Cr₂O₃ effect on the structure, optical, and radiation shielding properties of Na₂B₄O₇–SiO₂–CaO–Cr₂O₃ glasses

Abstract

65Na₂B₄O₇–25SiO₂–(10 − x) CaO–x Cr₂O₃ x = (0 ≤ x ≤ 5 mol.%) glass system was synthesized and optical, structural, and radiation shielding characteristics are examined. The glass density increased as Cr₂O₃ was added, while the molar volume decreased. FT-IR bands are correlated with the vibrations of BO₃ and BO₄. Cr³⁺ appears to convert BO₃ into BO₄, according to preliminary FT-IR results. $E_{{{\text{opt}}}}$ values are in the range of 2.57–3.31 eV. Increases in the $E_{{{\text{opt}}}}$ can be linked to density and N₄ variation. (Zeq) increased then decreased as the incident photon energy increased with the replacement of CaO by Cr₂O₃. $\sum R$ enhances as the Cr₂O₃ content of the glasses increases. G 5 is a better absorber of fast neutron when the FNRC of glass samples is compared. For neutron attenuation applications, the glass sample G 5 is the best option.

1 Introduction

Kodama noticed that the stoichiometric ratio of a wide range of binary sodium borate glasses Na₂B₄O₇ is established BO₃ is transformed into BO₄ [1,2,3,4]. At this ratio, Na₂O surrounds the network, preventing the surrounding soft B₂O₃ from deforming [5,6,7,8,9,10,11,12]. SiO₂ incorporated into alkali borate glasses improved their radiation and UV transmittance. As a result, alkali borosilicate glasses show promise for incorporating a variety of modifying oxides [13,14,15,16,17]. In technology, borosilicate glasses are extremely important. High-mechanical-stability household and laboratory glasses, as well as high-performance optical glasses, are some of their applications [15, 18,19,20].

Oxide glasses doped with transition metal ions (TMI) have recently attracted a lot of attention due to their appealing combination of physical and chemical characteristics. In recent years, TMI-doped borate, phosphate, silicate, and borosilicate glasses have been investigated physically, optically, and radiationally [21,22,23,24,25,26,27,28,29,30]. Glasses with semiconducting properties, such as Cr₂O₃, CdO, CuO, and others, are known as (TMO) glasses. There has been a lot of focus in recent years on borosilicate glasses containing various TMO, such as CoO, NiO, V₂O₅, and Cr₂O₃ [4, 31].

TMO-based glasses, such as Cr₂O₃, also have appealing optical properties, making them ideal for use as non-linear optical (NLO) materials. According to previous research, TMO-containing borosilicate glasses have a variety of intriguing physical, structural, radiation, and spectroscopic characteristics [16, 17, 32]. As a result of the above existing literature, we have expanded our investigations into TM in calcium borosilicate glasses. As a result, we’ve developed calcium borosilicate glasses in a variety of compositions with Cr₂O₃ substituted. The synthesized glasses are characterized using XRD, FT-IR, and UV–Vis–NIR spectroscopy. The optical of these glasses with the composition 65Na₂B₄O₇–25SiO₂–(10 − x) CaO–x Cr₂O₃, x = (0 ≤ x ≤ 5 mol.%) are investigated in this study. In addition to the aforementioned studies, photons, neutrons, characteristics of Cr³⁺ doped calcium borosilicate glasses will be investigated using theoretical code in this work.

2 Materials and methodology

Glasses with the following composition were formed using the traditional melt-quench procedure: 65Na₂B₄O₇–25SiO₂–10CaO, 65Na₂B₄O₇–25SiO₂–9CaO–1Cr₂O₃, 65Na₂B₄O₇–25SiO₂–8CaO–2Cr₂O₃, 65Na₂B₄O₇–25SiO₂–6CaO–4Cr₂O₃, 65Na₂B₄O₇–25SiO₂–5CaO–5Cr₂O₃. Starting materials for the fabrication of glasses included high purity (Aldrich) CaO (99.5%), Cr₂O₃ (99.9%), SiO₂ (99.5%), and Na₂B₄O₇ (99.5%). The mixtures were then homogenized using a magnetic stirrer for 10 min. Glass was melted at 1100 °C in a platinum crucible. A random error in the melting temperature is ±10 °C. The glasses were annealed at 375 °C for 2 h. To calculate densities in toluene, the Archimedes model was used. On a Perkin Elmer Frontier FT-IR measurements in the 400–1800 cm⁻¹ range were obtained using the KBr procedure. A random error in the center of FT-IR bands was found as ± 2 cm⁻¹. To establish a baseline and correct for noise, spectrum software was used. The optical description of these glasses was obtained in the wavelength range of 250–2500 nm by (JASCO V-670, Japan). The absorption coefficient (α), optical bandgap ($E_{{{\text{opt}}{.}}}^{{{\text{indir}}}}$), and refractive index ($n_{{\text{D}}}$) were all calculated using absorption spectra. As physical parameters related to optical energy, the following physical parameters were calculated: molar refractivity $R_{{\text{m}}}$, molar polarizability $\propto_{{\text{m}}}$, reflection loss $R_{{\text{L}}}$, metallization $M$, electronegativity $\chi$, electron polarizability $\propto^\circ$, optical basicity $\wedge$, Bulk module (K) and glass transition temperature $\left( {T_{{g\left( {thero.} \right)}} } \right){ }$:$R_{{\text{m}}} = Vm\left( {1 - \sqrt {Eopt./20} } \right), \propto_{{\text{m}}} = \left( {\frac{3}{4\pi N}} \right)R_{{\text{m}}}$. $R_{{\text{L}}} = \left( {\frac{{R_{{\text{m}}} }}{Vm}} \right)$ $M = 1 - \frac{{R_{{\text{m}}} }}{Vm}$, $\chi = 0.2688E_{{{\text{opt}}{.}}} \propto^\circ = - 0.9 \chi + 3.5$ and $\wedge = - 0.5\chi + 1.7, K_{{{\text{th}}}} = - 478.93 + 200.13 E_{{{\text{opt}}{.}}}$, $T_{{{\text{g}}\left( {{\text{thero}}{.}} \right)}} = - 701.87 + 403.33 E_{{{\text{opt}}{.}}}$ As physical parameters related to the refractive index $n_{{\text{D}}}$, $R_{m}$, $\propto_{m}$, $\propto_{0}^{2 - }$, and $\Lambda$ were calculated: $R_{m}$, $\propto_{m}$, $\propto_{0}^{2 - }$, and $\Lambda .$ $R_{{\text{m}}} = \left\langle {n^{2} - 1} \right.|n^{2} + \left. 2 \right\rangle Vm$, $\propto_{{\text{m}}} \left( {3|4\pi N} \right)R_{{\text{m}}} , \propto_{0}^{2 - } = \frac{{[\frac{Vm}{{2.52}}\left( {\frac{{n^{2 } - 1}}{{n^{2} + 2}}} \right) - \sum \propto_{{{\text{cat}}}} ]}}{{N_{o}^{2 - } }}$, and $\Lambda = 1.67\left( {1 - \frac{1}{{ \propto_{0}^{2 - } }}} \right)$.

Using the online version of the Phy-X/PSD software, the study’s goal was met by calculating all effective parameters that judge the prepared glasses shielding effectiveness [33]. Z_eq predictable with $eq = \frac{{{\text{Z}}1\left( {{\text{logR}}2 - {\text{logR}}} \right) + {\text{Z}}2\left( {{\text{logR}} - {\text{logR}}1} \right)}}{{{\text{logR}}2 - {\text{logR}}1}}$, The following parameters were calculated for G–P fitting: $P = \frac{{{\text{P}}1\left( {{\text{logZ}}2 - {\text{logZeq}}} \right) + {\text{Z}}2\left( {{\text{logZeq}} - {\text{logZ}}1} \right)}}{{{\text{logZ}}2 - {\text{logZ}}1}},$ EABF and EBF were calculated using G–P fitting. $B\left( {E,X} \right) = 1 + \frac{b - 1}{{K - 1}}$$(K^{x} - 1)$ for $K \ne 1$, $B\left( {E,X} \right) = 1 + \left( {b - 1} \right)x$ $K = 1$ where $K\left( {E,X} \right) = cx^{a} + d\frac{{\tanh \left( {\frac{x}{Xk} - 2} \right) - \tanh \left( { - 2} \right)}}{{1 - \tanh \left( { - 2} \right)}}$ for x ≤ 40.[30] and [40]

3 Results and discussion

3.1 Physical examinations

Figure 1 depicts the XRD of the samples under investigation. XRD shows no sharp peaks in these samples have a significant level of glassiness [29, 34,35,36].

Fig. 1

XRD of synthetic glasses

The density ($\rho$) and molar volume ($V_{{\text{m}}}$), are exemplified in Fig. 2. ($\rho$) of samples increased while ($V_{{\text{m}}}$), declined when Cr₂O₃ was added to them. The exchange of smaller CaO molecules (M = 56.077 g/mol, = 3.34 g/cm³) with thicker and heavier Cr₂O₃ (M = 151.99 g/mol, = 5.2 g/cm³) is the predominant cause of the increase in density. BO₃ have been transformed into BO₄ elements by the addition of modifier oxides like Cr₂O₃. The fact that BO₄ units are denser than BO₃ units demonstrates an increase in sample density [34, 37, 38].

Fig. 2

ρ and $V_{{\text{m}}}$ of synthetic samples

3.2 FT-IR investigations

FT-IR spectrum of fabricating samples is exhibited in Fig. 3. In Fig. 3, the broad bands are the result of several distinct bands overlapping. Therefore, a deconvoluted process is used to obtain exact band positions. The difference between experimental and simulated Fig. is small than 0.02%. As a result, FT-IR of glasses was deconvoluted with (Peak Fit v4.12) using Gaussian distribution to determine the exact band positions and structural unit concentration. Figure 4 depicts a typical glass deconvoluted FT-IR spectrum including band center (C), and relative area (A) as Table 1[8, 39,40,41,42]. (BO₃) is converted to (BO₄) in borosilicate glasses with low modifier oxide inclusions. For the borosilicate glasses, Si–O–B bonds must be established. The band at 442 cm⁻¹ is combined with the deformation modes of the network structure. This band could be attributed to the cationic vibration of Ca-O in (CaO₆). The (NaO₆), (CrO₆), SiO₄, and Si–O–B vibrations are linked to bands in the 507–534 cm⁻¹ range, which overlap with the O–Si–O. B–O–B bending vibrations of (BO₃) may be responsible for the bands observed at ~ 703 cm⁻¹. In borosilicate glasses with a large amount of alkaline earth oxides, SiO₄ tetrahedra with two NBOs can be found. Absorptions due to stretching vibrations of B–O–Si linkages between 952 and 1118 cm⁻¹ must be noted, indicating a possible linkage between silicate and borate structural units [45]. The bands of 1000–1080 cm⁻¹ due to the vibrations of the asymmetric stretching vibrations of Si–O–Si, O–Si–O⁻ [5]. The broadband between 836 and 1118 cm⁻¹ is designated to B–O bond stretching vibrations of BO₄. The band at 1226–1262 cm⁻¹ is recognized to asymmetric stretching vibrations of B–O bonds in (BO₃) units (NBO). The peaks at 1302–1357 cm⁻¹ explained by asymmetric stretching modes of borate triangles with NBOs. B–O⁻ stretching vibrations in (BO₃) related to1440 cm⁻¹. The O–H and H₂O bending vibrations in the sample may be responsible for 1534 and 1686 cm⁻¹. The assignments of glass samples are listed in Table 2.

Fig. 3

FT-IR of synthesized glasses

Fig. 4

De-convolution for synthesized glasses

Table 1 Gaussian fit of synthesized glasses, the band center is (C), and the relative area is (A)

Table 2 Assignments of FT-IR

$N_{4}$ fraction is defined as $N_{4} = \frac{{concentration of \left( {BO4} \right)}}{{concentration of\left( {BO4} \right) + concentration of\left( {BO3} \right)}}$ Table 1 shows the $N_{4}$ values for each of the glasses examined [46, 47]. The concentration of (BOs) increases with increasing Cr₂O₃ content, according to the Perusal of calculated values for $N_{4}$. After Cr₂O₃ is incorporated, BO₃ transforms into BO₄ tetrahedra. The glass network’s coherence improves, and the structure stiffens as a result.

3.3 Optical investigations

In the wavelength range 250–2500 nm, the UV–Vis absorption spectra of Cr₂O₃ doped calcium borosilicate glasses are shown in Fig. 5. In comparison to the G1 glass, the absorption edge of all doped glasses has shifted to a lower wavelength. Figure 6 depicts the absorption coefficient (α) of these glasses. (α) calculated as $\propto = \left( {2.303|d} \right) \times A$. Their intensities have also differed slightly. With Cr₂O₃ doping, the band’s absorption intensity has increased. The (Cr³⁺) is correlated to the identified absorption peaks ranging from 550 to 700 nm.

Fig. 5

UV–Vis spectra

Fig. 6

(α), of fabricated samples

The determination of the energy $E_{{{\text{opt}}{.}}}$ of the glasses is used Tauc's relation: $\alpha h\nu = C(h\nu - E_{{{\text{opt}}{.}}} )^{{\text{s}}} .$ The relationship between ($\alpha h\nu$)^1/2 and ($h\nu$) is depicted in Fig. 7. Table 3 demonstrates that the $E_{{{\text{opt}}{.}}}$ values are in the range of 2.57–3.31 eV [9, 43,44,45,46,47,48,49,50]. According to Babu and Cole, structural changes, and the formation of BOs cause differences in $E_{{{\text{opt}}{.}}}$ values. Increases in the $E_{{{\text{opt}}{.}}}$ can be linked to density and N₄ variation. Cr-ions occupy interstitial site positions, resulting in increased network compactness and $E_{{{\text{opt}}{.}}}$.

Fig. 7

($\alpha h\nu$)^1/2 against ($h\nu$) to calculate $E_{{{\text{opt}}}}$

Table 3 Optical explanations for glasses

Calculating ($R_{{\text{m}}}$), ($\propto_{{\text{m}}}$), ($R_{{\text{L}}}$), (χ),$M, K_{{{\text{th}}}}$ and $T_{{{\text{g}}\left( {{\text{thero}}{.}} \right)}}$ using values from the ($E_{{{\text{opt}}{.}}}$). The values of ($R_{{\text{m}}}$), ($\propto_{{\text{m}}}$), and ($R_{{\text{L}}}$) decrease, although (χ),$M$ increment. Because $V_{{\text{m}}}$ has decreased, these observations have been reduced. Because the values of ($\propto^\circ$ and $\wedge$) are different, they both decline. The increment in $K_{{{\text{th}}}}$ and $T_{{{\text{g}}\left( {{\text{thero}}{.}} \right)}}$ as Cr₂O₃ is thought to be caused by an increase in the bandgap. Table 3 displays the data values obtained.

($n_{{\text{D}}}$) was determined as $nD = \frac{{\left( {1 - R} \right)^{2} + k^{2} }}{{\left( {1 + R} \right)^{2} + k^{2} }}$. The investigated sample’s $n_{{\text{D}}}$ increases, as shown in Fig. 8. The relationship between $n_{{\text{D}}}$ and $\rho$ is similar. As a result, $n_{{\text{D}}}$ increases as Cr₂O₃, which is thought to be due to a density increase. Calculating $R_{{\text{m}}}$, $\propto_{0}^{2 - }$, and $\Lambda$ using values from the ($n_{{\text{D}}}$). The values of $R_{{\text{m}}}$, $\propto_{0}^{2 - }$, and $\Lambda$ are shown in Figs. 9, 10, 11. $R_{{\text{m}}}$, $\propto_{0}^{2 - }$, and $\Lambda$ have the same value as the refractive index.

Fig. 8

($n_{{\text{D}}}$), of manufactured samples

Fig. 9

($R_{{\text{m}}}$), of manufactured samples

Fig. 10

($\propto_{0}^{2 - }$), of manufactured samples

Fig. 11

($\Lambda$), of manufactured samples

3.4 Radiation attenuation capacities

Figure 12 shows the (Zeq) value of glass samples. (Zeq) increased then decreased as the incident photon energy was increased and CaO was replaced with Cr₂O₃. This result is due to the Compton scattering interaction. At energies greater than 1 MeV, the (Zeq) value decreases due to the pair creation interaction [22, 48, 51,52,53,54].

Fig. 12

(Zeq) for glasses

The variation of EAB and EBAF are presented in Fig. 13. EAF and EABF decrease as the density and Cr₂O₃ in the glasses increase. This also confirms that the photon energy and chemical structure of a material determines its EAF and EABF.

Fig. 13

EAF and EABF for G 1 and G 5 samples

Finally, we use effective removal cross-sections $\sum R$ to investigate the neutron attenuation behaviors of glasses. Figure 14 exemplifies the $\sum R$ of synthesized glasses. As shown in Fig. 15, $\sum R$ is a density-dependent parameter. $\sum R$ enhances as the Cr₂O₃ content of the glasses increases. G 5 is a better fast neutron absorber when the FNRC of glass samples is compared. For neutron attenuation applications, the glass sample G 5 is the best option [22, 48, 51,52,53,54].

Fig. 14

$\sum R$ for fabricated glasses

Fig. 15

FNRC with samples

4 Conclusions

Melt quenching was used to successfully fabricate chromium-modified calcium borosilicate glasses. The optical, structural, and γ shielding characteristics of these glasses are investigated. With CrO₆ octahedral structural units, Cr₂O₃ acts as network modifiers. With the addition of Cr₂O₃, the glass density increased while molar volume reduces. All glass compositions contain B₂O₃ in the form of BO₃ and BO₄ units, as well as SiO₂ in the SiO₄. The concentration of (BOs) increases with increasing Cr₂O₃ content, according to the Perusal of calculated values for N₄. After Cr₂O₃ is incorporated, BO₃ transforms into BO₄ tetrahedra. The glass network's coherence improves, and the structure stiffens as a result. $E_{{{\text{opt}}}}$ values are in the range of 2.42–3.18 eV. Increases in the $E_{{{\text{opt}}}}$ can be linked to density and N₄ variation. (Zeq) increased then decreased as the incident photon energy was increased and CaO was replaced with Cr₂O₃. $\sum R$ enhances as the Cr₂O₃ content of the glasses increases. G 5 is a better fast neutron absorber when the FNRC of glass samples is compared. For neutron attenuation applications, the glass sample G 5 is the best option. Incorporating Cr₂O₃ into the investigated glass compositions has a significant impact on their optical, structural, and γ shielding characteristics, according to the findings of this study. This research could be used in the future to improve optical efficiency and reduce radiation's harmful effects on organisms.s