Doping Effects of Pigment Oxides on Optical and Mechanical Properties of PbO-Based Glasses

The current academic study focuses on analysis and synthesization of a high density, high refractive indexed heavy metal oxide pigmented heat absorbent sodium silicate glass system xPbO-y(0.14Cu 2 O-0.05CuO-0.03SnO 2 ) -30Na 2 O-(70-0.22y-x)SiO 2 (x= 0,1.5,10 mol% and y = 0,1) explored with various ratios PbO doping via conventional melt annealing route, resulted optimally suited material for various linear and nonlinear optoelectronic applications. The fundamental physio-mechanical properties like density (ρ) , molar volume (V m ) , and oxygen packing density (OPD) of synthesized samples were analysed, alongside elastic moduli were computed utilizing experimental, Makishima-Mackenzie, & Rocherulle models. When the XRD data verified the substance's amorphous character, the FTIR study specified the vibrational bands associated with the silicate matrix’s structure. The visible optical properties, solar optical properties, refractive index (n) , extinction coefficient (k) optical dielectric constants, direct &indirect optical band gap, and Urbach energy ( E U ) were measured from computed spectral data collected by Jasco V-770 spectrophotometer in the solar spectrum wavelength spanning 190 nm - 1100 nm, as a result, the computed indirect optical band gap energy (E gind ) and, direct optical band gap energy (E gd ) were illustrated to be in the 1.64-2.61 and, 2.57-3.03 eV range respectively. Using the absorption spectra, the average of refraction index (n 0 ) , corresponding nonlinear refractive index (n 2 ) , molar refraction (R m ) , polarizability (α m ) , reflection loss (R L ) , optical transmission (T) , metallization criterion (M c ) , optical electronegativity (Δχ ∗ ) , third order nonlinear optical susceptibility (χ (3) ) have all been calculated, whereas the beneficiary parameter, optical basicity (Λ th ) has been also evaluated. All the above characterizations have been established and explored, paving the road for the created product to be an acceptable option for commercial construction, especially for exterior use in high-light areas as well as optoelectronic devices.


Introduction
Silicate glasses are the most popular commercially available glasses having high viscosity, which facilitates glass formation without crystallization [1].Multiple kinds of silicate glasses have numerous uses for building creation, decorative industries, electronic devices, radioactive and photovoltaic tools, acoustic-optic devices etc. because of their outstanding thermal resilience, thermo-mechanical properties, and chemical-based strength [2][3], and in optics for telecommunication applications due to their excellent transmission and low attenuation losses in the apparent and near-IR zones [4].Silicate glasses have become more prevalent in commercial and residential buildings for their excellent ability to capture and transmit visible daylight into buildings [5].Pure silicate glass forms noticeably clear glass having high transmission properties compared to other building coverings, and along with consequently, becoming the main provider of extra solar radiation inside the building, making the building residents unpleasant.However, this problem has been solved by doping specific amounts of transition metals or rare earth ions into silicate glasses making the glasses tinted and heat-absorbing without compromising their strength, which reduces and controls the significant amount of solar radiation transmission into the buildings.Among the transition metals, the valence configuration of copper in glasses influences not only the physical and chemical features yet its capability to create glasses [6].The outstanding brilliant sharp bluegreen colour glass is produced because of the existence of Cu 2+ ions according to ligand field theory [7].The copper atom's electronic configuration is [Ar] 3d 10 4s 1 , including two persistent ion states, Cu + and Cu 2+ .Due to entirely occupied five d-orbital cuprous ion (Cu + ) does not produce colouring [8], but Cu 2+ ion produces a colour centre featuring bands of absorption in the visible-light area and creates interesting bluish occasionally green colour in material [9].It has been studied that the intensity of colouring based on Cu 2+ concentration, and its coordination, including the alkalinity of glasses [8,9].Present-day Cu 2+ ion-doped glasses are the most popular research area due to their optical bistability [7,10].Besides doping with transition metals or rare earth ions, incorporating suitable proportions for heavy metallic oxides makes the glasses more useful.It has been observed that adding heavy metal oxides (BaO, Bi2O3, PbO, etc.) into the glasses improved some unique properties of glasses such as chemical resilience, refractive index, density, improving ability to resist devitrification, & reducing processing temp [11].Moreover, the heavy metal oxide silicate glasses have high values of the mass attenuation coefficients and excellent shielding properties against nuclear radiations [12,13].Many previous researchers observed that silicate glasses containing suitable amounts of heavy metal oxides showed enhanced linear and nonlinear optical properties [14], excellent infrared transmission [15], and low crystallization tendency [16].These multicomponent glasses with PbO have a broad application in enamels, optics such as lenses for optics, ultrasonic delay cables, electro-optic modulators, electro-optic toggles, solid-state laser resources, electrons boosts, television image tubes, and other related important optical electronic uses and glass-tometal sealing due to their low processing temperatures, high resistance to devitrification, high chemical durability, high optical density, and refractive index [17][18][19].Such spectacles can also be useful in additional scientific purposes like upconverting phosphors, mechatronics, dosimetry, radiation physics, along with waveguides for light since they have low phonon energy [20,21], along with specific uses in a certain field for heated as well as mechanical detectors, low-loss fibre optics as well infrared-transmitting components [22].The molecular significance of Pb 2+ in silica glass is currently being thoroughly investigated to show its fascinating function during glass creation in multiple structures, especially silicon dioxide [23][24][25][26][27][28][29][30][31].Earlier authors showed that in binary lead silicate glasses, Pb functions to be a glassmaker with a significant lead amount as well as an interconnected enhancer for a small amount of lead [32].PbO is not able to form a glass matrix on its own, but when mixed in suitable amounts with other glass-forming oxides like SiO2, B2O3, TeO2, and P2O5, it can create glass [33], and generate an ionic or covalent bond between oxygen [34].Besides transition metal ions and heavy metal oxides, it has been found that incorporating suitable amounts of SnO2 in silicate glass structure improved the compactness of the tinted glass which significantly facilitated the glass composition to be used against high photon energies [35].Earlier researchers also noticed that appropriate doping of SnO2 in their glass composition upgraded the glass photosensitivity, microhardness, and thermal stability [36,37].Ziemath et al. claimed that Sn 4+ cations in their glass composition worked like an interconnected former leading to more rigid glass development, by using the UV-visible absorbance & scattered reflection examination within the infrared spectrum [38].One disadvantage of SnO2 is that larger concentrations cause the opacity of silicate glass due to its limited solubility within the silica network [39], making it unwanted when the glass is used as a building construction material.Nevertheless, the above literature survey shows that incorporating a very little and controlled amount of Sn 4+ , Cu 2+ , Cu + , and Pb 2+ ions in a soda silicate glass improves the glass properties which may be suitable for widespread applications in various fields.Motivated by the above literature survey, this research work primarily focused on the development of PbO-based tint glasses with improved optical and mechanical properties for widespread applications.The other obvious objective was to optimize the PbO contents in the tint glass compositions for optimum physical, optical, and mechanical properties for building construction materials.A range of characterization techniques were employed to explore glass interconnection structures, which might be causally related via the improved physical, optical, mechanical, and optoelectronic properties of the examined tint glasses.

Experimental procedures 2.1. Preparation of tint glasses
A sodium silicate base glass (30Na2O-70SiO2) was used to prepare a range of tint glass compositions and the corresponding compositions are given in Table 1.A general formula can be expressed as xPbOy(0.14Cu2O-0.05CuO-0.03SnO2)-30Na2O-(70-0.22y-x)SiO2(x = 0,1.5,10mol% and y = 0,1) for all the prepared compositions.High-purity reagent grade cuprous oxide (Cu2O, 97% freshness), copper monoxide (CuO, 97% freshness) supplied through Avarice Industries, and lead oxide (PbO, 99.99% purity) supplied by Aldrich Chemical Co. were used as sources of Cu2O, CuO, and PbO, respectively.Tin oxide (SnO2, 98% purity), sodium carbonate (Na2CO3, 99% purity), and quartz (SiO2, 99% freshness) supplied through Loba Chemie were served as sources of SnO2, Na2O, and SiO2, respectively.All the respective batch compositions were weighted by utilizing an electronic micro analytical weighing machine having a precision of ± 0.0001 g, afterwards blended by using a high-powered ball mill (Amaze Instruments) at 400 rpm for 2 h for obtaining a homogeneous batch mixture.Each batch mixture was taken in the aluminium crucible for glass melting in an electric furnace at about 1400 °C during 6 h as per the melting profile as shown in Fig. 1(a).The molten glass was poured over a preheated alumina plate before chilling, pulverizing, later remelting around similar time-temperature profile to produce extra uniform glass formation.The remelted glass was finally poured onto a preheated iron mold having specific dimensions for obtaining rectangular samples.The readied rectangular fragments were annealed at 500 °C during 4 h by using a fixed time-temperature profile as illustrated in Fig. 1(b) to prevent them from shattering due to internal residual stresses.

Materials Characterizations
Density of the prepared tint glasses was ascertained during ambient temperature applying the law of Archimedes where water was utilized as the dipping liquid.The overall density assessment had an estimated deviation of about ± 0.004 g cm -3 .The prepared glasses' molar volume was determined by using the formula (  = /, where   is the molar volume,  is the molar mass and  is the density of the glass).The oxygen packing density () of the glass specimens was deduced applying the formula,  = (1000 ×  × )/, wherein the number of oxygen atoms per mole in a composition is denoted by ,  is the density of the glass, and  is the molecular weight of the glass [40].Each bulk glass sample was shaped and polished employing 400/800/1200 water-cooled silicon carbide (SiC) dusts & 6/3/1/0.025µm diamond paste followed by mechanical cutting using a water-cooled lowspeed diamond saw.All the determined attempts were done to secure that each side of the samples is aligned to each other having a fluctuation of below 0.05 cm and obtain maximum flatness of the sample surfaces.The photographs of the polished glass samples for optical characterization are shown in Fig. 2.
The optically polished glasses' ultraviolet and visible spectrum were captured employing Jasco V-770 double beam UV-VIS spectrophotometer (Japan) connected with PC UV-Win lab software, where the visible and solar optical characteristics of the pigmented glasses were determined by taking a weighted average of the experimental data over 360 nm to 830 nm.The data was gathered at 5 nm intervals considering the normal incidence of light in the ultraviolet and entire visible spectral zones, which comprises transmission in the specular transmission mode, reflection in the diffuse reflection mode, and absorption in the spectrum mode.The weighted factors for evaluating solar optical characteristics were taken in a US standard atmosphere containing 3.4 mm of ozone and 20 mm of precipitable H2O vapor, normally in sunshiny atmosphere [41].The Lambert-Bear equation (  =    −() ) was employed to calculate the materials absorption coefficient () for each glass at different photon energies ℏ(), wherein  is the sample thickness and   and   is the incident and transmitted photon intensities, correspondingly.

Fig. 2. Photographs of optically polished glass samples prepared for optical characterization.
All the synthesized tint glasses were pulverized into fine powders by mortar pestle for executing XRD analysis at room temperature.The fine powder was taken in a sample holder in Ragaku Smart Lab (9 KW) powder type X-ray diffraction apparatus of RIGAKU Corporation company (Japan) equipped with graphite monochromatic copper K radiation source ( = 1.540Å) and Ni filter tube ran at 40 kV & 20 mA current.All the XRD data were recorded throughout a span of 2 from 10º to 80º using a scan rate of 3º min -1 and all the sets of data were interpreted by applying PANalytical XPert High Score along with correlating using standard ICDD (International Center for Diffraction Data) cards.Infrared spectra of all the glass powder samples were analyzed throughout wavenumbers (4000-450 cm -1 ) at 4 cm -1 clarity in transmittance mode for illuminating functional groups that exist in the glasses.All the data were measured on a single-beam Nicolet iS5 FTIR spectrometer of THERMO Electron Scientific Instruments LLC Company (USA) at room temperature utilizing the KBr disc technique.The longitudinal (  ) along with shear (  ) ultrasonic wave velocities were calculated in an ambient temperature by utilizing an ultrasonic flaw detector machine, in which two quartz X-and Y-cut transducers are functioning at 5 MHz resonant frequency having an error of ± 10 m/s ambiguity.

Physical properties of the tint glasses
It has been found that all produced glasses are transparent.In the respective oxide glass systems, {xPbOy(0.14Cu2O-0.05CuO-0.03SnO2)-30Na2O-(70-0.22y-x)SiO2} authors denoted the composition of glass systems y(0), and y(1), when y=0, and y=1 correspondingly in the respective glass composition.OPD is a key parameter that describes the framework of glass & assesses the rigidity of the oxide system.

XRD analysis
The XRD spectrum of synthesized glass samples with different compositions and base glass which are all listed in Table 1 are displayed in Fig. 3.The spectra spanning the region of 2, 10° to 80° of all glass samples depict no distinct peaks indicating the irregular character of entire synthesized glass specimens due to the decided trace amount of doped ingredients and have been detected with a predominant initial hump in all the glass samples XRD data's due to the base glass as provided in a previous research paper [42].

FTIR Spectroscopy
The obtained FTIR spectral measurements of base glass and other all doped tint glasses with different compositions provided in Table 1 are displayed in Fig. 4. The infrared spectrum reveals two different distinct areas in the 500 -4000 cm -1 range.The distinctive vibrational bands, the majority that can be found in the smaller spectral region, are allocated to the IR spectral fingerprint region, although the functional group area, which showed in the larger spectral region, is crucial for identifying the sample's fundamental characteristics.Two moderately clear infrared bands develop around adjacent to 460 cm -1 & 783 cm -1 respectively, a considerably deep infrared wideband is observed on nearly 1038 cm -1 , two tiny dim infrared bands are detected at around 1384 cm -1 & 1625 cm -1 and a strong infrared wideband is seen at about 3440 cm -1 .The extensive broadband at roughly 1038 cm -1 in all the glass samples' FTIR spectra appeared because of uneven stretching vibration of the Si-O bond in the SiO4 tetrahedron groups that exist in the silicate phases of the glass specimens [43,44].A further moderately wide band on nearly 460 cm -1 in all the FTIR glass samples data are obtained due to the bending vibrations of O-Si-O bond in the SiO4 tetrahedron groups present in the glass samples and vibrations of metallic cations such as Pb 2+ [45,46].The attributed assignments of all the transmission peaks in all the glass samples' FTIR data sets are given in Table 3.No significant changes are observed in all the FTIR glass samples data and hence it is concluded that the determined amounts of metallic concentrations (Cu2O+CuO+SnO2), and PbO have shown no considerable influence on the silicate network structure.[45,46] 783 Due to the bending of conjugated SiO4 tetrahedral groups and oxygen atoms connected perpendicularly to the Si-Si axis within the Si-O-Si plane, in the SiO2 glass network structure.
[ 45,47,48] 1038 Uneven stretching of the O-Si-O bond within the SiO4 tetrahedral group.[43,44] 1384 Due to the antisymmetric vibrations of oxygen atoms connected to Si-O-Si groups [43] 1625 Due to the vibration of the H2O molecule and symmetric stretching of O-H bonds [43,47] 3440 Associated with the stretching of the (OH) group and molecular water. [42]

UV-VIS Spectroscopy
The spectral reflection and transmission in the visible region and absorbance in the ultraviolet and visible region of respective rectangular optical polished glass samples (S1, S2, S3, S4, &S5) having thicknesses between 7.96 to 8.10 mm with different compositions (Table 1) are shown in Fig. 5.The measured reflections of the colored glass samples S1, S2, S3, S4, and S5 exhibit its highest intensity band in the visible range about 830 nm, 528 nm, 528 nm, 497 nm, and 484 nm, respectively (Fig. 5a).Similarly, the acquired transparency of the glass samples S1, S2, S3, S4, and S5 reveal their maximum peak in the visible range of about 830 nm, 530 nm, 531 nm, 488nm, and 491 nm respectively (Fig. 5b).

Visible Optical Properties
The reflectance, transmittance, and absorbance of selected samples (S1, S2, S3, S4, & S5) spanning the visible light wavelength of 360 nm to 830 nm are measured experimentally applying ISO standards [49], as well as the weighted mean of visible optical characteristics are calculated using the Eq. ( 1), Eq. ( 2), and Eq. ( 3) which are provided bellow.
= 100 −   −   (3) Where  is wavelength intervals,   is the relative spectral distribution of illuminant D65, () is spectral luminous efficiency for the field of view vision deciding the average observer for spectrophotometric study, () is spectral transmittance (%), () is spectral reflectance (%) while a correlation (Eq.( 3)) provided the absorption from glass specimens over the visible region.All the measured visible optical properties of all glass samples obtained by using a UV-VIS spectrophotometer are provided in Table 4.The mentioned visible characteristics are essential when assessing daylighting into houses.

Solar Optical Properties
The solar optical characteristics of selected glass specimens in the complete visible spectrum wavelength between 360 nm to 830 nm employing British along with ISO standards are assessed by the Eq. ( 4), Eq. ( 5), and Eq. ( 6) provided bellow [5].
= 100 −   −   (6) Where,   is the relative spectral distribution of the solar radiation (W/m 2 ), whereas relationship (Eq.( 6)) gives solar absorbance.Solar optical properties have a significant impact on heating & cooling burdens, that enhance building power usage.These properties are essential in assessing heat load in dwellings across windowpanes and are provided in Table 4.

Refractive index (𝒏) and extinction coefficient (𝒌)
The real component of the complex refractive index is the index of refraction (), which is connected to the reflection function () and the extinction coefficient () as per Fresnel theory which is provided in Eq. (7).
The algorithms mentioned in Eq. ( 8), and Eq. ( 9) are employed to compute the refractive indexes of entire synthesized glass specimens having various compositions.  = 10 − × 100 Where,   denotes per cent transmittance or per cent transmittance constant, while  represents absorbance.The extinction coefficient () is determined by implementing the Eq. ( 10). =  4 (10) wherein  &  signify for materials' absorption coefficient and wavelength correspondingly.Connecting and quasi anions and cations in the Ultraviolet region, as well as grid oscillations in glass networking in the infrared region, are two dominant transmission aspects which influence glass system's refractive index [50].The dispersion curves of refractive indexes and extinction coefficients for all five prepared glass specimens are illustrated in Fig. 6 and Fig. 7, which present that the refractive index (), and extinction coefficient () improve within ultraviolet, and visible area with the addition of the respective determined amount of metal oxides (Cu2O+CuO+SnO2), and PbO (Table 1) in the glass composition.
Fig. 6.The distribution plot of refractive index () vs wavelength of all prepared glass specimens.

Complex dielectric constant
The optical complex dielectric constant, that is determined by molecular mechanisms originating from photon interactions with electrons, is indeed a factor of refractive index  and extinction coefficient  .The complex dielectric constants contain real and imaginary components, designated by ℰ  (ℰ  =  2 +  2 ), and ℰ  (ℰ  = 2) [50].The dispersion curves for the real component of the complex dielectric constant (ℰ  ) as well as the exponent of the complex dielectric constant (ℰ  ) of all five glass samples are depicted in Fig. 8, which becomes evident that both parts {real (ℰ  ), & imaginary(ℰ  )} of the complex dielectric constant develop highly within ultraviolet, and visible area with the addition of the respective determined amount of metal oxides (Table 1) inside sodium silicate glass structure.

Assessment of the optical energy gap
The Tauc's plot of five similar optical polished glass specimens with nearly equal thicknesses but varying compositions for both indirect & direct transition are provided in Fig. 9 and Fig. 10 respectively.The Davis and Mott formula ( Eq. ( 11) ) is applied to estimate the energy gap of the synthesized samples [50].
(ℎ) = (ℎ −   )  (11) Where,  is a constant,   is an optical energy gap, ℎ is a plank constant, and  is an index number having values of 1/2, 2, 3/2, and 1/3 according to the electronic transition pathway.Usually, the values of  for permitted electronic transitions are 1/2 for direct transition and 2 for indirect transition.For all five glass samples with varying compositions, the tauc's plot is constructed among (ℎ) 1  ⁄ on the ordinate with photon energy (ℎ) on the abscissa to assess the optical band gap.The optical band gaps are determined using the tauc's graph curve's linear section by inference at (ℎ)  = 0 (where, r=0.5 for indirect transition and r=2 for direct transition).The optical energy gap results for all five glass specimens are provided in Table 4 when the optical energy gap values of pure 30Na2O-70SiO2 glass are obtained from prior author research articles [51].Fig. 11 shows that the resulting optical energy gap (indirect, & direct) of the y(1) glass series shows a significantly reduce amount than y(1) glass series, and both in the glass series the optical energy gap (indirect, & direct) reduce with the addition of respective amounts of PbO ( 0≤x≤10, x in mol%). .The molar refraction of synthesized glass specimen is evaluated by the following Lorentz-Lorenz equation Eq. ( 15) [52].
)   (12) where, the refractive index ( 0 ) is calculated by the Eq. ( 13) while the achieved values are presented in Table 5.The ( 0 ) ranges (2.51-2.91)are regarded as significant and evolve as the addition of the determined amount of metallic concentration (<0.22mol%) (Cu2O+CuO+SnO2), and increasing PbO (0≤x≤10, x in mol%) concentration in the studied glass system.As an outcome, the glasses under review can be employed as effective prospects for a wide range of optical purposes.The amplitude of electrons interacting with an electric field is determined by a molecule's electronic polarizability (  ), and this can be defined as a function of molar refraction as used in Eq. ( 14) [52]: The (  ) and () values of the produced glass specimens were determined by Eq. ( 15), and ( 16) respectively.
The metallization criterion factor (  ) determines if a material is metallic or insulator.The (  ) values of entire synthesized glass specimens are computed through Eq. (17).
The (  ),(  ),(  ), (), (  ) values of entire produced glass specimens are depicted through the bar graph of Fig. 12( values of these developed glasses are less than their (  ) values respectively, we may deduce that the prepared glasses are non-metallic (insulators) [52].computed by Tauc's approach.The optical electronegativity ( * ) indicates the type of bonding in the samples [53].The high and low ( * ) value specifies ionic and covalent bonding respectively.The ( * ) value of all the prepared samples is determined through Eq. ( 18)  * = 0.2688 (  ) The obtained values of ( * ) are illustrated through the bar graph of Fig. 13(a), while the calculated ( * ) values are judged poor, so the bonding characteristic of the prepared specimens may be classified as covalent bonding.The third-order nonlinear optical susceptibility ( (3) ) in the esu unit of the examined glasses is assessed by using the Eq. ( 19), while the obtained values ( (3) ) of entire examined glass specimens are depicted through the bar graph of Fig. 13(b).It is clearly noticed that ( * ), & ( (3) ) values reduce and enhance respectively due to the addition of a determined amount of metallic oxide (<0.22mol%) (Cu2O+CuO+SnO2), and the increasing amount of PbO (0≤x≤10, x in mol%) concentration in the investigated glass systems. (3) in which  is fixed and approximately 1.7 ×10 10 .The nonlinear refractive indexes ( 2 ) for all selected glasses are computed through the following Eq.( 20) and listed in Table 5.

Measurement of the Urbach energy
Urbach energy has been employed to assess energetic disorder at a semiconductor or insulator's band borders and is only faintly influenced by temperature.The weak crystalline and chaotic amorphous materials contain proximal states that are stretched in the band gap and generated as band ends in the conventional band gap.The Urbach empirical rule defines the absorption coefficient () as a function of photon energy (ℎ) in the poor photon energy domain.The Urbach empirical rule is presented in Eq. (21).
where,  0 and   denote constant and band tail energy or Urbach energy respectively.Considering the logarithms of both sides of Eq. ( 22), we obtain As a result,   = 1  , wherein  represents the gradient of a straight line derived by graphing () versus incident photon energy (ℎ).The graph of () vs incoming photon energy (ℎ) of prepared samples with varying compositions is provided in Fig. 14 to calculate the Urbach energy of every specimen.The Urbach value fluctuates between 0.0596 to 0.0684 eV for the glass specimens in the investigation (as shown in Table 4).The Urbach energy rises as the metallic concentrations (<10.22 mol%) (Cu2O+CuO+SnO2+ PbO) of the glass grow, implying that the defect concentrations in the glass matrix additionally develop.

Analysis of UV-Vis's absorption edges
The absorbance spectrum of prepared glass samples is primarily influenced by parent glass composition, melting temperature, duration of the melting process, partial pressure of oxygen throughout melting, annealing temperature, rate of cooling, additionally, the background losses (reflection loss, absorbance caused by OH groups, IR edge, etc.) detected in the absorbance spectra due to dopants, refining compounds, other absorbent impurities [54].The resulting absorption assessment of the concerned largely metallic doped glass specimens (S3, S4, S5) reveals its maximum absorbance of around 747 nm in the visible area (Fig. 5(d)), and all the glass specimens show its maximum absorbance of around 316 nm in the UV region (Fig. 5(c)).At conventional melting circumstances, in the currently prepared glass samples (S3, S4, S5) the metallic element copper appears in the form of Cu 2+ ions while some of it exists as Cu 0 and Cu2O [55][56][57][58].Previously, researchers found the absorption band caused by Cu 2+ ions at 786 nm in silicate glasses, 1048 nm in aluminoborophosphate glasses, and 1390 nm in sodium aluminoborate glasses [59][60][61][62][63].The currently prepared glass samples (S3, S4, S5) containing Cu2O, CuO exhibit a growing single broad absorption band from 600 nm to 830 nm (Fig. 5(d)), which is very conceivable related to the assignment of an electronic transition of one of the ingredient's cupric ions.The obtained rising band might be generated by the electronic transition from 2 Eg → 2 Tg energy level in octahedral coordination of Cu 2+ ion, implying a distorted octahedral symmetry for cupric ion in the current S3, S4, S5 glass samples [63,64].The all-glass samples (S1,S2,S3,S4,S5) exhibit a high charge transfer ultraviolet absorption band around 316 nm which may be caused by iron impurities as well as the contribution of Pb 2+ ions present in the all-respective glass samples [65].

Optical basicity of the tint glasses (𝜦 𝒕𝒉 )
The optical basicity parameter () can be utilized to categorize an assortment of oxidic glasses according to their basicity order and implies oxide glass's capacity to produce a negative charge to the probing ion [66,67].It relates characteristics like refractive index independently of the anionic configuration of the glass under concern [66].Duffy and Ingram stated that the optical basicity of glass might be expected by considering its composition and proposed the Eq. ( 23) to compute this parameter [67]. ℎ = ∑      (23) Where,   is the equivalent fraction determined by the quantity of oxygen given by each oxide to the total glass stoichiometry and   is the basicity attributed to the respective oxide [68,69].The basicity moderating parameter (  ) is determined by applying the Eq. ( 24) [70].  = 1.36(  − 26) (24) Wherein   is the cation's Pauling electronegativity.The optical basicity ( ℎ ) of the prepared glasses is examined and reported through the bar graph of Fig. 15.All cations available in the glass matrices and their Pauling electronegativity (  ), optical basicity moderating parameter (  ), and optical basicity () are listed below in Table 6.The measurements of optical basicity ( ℎ ) rise from 0.5986 to 0.6508, as the addition of metallic oxides (<0.22mol%) (Cu2O+CuO+SnO2), and PbO (0≤x≤10, x in mol%) concentration rises, caused by expanding electrons on oxygen atoms [69].[72], depending on the chemical composition, packing density(  ) and dissociation energy per unit volume (  )of the respective glasses.The mechanical properties such as Young's(  ), bulk (  ), shear(  ), longitudinal (  ) modulus, Poisson's ratio (), fractal bond connectivity (  ), and hardness (), according to the MM model were computed by using the formulas listed below and the corresponding mechanical properties of the glasses are shown in Table 8.
Where,   and   denote Avogadro's number and mole fraction of component , respectively, and   and   signify the Pauling ionic radii of cation and oxygen, respectively, in an oxide,     system.  = 2    (33) =   + (  The fractal bond connectivity (  ) represents structures of the studied glass samples which shows 3.00 to 2.40 [71].The (  ) value becomes 1, 2, 3 for chain, layer structure, and 3D networks of tetrahedral coordination polyhedral systems correspondingly.These obtained (  ) values of the studied glass specimens are very similar to 3, implying a 3D layer glass network structure.The mechanical properties of the examined glass specimens are illustrated in Fig. 16, and the properties are reduced with the increase of PbO (0≤x≤10, x in mol%) concentrations in pure sodium silicate glass network structure, and the determined number of metallic oxides (Cu2O+CuO+SnO2) (<0.22mol%) added sodium silicate glass structure respectively.The properties in Fig. 16 also show that the properties of the y(1) glass series are well improved than the properties of y(0) glass series due to the addition of metallic oxides (Cu2O+CuO+SnO2) (<0.22mol%) in the sodium silicate glass networks.Both glass series (y (1), and y(0)) are decreased with increasing concentrations of PbO (0≤x≤10, x in mol%) due to decrease packing density (  ), and dissociation energy (  ) of the examined glass specimens.The packing density (  ) of the studied glass samples is reduced with increasing PbO mol% due to an increase in the studied glasses' molar volume (  ) (cm 3 ).Similarly, since the bond force of Pb-O is lesser than of Si-O, the dissociation energy of the glasses lowered when the PbO (mol%) concentrations rose in the glass latticework.Hence, rigidity including total modulus of elasticity of the studied glass samples decrease with increasing PbO mol% due to reducing of (  ), and (  ) values, and subsequently due to the increase of molar volume (  ) (cm 3 ) also.

Information Accessibility
Under an appropriate request, the associated contributor will supply the datasets employed or validated throughout the present research.

Fig. 1 .
Fig. 1.(a) Time-temperature profile for the melt-quenching process, and (b) time-temperature profile for the annealing process.

Fig. 5 .
Fig. 5. Spectral reflections (a) in the visible region, spectral transmissions(b) in the visible region, and spectral absorbance(c) in the ultraviolet and visible region and spectral absorbance(d)in the wavelength range of 600 to 830 nm in the visible region respectively.

Table 3 . FTIR spectrum allocations of all prepared glass compositions. Wavenumber (cm -1 ) Bonding Sources 460
Bending vibrations of O-Si-O bonds in SiO4 tetrahedral groups including oscillations of metal cations such as Pb 2+

Table 8 . Mechanical properties of the glasses according to the Makishima & Mackenzie model.
(40)all-similar mechanical parameters have been computed by the Rocherulle model also, where the packing density parameter in the Makishima and Mackenzie model has been informed as in Eq.(40), and (41), and shown in