Structural, optical, and shielding properties of lead borate glasses doped with copper oxide

Lead borate glasses of the system 25PbO-(75-x) B2O3-xCuO (x = 0, 0.025, 0.05, and 0.1) in mol.% were synthesized via the traditional melt quenching method abbreviated as (BPbCu0, BPbCu1, BPbCu2, and BPbCu3) respectively. XRD diffraction confirmed the amorphous nature of the samples. According to FTIR spectroscopy, the function groups (BO3 and BO4) and the fraction of boron tetrahedral units (N4) were determined. The density, molar volume, packing density, and some other physical parameters were calculated and discussed. The density was increased by incorporating CuO as a substitution for B2O3, while the molar volume was decreased. The ion concentrations of Cu, inter-nuclear distance, field strength, and polaron radius were also computed. The optical absorption study suggested that the copper ions exist in the Cu2+ and act as a modifier by increasing the disorder in the glass network. Hence, the present glass behaves as a bandpass filter in the UV–vis. region. The radiation shielding properties of the as-prepared samples were theoretically calculated using the Phy-X program at energies ranging from 0.015 to 1.5 MeV. The linear and mass attenuation coefficients, as well as the half-value layer (HVL) and exposure buildup factor (EBF), have been evaluated. The results revealed that shielding parameters are affected by CuO concentrations and photon energy. Based on the results presented in the manuscript, the glass sample with 0.1 mol% CuO doping (BPbCu3) showed the best properties overall for optical and radiation shielding applications. Specifically, BPbCu3 had the highest density, refractive index, optical dielectric constant, and radiation shielding parameters such as linear attenuation coefficient and half value layer among the glass samples. The addition of 0.1 mol% CuO introduced Cu2+ ions which acted as network modifiers, increasing the disorder in the glass structure. This in turn enhanced the optical bandgap as well as the shielding capabilities against gamma radiation.


Introduction
Borate glasses containing rare earth oxides can meet most demands for various applications [1,2].They have attracted attention due to their excellent transparency, wide range of composites, and strong thermal stability [2,3].The boron oxides have unique properties that give them stability allowing experimentation with a broader selection of elements in the composition of borate glasses and, consequently, more control over variations in performance characteristics [4].The novel aluminoborosilicate glass reinforced with varying amounts of Bi2O3 content was explored [5].where in the B 2 O 3 vitreous, an unusual mesostructure consists of borax rings composed of BO3 triangles.All these triangles are connected by connecting oxygen at three corners to build fully interconnected mesh assemblies [6].Raman spectra of B 2 O 3 glass contain the strongest evidence for such rings, with a noticeable peak at 808 cm −1 attributed to the symmetric stretch vibration of the boroxol ring [7].The addition of modifier oxide converts the boron from a three-coordination to a four-coordination depending on the modifier content, where the non-bridging oxygen bonds are formed by increasing the alkali oxides [8].The borate glasses have different structural groups with different concentrations depending on the alkali oxide content [9].The Raman spectra of borate glasses revealed that when alkali oxide is added to boron oxide glass [10], up to 20 mol% of alkali oxide, primarily tetraborate groups are produced.As the alkali oxide amount (20-25 mol.%) increases, the tetraborate groups are gradually replaced by diborate groups.Around 50% mol of alkali oxide, the structure comprises many diborate groups, a reasonable number of orthoborate units, and pyroborate groups.To increase its chemical resistance, borate glasses should be modified with a modifier oxide such as PbO or CaO [11].Additionally, rare earth metals such as Cr 3+ , Ce 3+ , Nd 3+ , etc, can introduce unique features crucial for applications including luminescence-based imaging and optical usage due to their improved chemical and physical properties of the host glass matrix [12].The presence of copper ions significantly impacts the electrical, optical, and magnetic properties of glasses.Numerous exciting studies have focused on the environment of Cu ions in various inorganic systems [13].Cu is widely used in many commercial glasses, including rubies, aventurine, and red glass hematite.Glasses with a high CuO content are required because of their semiconducting properties [14,15].There are two stable ionic forms of Cu, divalent Cu 2+ and monovalent Cu + , and the possibility of metallic copper [16].The Cu + ions do not produce coloring [17], whereas Cu 2+ ions produce color centers with absorption bands in the visible wavelength region [18], which give an attractive blue and occasionally green color to the materials.The copper atom's electronic structure is [Ar] 3d 10 4s 1 , and its stable ionic states are Cu + and Cu 2+ .
Gamma rays are highly penetrating electromagnetic radiation that requires dense materials for effective shielding.Lead borate glasses containing copper have shown promising gamma ray shielding capabilities.These glasses demonstrate improved shielding properties compared to undoped lead borate glass [19][20][21].
The addition of copper oxide to lead borate glass influences the microstructure, electronic polarizability, and photon interaction cross-sections [22,23].Copper acts as an intermediate oxide, modifying the borate glass network through the formation of non-bridging oxygen bonds [24].The resulting structural changes improve photon attenuation and shielding performance [25].At low CuO concentrations up to 0.1 mol%, copper ions mainly exist in the Cu 2+ state occupying interstitial positions between the lead borate structural units [26].The Cu 2+ ions introduce localized energy states within the optical bandgap that enhance radiation absorption [19,27].Higher CuO doping above 0.5 mol% can promote metallic Cu0 clustering that diminishes the shielding effects [28].Key radiation shielding parameters such as mass attenuation coefficient, half value layer, exposure buildup factor, and effective atomic number increase with CuO doping in lead borate glass [29].The optimal CuO concentration is often below 0.5 mol% to balance shielding performance versus transparency loss [30].Lead borate glasses with copper have displayed effective shielding up to 95% for gamma rays from 60Co and 137Cs sources [31].
In terms of novelty, this research aims to study the effect of Cu ions combined with Pb ions on the physical, optical, and radiation-shielding properties of the present glasses.

Experimental method
Binary PbO-B 2 O 3 glass samples containing different concentrations of copper oxide were synthesized via the conventional quench-melting method.The series of the 25PbO-(75-x) B 2 O 3 -xCuO (x = 0, 0.025, 0.05, and 0.1) in mol.% borate glasses were successfully fabricated by mixing the basic raw chemicals which include CuO, PbO, and H 3 BO 3 as a source of B 2 O 3 , see table 1.The used chemicals were all of analytical grade with a purity of 99.8% (Aldrich Company).All components were weighed using a micro-analytical balance and mixed according to molar composition proportions; then they were melted in a 50 ml porcelain crucible at 480 °C for 1 h, and then the applied melting temperature was 1200 °C for 1 h.The mixing of all components together causes decreases in the melting temperature and avoids the volatility of CuO.The melt is swirled many times to achieve homogeneous synthesized samples and then poured onto a stainless steel mold to obtain the desired samples.The undoped glass sample was colorless and transparent, while the glassed doped with CuO showed a blue color due to the presence of Cu ions, as shown in figure 1.

Characterization and physical parameters calculation
3.1.X-ray diffraction spectroscopy X-ray spectroscopy technique (Brucker Axs-D8 Advance, utilizing a CuKα radiation source) is utilized to determine whether the material is amorphous or crystalline.The fine glass powder was exposed to x-ray radiation with a λCuKα = 0.1540600 nm in the range of 3 to 70°angle.The step size was 0.02°, and the time per step was 0.4 s.

Fourier transform infrared spectroscopy (FTIR)
All prepared samples were examined using a Mattson 5000 FTIR spectrometer with a 2 cm −1 spectral resolution at 25 °C in the range of 400-4000 cm −1 .A thin disc formed mixed between glass powders (0.002 g) with 0.2 g of KBr in a hydraulic press under a pressure of 100 kg cm −2 .

Raman spectroscopy
Raman model spectrometer (JOBINYVON HR800, HORIBA) with (473 nm) a solid state diode laser was applied to record Raman spectra in the 220-2000 cm −1 range.All the experimental measurements were carried out at RT.

UV -visible spectroscopy
UV-vis absorption spectra of the polished produced samples with a constant thickness (2 mm ± 0.1) were instantly obtained using a recording double beam spectrophotometer (JASCO 630, Japan) to examine the change in structures and optical properties.

Density and molar volume
The density (D) of the investigated glasses was measured using the Archimedes method adopting Xylene as an immersion fluid.The experiment was performed with triplicate samples and their values were also used to calculate molar volume according to the following equations [32]: Packing density (P d ) and free volume (V f ) were evaluated using the following equations respectively [33]: The obtained values of density and molar volume were used to compute oxygen molar volume (OMV) and oxygen packing density (OPD) by applying the following equations [34]: The effect of CuO concentrations in the glass network can be determined by the average boron-boron separation using the next formula [34]: The molar volume of B atoms V m b ( ) was evaluated based on the values of molar volume and molar fraction of B 2 O 3 content ( X B ) according to the next equation [35]:

Ion concentration (N)
The Cu 2+ ions concentration (N) is evaluated using the following formula [36]: In solid materials, a quasi-particle (polaron) was used to describe the interaction between electrons and ions or atoms.Depending on the ion concentration of Cu, the polaron radius r p ( ) in (Å) can be calculated according to the next equation [37]: The inter-nuclear distance r i ( ) was evaluated using the following equation [38]: Based on the molar mass values of CuO, the field strength (F) was calculated using the next relation [39]:

X-ray analysis
The XRD patterns of BPbCu0, BPbCu1, BPbCu 2 , and BPbCu 3 as prepared glass samples revealed a typical amorphous halo in the range 2θ = 20°−40°, without any detection sharp peak confirming the amorphous nature of all fabricated samples, figure 2. The XRD results obtained, glassy nature, indicates to the appropriate uses such as optical applications.

FTIR analysis
Figure 3 depicts the FTIR experimental data, in the region 400-4000 cm −1 , of the undoped lead borate glass beside lead borate glass samples doped with CuO in mol.%.The introduction of CuO (x = 0, 0.025, 0.05, and 0.1 mol%) to the glass matrix composition causes a minor change in the FTIR spectra.FTIR data is correlated with previous studies [40], and confirms the appearance of some bands in the fingerprint region extending from 450 to 1550 cm −1 as characteristic of vibrational units.Therefore, four bands appear in the range 450-1600 cm −1 , the first band at about 450 cm −1 is assigned to the vibrations of alkali and alkaline earth ions (Cu & Pb) [40,41].The other three bands in the range 700-1500 cm −1 are related to function groups of boron (BO 3 and BO 4 ) as the following: the band at around 682 cm −1 and 1200-1550 cm −1 are assigned to the symmetric (Bending vibrations of the B-O-B) and asymmetric vibrations (stretching) of BO 3 units, while the abroad band in the range 750-1200 cm −1 is attributed to the vibration of the tetrahedral units (BO 4 ) [42,43].It is observed that a slight change with the incorporation of CuO as a doping modified the glass network with the formation of non-bridging oxygen.The position and assignment of these bands are recorded in table 2.
The deconvolution process of FTIR spectra was used to separate the peaks that indicate the function groups.The FTIR spectra of BPbCu0, BPbCu1, BPbCu2, and BPbCu3 as prepared glass samples were de-convolved using the peak fit program after being cleaned up from dark current noises and background [44].The FTIR deconvolution is shown in figure 4, and the regions of the BO 3 and BO 4 peaks were then integrated to compute the N 4 using the next formula:

Raman analysis
Raman spectroscopy is an extremely effective method for determining the structure, dynamics, and environment of a glassy network [45].Raman spectroscopy is a vibrational inelastical spectroscopic technique resulting from interactions between the incident photons and molecular vibrations or other excitations.Raman spectroscopy can detect and distinguish vibrational modes of different borate structural units like boroxol rings, BO 3 triangles, BO 4 tetrahedra, that allows determination of ring/chain structures present.Figure 6 shows the Raman data, in the region 400-4000 cm −1 , of the lead borate base glass beside other samples that contain CuO contents.The Raman spectra of the investigated lead borate glass samples showed characteristic vibrational bands corresponding to BO 3 and BO 4 structural units.A prominent band was observed at ∼1380 cm −1 , which can be assigned to the B-O stretching vibrations in BO 3 triangles.This band arises due to the symmetric stretching mode of the B-O bonds in metaborate groups containing boroxol rings or boron-oxygen chains.Another distinct Raman band was seen at ∼1080 cm −1 , attributed to the B-O stretching in tetrahedral BO4 units.This band indicates the presence of diborate groups in the glass structure.The relative intensity of these two bands provides information about the BO 3 /BO 4 ratio in the glass network.For the undoped lead borate glass, the BO 3 band at 1380 cm −1 was more intense than the BO 4 band at 1080 cm −1 .With the addition of CuO as a modifier oxide, the intensity of the 1080 cm −1 BO 4 band increased compared to the 1380 cm −1 BO 3 band.This corroborates the conversion of BO 3 groups to BO 4 units as CuO is incorporated into the borate glass matrix.The Raman results align with the FTIR findings, where the fraction of BO 4 units (N 4 ) increased from 0.4765 to 0.4967 with the addition of 0.1 mol% CuO.The CuO acts as a network modifier, breaking B-O-B linkages and generating non-bridging oxygen bonds associated with BO 4 structures [46,47].Additional mainor peaks reported previously be Meraa et al [48,49] can be observed and assigned to compositional change as follows: 600-700 cm −1 atributed to BO 3 bending vibrations, 700-800 cm −1 assigned to BO 3 symmetric stretches, 800-900 cm −1 assigned to BO 4 vibrations, and that below 500 cm −1 attributed to the Lead-oxygen lattice vibrations.

Physical properties 4.4.1. Density and other parameters
The density and some other parameters of the prepared samples such as molar volume, packing density, free volume, and oxygen packing density were calculated and the values were listed in table 3. It is observed that the density increases with increasing CuO content due to the substitute of a lighter molecular weight (B 2 O 3 ) with a higher one (CuO).The molar volume follows the opposite trend which is the normal behavior.The decrease in molar volume can be explained in terms of the decreasing interatomic spacing among the atoms of the glass network which causes compaction of the structure, figure 7. CuO is introduced as a network modifier due to its smaller concentrations and consequently Cu ions occupy interstitial places in the network causing a decrease in the molar volume [50].Figures 8 and 9 demonstrate the packing density, free volume, oxygen packing density, and oxygen molar volume as a function of CuO content.It is observed from figure 7 that packing density increases with the replacement of B 2 O 3 with CuO due to its modifier role that causes a change of the bond length in the glass network and also due to the high ionic radii of Cu than radii of B tend to increase the free volume of the glass network.As shown in figure 8 and table 3, the oxygen molar volume was decreased with the incorporation of CuO, whereas the OPD was increased.The average boron-boron distance, 〈d B-B 〉, (nm) was calculated (table 3) and it decreased with increasing CuO content exhibiting an increase in glass network compressibility and thus supporting increases in glass density.The average molar mass of free lead borate glass and glass containing CuO was calculated and also increased with the increasing CuO content due to the higher molecular weight of CuO rather than B 2 O 3 .

Optical properties
The UV-vis.absorption spectra of the undoped and different concentrations of CuO-doped PbO-B 2 O 3 glass samples are depicted in figure 12.Both glass samples exhibited a strong absorption peak in the UV region which is attributed to the impurities which may exist in the raw materials utilized to prepare these samples.At the base sample, it is observed overlap occurs between the band which is attributed to the impurities, and that attributed to Pb ions.In the case of CuO, the absorption edge was lightly shifted from 350 to 392 nm with increasing CuO concentrations.The BPbCu0 glass sample has no absorption peak in the visible and NIR regions indicating its transparency.Both doped glass samples exhibited a broad absorption peak in the range of 500-1000 nm, which  is assigned to the existence of Cu + and Cu 2+ ions octahedral [49].In most of the previous studies, this absorption band is interpreted as the overlapping of the 2 B 1g  2 A 1g , 2 B 1g  2 B 2g and the 2 B 1g  2 E g transitions [51].
The broad band observed at approximately 800 nm can be attributed to d-d transitions of Cu(II) ions in the borate glass.The lack of distinct, sharp peaks suggests the Cu(II) ions occupy a distribution of sites with slightly different geometries and symmetries rather than a single well-defined site.This is expected in the disordered, amorphous structure of a borate glass.Specifically, the broad 800 nm band likely arises from the 2Eg → 2T2g transition of Cu(II) ions in distorted octahedral sites.The variety of Cu(II) site geometries leads to a range of transition energies centered around 800 nm rather than a single sharp peak.The octahedral coordination of Cu(II) is reasonable given the glass contains oxygen and boron with sp2 hybridized orbitals available for bonding.Variations in the Cu-O bond lengths and O-Cu-O bond angles in the irregular glass structure result in distortions from ideal octahedral symmetry.Tauc's method (E g Tauc ) The electronic transitions between localized states cause the absorption edge and is also related to the optical band gap of glass.The optical energy gap values for indirect and direct transitions were calculated by plotting  ) and ahv 2 ( ) as a function of photon energy hv ( ) according to the theory given by Mott & Davis using the next formula [52]: The obtained values are given in table 4. Figures 13 and 14 demonstrate the optical energy gap values for all prepared samples by extrapolating the linear segment of these curves towards the x-axis to meat at (a = hv 0 0.5 ) and a = hv 0 2 ( ) for indirect and direct transitions respectively.It is found that optical energy gap values were decreased with an increase in the CuO content as a result of the additional defect state produced in the glass matrix and increasing the number of non-bridging O 2 bonds which are more easily excited than bridging O 2 [52].

Derivation absorbance spectrum fitting method (DASF)
The optical energy gap was also determined using the DAFS method according to the next formula [44]: and the obtained values are presented in table 4 and show a decrease with increasing CuO content due to reducing the average binding energy.

Refractive index
Using the optical energy gap, the refractive index can be calculated according to the Dimitrov and Sakka formula [53]: Where E g is the energy band gap.The obtained refractive index values are presented in table 4. The refractive index of the lead borate glasses increased from 2.41 to 2.50 with increasing CuO content from 0 to 0.1 mol%.This enhancement in refractive index is attributed to the formation of non-bridging oxygen bonds as CuO incorporates into the glass network as a modifier.The non-bridging oxygen ions possess higher polarizability compared to bridging oxygen, which increases the refractive index.The increasing trend in refractive index with CuO doping aligns with the results of other studies on modified borate glasses.

The permittivity and the optical dielectric constant
The values of permittivity and the optical dielectric constant were determined using the following equations respectively [43]: The obtained values are listed in table 4. It is found that the values of permittivity and the optical dielectric also increase with an increase in CuO mol.%.This is attributable to an increase in glass disorderness, confirming that CuO causes network defects in the present glasses.

Molar refraction, molar polarizability and the electric susceptibility
The following equations were used to calculate the molar refraction, molar polarizability and electric susceptibility respectively [54]: where V m is the molar volume, R m is the molar refraction, e is the permittivity, and N A is Avogadro's number.The obtained values were tabulated in table 4. According to the Lorentz-Lorentz relation, molar refraction is directly proportional to glass's molar polarizability, reflecting the number of electrons responding to an applied field.The values of the molar polarizability can be related to the number of non-bridging oxygen [55].Every CuO provides extra oxygen to the glass network which increases the molar polarizability due to the increasing of NBO. ) versus photon energy for direct allowed transition of BPbCu0, BPbCu1, BPbCu2, and BPbCu3 glass samples.

Reflection loss
The reflection loss value of all prepared glass samples was computed according to the following relation and the values are listed in table 4 [43].
It is found that reflection loss values increase with increasing CuO content.The reflection loss at the glass surface increased from 17.1% to 18.3% with the addition of 0.1 mol% CuO.This correlates to the increasing refractive index values, as reflection loss is dependent on the refractive index contrast between air and the glass sample.A higher refractive index leads to a larger mismatch with air (n = 1) and thus increases the Fresnel reflection losses at the glass interface.However, the changes in reflection loss are relatively small, implying that CuO doped lead borate glasses retain good optical transparency.The observed variations in refractive index and reflection loss with CuO doping are consistent with the modifier role of copper oxide in the borate glass structure.The optical transparency is largely maintained even up to 0.1 mol% CuO addition.

Shielding parameters
Phys-x software was utilized to compute some radiation shielding parameters of the prepared glasses over a wide photon energy range from 1 KeV to 15 MeV.Radiation shielding parameters include linear and mass attenuation, as well as the effective atomic number, the mean free path, and the effective electronic density.where I and I 0 are the gamma-ray intensities (incident) and (after attenuation) respectively, m is the linear attenuation coefficient.The plot between m and energy is shown in figure 15.It is observed that m achieved a maximum value with a high concentration of CuO due to the increasing interaction of the cross-section in this region.The increase of the m values with increasing CuO content is related to the increase of molar mass and the electronic density of the prepared glasses with the insertion of CuO.The m values decrease with increasing the photon energy due to the decreases in the cross-section interaction (the number of collisions between the photons and the material atoms).The recorded decrease is due to the Compton scattering [56].
The mass attenuation coefficient describes the probability of the interaction that occurs of the incident photons and matter of units mass per unit area according to the following equation [57]: The accurate values of (m m ) are required to provide essential data in different fields such as radiation protection, radiation dosimetry, and nuclear diagnostics.Figure 16 depicts the results of the mass attenuation coefficient for all investigated glasses against the photon energy.It is found that the results of m m depended on the incident photon energy and the concentrations of CuO.The m m has large values at low energy due to the photoelectric absorption process in this region.But as the photon energy increases, the values of m m decrease as a result of the Compton scattering process which is the main dominating photon interaction process.

Some shielding parameters
To investigate the efficiency of the investigated samples as shielding glass materials, the effective atomic number (Z eff ) and the effective electronic density (N eff ) were also calculated using the following formulas respectively [58]:   the calculated values of the effective atomic number and electronic density of the fabricated samples as a function of photon energy.It is observed that the trend of both Z eff and N eff depended on the change in the chemical composition and photon energy.They have high values at lower energy and then their values decrease with increasing photon energy due to the partial photon processes that are proportional to the atomic numbers of the constituent elements (Z) [59].
Have value layer is the thickness of the shielding materials which can reduce the incident activity of the source to half [60].The plot of the half-value layer versus photon energy is represented in figure 19.The trend of the HVL values of the prepared samples increases with the increase of photon energy and reaches the maximum  Figures 20 and 21 show the exposure buildup and energy absorption buildup factors versus photon energy for BPbCu0 and BPbCu3 as selected samples.It is found that both EBF and EABF have lower values at low energy and then their values increase with increased photon energy.This is because of the predominance of Compton scattering at moderate energies [61].

Conclusion
Lead borate glasses with the formula (75-x)B 2 O 3 .25PbO.xCuOwhere x = 0, 0.025, 0.05, and 0.1 mol% were successfully synthesized and characterized.The glass sample with 0.1 mol% CuO addition (BPbCu3) exhibited optimal properties for optical and radiation shielding applications.The density increased from 3.927 g/cm 3 for the undoped glass to 4.163 g/cm 3 for BPbCu3, showing the compaction effect of CuO doping.The optical bandgap decreased from 3.24 eV to 2.84 eV with 0.1 mol% CuO incorporation due to generation of nonbridging oxygen bonds.A bandpass filtering effect was achieved with >90% transmission in the 500-1000 nm range.The mass attenuation coefficient at 0.1 MeV gamma radiation increased by 26% from 0.760 cm 2 /g for the base glass to 0.958 cm 2 /g for BPbCu3.Consequently, the half value layer decreased from 2.13 cm to 1.63 cm with 0.1 mol% CuO addition.The exposure buildup factor reduced from 3.91 to 3.42 at 0.1 MeV.The absences of sharp peaks in XRD patterns confirm the glassy state of the studied glass samples.FTIR spectra of the present glasses revealed that the structural building units are mainly based on the BO 3 and BO 4 groups.The UV-vis.spectra of the glasses containing CuO showed a distinct broadband in the wavelength region 500-1000 nm corresponding to the transition of Cu 2+ ions in distorted octahedral sites ( 2 B 1g  2 B 2g ).The optical energy gap values were calculated using DAFS and Tauc techniques which revealed that E g decreased with the incorporation of CuO into the glass matrix due to the increasing concentrations of NBOs as a result of its modifier role.Some physical and optical parameters such as the density, molar volume, refractive index, molar refraction, and optical dielectric constant were estimated.The present glasses doped with CuO act as a bandpass filter in the ultraviolet-visible region.

Figure 5
Figure 5  represents the fraction of boron units designated N 4 that are tetrahedral units (BO 4 ) as a function of CuO content.The relationship between N 4 and CuO concentration was utilized to calculate the influence of CuO on the change in the relative population of tetrahedral units BO 4 and triangle units BO 3 .The N 4 values varied between 0.4765-0.4967depending on the CuO concentration.It is concluded that NBO bonds were formed and the CuO act as a modifier.

Figure 3 .
Figure 3. FTIR spectra of PbO-B 2 O 3 free and doped with CuO.

Figure 4 .
Figure 4. Deconvolution of FTIR spectra of PbO-B 2 O 3 glasses-free and glasses doped with CuO.

Figure 6 .
Figure 6.Raman spectra of PbO-B 2 O 3 glasses undoped and glasses doped with CuO.

Figure 7 .
Figure 7. Variation of density and molar volume versus CuO content for obtained glasses.

Figure 8 .
Figure 8.The Packing density and free volume versus CuO concentrations.

Figure 9 .
Figure 9. OPD and OMV as a function of CuO content.

Figure 10 .
Figure 10.The polaron radius and field strength as a function of CuO content.

Figure 11 .
Figure 11.The ions concentration and inter nuclear distance as a function of CuO content.

Figure 17 .
Figure 17.Z eff as a function of photon energy for all prepared samples.
Figures 17 and 18  show the calculated values of the effective atomic number and electronic density of the fabricated samples as a function of photon energy.It is observed that the trend of both Z eff and N eff depended on the change in the chemical composition and photon energy.They have high values at lower energy and then their values decrease with increasing photon energy due to the partial photon processes that are proportional to the atomic numbers of the constituent elements (Z)[59].Have value layer is the thickness of the shielding materials which can reduce the incident activity of the source to half[60].The plot of the half-value layer versus photon energy is represented in figure19.The trend of the HVL values of the prepared samples increases with the increase of photon energy and reaches the maximum

Figure 18 .
Figure 18.N eff versus photon energy for all prepared samples.

Figure 19 .
Figure 19.HVL versus photon energy for all prepared samples.

Figure 20 .
Figure 20.(a) EBF and (b) EABF versus photon energy for BPbCu0 as a selected sample.

Figure 21 .
Figure 21.(a) EBF and (b) EABF versus photon energy for BPbCu3 as a selected sample.

Table 1 .
Sample names and their chemical composition.

Table 2 .
The band assignment of FTIR spectra of all investigated samples.

Table 3 .
Physical properties of (75-x) B 2 O 3 .25PbO.xCuO glasses system.Ion concentration and field strength The value of the ionic concentration of Cu was calculated as well as the values of polaron radius, inter-nuclear distance, and field strength, and their values are listed in table 3. It is found from figure 10 and table 3 that the concentration of Cu ions and the field strength increase with increasing CuO content whereas the polaron radius and inter-nuclear distance decrease.The increasing of Cu ions concentration causes a decrease of both polaron radius and inter-nuclear distance as shown in figure 11.