Investigation of Structural, Electrical and Gamma-Ray Attenuation Characteristics of MnO-Doped Bi2O3-H3BO3-P2O5 Glasses

Abstract

The importance of development of lead-free glasses for high-performance radiation shielding materials with tailored capacitive characteristics are critical for advanced optoelectronic and radiation protection applications.This study investigates influence of compositional impact of substituent (MnO) asglass network modifier on its structural rearrangements, dielectric performance, and ray attenuation capability.Phosphate Glasses of heavy-metal oxide with stoichiometric proportion of 40 Bi2O3–35 H3BO3–(25?x) P2O5–xMnO, where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%, have been prepared using melt-quenching technique. Influence of substitution of MnO as a compositional modifier on capacitive and ? radiation shielding has been reported. Apart from structural investigation such network arrangement, density, molar volume also be studied. In radiation shielding, various parameters such as mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL) &mean free path (MFP) have been calculated to explore influence of MnO as compositional modifier on radiation shielding ability. To get exact information about radiation response of substitution of compositional modifier (MnO) on phosphate glasses (40 Bi2O3–35 H3BO3–(25?x) P2O5–xMnO, where x = 0.5, 1.0, 1.5, 2.0 & 2.5 mol%,), experimentally calculated radiation parameters have been compared with theoretically calculated radiation parameters using measured using a (_^137)Cs source (4.5 µCi, 662 keV), closely aligned with theoretical predictions from XCOM NIST software &source coupled with a Geiger-Müller counter. For electric characteristics, frequency dependent ?\'& ?\"and ?ac at room temperature be investigate and understand polarization and charge-transport mechanisms. Presence of multivalent manganese ions facilitates small polaron hopping (Mn2+ ? Mn3+), significantly modulating the dielectric permittivity (?\'& ?\"), dielectric loss (Tan?), and AC conductivity as functions of frequency and temperature. Theseobtained results may provide useful information of developing multifunctional phosphate-borate glasses for radiation shielding and radiation-resistant electronic applications.

Introduction

The text investigates heavy-metal oxide phosphate-borate glasses modified with MnO as potential gamma-radiation shielding materials. The research is motivated by the growing use of ionizing radiation in medicine, nuclear energy, industry, and space applications, along with the limitations of conventional shielding materials such as lead and concrete. Heavy-metal oxide glasses are presented as attractive alternatives because they can provide high radiation attenuation while also being relatively dense, transparent, chemically stable, durable, and easier to fabricate.

The study focuses on a glass system with the composition:

40Bi?O?–35H?BO?–(25−x)P?O?–xMnO,
where x = 0.5, 1.0, 1.5, 2.0, and 2.5 mol%.

Experimental methodology

The glass samples were produced using the melt-quenching technique. Appropriate amounts of Bi?O?, H?BO?, P?O?, and MnO were mixed, melted at approximately 950°C, poured into graphite molds, and annealed at 400°C to reduce internal stresses. Their densities were measured using Archimedes' principle, and molar volume was calculated from density and molar mass.

Radiation-shielding performance was evaluated using gamma sources, particularly ¹³?Cs (662 keV) and ??Co (1173 and 1332 keV). Important shielding parameters included:

• Mass attenuation coefficient (MAC)
• Linear attenuation coefficient (LAC)
• Half-value layer (HVL)
• Tenth-value layer (TVL)
• Mean free path (MFP)

Theoretical attenuation coefficients were also calculated using NIST XCOM and compared with conventional materials such as barite concrete.

Structural and morphological findings

X-ray diffraction (XRD) showed broad diffuse halos without sharp crystalline peaks, confirming that the prepared materials are predominantly amorphous glasses. Increasing MnO caused subtle changes in the short-range structural arrangement but did not destroy the glassy structure.

SEM analysis showed smooth, compact, and relatively homogeneous surfaces without significant pores, cracks, crystalline grains, or phase separation. This indicates that MnO was successfully incorporated into the glass network.

Radiation-shielding results

The main finding is that increasing MnO content generally improves gamma-ray attenuation, particularly at higher MnO concentrations. The improvement is attributed to:

• Increased effective atomic number.
• Increased density and electron density.
• Greater probability of photon interaction.
• Structural modification and compactness of the glass network through Mn–O and P–O–Mn bonding.

The 2.5 mol% MnO composition generally exhibited the strongest shielding performance among the investigated compositions.

At higher MnO concentrations, the glass showed:

• Higher mass and linear attenuation coefficients.
• Lower HVL and TVL.
• Lower mean free path.

For example, at 2.5 mol% MnO, the reported minimum HVL values were approximately 1.03 cm for ¹³?Cs, 0.88 cm for ??Co at 1173 keV, and 0.68 cm for ??Co at 1332 keV. The corresponding minimum TVL values were approximately 3.4, 2.9, and 2.3 cm, respectively.

A lower HVL, TVL, or MFP indicates that less material thickness is required to attenuate radiation, making the glass more effective as a shielding material.

Dielectric and electrical properties

The study also examined the dielectric behavior of the glasses. Dielectric permittivity was found to be higher at low frequencies and decreased as frequency increased. This behavior was attributed to space-charge, interfacial, and electrode polarization at low frequencies, while faster electric-field variations limit the response of charge carriers and dipoles at high frequencies.

MnO incorporation also affects the glass's electrical behavior through Mn²?/Mn³? mixed-valence hopping, non-bridging oxygen formation, and localized charge carriers.

The AC electrical conductivity increased with frequency and with increasing MnO content. The conductivity was interpreted using Jonscher's universal power law:

σ(ω) = σdc + Aω?

where σdc represents frequency-independent conductivity and the second term describes the frequency-dependent AC contribution.

Conclusion

This research explores the impact of MnO doping on the structural and gamma-ray shielding characteristics of bismuth borate glasses. Important key properties such as mass attenuation coefficient (MAC), half-value layer (HVL), density, optical behavior, and elastic parameters were calculated. Experimental MAC values, measured using using radio isotopes 137Cs (662 keV), 60Co (1173 keV) & 60Co (1332 keV) photon energies. We observe that systematic growth of both attenuation coefficients with MnO content confirms that manganese acts as an effective modifier that enhances the gamma-ray shielding competence of the bismuth boro-phosphate glasses studied here. The results also confirm that controlled MnO incorporation can effectively tailor the radiation attenuation characteristics of Bi2O3-rich phosphate glasses, making them promising candidates for compact gamma-radiation shielding applications.MFP results corroborate the HVL, TVL, MAC and LAC findings and confirm that the 40Bi2O3–35H3BO5–22.5P2O5–2.5MnO glass exhibits the most favorable photon-shielding characteristics among the studied compositions, making it a promising candidate for gamma-radiation shielding applications.

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Copyright © 2026 Mallo Devi, Sunil Kumar Dwivedi, Pawan Heera . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.