Effect of Bi2O3 on mechanical features and radiation shielding properties of boro-tellurite glass system

This paper focuses on the effect of Bi₂O₃ content (up to 80 mol%) on mechanical features and radiation shielding characteristics of boro-tellurite glasses within TeO₂–B₂O₃–Bi₂O₃ system. The basic mechanical parameters such as oxygen molar volume, packing density, hardness, and elastic moduli were studied based on Makishima–Mackenzie's theory. The shielding studies of the TeO₂–B₂O₃–Bi₂O₃ glasses included gamma, electron and neutron radiations. The newly developed Phy-X/PSD program and Geant4 simulation were used to calculate the shielding parameters such as mass attenuation coefficient (μ/ρ), tenth value layer (TVL), mean free path (MFP), stopping power (ψ_e)), removal cross section (RCS), CSDA range, effective atomic number (Z_eff), and half value layer (HVL). The concentration of Bi₂O₃ content had a significant effect on the gamma shielding competence of the investigated glasses. Form the results of gamma shielding studies, the highest μ/ρ (99.845 cm²/g) occurred at 0.015 MeV for TBB80 and the lowest μ/ρ (0.039 m²/g) occurred at 4 MeV for TBB40. The maximum values of Z_eff for gamma interaction occurred at 0.02 MeV and they were 77.26, 78.81, 79.94, 80.80, and 81.48 for TBB40, TBB50, TBB50, TBB60, TBB70, and TBB80, respectively. The gamma shielding features of the investigated glasses were compared with those of various ordinary concretes, and Pb-free, Pb-based, and commercial glasses. The Bi₂O₃ content had also a considerable influence on the electron shielding competence of the tested glasses. The maximum values of Z_eff for electron interaction occurred at 14 MeV and they were 44.58, 47.72, 50.41, 52.75, and 53.73 for TBB40, TBB50, TBB50, TBB60, TBB70, and TBB80, respectively. The results revealed that the bismuth boro-tellurite glasses could be useful for the shielding against gamma, electron, and neutron radiations, wherein the Bi₂O₃ content can be balanced according to the type and energy of radiation.     

Radiation attenuation properties of bioactive glasses doped with NiO

This paper focuses on the evaluation of the radiation attenuation properties of 15CaF₂-10CaO-5B₂O₃-(65-x)P₂O₅-xNiO-5BaO (where 0 ≤ x ≤ 1.0 mol%) bioactive glasses. The radiation attenuation features of these glasses were investigated by determining different factors including mass attenuation coefficient (μ/ρ), exposure and absorption buildup factors (EBF and EABF), neutron removal cross section (NRCS), and effective atomic number (Z_eff) for photon, proton, and carbon ion interactions. Geant4 toolkit and Phy-X program were employed for simulations and calculations procedures. The results revealed that NiO content in the studied bioactive glasses has a significant effect on photon interaction and an insignificant effect on the charged particle interactions. The Z_eff values of the studied glasses were observed in the range of 18–20 for photon interaction, 10.7–10.9 for proton interaction, and 10.0–10.7 for carbon ion interaction. The NRCS values were 0.087, 0.088, 0.089, 0.090, and 0.091 cm^-1 for x = 0, 0.4, 0.6, 0.8 and 1.0 mol%, respectively. The studied bioactive glasses showed a good ability to attenuate gamma radiation at energies of medical applications.     

Comparative investigation of physical,X-ray and neutron radiation shielding properties for B2O3-MnO2-CdO borate glasses

B₂O₃-MnO₂-CdO ternary oxide glasses with amorphous properties were synthesised using the melt-quenching method. Structural and physical property analyses showed that the amount of non-bridging oxygen and the system stiffness increases, and the oxide network filling is more tightly packed as cadmium oxide (CdO) gradually replaces manganese Oxide (MnO₂) in the glass. The radiation-shielding performance of the B₂O₃-MnO₂-CdO glasses was evaluated using the shielding parameters calculated by the MCNPX simulation and the Phy-X program. Glasses with 40% and 50% CdO loading exhibited an average specific lead equivalent (PbE) of 0.241 and 0.294 mmPb/mm in the medical X-ray diagnostic area at 0.03–0.08 MeV; thus, they could fully meet the specific PbE requirements for application as "protection devices against diagnostic medical X-radiation". Furthermore, their photon attenuation capability is superior to that of various commercial shielding glasses in fast-neutron nuclear applications at 1°–10³ MeV. In addition, compared to the borate glass systems studied in the literature, B₂O₃-MnO₂-CdO glasses have fast neutron removal cross-sections of 0.125 cm⁻¹ at a smaller density of 3.9043–4.8135 g/cm³, making them potentially excellent fast neutron absorbers.     

Gamma radiation attenuation characteristics for lithium-zinc-tellurite glasses using Geant4 code and PDS computer software

Six glass samples with the composition of TeO₂-Li₂O-ZnO were analyzed for their radiation shielding properties. The radiation shielding factors for the lithium-zinc-tellurite glasses were reported using the Geant4 code and Phy-X/PSD program. The transmission factor (TF) was determined for different thicknesses and the results revealed that the TF decreases with increasing the thickness of the glass. For TeLiZ1, increasing the thickness of the sample from 0.4 cm to 1.6 cm led to decrease the transmission of the photon from 0.84 to 0.48 at 0.5 MeV and from 0.94 to 0.76 at 4 MeV. The radiation protection efficiency (RPE) results showed that a thicker glass sample absorbs a higher number of photons, implying that lower radiation pass among the glass, increasing RPE. Also, the glass coded as TeLiZ6 has higher RPE than that of TeLiZ1 glass which suggests that at higher content of TeO₂ (85 mol%), the more efficient the glass is at shielding the incoming photons. The linear attenuation coefficient (LAC) obtained by both methods (Geant4 and Phy-X/PSD showed a good agreement for all the glasses and at all investigated energies. The LAC indicates a strong energy dependence, especially at low energies. The LAC also increases as more TeO₂ is added to the glasses. TeLiZ6 (85TeO₂-15Li₂O, ρ = 5.164 g/cm₃) has the highest RPE and lowest TF, while TeLiZ1 (60TeO₂-15Li₂O-25ZnO, ρ = 4.976 g/cm³) has the lowest RPE and highest TF. The tenth value layer (TVL) was also determined and it was observed that TVL increases with increasing energy, reaching a maximum value at 10 MeV and varying between 12.919 and 13.808 cm. By contrast, the minimum TVL is reported at 15 keV and varies between 0.0106 and 0.0112 cm. The addition of TeO₂ decreases the TVL, with TeLiZ6 having the least TVL.     

Role of TeO2 in radiation shielding characteristics of calcium boro-tellurite glasses

In this paper, the role of TeO₂ in radiation attenuating characteristics of xTeO₂ -10CaF₂-(60–0.6x) B₂O₃ -(30–0.4x) CaO glass system with x = 20, 25, 30, 35 and 40 wt% was investigated. The gamma radiation studies were carried out by utilizing Geant4 simulations and the newly developed Phy-X/PSD program. The gamma-shielding characteristics of the present glass samples were examined in terms of mass attenuation coefficient (μ/ρ), and some other related factors such as the effective atomic number (Z_eff), and mean free path (MFP). The electron radiation-shielding characteristics were tested by determining the stopping power (ψ_e) and CSDA range for each glass specimen. The neutron radiation-shielding characteristics were explored by evaluating the removal cross section (RCS) for the tested glasses. Moreover, the G-P method was employed to investigate the exposure buildup factor (EBF) for photon energies up to 15 MeV. The results showed that the TeO₂ content had a significant influence on the shielding ability of the investigated glasses against gamma and neutron radiations. In contrast, the TeO₂ content had an insignificant influence on the electron radiation-shielding capacity of the glasses involved. Additionally, the nuclear-shielding properties of the studied samples were compared with those of standard nuclear radiation shields. It can be concluded that the present calcium boro-tellurite glasses have a promising future to be used as a shielding material against gamma, electron and neutron radiation, wherein the TeO₂ concentration can be balanced according to the desired application.     

An extensive investigation on gamma-ray and neutron attenuation parameters of cobalt oxide and nickel oxide substituted bioactive glasses

This study aimed to investigate the gamma-ray and neutron attenuation parameters of cobalt oxide and nickel oxide substituted ten bioactive glasses. The mass attenuation coefficient ($\text{μ}/\text{ρ}$) for the selected bioactive glasses was calculated using MCNPX code in photon energy range (0.02?MeV - 20?MeV) and the results were compared with the output of WinXcom software. Other vital gamma-ray attenuation parameters such as half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Z_eff), and effective electron density (N_el) for the selected bioactive glasses were also calculated for each approach. Gamma-ray and neutron transmission factors as well as neutron effective removal cross-sections of each bioactive glass (ΣR) were also taken into consideration to underline the distinctive parameters. Additionally, exposure buildup factor (EBF) values were found with G-P fitting approach depending on the energy and penetration depths. The results points that, the lowest HVL, TVL and MFP values and the highest neutron effective removal cross-sections (Σ_R) values are the characteristics of NiO4C and CoO-4. The results indicate that the density of the material affects the photon and neutron interaction parameters. While NiO4C has the lowest TF values for both gamma and neutron radiation, the highest Σ_R values are collected from NiO4C glass material. The gamma and neutron transmission factors (TF) of the studied bioactive glasses support the aforementioned results. The lowest Z_eff values were generated for 45S5C and 45S5 ordinary glasses, while CoO-4 and NiO4C doped glasses are having the highest values of Z_eff. EBF values of the glasses were also calculated in the energy range 0.015–15?MeV up to 40 mfp. The smallest EBF values were measured for CoO-4 and NiO4C glasses. It can be concluded that NiO4C bioactive glass outperformed compared to other studied samples and is a promising bioactive glass for gamma-ray and neutron attenuation.     

Mechanical and radiation shielding properties of tellurite glasses doped with ZnO and NiO

This study examines the basic mechanical parameters and radiation shielding properties of (100−x)TeO₂+xZnO+4NiO glasses (where x = 9.6, 19.2, 28.8, and 38.4 mol%) glass system. The mechanical study included basic parameters such as hardness, packing density, elastic moduli, and Poisson's ratio. Shielding ability of the glasses was tested against gamma and neutron radiations as well as against charged particles such as electron, proton, and alpha. Geant4 simulations and theoretical calculations by using Phy-X computer program were carried out to estimate mass attenuation coefficient (μ/ρ), neutron removal cross section (RCS), transmission factors namely; half value layer (HVL) and mean free path (MFP), and effective atomic number for total interaction of gamma (Z_eff-G), electron (Z_eff-E), proton (Z_eff-P), and alpha (Z_eff-A) radiations. The results showed that ZnO concentration had a significant influence on the mechanical properties and the shielding capability for glasses involved. The values effective atomic number were in the range of 30.2–46.1 for Z_eff-G, 21.2–26.5 for Z_eff-E, 16.9–19.7 for Z_eff-P, and 15.3–18.6 for Z_eff-A, respectively. The current glasses can act as superior shielding material as compared with those of Pb-free glasses, commercial glasses, and traditional concrete.     

Ionizing radiation attenuation competences of gallium germanate-tellurite glasses utilizing MCNP5 simulation code and Phy-X/PSD program

Gamma radiation, neutrons, protons, and alphas particles shielding competences for gallium germanate-tellurite (GeO₂.TeO₂.Ga₂O₃) glasses doped with Pr₆O₁₁ were tested. The investigated glasses were named as GTGPr1, GTGPr2, GTGPr3, and GTGPr4. Mass attenuation coefficients (MAC) for the proposed glasses were calculated utilizing Phy-X/PSD program and simulated by MCNP5 simulation codes in the photon energy range of 0.015–15 MeV. With the help of MAC values, the linear attenuation coefficient (LAC), half value layer (HVL), mean free path (MFP), and effective atomic number (Z_eff) were calculated. Moreover, the absorbed dose received from ¹³⁷Cs with activity 10 μCi was calculated in presence of the studied glasses. Buildup factors (BUFs) include exposure buildup factor (EBF), and energy absorption buildup factor (EABF) for all investigated glasses were also calculated. Results reflected that the GTGPr4 glass has the highest MAC, LAC values and lowest HVL among other selected germanate glasses. The values of Z_eff were around 0.04 MeV varied between 43.07 and 48.19, while at 1.5 MeV were between 18.70 and 21.25. The GTGPr1 possesses the highest values of BUFs around the studied range of energy, while GTGPr4 glasses possesses the lowest values. Moreover, the fast neutron removal cross section was (Σ_R = 0.02151 and 0.01942 cm² g⁻¹) for GTGPr1 and GTGPr4, respectively. The investigated glasses can be useful to construct superior radiation shielding materials to use in nuclear medicine applications.     

Synthesis and experimental characterization on fast neutron and gamma-ray attenuation properties of high-dense and transparent Cadmium oxide (CdO) glasses for shielding purposes

We present synthesis and thorough characterization phases of newly developed 20P₂O₅·30TeO₂.(50-x)ZnO.xCdO (x = 0, 2, 4, 6, 8, 10 mol%) glasses. Experimental gamma-ray and neutron transmission systems are used in terms of exploring the monotonic effects of increasing CdO reinforcement on behavioural changes of synthesized glasses through well-known melt-quenching method. A conventional gamma-ray setup along with a high purity germanium detector as well as ¹³³Ba radioisotope is used for determination of attenuation coefficients. Glass shields are irradiated with a²⁴¹Am/Be neutron source using the Canberra NP-100B BF3 gas proportional detector. The addition of 10% mole CdO to the basic glass composition had a significant favorable impact on the transition resistance to gamma and neutron radiation. In comparison to all available shielding materials, (except RS-520), the C10 sample demonstrated superior gamma-ray attenuation capabilities. According to results, C glasses generally exhibit superior neutron attenuation capabilities than conventional moderators. It can be concluded that C glass family may be considered as suitable gamma-shield and neutron moderator in different types of applications from research to medical radiation fields.     

Physical,optical and gamma radiation shielding competence of newly boro-tellurite based glasses: TeO2–B2O3–ZnO–Li2O3–Bi2O3

Herein, a traditional melt quenching method was utilized to synthesize glasses with a nominal chemical composition (80-x)TeO₂-xB₂O₃–5ZnO–5Li₂O₃–10Bi₂O₃: 30≤ x ≤ 80 mol%). The produced sample was coded as TBBZL30 to TBBZL80. X-ray diffraction (XRD) has been employed to test the amorphous nature of the synthesized samples. In the range of 200–500 nm wavelength, UV–Vis spectra for the glasses have been performed. Optical energy gaps ($E_{gap}$) have been determined based on the absorption measurements. With the help of ($E_{gap}$), refractive index (n), molar polarizability (α^M), metallization criterion (M^Cri.), molar refractivity (R^M), static dielectric constant (ε^Sta.), optical dielectric constant (ε^Opt.), reflection loss (R^L) and optical transmission (T^Opt.) have been calculated. For the fabricated boro-tellurite glasses, Phy-X/PSD was used to report some shielding factors for several energies between 15 keV and 15 MeV. The maximum attenuation for all samples took place at 15 keV and the mass attenuation coefficient varied between 52.309 and 57.084 cm²/g. The linear attenuation coefficient (LAC) results demonstrated that TBBZL80 has the highest attenuation than the rest of samples which is due to high content of TeO₂ (containing 80 mol% of TeO₂) whereas TBBZL30 has the lowest attenuation. The LAC for the fabricated samples varied between 230.160 and 351.064 cm-¹ at 15 keV. The minimum effective atomic number (EAN) occurred between 0.8 and 4 MeV and varied between 15.16 and 17.35 for TBBZL30 and 25.10–28.33 for TBBZL80. The addition of TeO₂ was found to enhance the EAN and improved shielding properties for the tested TBBZL glass systems.     

Mechanical and nuclear shielding properties of sodium cadmium borate glasses: Impact of cadmium oxide additive

In this study, highly effective radiation shielding glass materials with different amount of CdO additive were investigated in terms of nuclear shielding performance. Moreover, mechanical properties have been determined. The μ_m values were computed using XCOM and XMuDat program. The gamma and neutron shielding parameters such as μ_m, HVL, Z_eff, EBF, EABF, SAFE, b_co, b_ico, σ_co and σ_abs are calculated to understand the radiation shielding performances of investigated glasses. The results show that μ_m, Z_eff and σ_abs values increase as the CdO content increases. The S7 sample has the lowest HVL, MFP, EBF, EABF, SAFE, b_co, b_ico and σ_co values. Therefore, S7 glass sample (70 mol% of CdO) which has also the highest number of bonds per unit volume can be considered as a superior material for radiation shielding applications. The outcomes of this study can be very useful for future applications of investigated glass materials in medical and industrial radiation fields.     

WS2/bioactive glass composites: Fabrication,structural, mechanical and radiation attenuation properties

Ionizing radiation interaction might occur during diagnostic imaging and radiotherapy procedures. It has been reported that gamma-ray radiation can damage the living cells through the energy transfer. Therefore, investigation the ionization radiation attenuation properties of biomaterials have a crucial importance. In the current study, tungsten disulphide (WS₂) nanopowder-containing borate-based bioactive glass composites were prepared. Their physical, structural, mechanical and ionization radiation attenuation properties were investigated in detail. Monte Carlo simulations and radiation attenuation properties were studied through MCNPX and Phy-X/PSD. Results showed that sintering performed at 575 °C for 1 h in air atmosphere caused formation of some tungsten trioxide in the structure. Addition of WS₂ nanopowders increased the bulk density and improved the mechanical properties of the prepared bioactive glass composites. Simulation studies revealed the influence of WS₂ content on reduction the build-up factors and enhancement of the photon attenuation ability for all the considered photon energies.     

Influence of Bi2O3 concentration on barium-telluro-borate glasses: Physical,structural and radiation-shielding properties

In this study, a series of Bi₂O₃ reinforced bariumtelluroborate (TBX) glasses with the nominal composition 20TeO₂ + (50-x)B₂O₃ + 29.5BaO + xBi₂O₃ + 0.5Er₂O₃ (where x=0,5,10,15 and 20 in wt%) were manufactured using traditional melt-quenching method. The structural and compositional studies were performed by using XRD and FTIR spectra. In general, the glass matrix consists of the trigonal-planar and tetrahedral units of borates, tellurate and tellurite groups of tellurites, and the non-bridging oxygen (nBO). In addition to that, BiO₃ and BiO₆ groups are present in top-order glasses. The gamma-ray shielding (γ-RS) ability was evaluated through the vital parameters like the mass-attenuation coefficient (MAC), mean free-path (MFP), half-value layer (HVL), and effective atomic-number (Z_eff). TB20 glass is happened to be the best candidate by giving the highest value for MAC and the lowest MFP and HVL, owing to its large density, 6.922 g/cm³. The fast neutron-removal cross-section (∑R) is assessed to investigate the neutron shielding capacity of TBX glasses. The γ-rays shielding properties of TBX glasses were observed better than some ordinary shields such as barite-concrete and commercial shielding glasses developed by SCHOTT Company.     

Review: Elaboration,structure, and mechanical properties of oxynitride glasses

Oxynitride glasses are glasses where threefold coordinated nitrogen atoms substitute for twofold oxygen ones, hence resulting in a larger interatomic cross-linking degree. Such glasses were first observed at the grain boundary in silicon nitride ceramics, where they govern the high-temperature behavior. Later, they were prepared as bulk materials and motivated numerous researches, thanks to their large viscosity, glass transition range, elastic moduli, hardness, and fracture toughness among inorganic and non-metallic glasses. In different chemical systems that were investigated, the synthesis routes and the sources for these exceptional mechanical properties are reviewed. Oxynitride glasses are not easy to process and suffer from the loss of transparency as nitrogen is incorporated over some critical content. Nevertheless, they are attractive “specialty” glasses in various niche areas, thanks to their large refractive index and dielectric constant, improved chemical durability, high softening point, etc., and majorly to their exceptional mechanical properties.     

Gallium (III) oxide reinforced novel heavy metal oxide (HMO) glasses: A focusing study on synthesis,optical and gamma-ray shielding properties

In this study, three heavy metal oxide glasses (A:46.0PbO-42.0Bi₂O₃-12.0Ga₂O_3, B:45.94PbO-42.66Bi₂O₃-10.0Ga₂O₃-1.4BaO, C:72.8PbO-17.0GeO₂-10.2Ga₂O₃) were synthesized to determine their optical and gamma-ray shielding properties in terms of assessing their potential applications in medical and industrial radiation facilities. Glasses were synthesized using melt quenching method. The optical band gap energy is calculated by the absorption spectrum measured at room temperature. We found a large band at 500 nm that refers to Bi+ions and appears to samples A and B that contain Bi₂O₃ in their compositions. Optical band gap energies were reported as 2.014 ev, 2.055 eV and 2.430 eV for A, B and C samples, respectively. Next, fundamental gamma-ray parameters were also determined using MCNPX general Monte Carlo code and Phy-X/PSD in 0.15–15 MeV photon energy. Our findings clearly showed that the B sample, which includes the highest concentration of Bi₂O₃, has a considerable advantage in terms of gamma-ray attenuation. Moreover, the results also showed that sample B has significantly higher attenuation properties than shielding concretes and several glass shields. It can be concluded that Bi₂O₃ is a useful component for heavy metal oxide glasses in terms of improving gamma-ray shielding capabilities for radiation shielding applications.     

Simulations of silver-doped germanium-selenide glasses and their response to radiation

Chalcogenide glasses doped with silver have many applications including their use as a novel radiation sensor. In this paper, we undertake the first atomistic simulation of radiation damage and healing in silver-doped Germanium-selenide glass. We jointly employ empirical potentials and ab initio methods to create and characterize new structural models and to show that they are in accord with many experimental observations. Next, we simulate a thermal spike and track the evolution of the radiation damage and its eventual healing by application of a simulated annealing process. The silver network is strongly affected by the rearrangements, and its connectivity (and thus contribution to the electrical conductivity) change rapidly in time. The electronic structure of the material after annealing is essentially identical to that of the initial structure.     

Effect of TiO2 addition on thermal and mechanical properties of Y-Si-Al-O-N glasses

Y-Si-Al-O-N glasses are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of oxynitride glass phases determine the sintering/shrinkage behaviour. Several investigations on oxynitride glass formation and properties have shown that addition of nitrogen increases glass transition and softening temperatures, viscosity, elastic modulus and hardness. In the present study, effect of TiO₂ addition on thermal and mechanical properties of Y-Si-Al-O-N glasses is investigated since the most typical Si₃N₄ ceramics for bearing applications are fabricated using a Si₃N₄-Y₂O₃-Al₂O₃-TiO₂-AlN system. Addition of TiO₂ is effective in preparing Y-Si-Al-O-N glasses with lower glass transition temperatures and with higher hardness.     

Bioactive glasses and direct effect of increased K2O additive for nuclear shielding performance: A comparative investigation

This study aimed to provide a large-scale investigation on direct effect of K₂O additive nuclear radiation shielding properties of calcium phosphate based bioactive quaternary P₂O₅–CaO–Na₂O–K₂O glasses. A gamma ray attenuation setup has been modeled in MCNPX (v-2.6–0) simulation code using Monte Carlo simulation technique. Next, all the bioactive glasses have been defined considering their chemical properties and material densities, respectively. The mass attenuation coefficients (MAC) have been calculated by using MCNPX code and obtained results have been used for determination of another vital gamma-ray shielding parameters. Moreover, a detailed calculation has been done for determination of exposure buildup factor (EBF) and energy absorption buildup factor (EABF) of investigated bioactive glasses which should be considered as important parameters for interaction properties of ionizing radiation with material environment. In addition, effective removal cross sections for fast neutrons have been calculated. To compare our results, obtained HVL values of the present investigation have been compared with copper oxide and cobalt oxide substituted bioactive glasses. Among the investigated bioactive glasses, the maximum MAC values were reported for PCNK60 sample with higher K₂O additive. It can be concluded that chemical structure of additive materials in the bioactive glasses is strongly related with the radiation attenuation properties of bioactive glasses.     

Effect of ion substitution on properties of bioactive glasses: A review

Bioactive glasses and glass-ceramics have recently found key applications in biomedicine, mainly for bone repair and replacement. Recent developments in the field of tissue engineering have re-invigorated the quest to enhance the physical and biomedical effectiveness of bioactive glasses and glass-ceramics by incorporation of different elements into the composition of these materials. Although most elements are included in the bioactive glass for the therapeutic benefits (e.g., Ag and Sr), they influence the structure and bioactivity of the glass. This review systematically discusses the influence of the addition of silver (Ag), magnesium (Mg), strontium (Sr), zinc (Zn), aluminum (Al), potassium (P), fluoride (F) and zirconia (ZrO₂) elements on the chemical, physical and therapeutic properties of bioactive glasses and glass-ceramics, which are expected to play an important role in the future of bone regenerative medicine. This article describes where these dopant ions fit into the glass structure and how these affect the delivery and properties of the glass as a whole.