Investigation of optical, physical, and gamma-ray shielding features of novel vanadyl boro-phosphate glasses

Journal of Non-Crystalline Solids 533 (2020) 119905

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Investigation of optical, physical, and gamma-ray shielding features of novel vanadyl boro-phosphate glasses

T

Y.S. Rammaha, Gökhan Kilicb, R. El-Mallawanya, U. Gökhan Isseverb, F.I. El-Agawanya,

⁎

a b

Physics Department, Faculty of Science, Menoufia University, 32511 Shebin El Koom, Egypt Eskişehir Osmangazi University, Faculty of Science and Letters, Department of Physics, Eskişehir, Turkey

ARTICLE INFO

ABSTRACT

Keywords: Boro-phosphate glasses ASF DASF γ-ray WinXCOM

In this paper, novel vanadyl boro-phosphate glasses with the chemical formula (100 − x)(0.5V2O5 -0.5P2O5)xB2O3 (x = 0, 2, 4, 6, 8 mol%) have been synthesized using melt-quenching method. The amorphous state of the glasses was checked through XRD measurements. UV–vis spectra were recorded in the range of 200–1100 nm wavelength. The optical energy band gaps via Tauc's model, absorbance spectrum fitting (ASF), and the first derivation of the absorption spectrum fitting (DASF) methods have been calculated for all glasses. Urbach's energy and refractive index of the prepared glasses also calculated. Gamma-photons shielding capability of the proposed glasses have been evaluated in terms of mass attenuation coefficient (μ/ρ) which calculated using WinXCOM software. Based the (μ/ρ), half value layer (HVL), mean free path (MFP), and effective atomic number (Zeff) were calculated. The results show that energy gaps for all glasses were close together, but the index of refraction was high around 4. Results of HVL, MFP, and Zeff confirmed that VPB0 glass sample (free with boron) has good attenuation capability compared to other VPB (with boron additions) glasses. Moreover, gamma-ray protection ability of the current glasses was compared with that of some commercial glasses. It can be concluded that the prepared glass samples could be useful to design or develop novel shields for radiation protection applications.

1. Introduction With the advancing technology, diversity of glasses that have been synthesized as goal-oriented has reached an enormous extent. Establishing the characteristics of these synthesized glasses has made great progress recently and gained an important place in the materials science. Glass structures containing vanadium, which is one of the basic compounds forming glass network are found in the literature [1]. Vanadium containing glasses are interesting in respect to their semiconducting properties and find place in most electronic applications [2]. These applications are basically memory and optical switching, fiber optic and other solid-state devices. Vanadium doped glasses are known to be n-type semiconductors for low V+4/V+5 ratio [3]. Having semiconducting property resulted in the examination of the characteristics of these glasses in electrical, optical, and structural areas [4–6]. Phosphate based glasses are interesting materials for electronic devices by being eco-friendly and also by having low melting points, ultraviolet transmittance properties and thermal expansion coefficients [7]. Having high transmittance values make rare earth elements appropriate hosts and therefore they are being used in laser applications

⁎

[8–10]. Their most important disadvantage is being highly hygroscopic. In addition, alkaline oxide doped phosphate glasses are more durable and stable [11]. Phosphate glasses’ forming glasses by combining with boron oxide increases durability in a similar manner [12–14]. Structural and optical properties of phosphate glasses are frequently encountered in the literature. Vanadium phosphate glasses have excellent properties such as low melting points, high thermal expansion and high UV transmittance [15], however undoped, pure V2O5-P2O5 glasses sensitivity to moisture is still an important problem. Electrical conductivity and structural properties of these glasses have been examined and studies directed to advance their conductivity mechanisms have been performed [16,17]. In addition, focusing on structural studies to eliminate sensitivity to moisture is another fact that can be seen in the literature. In these studies, B2O3 was also observed to be present in the structure as a regulator in addition to alkaline and earth alkaline elements [18]. Optical amplifiers in telecommunication, phosphorescence materials and electrochemical batteries are among the area of utilization for glasses prepared by doping boron containing vanadium-phosphate glasses with rare earth elements [19].

Corresponding author. E-mail address: [email protected] (F.I. El-Agawany).

https://doi.org/10.1016/j.jnoncrysol.2020.119905 Received 21 November 2019; Received in revised form 10 January 2020; Accepted 11 January 2020 0022-3093/ © 2020 Elsevier B.V. All rights reserved.

Journal of Non-Crystalline Solids 533 (2020) 119905

Y.S. Rammah, et al.

glasses as radiation shielding materials examines in terms of evaluation the mass attenuation coefficient factor (μ/ρ), half value layer (HVL), mean free path (MFP), and effective atomic number (Zeff) [20–27]. The current study aims to investigate the optical, physical, and gamma radiation shielding parameters of vanadyl boro-phosphate glasses. To achieve this objective, the following steps have been carried out: 1 Five samples of vanadyl boro-phosphate glasses with chemical composition V2O5-P2O5-B2O3 have been synthesized. 2 Molar volume and density of the synthesized glasses have been determined. 3 The non-cyrstallinity of the proposed glasses proved via X-ray diffraction (XRD) measurements. 4 UV–vis data in the wavelength range of 200–1100 nm were recorded for all synthesized glasses. 5 Depending on the absorption spectra, the optical energy band gaps and refractive indices were evaluated by Tauc's, ASF, and DASF methods. 6 The (μ/ρ) has been computed using WinXCOM program. 7 Depending on the (μ/ρ), effective shielding parameters such as half value layer (HVL), mean free path (MFP), and effective atomic number (Zeff) have been evaluated. 2. Experimental work Glass composition has been chosen as (100 − x)(0.5V2O5 −0.5P2O5).xB2O3 (x = 0, 2, 4, 6, 8 mol%). Method that we have used to synthesize the samples was melt-quenching method and powder mixtures have been prepared by using chemicals with high purity (Alfa Aesar). Mixtures were placed into porcelain crucibles in high temperature furnace within atmospheric environment for the reaction to take place for a period of 90 min at 1100 °C. Molten sample taken out of the high temperature furnace was given shape in a graphite mould. Cylindrically shaped glass blocks were kept in another furnace for 60 min at 400 °C in order to prevent breaking and cracking and at the end of the period this annealing furnace was closed and the samples were left in the furnace to cool to room temperature. Samples were labeled as VPB0-VPB8 according to xB2O3 = 0–8 mol%, then cut and polished for optical measurements and were powdered for XRD measurements. A photo for VPB0-VPB8 glasses is shown in Fig. 1. Densities (D) of the glasses were determined with a KERN brand ABT 100–5 m model analytical scale having 0.00001g precision and its density kit. For densities calculated with the Archimedes principle, methanol (ρ0 = 0.791 g cm−3) was used as contact liquid at room temperature (20 °C). Samples codes, chemical composition, and weight fraction of elements for V2O5-P2O5-B2O3 glasses are shown in Table 1. XRD measurements were performed on powdered samples with Bruker D8 Advance device between 10 and 90° with steps of 0.01° and 18.8 s step time at 25 °C room temperature. UV–vis spectrophotometry measurements were carried out by Analytic Jena Specord 210 Plus tools in the range of 200–1100 nm at room temperature.

Fig. 1. Photo for VPB0-VPB8 glasses.

Glass structures containing high ratio of vanadium and phosphate have interesting transmittance character due to high vanadium ratio. Due to narrow optical band gap the observed glasses may be transparent in the IR region, beyond visible region with our study. These black vanadium-phosphate glasses containing boron have band shaped transmittance in the infrared region and therefore are appropriate infrared detector materials for the aforementioned region. Though optical, thermal and structural properties of V2O5-P2O5B2O3 glass structures having different compositions have been encountered in the literature, their radiation shielding properties cannot be found. Therefore, in this study we have also focused on this issue in addition to their optical properties. Due to gamma and X-rays are applied in several applications such as agriculture, medical, scientific research, and engineering applications, human, animal and plants exposed to these radiation by direct or indirect way. In order to avoid the harmful effects of radiation, glasses can be used as radiation shielding materials as alternate to the traditional materials (concretes, rocks, bricks, alloys, and polymer) [20–25]. This is because glasses have easy in designing, non-toxic to the environment, low cost, and transparent to visible light. The capability for using borate glasses as radiation shielding materials was reported via many researchers and investigators [20–27]. The capability of using

Table 1 Sample code, chemical composition, Wt. fraction of elements, density, and molar volume for P2O5 - V2O5 - B2O3 glasses. Sample code

Weight fraction mol% V2O5 P2O5

B2O3

Wt. fraction of elements in each sample B O P

V

Density (D) g cm−3

Molar volume (Vm) cm3 mol−1

VPB0 VPB2 VPB4 VPB6 VPB8

50 49 48 47 46

0 2 4 6 8

0.000000 0.002702 0.005466 0.008296 0.011194

0.314624 0.311887 0.309086 0.306220 0.303284

2.89069 2.83632 2.82846 2.82151 2.81232

56.87701 56.43365 55.93807 55.42170 54.94633

50 49 48 47 46

0.494076 0.495775 0.497514 0.499295 0.501117

2

0.191300 0.189636 0.187933 0.186190 0.184405

Journal of Non-Crystalline Solids 533 (2020) 119905

Y.S. Rammah, et al.

Fig. 2. Density and molar volume of VPB0-VPB8 glasses.

Vm =

x i Mi D

(2)

where xi is the mole ratio of the component, Mi is the molecular weight of the component [28]. Density of undoped VPB0 glass was found to be 2.89069 g cm−3. In glasses doped with boron, increasing amount of B in the glass network resulted in decrease in the density. As it can be seen in Fig. 2, the glass sample doped with 8% B2O3 has the lowest density. Similarly, molar volume also decreased linearly. B2O3 replaces V2O5 and P2O3 within the structure. B2O3 has smaller molar mass compared to V2O5 and P2O5, (m(P2O5) = 141.94 g mol−1, m (V2O5) = 181.88 g mol−1, and m(B2O3) = 69.62 g mol−1). For this reason, the density and molar volume decrease with increasing amount of B2O3. 3.2. XRD spectra Fig. 3 demonstrates XRD patterns of undoped VPB0 glass and Bdoped VPB (VPB2-VPB8) glasses. Fig. 3 confirms that samples have amorphous character far from regular crystalline structure. The hump which is found at 20–30° region is a characteristic hump that is observed in vanadium-phosphate glasses. According to theoretical data, characteristic peaks with high intensity of (VO)2P2O7 (ICDD:00-0410697), P2O5 (ICDD:00-023-1301), VO2 (ICDD:01-072-0514), BPO4 (ICDD:00-011-0237) compounds are known to be present in this region. The hump found within this region may considered to be due vanadium and phosphate in VPB0 glasses, and additionally due to various compounds of boron in VPB glasses.

Fig. 3. XRD pattern of VPB0-VPB8 glasses.

3. Results and discussion 3.1. Density and molar volume Sample weights were determined first by individually weighing them in air and then in methanol. The following equation was used in the determination of the densities (D) of each sample:

D=

Wa Wa

Wl

.

0

3.3. UV–vis measurements When transmittance and absorption curves of the samples are examined, the most prominent characteristic is the fact that samples absorb the visible region completely and absorption edge is found around 1700 nm as shown in Fig. 4. According to absorption spectra, entrance of boron to the structure changes the position of the absorption edge though slightly, and also increases transmittance. Transmittance values of these glasses that absorb the light completely, within the interval of

(1)

where Wa is the weight of the glass in air, Wl it is the weight in the fluid, and ρ0 is the density of the fluid. The following equation was used in the calculation of molar volumes of samples (Vm),

3

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between higher and lower energy level, this kind of transfer namely allowable direct transition (constant momentum and energy). While the allowable indirect transition is the type which occurs when the electron transfer from higher level to the ground state and undergoes a momentum and energy change [29,30]. The allowable direct and indirect energy band gaps corresponding to optical energy were studied formerly by Tauc's [31], Mott and Davis [32]. Recently, the optical band gaps calculated by Alarcon et al. [33], Souri and Shomalian [34], and Souri and Tahan [35] using absorbance spectrum fitting (ASF) method and also evaluated by Souri and Tahan [35] and Ali et al. [36] using the first derivation of the absorption spectrum fitting (DASF). In this study the band gaps corresponding to the optical energy for the studied glasses were calculated using the aforementioned methods. Tauc s ) 3.4.1. Tauc's model, (EGap To determine the optical energy band gap using Tauc's model, the optical absorption coefficient α(ν) was calculated via Eq. (3) [37,38]:

( ) = 2.303 Fig. 4. UV–vis-IR absorption spectra for VPB0-VPB8 glasses.

A d

(3)

In above equation, A and d signifier to the absorbance in arbitrary units and the sample thickness in cm, respectively. Eq. (3) has reformatted by Mott and Davis as in Eq. (4) [32]:

1700–2900 nm are between 30% and 45% and exhibits bandpass characteristic. Change in the position of the absorption edge also led to a change in optical band values. This is especially considered to be due to the change in the amount of vanadium.

( )=C

(h

Tau s r EGap )

h

(4)

where hν and C refer to the incident photon energy and a constant mainly depends on the transition probability. The power (r) denotes to the type of electronic transition, where r = 0.5 for direct allowable transition and r = 2.0 for indirect allowed transition [32]. Fig. 5 depicts the variation of (αhν)2 measured by (m−1 eV)2 as a

3.4. Optical energy band gap, (EGap) It is well known that in amorphous substances, a photon of light produces as a result of transfer of an electron by the energy difference

Fig. 5. Variation of (αhν)2 with hν for VPB0-VPB8 glasses. 4

Journal of Non-Crystalline Solids 533 (2020) 119905

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Fig. 6. Variation of (αhν)1/2 with hν for VPB0-VPB8 glasses.

function of (hν) measured by (eV) for direct allowable transition for the Tauc s prepared glasses (VPB0-VPB8). The values of EGap , dir were evaluated by extrapolating the straight line passing through almost number of points Tauc s of drawn plots at the values where (αhν)2 = 0. The EGap , dir = 0.691, 0.700, 0.692, 0.704, and 0.688 eV for glass sample VPB0, VPB2, VPB4, VPB6, and VPB8, respectively as shown in Fig. 5. Fig. 6 illustrates the variation of (αhν)1/2 measured by (m−1 eV)1/2 as a function of (hν) measured by (eV) for indirect allowable transition for the (VPB0-VPB8) Tauc s glasses and values of EGap , indir were determined by extrapolating the straight line of the drawn plots which passing through almost number Tauc s of points at the values where (αhν)0.5 = 0. The EGap , indir = 0.563, 0.559, 0.547, 0.563, and 0.560 eV for glass sample VPB0, VPB2, VPB4, VPB6, and VPB8, respectively. Results reveal that the band gaps for optical energy in direct transition were greater than those in indirect transition. Also, the values of energy band gaps in each transition were close together, this reflects that addition of V2O5 in glass samples do not affect significantly on optical band gaps.

optical energy gap, the light velocity, and Planck's constant. Eq. (5) can be rewritten as:

A( ) = D

1

1

1 cut

1

r

(6)

cut r-1

where D=[C(hc) d/2.303]. Eq. (6) confirms that the optical energy band gap can be evaluated only by using the absorbance data without the need for thickness of the glass sample. This model called the absorbance spectrum fitting (ASF). Furthermore, the optical energy band gap in ASF model can be calculated directly from λcut by Eq. (7): ASF EGap =

hc cut

=

1239.83 (7)

cut 2

Fig. 7 shows the dependence of (A/λ) on the reciprocal of wavelength (λ−1) measured in (nm−1) for direct allowable transition for the ASF proposed glasses (VPB0-VPB8). The values of EGap , dir were estimated by extrapolating the straight region passing through almost number of points of drawn graphs at the values where (A/λ)2 = 0 and substituting ASF in Eq.(7). The EGap , dir = 0.698, 0.701, 0.699, 0.707, and 0.694 eV for glass sample VPB0, VPB2, VPB4, VPB6, and VPB8, respectively as depicted in Fig. 7. Fig. 8 depicts the dependence of (A/λ)0.5 on (λ−1) for indirect allowable transition for the (VPB0-VPB8) glasses and values of ASF EGap , indir were determined by extrapolating the straight region of the drawn graphs which passing through almost number of points at the values where (A/λ)0.5= 0 and substituting in Eq.(7). The ASF EGap , indir = 0.562, 0.558, 0.540, 0.562, and 0.559 eV for glass sample

ASF 3.4.2. ASF method, (EGap ) Alarcon et al. [33], Souri and Shomalian [34], and Souri and Tahan [35] have been established that the α (ν) can be expressed as function of the photon wavelength (λ) as:

( ) = C (hc )r

1

r

(5)

λcut, c, and h express to the wavelength cut-off corresponding to the

5

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Fig. 7. Dependence of (A/λ)2 on λ−1 for VPB0-VPB8 glasses.

The dependence of d{ln[A(λ)/λ]}/d(1/λ) on (λ−1) for the proposed DASF glasses (VPB0-VPB8) is represented in Fig. 9. EGap values for the present glasses were calculated using Eq.(10) and were observed as 0.690, 0.699, 0.692, 0.703, and 0.687 for the samples labeled as VPB0, VPB2, VPB4, VPB6, and VPB8, respectively. One can observe that there is a good agreement between values evaluated using the above three methods. All values of optical energy band gap for VPB0-VPB8 glasses by different models were listed in Table 2.

VPB0, VPB2, VPB4, VPB6, and VPB8, respectively as shown in Fig. 8. Results were obtained by Tauc's and ASF methods were in good agreement. DASF 3.4.3. DASF method, (EGap ) DASF is the abbreviation of the derivation of absorption spectrum fitting. This model is used to investigate the optical energy band gaps for the material and the nature of the optical transitions in semiconductors. In this model Eq. (6) can be expressed as [35,36]:

ln

A( )

1

= ln(D) + r ln

3.4.4. Urbach's energy In the range of low photon energy, Urbach's empirical rule controlled the absorption coefficient (α) as in Eq. (11):

1 (8)

cut

Then 1]}

d {ln[A ( ) d ( 1)

=

(

=

r 1

1 cut

)

(9)

cut

DASF values can be calculated by: the optical energy gap EGap

hc cut

=

1239.83 cut

hv EU

(11)

where αo and EU denote to a constant and Urbach's energy, which is often described the width of the band tail due to localized states in the band gap that is associated with the disordered or low crystalline materials. Eq. (11) can be rewritten as:

As shown in Eq. (9), there should be a discontinuity in the d{ln 1 1 [A(λ)/λ]}/d(1/λ) against to λ−1 graph at = by the value of λcut,

DASF EGap =

0 exp

ln = ln

(10)

6

0

+

hv EU

(12)

Journal of Non-Crystalline Solids 533 (2020) 119905

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Fig. 8. Dependence of (A/λ)0.5 on λ−1 for VPB0-VPB8 glasses.

Therefore, Urbach's energy (EU) can be obtained from the slope of the straight line of graphing ln(α) against (hν). Fig. 10 shows the dependence of ln (α)on the photon energy (h ) for (VPB0-VPB8) glasses. Urbach's energies were collected in Table 2. Results show that the prepared glasses have minimum Urbach's energies reflecting most stable and homogeneous glasses with minimum defects and decreasing of disorder in the glass samples prepared [38].

previously results in Ref. [1]. This confirm that the proposed glasses can be used as promising materials for photoelectronic and optical filter devices. 3.5. Gamma-rays shielding parameters Gamma ray penetration through a newly prepared vanadyl borophosphate glasses VPB0-VPB8 can be explained by Beer-Lambert law [41,42]:

3.4.5. Refractive index for the proposed glasses Utilization the proposed glasses in different optical fields mainly depends on the optical refractive index factor (n). Therefore, n was calculated for all investigated glasses in the present study. The refractive index in direct and indirect allowable transitions in Tauc's, ASF, and DASF methods was determined using Eq. (13) [39,40]:

n2 1 =1 n2 + 2

EGap 20

I = I0 e

µt

(14)

where I0 refers to the maximum photon numbers, I refers to the photon number after penetrating the glass material of thickness (t), and µ refers to the linear attenuation coefficient expressed in (cm−1). µ describes the photon interactions with the glass material. Dividing the linear attenuation coefficient values by the density of the glasses, one get the mass attenuation coefficient values (MAC) which describes the incident photon interactions per unit mass of absorber (VPB glasses). The attenuation coefficients can be easily calculated through the mixture rule [43–47]:

0.5

(13)

The obtained n values for the present samples are collected and listed in Table 2. The refractive indices for the examined samples were inversely with the value of optical energy band gaps. In addition, n of all glasses was high (close to 4), this result is somewhat agree with

7

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(Z = 23) forming the glass, respectively. For example, MACs values for VPB0- VPB8 glasses were found (15.47 cm2/g for VPB0 and 14.96 cm2/ g for VPB8 at 0.015 MeV). In intermediate photon energy region (E > 3 MeV); the region of Compton scattering (CS) prominence as CS varies with Z, MACs values exhibit a slow decrease. In high photon energy (E > 10 MeV), pair production (PP) is more prominent as PP varies with Z2, MAC started to increase again. It is clearly seen that from Fig. 11 that the decrease in V2O5 and P2O5 in the glass composition decreasing the MAC values as both phosphate (Z = 15) and vanadium (Z = 23) considered the heaviest element in this composition, while the boron; light element (Z = 5) increased (see Table 3). So, VPB0 glass samples considered best shield compared to other prepared VPB glasses. Another parameter that ensured the shielding capability of the glass material is the half value layer (HVL). HVL is the thickness at which 50% of the incident gamma photons attenuated and can be calculated by the following relation [43–47]:

HVL =

=

Wi

µ (15)

i

i

(16)

Fig. 12 shows the plot of the HVL for the VPB0-VPB8 glasses versus the photon energy in the range 0.001–20 MeV. HVL of all glasses exhibits small values in low energy photons because of the inverse dependence of HVL on the attenuation coefficient which have the highest values in this region. With increasing the photon energy, HVL also increased while reaching to its maximum values at E > 10 MeV. The input figure in Fig. 12 ensured that VPB0 glass sample has the lowest HVL, while the maximum HVL is reported for VPB8 (see Table 3). This ensured that VPB0 glass sample have good attenuation capability compared to other VPB prepared glasses. Similarly, mean free path (MFP) is another parameter illustrates the photon interaction with the glass material and estimates the attenuation ability of the glasses. MFP defined the distance travelled by the photon before scattering or absorption. It is inversely depended on the LAC, and can be calculated according to the following equation [43–47]:

Fig. 9. Variation d{ln[A(λ)/λ]}/d(1/λ) with λ−1 for VPB0-VPB8 glasses.

µ

0.693 LAC

where( )i is the mass attenuation coefficient of ith constituent element and wi is the weight fraction of the ith constituent element in the glass sample. These attenuation coefficients for the prepared VPB0-VPB8 glasses have been estimated theoretically based on WinXCOM software online program [48]. The weight fractions of each element formed the glasses are shown in Table 1. MAC values for all VPB glasses have been plotted with respect to photon energy in a wide range 0.001–20 MeV (see Fig. 11). It is clear from Fig. 11, in low photon energy region; the region of photoelectric absorption (PA) cross section prominence as PA varies with Z4/E3.5 [49], MACs for all VPB0-VPB8 glasses exhibit a sharp and exponential decrease with the increase in the energy except for two characteristic points at 0.002145, and 0.005465 MeV, respectively. At these two points, according to the dependence of PA on Z4, a distinguished peaks and an increase in the MAC values were found and attributed according to the K- absorption edge of P (Z = 15), and V µ

MFP =

1 LAC

(17)

The plot between MFP versus the photon energy in energy range 0.001–20 MeV is illustrated in Fig. 13. Fig. 13 shows that MFP values exhibit very small values at low energy photon 0.001–0.1 MeV as it inversely proportional to LAC and also 1/E3.5. MFP increased with increasing the photon energy till reaching its maximum values at E > 10 MeV (see Table 4). Similarly, the inset Figure in Fig. 13 shows that VPB0 has the lowest MFP which reflects more interactions of the incident photons with the sample and VPB8 has the maximum values. All obtained data for MAC, HVL, and MFP reflects the best shielding capability of VPB0 glass sample. For using such VPB0-VPB8 glasses in the field of radiation protection, one must calculate the effective atomic numbers Zeff. It can be easily calculated using the following equation [50,51]:

Table 2 Optical energy band gap, refractive index, and Urbach's energy for VPB0-VPB8 glasses. Sample code

VPB0 VPB2 VPB4 VPB6 VPB8

Optical energy band gap, eV ASF

Tauc's

ASF Direct EGap , dir

ASF Indirect, EGap , indir

Tauc s Direct EGap , dir

Tauc s Indirect EGap , indir

0.698 0.701 0.699 0.707 0.694

0.562 0.558 0.540 0.562 0.559

0.691 0.7 0.692 0.704 0.688

0.563 0.559 0.547 0.563 0.56

8

DASF DASF, EGap

Refractive index ASF

Tauc's

Direct

Indirect

Direct

Indirect

0.690 0.699 0.692 0.703 0.687

3.749 3.746 3.748 3.736 3.755

3.986 3.995 4.097 3.986 3.993

3.76 3.746 3.759 3.74 3.765

3.985 3.993 4.017 3.985 3.991

DASF

3.761 3.748 3.759 3.741 3.767

Urbach's energy EU (eV)

0.1282 0.1249 0.1191 0.1254 0.1194

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Zeff =

() () µ

fA i i i Aj j Zj

i

µ

j

(18)

where Zj and Ai refer to atomic number and atomic weight of the ith constituent element, respectively fi is the fractional abundance. Fig. 14 presents the dependence of Zeff on the photon energy in the range 0.01–20 MeV. These data were extracted by the aid of Auto Zeff software program [52]. It is seen from Fig. 14 that Zeff strongly depended on the chemical composition of the elements forming the glasses besides the photon energy. Table 1 shows that the weight fractions of both V2O5 and P2O5 decreased and B2O3 increased in the composition. This behavior caused to the increase in Zeff values. This behavior can be similarly discussed as MAC according to the main three processes of gamma interaction with matter; PA, CS, and PP. In low energy photons Zeff increased as PA cross section increased, at E > 3 MeV, slow dependence of Zeff on photon energy, beyond E > 10 MeV, Zeff tends to increased again. All Zeff data ensured the good shielding ability of VPB0 glasses which has the highest Zeff values compared with other prepared VPB glasses. All Zeff values are gathered in Table 4. In addition, in order to investigate the shielding capability of the VPB0-VPB8 glasses, Fig. 15 shows the comparison between HVL values of VPB0-VPB8 samples with other commercial materials at different

Fig. 10. Variation of lnα with hν for VPB0-VPB8 glasses.

Fig. 11. Mass attenuation coefficient values of VPB0-VPB8 glasses at different photon energies. 9

Journal of Non-Crystalline Solids 533 (2020) 119905

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Table 3 MAC and HVL values for VPB0-VPB8 prepared glasses at different photon energy. Photon energy (MeV)

MAC, cm2/g VPB0 VPB2

VPB4

VPB6

VPB8

HVL, cm VPB0

VPB2

VPB4

VPB6

VPB8

0.001 0.002 0.00215 0.004 0.00547 0.006 0.008 0.01 0.015 0.02 0.04 0.06 0.08 0.1 0.2 0.4 0.6 0.8 1 1.5 2 4 6 8 10 15 20

4675 747 1041 198.8 244.6 193.2 89.42 48.41 15.47 6.785 0.9831 0.3876 0.2415 0.1873 0.1223 0.0923 0.07774 0.06825 0.06136 0.05004 0.04327 0.03126 0.02684 0.02474 0.02362 0.0225 0.02232

4655 743.2 1030 196.5 240.8 190.2 88 47.64 15.22 6.676 0.9695 0.3837 0.2399 0.1865 0.1223 0.09231 0.07776 0.06827 0.06138 0.05005 0.04328 0.03123 0.0268 0.02469 0.02356 0.02242 0.02222

4644 741.2 1025 195.3 238.8 188.6 87.26 47.23 15.09 6.62 0.9624 0.3817 0.2391 0.1862 0.1222 0.09232 0.07776 0.06828 0.06138 0.05005 0.04328 0.03122 0.02678 0.02466 0.02352 0.02237 0.02216

4634 739.1 1019 194.1 236.7 187 86.51 46.82 14.96 6.562 0.9551 0.3797 0.2383 0.1858 0.1222 0.09232 0.07777 0.06829 0.06139 0.05006 0.04328 0.03121 0.02676 0.02463 0.02349 0.02232 0.02211

5.128E−5 3.209E−4 3.895E−4 2.303E−4 0.00121 0.0029 9.801E−4 0.00124 0.00268 0.00495 0.0155 0.03533 0.24386 0.61851 0.99269 1.27995 1.70873 1.96022 2.59735 3.08381 3.5126 3.90703 4.79087 5.54045 7.66907 8.93201 9.69018

5.238E−5 3.279E−4 3.98E−4 2.358E−4 0.00124 0.00297 0.00101 0.00127 0.00275 0.00509 0.01593 0.0363 0.25024 0.63347 1.01508 1.30728 1.74273 1.9978 2.64714 3.14252 3.57941 3.98127 4.88271 5.64665 7.81858 9.11002 9.88793

5.263E−5 3.297E−4 4.001E−4 2.379E−4 0.00125 0.00299 0.00102 0.00129 0.00278 0.00514 0.0161 0.0367 0.25272 0.63854 1.0213 1.31372 1.74882 2.00335 2.6542 3.15084 3.58883 3.99169 4.8953 5.66104 7.84533 9.14215 9.92344

5.289E−5 3.314E−4 4.022E−4 2.396E−4 0.00126 0.00302 0.00103 0.0013 0.00281 0.0052 0.01628 0.0371 0.25521 0.64347 1.02724 1.31908 1.75438 2.00993 2.66045 3.15861 3.59715 4.00152 4.90736 5.67498 7.86717 9.17151 9.95998

5.318E−5 3.334E−4 4.0469E−4 2.418E−4 0.00127 0.00305 0.00104 0.00132 0.00285 0.00526 0.01647 0.03755 0.258 0.64897 1.03406 1.32624 1.76137 2.0165 2.66915 3.16852 3.60837 4.01394 4.92241 5.69353 7.89541 9.20836 10.0047

4665 745.1 1036 197.7 242.7 191.7 88.72 48.03 15.34 6.731 0.9764 0.3857 0.2407 0.1869 0.1223 0.0923 0.07775 0.06826 0.06137 0.05004 0.04327 0.03125 0.02682 0.02471 0.02359 0.02246 0.02227

Fig. 12. Half value layer values of VPB0-VPB8 glasses at different photon energies.

Fig. 13. Mean free path values of VPB0-VPB8 glasses at different photon energies.

photon energy. VPB0-VPB8 samples were found to have higher gamma shielding capabilities than both ordinary and Hematite – Serpentine concretes [53], and RS-253-G18. RS-360 [54] was found to have high shielding capability when compared with the VPB glasses.

1 The density of the synthesized glasses was found to be 2.89069 g cm−3 for undoped VPB0 glass sample and decreased for doped VPB with boron. 2 Amorphous state of the VPB0-VPB8 glasses was proved by XRD measurements. 3 The indirect optical energy band gaps from 0.563 eV to 0.547 in Tauc's method, while changed from 0.562 eV to 0.540 eV in ASF method. Urbach's energy changed from 0.1283 to 0.1191. 4 Refractive index of the prepared glasses was around 4. 5 VPB0 glass sample has the lowest HVL and MFP values, while the maximum HVL and MFP is reported for VPB8 (see Table 3 and 4). 6 VPB0 sample has the highest Zeff values, while the lowest Zeff values is reported for VPB8 (see Table 3).

4. Conclusion The present study focuses on investigation the structure, physical, optical properties of novel vanadyl boro-phosphate glasses with the chemical form of (100 − x)(0.5V2O5 − 0.5P2O5).xB2O3 (x = 0, 2, 4, 6, 8 mol%). In addition, gamma-rays shielding capability of the prepared glasses VPB0-VPB8 also has been evaluated. Results reveal the following items: 10

Journal of Non-Crystalline Solids 533 (2020) 119905

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Table 4 MFP and Zeff values for VPB0-VPB8 prepared glasses at different photon energy. Photon energy (MeV)

MFP, cm VPB0

VPB2

VPB4

VPB6

VPB8

0.001 0.002 0.00215 0.004 0.00547 0.006 0.008 0.01 0.015 0.02 0.04 0.06 0.08 0.1 0.2 0.4 0.6 0.8 1 1.5 2 4 6 8 10 15 20

7.399E−5 4.631E−4 3.323E−4 0.00174 0.00141 0.00179 0.00387 0.00715 0.02236 0.05099 0.35189 0.89251 1.43246 1.84697 2.8286 3.74798 4.44994 5.06869 5.63784 6.91323 7.99487 11.06648 12.8889 13.98295 14.64599 15.37503 15.49902

7.558E−5 4.732E−4 3.403E−4 0.00178 0.00145 0.00184 0.00397 0.00734 0.02298 0.05238 0.36109 0.9141 1.46477 1.88641 2.88283 3.81982 4.53466 5.1651 5.74498 7.04575 8.14813 11.28222 13.14577 14.26829 14.94572 15.69766 15.83159

7.595E−5 4.757E−4 3.433E−4 0.0018 0.00147 0.00186 0.00402 0.00742 0.02323 0.05296 0.36467 0.92142 1.47374 1.89571 2.89084 3.83002 4.54667 5.17869 5.76001 7.06392 8.16888 11.32082 13.19214 14.31953 15.00634 15.76937 15.91131

7.632E−5 4.782E−4 3.458E−4 0.00181 0.00148 0.00188 0.00406 0.0075 0.02349 0.05354 0.36827 0.92853 1.48231 1.90344 2.90033 3.83904 4.55787 5.19069 5.7742 7.08132 8.18901 11.35234 13.23451 14.37227 15.06888 15.84355 15.99369

7.673E−5 4.811E−4 3.489E−4 0.00183 0.0015 0.0019 0.00411 0.00759 0.02377 0.05419 0.37229 0.93647 1.49215 1.91377 2.90981 3.85158 4.57218 5.20689 5.79212 7.10304 8.21577 11.39309 13.28768 14.4368 15.13743 15.93093 16.08224

Photon energy (MeV)

Zeff VPB0

VPB2

VPB4

VPB6

VPB8

0.01 0.015 0.02 0.04 0.06 0.08 0.1 0.15 0.2 0.4 0.6 0.8 1 1.5 2 4 6 8 10 11 12 13 14 15 16 18 20

14.60535 14.80533 14.91132 14.89832 14.47403 13.84075 13.16865 12.07559 11.62875 11.24583 11.18916 11.17181 11.16437 11.16363 11.19241 11.35937 11.51583 11.64115 11.74181 11.77714 11.81235 11.84432 11.87192 11.8976 11.91914 11.95655 11.98439

14.55387 14.7521 14.85715 14.84158 14.41594 13.77214 13.10144 12.00728 11.56225 11.18256 11.1264 11.10925 11.10179 11.10115 11.13007 11.29648 11.45256 11.57745 11.67795 11.71329 11.74845 11.78019 11.80781 11.83329 11.85492 11.89232 11.92024

14.50181 14.69826 14.80237 14.78419 14.35719 13.70277 13.03347 11.93607 11.49501 11.11858 11.06292 11.04598 11.0385 11.03796 11.06702 11.23287 11.38857 11.51303 11.61337 11.64871 11.68384 11.71533 11.74298 11.76826 11.78998 11.82736 11.85536

14.44912 14.64378 14.74693 14.72611 14.29773 13.63255 12.96071 11.86376 11.42695 11.05383 10.99868 10.98188 10.97443 10.97388 11.00322 11.16851 11.32382 11.44784 11.54802 11.58335 11.61844 11.64969 11.67736 11.70244 11.72426 11.76162 11.7897

14.39583 14.58867 14.69086 14.66737 14.2376 13.56153 12.8833 11.79061 11.35811 10.98828 10.93367 10.91682 10.90962 10.90883 10.93796 11.1034 11.25832 11.3819 11.48191 11.51725 11.5523 11.5833 11.61099 11.63586 11.65778 11.69513 11.72329

Fig. 14. Effective atomic numbers of VPB0-VPB8 glasses at different photon energies.

Fig. 15. Comparison of HVL values of VPB0-VPB8 prepared glasses at different photon energy.

The above-mentioned results ensure that VPB0 glass sample have good attenuation capability compared to other VPB prepared glasses. VPB0VPB8 samples were found to have higher gamma shielding capabilities than both ordinary, Hematite – Serpentine concretes, and RS-253-G18 commercial shielding materials.

analysis, Writing - original draft, Writing - review & editing. U. Gökhan Issever: Conceptualization, Formal analysis, Writing - original draft, Writing - review & editing. F.I. El-Agawany: Conceptualization, Formal analysis, Writing - original draft, Writing - review & editing.

CRediT authorship contribution statement

Declaration of Competing Interest

Y.S. Rammah: Conceptualization, Formal analysis, Writing - original draft, Writing - review & editing. Gökhan Kilic: Conceptualization, Formal analysis, Writing - original draft, Writing review & editing. R. El-Mallawany: Conceptualization, Formal

Authors declare that they have no conflict of interest.

11

Journal of Non-Crystalline Solids 533 (2020) 119905

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