Effect of immersion liquids on physical properties of Pr3+-ions doped lithium zinc borate glasses

Our research focused on the creation of lithium zinc borate glasses that were doped with Pr3+ ions. Specifically, our study focused on the effects of substituting lithium with Pr2O3. Our x-ray diffractometer analysis indicated that the glasses were amorphous, which was as expected. We have also evaluated the impact of adding Pr2O3 using toluene and xylene immersion liquids, and we found that these liquids had unique effects on the glass properties. Furthermore, we examined density changes using the Archimedes principle and estimated physical parameters. We carefully analysed the variations in NBO that were caused by Pr2O3, and our results provide valuable insights into the structural behaviour of these glasses.


Introduction
Recent research [1][2] [3]has shown that borate-based glasses have various practical applications.These include creating thin amorphous films for batteries, developing bioactive glasses for tissue engineering, nuclear waste disposal [4], photonic applications, tuneable or short pulse lasers, optic fibre amplifiers and fibre lasers.The thermal activation of alkali ions within the glass enables them to move swiftly from one side to another.This facilitates the replacement of alkali ions near the glass surface by other ions of the same valence [5].By incorporating alkali ions into the borate network, the Tg is increased while the thermal expansion coefficient is lowered [6].The addition of transition metal ions, like ZnO, to glassy systems creates various dopant sites through strong interactions.This leads to optical and spectral properties with high intensity.ZnO-doped glasses are a popular choice for developing optoelectronic devices, solar converters, ultraviolet-emitting lasers, and gas sensors due to their favourable properties [7] [8].These glasses possess visual, electrical, and magnetic properties, while also being non-toxic and non-hygroscopic.Pr 3+ ions have great potential in photonic devices, particularly in white light emitting diodes (WLEDs).As far as we know, besides Eu 3+ and Sm 3+ rare earth (RE) ions, Pr 3+ is another well-known RE ion with an ideal luminescent center at around 600 nm for emitting red light.These emission centres are highly beneficial for producing high-color rendering index glasses for WLED applications [9].This application requires high emission line intensities and is becoming increasingly popular in industries that use X-rays [10] and gamma radiation for technical and medical purpose.The use of gamma rays in medicine, agriculture, and industries such as nuclear reactors and nuclear waste storage [4]requires the development of new and improved shielding materials [3][10].Laser technology, created using Pr 3+ ions doped/codoped glass systems, has great potential for eye-safe remote sensing and medical surgery applications [11].These reports have inspired us to select the composition and rare-earth for preliminary studies aimed at understanding the physical and optical parameters of lithium-zinc-borate glass.

Synthesis and characterization
By utilizing the high-quality precursors of 99.9% purity, lithium zinc borate glasses doped with different concentrations of Pr 3+ were prepared using the melt-quenching process.The initial precursors of the glass composition include lithium carbonate (Li2CO3), zinc oxide (ZnO), boric acid crystals (H3BO3), and praseodymium oxide (Pr2O3).The stoichiometric mixture of glass LZBPr series prepared includes (20-x) Li2CO3 -15 ZnO -65 H3BO3-x Pr2O3 (where, x = 0.25, 0.5, 0.75, and 1.0 mol %).These starting materials measuring 10gram stoichiometric batches, consisting of different concentrations of Pr 3+ were mixed thoroughly and ground using an agate motor with the pestle, to obtain smooth and fine powders.These fine powders were then transferred to the unglazed porcelain crucibles and melted in a furnace.During this melting process, the crucibles were taken out at the temperature of around 900 o C and swirled for few times to ensure the homogeneity of the mixtures.Next, the obtained molten mixtures at 980 o C were moulded into small circular discs by following rapid quench through the preheated brass plates.The flow chart for the preparation of glass samples and prepared glass samples is illustrated in Figure 1.The uniform and smooth surface required for the characterization of the samples was obtained by fine polishing with suitable grades of emery paper.Lastly, the synthesized glass samples are annealed at 250 o C for 4 hours for the removal of the thermal stress and strain.

Density measurement and thickness measurement
Densities of the LZBPr series samples synthesized were determined through Archimedes principle using xylene and toluene as immersion liquids, separately.The density is evaluated using the relation [12][13][14][15], 3  (1) 3 Where, Wair, Wxylene, and Wtoluene are the weights in air, weight of xylene, and weight of toluene for LZBPr glass series.xylene and toulene are 0.876 and 0.866 g/cm 3 .The apparatus used for the determination of density is displayed in Figure 2 (a).The thickness of the individual samples is measured using the digital vernier caliper shown in Figure 2 (b).

Molar volume (Vm)
Molar volume (Vm) of the prepared LZBPr glass series is calculated through the following expression, Where, M.W (g/mol) will be molar weight of the LZBPr series.

Reflection loss (RL%), Dielectric constant (), and Optical dielectric constant op
The refractive index of the LZBPr glass series is determined via the Abbe refractometer.The Reflection loss (RL%) of synthesized glass samples can be calculated from the refractive index given by Dielectric constant () can be expressed in terms of refractive index for individual samples using Optical dielectric constant can be obtained using the expression, IOP Publishing doi:10.1088/1757-899X/1300/1/0120434

Molar refraction (Rm) and molar polarizability (αm)
Molar refraction (Rm) can be calculated in terms of refractive index and molar volume Vm using the relation The polarizability (αm) of the prepared glasses can be calculated using the relation, Where, Z = 3 is the charge of rare earth ion.

Concentration of Praseodymium ions (𝐶 𝑃𝑟 3+ ), inter-ionic distance (ri), Polaron Radius (rp), and Field strength (Fs)
The concentration of praseodymium ions ( Pr 3+ ), inter-ionic distance (ri), polaron radius (rp), Field strength (Fs) is determined using the following equations Where,   3+ is mass of Pr 3+ -ions, W is molecular weight of the Pr 3+ powder, TM is the total mass of chemical composition, and Z is the charge of Pr 3+ -ion.

Results and discussions
All the physical and optical parameters which where estimated [15] are tabulated in Table 1, 2 & 3.
The immersion liquid effect is evidenced in Table 1. for LZBPr series.Density and molar volume serve as significant physical parameters that have been utilized to investigate the level of compactness or openness within the glass network's structure.The LZBPr series glass variations demonstrate densities ranging from 2.62 to 2.77 g/cm³ for Toluene and 3.06 to 3.36 g/cm³ for Xylene.This disparity in densities is attributed to the fact that the density of Xylene is higher than that of Toluene.The molar volume of LZBPr series glass variants falls within the range of 25.40 to 27.59 cm³ for Toluene and 21.94 to 24.96 cm³ for Xylene.This variation is attributed to the significantly lower molecular weight of lithium compared to praseodymium.This expansion in molar volume occurs due to the incorporation of Pr 3+ ions into the network's interstitial spaces, causing structural transformations.This expansion in volume is primarily attributed to the formation of non-bridging oxygens (NBOs) that emerge within the glass structure during the modification process.From Table 2. you can see that the physical and optical parameters are unaffected by the density.The refractive loss (%) is minimal, and the numerical aperture value falls within the required range for fiber fabrication [16].The variation in density among immersion liquids leads to differences in all recorded physical parameters (molar refraction, molar polarizability, concentration, polaron radius, ionic radius, field strength), as detailed in Table 3.

Conclusions
Our research involved the preparation of lithium-zinc-borate glasses doped with Pr 3+ ions, through the use of the melt quenching method.Our main focus was on the effects of substituting lithium with Pr2O3.After conducting x-ray diffractometer analysis, it was clear that the glasses were indeed amorphous.We also investigated the influence of adding Pr2O3 with different immersion liquids, toluene and xylene, and found that each had unique effects on the glass properties.Additionally, we used the Archimedes principle to measure density changes and estimate physical parameters.Through

Figure 1 .
Figure 1.Flow chart for glass preparation and the synthesised Pr 3+ doped LZB glasses.

Figure 2 .
Figure 2. Apparatus used for the determination of (a) density and (b) thickness.

Table 1 .
Density of two different immersion liquids

Table 2 .
Physical and optical parameters unaffected by density

Table 3 . Physical parameters which are affected by two different immersion liquid
careful analysis, we were able to identify the variations in NBO caused by Pr2O3, providing valuable insights into the structural behaviour of these glasses.