorbed dose due to a radioactive (gamma) source positioned one-meter away from an absorber is proportional to the specific constant (Γ). Figure 6b plots Γ against energy for GZr8, GZr8Al4, and GZr8Al8. The dose absorbed in a medium is directly proportional to Inline graphic, E, distance from the source, absorber thickness, and the photon source strength70. The energy response of Γ is dictated by photon energy and Inline graphic. Therefore, the energy response is similar to that of Inline graphic for energy below 1 MeV. The high energy and pair production absorption process is responsible for the increase in the Γ-values of the glasses. Comparatively, AlON-deficient glasses had higher Γ at energies below 1 MeV due to photoelectric absorption of photons at absorption edges of low-Z atoms. Above this energy, the differences in the glasses do not significantly results in different values of Γ.

The absorbed doses in different thicknesses of the glasses are displayed in Fig. 7.

Fig. 7.

Fig. 7

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Gamma dose rate (Dr) at different energies and glass thicknesses.

The figure shows plots of Dr against energy for glass thicknesses of 1 mm, 5 mm, 10 mm, and 15 mm. Due to geometric and exponential attenuations, the photon dose rate slows down with the thickness of the glass and vary directly as Γ. The highest dose rates values were obtained at 15 keV for GZr8, with value of 324 MR/hfor 1 mm glass thicknesses. For GZr8Al4, the value is 322 MR/h, while the corresponding value for GZr8Al8is 324 MR/h, respectively. The differences between the dose rates are very thin, especially at high energies. At equal thickness and the same photon energy, AlON-deficient glass has higher Dr due to lower Inline graphic.

Photons suffer two fates after interaction with matter: they are scattered or absorbed. Scattering compromises shielding; hence, a good shield should completely absorb photons within the energy spectrum of the application. The scattering of photons leads to photon-build-up within the interacting medium. The buildup affects different radiation quantities in different ways; therefore, buildup factors are named depending on the interaction quantity of interest. The exposure and energy absorption (EBF and EABF) of GZr8, GZr8Al4, and GZr8Al8 were computed and plotted for different gamma radiation path within 40 mfp in Fig. 8 and Fig. 9. The buildup factors increase with the thickness due to multiple scatterings in thicker glasses. The buildup factors (BUFs) are higher at the energy region where incoherent scattering dominates the interaction processes. In addition, increasing BUFs were observed at the end of the energy spectrum due to scattering of low-energy photons released due to the annihilation of positron–electron pairs. Unusually high BUFs were also recorded at 30 keV for all the glasses. The intensity of this spike, however, reduces as AlON content increases. The reduction in the BUF spike can be attributed to the scattering of photons released during the de-excitation of Ba atoms, whose absorption edge is around 37 keV. This shows that the application of a shield at an energy close to the absorption edge of its constituent atom may not be efficient; a material is transparent to its fluorescence. The introduction of AlON, however, quenched the BUFs. The doping of AlON into the matrix of studied glasses quenches BUFs and enhances photon shielding ability of the GZr8 glass system (Fig. 9).

Fig. 8.

Fig. 8

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Exposure buildup factor (EBF) with respect to the concentration of Bi and a function of photon energy in the prepared glasses.

Fig. 9.

Fig. 9

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Energy absorption buildup factor (EABF) with respect to the concentration of Bi and a function of photon energy in the prepared glasses.

Conclusion

The melt-and-quench process was used to fabricate the Zr-based (Na2O–Bi2O3–SiO2–BaO–Fe2O3–ZrO2) glass, which was homogeneously mixed with AlON powder in varying quantities (0, 4, and 8% by weight). The measured density of the glasses increased from 2.90 to 3.11 g/cm3, and the hardness increased from 4.89 to 6.33 GPa as the AlON mass proportion increased from 0 to 8%. AlON could thus increase the resilience of the glasses against mechanical failure and deformation, making them useful in high strength applications. The introduction of AlON increased the effective Z and atomic density of the glasses. Inline graphic. The values Inline graphic and Inline graphic vary from 14.65–55.13 and 2.92 × 1023–10.99 electrons/g for GZr8, 14.41–55.74 and 2.92 × 1023–11.17 × 1023 electrons/g for GZr8Al4, and 14.10–55.01 and 2.93 × 1023–11.18 × 1023 electrons/g for GZr8Al8. The order Inline graphic and Inline graphic vary inversely to one another due to the decrease in the average Z/A value with respect to Z. The maximum Inline graphic values of 32.80 cm2/g, 32.6818 cm2/g, and 31.22098 cm2/g for GZr8, GZr8Al4, and GZr8Al8 were obtained at 15 keV. AlON-deficient glasses had higher Γ at energies below 1 MeV due to the photoelectric absorption of photons at the absorption edges of low-Z atoms. AlON reduced photon transmission through the glasses and prevent photon build up in them. GZr8Al8 good potential to displace many existing shielding materials, including commercial and recently recommended shielding glasses, shielding concrete samples, and rocks, in shielding applications. The AlON-rich glass can be used for radiation source shielding in medicine, laboratory, and places where tough glasses are required. The use of AlON to increase density, mechanical strength, and gamma-radiation interaction properties of other glass and ceramic materials could be used to increase their durability in radiation environment. The impact of radiation on the general properties of the glasses and ceramics could however be studied to highlight their stability in radiation environments.

Acknowledgements

The authors express their gratitude to Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2025R48), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. Moreover, the authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University, Saudi Arabia for funding this work through Large Groups Project under grant number R.G.P2/76/46.

Author contributions

Jamila S. Alzahrani, Z.A. Alrowaili, I.O. Olarinoye, Chahkrit Sriwunkum, Imen Kebaili, and M.S. Al-Buriahi wrote the main manuscript text and prepared figures. All authors reviewed the manuscript.

Data availability

The authors declare that the data supporting the findings of this study are available within the paper.

Declarations

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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