Next Article in Journal
Method for Viewing Real-World Scenes while Recording Video
Previous Article in Journal
Path Following and Obstacle Avoidance for Unmanned Aerial Vehicles Using a Virtual-Force-Based Guidance Law
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Applied Sciences
Volume 11
Issue 10
10.3390/app11104603
applsci-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications

by
Soyoung Kim
1,2,
Karam Han
1,
Seonhoon Kim
1,
Linganna Kadathala
1,
Jinhyeok Kim
2,* and
Juhyeon Choi
1,*
1
Korea Photonics Technology Institute, 9, Cheomdan Venture-ro 108beon-gil, Buk-gu, Gwangju 61007, Korea
2
Department of Materials Science, Chonnam National University, 77, Yongbong-ro, Buk-gu, Gwangju 61186, Korea
*
Authors to whom correspondence should be addressed.
Appl. Sci. 2021, 11(10), 4603; https://doi.org/10.3390/app11104603
Submission received: 25 March 2021 / Revised: 29 April 2021 / Accepted: 6 May 2021 / Published: 18 May 2021
(This article belongs to the Special Issue Recent Advances in Functional Optical Glasses for Lens and Fibers: Synthesis, Modification, and Applications)
Browse Figures
Review Reports Versions Notes

Abstract

:
Today, the most common way of laser sealing is using a glass frit paste and screen printer. Laser sealing using glass frit paste has some problems, such as pores, nonuniform height, imperfect hermetic sealing, etc. In order to overcome these problems, sealing using fiber types of sealant is attractive for packaging devices. In this work, (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glasses (mol%) incorporated with xM(PO3)n concentration (where M = Mg, Al, n = 2, 3, respectively) were fabricated and their thermal, thermomechanical, and structural properties were investigated. Most importantly, for this type of sealing, the glass should have a thermal stability (ΔT) of ≥80 °C and the coefficient of thermal expansion (CTE) between the glass and panel should be 1.0 ppm/°C. The highest thermal stability ΔT of the order of 93.2 °C and 112.9 °C was obtained for the 15 mol% of Mg(PO3)2 and Al(PO3)3 doped glasses, respectively. This reveals that the bond strength and connectivity is more strongly improved by trivalent Al(PO3)3. The CTE of a (70-x)V2O5-5ZnO-22BaO-3B2O3-xAl(PO3)3 glass system (mol%) (where x = 5–15, mol%) is in the range of 9.5–15.5 (×10−6/K), which is comparable with the CTE (9–10 (×10−6/K)) of commercial DSSC glass panels. Based on the results, the studied glass systems are considered to be suitable for laser sealing using fiber types of sealant.

1. Introduction

Laser hermetic sealing is an excellent way to protect delicate components in harsh environments for reliable packaging [1,2]. The sealing industry has focused more attention on laser sealing as it is very effective and reliable in packaging systems, including dye-sensitized solar cells (DSSC), organic light-emitting diodes (OLEDs), solid oxide fuel cells, etc., that should be highly stable and maintain initial efficiency for more than 10 years under a harsh environment. To improve the durability of the DSSC modules, the long-term stability should be assured without electrolyte leakage after laser sealing [3,4,5]. Furnace-based thermal sealing and laser-assisted sealing using glass frit have been popular processes until now. In the case of laser sealing using glass frit, on one hand, glass material should show a relatively low glass transition temperature and high absorption efficiency at laser wavelength. On the other hand, the coefficient of thermal expansion between the sealing glass and the substrate should be matched to maintain high durability after sealing. However, the laser sealing process using glass frit has the disadvantage that pores are present and the sealed surface is not uniform in thickness due to evaporation of resin applied by screen printing, which cause the durability to diminish. In view of this, laser sealing using fiber types of sealant has received significant interest, owing to its ability to reduce the defect rate by improving the sealant thickness [6]. It also controls the shape to prevent the formation of internal defects, such as pores and gas, during the process. Thus, fewer pores, uniform height of the sealed surface, and low-cost sealing can be achieved using fiber types of sealant [6]. There are several requirements for materials of fiber types of sealant. In the process of glass frit, the thermal stability (ΔT) of glass frit materials is not the main factor for the laser sealing process, but the ΔT of fiber types of sealant needs to be 80 °C or more for the glass fiber to be able to be drawn to a thickness of hundreds of microns without crystallization. Further, the sealing glass material should have a low glass transition temperature and, thereby, a low thermal energy transfers to packaging devices. Moreover, the coefficient of thermal expansion (CTE) of sealing glass material should be similar to that of the panel. The CTE difference between the glass panel and sealing glass should be lower than 1.0 × 10−6 K−1.
In the case of laser sealing glass, it started with major compositions containing PbO in the early 1990s. However, due to environmental regulations, vanadium-based glass as a sealant has been considered a more promising candidate [7,8]. Among the candidate compositions, V2O5-P2O5-based glasses have been studied a lot in order to overcome the narrow glass-forming area of vanadium-based glass. It was reported that, when P2O5 is added into V2O5-based glass systems, the glass formation stability is improved [9,10]. However, there is a limit to its application as a sealing glass due to poor chemical durability and low water resistance [11]. Therefore, the addition of third and fourth components are required to overcome these limitations.
In this work, (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) was prepared by the melting and casting method. The Al(PO3)3 and Mg(PO3)2 metaphosphates were used as a source for trivalent Al2O3 and divalent MgO [12]. Incorporation of Al(PO3)3 increases the degree of structural polymerization through forming crosslinked P-O-Al bonds. The Al(PO3)3 plays a role in increasing the thermal stability and reducing the crystallization tendency in the glass network. The glass transition temperature (Tg), glass thermal stability (ΔT), the coefficient of thermal expansion (CTE), and structural properties with respect to metaphosphate contents were determined for the purpose of fiber types of sealant. For the laser sealing process, we selected workable glass compositions with a low glass transition temperature of <300 °C, higher glass thermal stability of above 80 °C, and CTE matching with DSSC panels having 9–10 (×10−6/K) of CTE. In addition, the glass composition with low glass transition temperature and higher glass thermal stability was further optimized in order to convert into fiber types of sealant, rather than the conventional laser sealing using glass frit for sealing DSSC panels.

2. Experimental Details

2.1. Glass Fabrication

Table 1 shows the mole fractions of chemical constituents of V2O5-ZnO-BaO-B2O3-M(PO3)n (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) based glasses. The glasses were prepared by the melt-quenching method. Reagent grade chemicals of V2O5 (99.9%), ZnO (99.9%), BaO (99.99%), B2O3(99.9%), and M(PO3)n (99.9%) were used as raw materials to fabricate the glass ingots. The batch chemicals (about 50 g) were weighed using a microbalance and then crushed using a ball mill with zirconia balls for 30 min to get a homogeneous mixture. Then, the well-mixed powder was transferred into an alumina crucible and kept in an electric furnace for the melting process. For the preparation of glasses, a two-step melting process was applied, i.e., in the 1st step, the glass composition was melted at 550 °C for 30 min, and in 2nd step, the temperature was raised to 700 °C and the glass composition was then heated under N2 atmosphere for 30 min (see Figure 1). Then, the melt was poured onto a preheated brass mold and transferred to another electric furnace for the annealing process to remove internal stress. The glass ingots were annealed at 280 °C for 3 h. The glass ingots were used to examine the feasibility for laser sealing through physical, thermal, and structural properties.

2.2. Characterization

Density was measured at room temperature by the Archimedes’ method with an electronic densimeter (Qualitest USA, MD-300S). The amorphous nature of glasses was evaluated by means of X-ray diffractometer (X’pert Pro, Panalytical) with CuKα (=1.542 Å) used as source. Differential scanning calorimetry (DSC 204 F1, NETZSCH) was used for thermal behavior of the glass samples. The measurement was carried out in the range of 25–550 °C at a heating rate of 10 °C/min and under N2 atmosphere. Thermomechanical analysis (TMA) was carried out using a dilatometer (DIL402F3, NETZSCH) in the range of 25–450 °C, with a heating rate of 5 °C/min under N2 atmosphere. Glass samples with a dimension of 5 × 5 × 8 mm3 were used for the measurement. Raman data were acquired in the range from 50 to 1600 cm−1, with 0.5 cm−1 resolution by the spectrometer (Horiba Jobin-Yvon, France). A diode laser operating at 515 nm was used as an excitation source. The X-ray photoelectron spectroscopy analysis was carried out by a spectrometer (NEXSA, Thermo Fisher Scientific., Waltham, MA, USA). The product of Gaussian and Lorentzian functions was used for the curve fitting.

3. Results and Discussion

3.1. Density and Molar Volume

Density of glass is a property of interest where it reflects any structural variations in a glass network, and the measured density of a glass is usually used to calculate molar volume. Density was measured for different M(PO3)n contents in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg mol%, n = 3, 2, respectively) a glass system. Figure 2a shows that the density of (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) decreased from 3.53 g/cm3 to 3.43 g/cm3 and 3.25 g/cm3 with an increase in Mg(PO3)2 and Al(PO3)3 contents up to 15 mol%, respectively. In other word, a reduction of density for substituting 15 mol% Mg(PO3)2 and 15 mol% Al(PO3)3 instead of V2O5 was found to be 3.36% and 8.49%, respectively. Generally, variation of density can be easily explained by molecular weight and atomic density, i.e., as the elements of the lower molecular weight and atomic density were replaced with the elements with a heavier molecular weight and atomic density, the density of the glass system would be increased. Several studies reported these trends, i.e., the increase of the density in the P2O5-Al2O3-BaO-La2O3 and ZnO-B2O3-P2O5-TeO2 glass system by replacing elements with those of a heavier molecular weight [13,14]. Our current results on density are in opposition to this trend. To analyze the variation of the density in terms of atomic density in the current glass system, we compared the atomic density among the three elements, i.e., V2O5, Al(PO3)3, Mg(PO3)2 (atomic density: 3.36, 2.78, 2.74, respectively). Replacement with a relatively lighter atomic density coincided with the decreasing trend of density. However, although the atomic densities of Mg(PO3)2 and Al(PO3)3 are very similar, the reduction widths of the two values of density could not be explained. In other words, discussion of density based on molecular weight and atomic density could not be completely applied to all glass systems.
The molar volume (Vm) was calculated using Equation (1) as shown below [15]:
V m = M d ( i n   cm 3 mol − 1 )
where M is the molar mass and d is the density of the glass. As shown in Figure 2b, the molar volume was plotted as a function of xM(PO3)n (where M = Al, Mg mol%, n = 3, 2, respectively) in the (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) glass system. It was founded that molar volume increased from 47.39 cm3/mol to 49.05 cm3/mol and 55.60 cm3/mol, with an increase in Mg(PO3)2 and Al(PO3)3 contents up to 15 mol%, respectively. The basic building units of a phosphate glass system are the PO4 tetrahedra. These tetrahedrons are connected through bridging oxygen to form different phosphate structures. The chains and rings are linked through terminal oxygen bonded with the modifying cations [15]. It can be seen that the volume of M(PO3)n (where M = Al, Mg, n = 3, 2, respectively, mol%) is larger than that of V2O5. The number of tetrahedrons in the current system is proportional to the ionic status of cation, i.e., divalent (M = Mg) and trivalent (M = Al) metal ions. A similar study by Tsuchida et al. presented that the substitution of Pb(PO3)2 by Al(PO3)3 creates a more open glass structure, leading to an increase in molar volume of the glass system [16]. In other words, the molar volume of a 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3 glass system is larger than that of a 55V2O5-5ZnO-22BaO-3B2O3-15Mg(PO3)2 (mol%) glass system, indicating that Al(PO3)3 has more capability for connecting and corner sharing PO4 tetrahedra than Mg(PO3)2. This will be discussed in more detail by Raman analysis in Figure 6 and X-ray photoelectron spectroscopy (XPS) analysis in Figure 7.

3.2. Thermal Properties

One of the most important characteristics for evaluating the glassy state and thermal properties is glass transition temperature. Figure 3a presents the differential scanning calorimetry (DSC) traces, measured in the range of 25–550 °C, for the (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) (where M = Al, Mg mol%, n = 3, 2, respectively). The traces were obtained for different metaphosphates at various concentrations. The distinctive temperatures, such as the glass transition temperature (Tg), crystallization onset temperature (Tx), and peak crystallization temperature (Tp), were evaluated from the DSC curves as shown in Figure 3b. The Tg is obtained by drawing the tangent to the endothermic peak, while the Tx is taken as the temperature at which heat flow starts to increase from its constant value. We investigated the effect of monovalent (M = Na), divalent (M = Mg), and trivalent (M = Al) metal ions of xM(PO3)n on thermal properties, such as Tg, Tx, and Tp, as shown in Figure 3b. When the concentration of xM(PO3)n was increased up to 15 mol% (M = Mg, Al), it was observed that the Tg increased from 263 °C to 289 °C and 302 °C, respectively. However, the Tg of the 55V2O5-5ZnO-22BaO-3B2O3-xNaPO3 glass system was not considerably changed with respect to NaPO3 concentration. The Tx increased linearly from 293 °C to 383 °C and 405 °C, respectively, with an increase in Mg(PO3)2 and Al(PO3)3 contents up to 15 mol%. The increased NaPO3 content up to 15 mol% led to the slight increase of Tx from 263 °C to 274 °C. In brief summary, this concludes that the Tg and Tx increased in the order of Al(PO3)3, Mg(PO3)2, and NaPO3 added in the (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) glass system.
This behavior can be related to the bond strength of the glass network which can be explained in terms of the cation field strength (which is the charge divided by the square of the cation oxygen distance). In other words, thermal properties of glass could be influenced by various metaphosphate species, because M(PO3)n with different metal cations showed different cation field strength depending on their charge, as shown in Table 2 [17,18]. It can be seen that the Z/α increases in the order of cation, i.e., monovalent (M = Na), divalent (M = Mg), and trivalent (M = Al) metal ions. The reason behind trivalent Al(PO3)3 with a high Z/α having the highest Tg and Tx was analyzed. As plotted in Figure 3b, it was observed that the degree of increase in Tg, Tx, and Tp is closely related to the Z/α of cation, in order, in the present glass system. Muñoz-Senovilla et al. reported that the increase in Tg with Z/α was described according to different cation in alkali and alkaline earth phosphate glasses. It might then be due to the rise of the glass network strength and connectivity [15]. The trends on increase of Tg according to Z/α coincide with other studies mentioned above in the current study. In considering the effect of the divalent and trivalent metal cation in M(PO3)n, Schneider et al. studied the short-range structure and cation bonding in a (1-x)Ca(PO3)2-xAl(PO3)3 glass system. Increasing Al(PO3)3 led to the increase in Tg, which can be understood in terms of the replacement of Ca-O bonds by stronger Al-O bonds, i.e., bridging neighboring phosphate chains. In this way, the mobility of the phosphate segments become more restricted, causing an increase in Tg [18]. Tsuchida et al. reported that an increase of Al(PO3)3 in a (1-x)Pb(PO3)2-xAl(PO3)3 glass system leads to the increase of Tg. This phenomenon stems from the fact that Al atoms established stronger, more covalent bonds with nonbridging oxygen. Crosslinking of phosphate chains through Al-O-Al bridges restricts the mobility of these groups, increasing the Tg of the glass [16]. Based on those references, the divalent (M = Mg) and trivalent (M = Al) metal cations cause structural changes, leading to different thermal properties. As a result, the effect of Al-O bonds or crosslinking of phosphate chains through Al-O-Al bridges by Al(PO3)3 was more dominant than that of Mg(PO3)2, causing higher Tg and Tx than that of Mg(PO3)2 in the (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) glass system.
Thermal stability (ΔT) is frequently characterized by the difference between Tg and Tx, ΔT = Tx − Tg. It has been well known that the higher the thermal stability for a glass composition, the higher the crystallization resistance during heat treatment [19]. Figure 4 shows the variation of quantitative values of ΔT with respect to xM(PO3)n concentration in a (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively mol%). When increasing the concentration of M(PO3)n up to 15 mol% (M = Mg, Al), it was observed that the ΔT increased from 30.4 °C to 93.2 °C and 112.9 °C, respectively. However, the ΔT remained almost constant regardless of NaPO3 concentration, incorporated up to15 mol%. Per review on the thermal effect of phosphate content in a glass system, Armando Mandlule et al. reported that, in a P2O5-CaO-Na2O glass system, network connectivity, chain length, and molar volume increase in structural behavior as P2O5 increases [20]. Ahmed et al. and Amos et al. suggested that the density of phosphate glasses is also affected by the phosphate chain length [21,22]. As explained above in Figure 3, structural changes and thermal properties are affected according to the ionic status of cation, i.e., monovalent (M = Na), divalent (M = Mg), and trivalent (M = Al) metal ions. The enhanced glass stability is caused by a lower mobility of longer phosphate chains in the glass network, resulting in a higher energy barrier for rearrangement and subsequent crystallization. The effect of Al(PO3)3 was stronger than that of Mg(PO3)2 on a lower mobility of longer phosphate chains, leading to a higher exhibited ΔT in a (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) glass system.

3.3. Thermomechanical Properties

CTE is one of the important properties to assess the feasibility of the glass material for laser sealing application. Well-matched CTE can guarantee its lifetime during the sealing process, along with long-term operation from thermal shock [23,24,25]. It is well known that the expansion of a glass material depends mainly on the internal network structure, the arrangement of the constituting building units, and the bond strength between the atoms involved. Thermomechanical analysis of the present glasses was carried out by using the dilatometer in the range of 25–450 °C. The dilatometer is used for characterizing the dimensional changes (length or volume) of glass material as a function of temperature. The coefficient of thermal expansion is obtained by linear fitting the dilatometric curves. Figure 5 shows the variation of CTE in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, n = 3, 2, respectively, mol%) glass as a function of metaphosphate concentration. The results show that as xM(PO3)n (where M = Al, Mg, n = 3, 2, respectively, mol%) concentration increases, the CTE reached the highest values of 13.88 × 10−6/K and 9.991 × 10−6/K at x = 12.5 mol%, respectively.
According to Tsutomu et al., it was reported that the increase of CTE is due to a decrease in the cation field strength, along with the increase of radius of alkali cations in a R2O-Al2O3-P2O5 and R2O-P2O5-WO3 glass system, analogous to the case of silicate glasses [26]. However, it can be seen that cation field strength is in the order of Na(0.961 Å−2) < Mg(3.858 Å−2) < Al(10.679 Å−2) as listed in Table 2. Accordingly, it is expected that the CTE of Mg(PO3)2 should be higher that of Al(PO3)3 in a (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, n = 3, 2, respectively, mol%) glass system, because the cation field strength of Mg was lower than that of Al. However, the opposite trend of CTE was observed. Bingham et al. studied the effect of monovalent and divalent modifiers in a ((1-x)-(0.6P2O5–0.4Fe2O3))-xRySO4, glass system (x = 0 - 0.5 in increments of 0.1 and R = Li, Na, K, Mg, Ca, Ba, or Pb and y = 1 or 2). They reported that the increase of monovalent and divalent modifier contents elevates the CTE (50–300 °C), Tg, Td, and Tliq in a ((1-x)-(0.6P2O5–0.4Fe2O3))-xRySO4, glass system. It was assumed that the addition of alkaline earth, such as MgO, depolymerizes the glass structure (P-O-P bonds → P-O-M bonds), resulting in the increase of Tg and Td [26,27]. In the present study, the effect of monovalent NaPO3 on Tg was less dominant compared to those of divalent Mg(PO3)2 or trivalent Al(PO3)3 in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%), as explained in Figure 3. In terms of the thermomechanical properties, the substitution of Al(PO3)3 in the current glass system led to a strong effect on CTE compared to Mg(PO3)2. As discussed in several studies, it indicates that the network bonding and connectivity is more strongly influenced by divalent Mg(PO3)2 or trivalent Al(PO3)3 than monovalent NaPO3, and is consistent with the greater field strength and M–O bond strength of divalent Mg(PO3)2 or trivalent Al(PO3)3. However, the increase in CTE with increasing modifier content would appear to dispute this structural assertion, as thermal expansion is also strongly influenced by the strength of network bonding, its connectivity, and the interactions between cations and nonbridging oxygen [28]. The CTE can also be explained based on the density. It is well known that the decreasing trend of density causes an increase in volume expansivity, resulting in an increase in the CTE of glass. Accordingly, in the present study, the density of the glasses decreased with respect to metaphosphate content at various concentrations, causing an increase in the CTE (see Figure 2 and Figure 5).

3.4. Structural Properties

Vibrational spectroscopy, namely Raman spectroscopy in this work, can supply useful information about the structure of non-crystalline materials. In comparison with IR spectroscopy, Raman spectroscopy is more sensitive to vibrations of bonds with a high covalence, which is advantageous for the study of changes in the structure of the phosphate backbone (P–O bonds) and the vibrations of V–O bonds in which a higher content of covalence (higher polarizability) is also assumed, contrary to the higher ionicity of Zn–O bonds. Figure 6 shows the Raman spectra of a 55V2O5-5ZnO-22BaO-3B2O3-15M(PO3)n (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glass system modified with M(PO3)n concentration up to 15 mol%. As is seen from the spectra, all the studied glasses showed the characteristic vibration bands of vanadium and phosphate. The peak position and assignment of the vibrational bands observed at around 275, 491, 706, 991, 1120, and 1326 cm−1 are shown in Table 3. The distinctive bands related to the V2O5 are observed at 291, 399, 665, 799, and 1154 cm−1 which are assigned as shown in Table 3. The short-range order of phosphate glasses has been commonly described by the concepts of four different phosphate structural units derived from PO4 tetrahedra, labeled as Qn, where the superscript n = 0, 1, 2, and 3 denotes the number of bridging oxygen per tetrahedron [29]. Q0 represents the orthophosphate groups, Q1 indicates the terminal units of chains or pyrophosphate groups (Q1-Q1), Q2 corresponds to metaphosphate groups, and Q3 attributes to ultraphosphate groups. As shown in Figure 6, it is clear that the intensity and bandwidth of the Raman bands increased with the substitution of different metaphosphates, as compared to that of base VZBB glass. It is worth mentioning that the intensity and bandwidth of the distinctive bands observed at around 275, 706, and 991 cm−1 significantly increased when Al(PO3)3 metaphosphate substituted for V2O5 due to the formation of strong V–O–Al coupling and a broadening and merging of bands. The decrease in broadening of the bands is clearly observed, with decreasing charge and covalence of the ions from Al3+ through Mg2+ to Na+. Furthermore, Raman spectra also showed the shift of the P-O-P band to lower energies, with decreasing charge and covalence of the ions from Al3+ through Mg2+ to Na+. This indicates that the Al bands merge together with the phosphate network deformation bands due to coupling of Al–O–P. Other bands also show some degree of merging. This behavior is validated from the XPS studies in a M(PO3)n modified (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glass system.
Structural analysis via X-ray photoelectron spectroscopy (XPS) was carried out to identify the correlation between the change in thermal properties and the structural change depending on M(PO3)n in a (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, n = 3, 2, respectively, mol%) glass system. A nonlinear, least-squares algorithm was employed to determine the best fit to the O 1s spectra, with three Gaussian–Lorentzian curves in order to distinguish various oxygen bonding sites (such as BO and NBO). The fraction (relative abundance) of various oxygen bonding sites was determined from the respective area ratios obtained from optimized fits. Figure 7 shows the high-resolution XPS spectra along with their deconvoluted curves for the O 1s core level for AP15 and MP15. The resulting peak positions and area under the peaks of the different oxygen sites from the curve fitting of O 1s core levels for specimens are displayed in Table 4. Typically, the 1s O peak of oxide glass consists of two components: bridging oxygen (BO) at a higher energy and nonbridging oxygen (NBO) at a lower energy [30,31]. In particular, it has been reported that the XPS spectra of a P2O5-V2O5-based glass system was deconvoluted into more than three curves [32,33]. In this work, the area of the BO peak at 532.55eV shows 33.95 % and 32.46 % for Mg(PO3)2, and Al(PO3)3, respectively. The area of the BO peak indicating P-O-P bonds is not significantly distinguished by the type of Mg(PO3)2 and Al(PO3)3. On the other hand, the areas of BO peaks at 531 eV are 29.55 % and 40.24 % for Mg(PO3)2 and Al(PO3)3, respectively, as shown in Figure 7.
XPS studies on vanadium phosphate-based glasses reported that the P-O-P bonds as a BO structure would have the strongest covalent bonds, since the Pauling electronegativity is in the order of P (2.19), V (1.63), Al (1.61), Mg (1.31), and Ba (0.89). Consecutively, the binding energy would be weakened in the order of P-O-V, P-O-Al, V-O-V, and V-O-Al bonds as intermediate BO structures, and P-O-Mg, V-O-Mg, P-O-Ba, and V-O-Ba bonds as NBO structures [32,33]. The area of BO peak at 531 eV by Al(PO3)3 is larger than that by Mg(PO3)2, which means that Al(PO3)3 preferentially formed intermediate BO, such as P-O-Al bonds in the current glass system. On the other hand, it is believed that the area of NBO peak from Mg(PO3)2 means the forming of major P-O-Mg and V-O-Mg bonds, as well as the V-O-Ba and P-O-Ba bonds in a 55V2O5-5ZnO-22BaO-3B2O3- Mg(PO3)2 (mol%) glass system. A similar effect by Al3+-ions reported that the relative fractions of P-O-P bonds (BO) and P-O-Na bonds (NBO) decrease, and the fraction of P-O-Al bonds (BO) increases with an increase of Al2O3 content in an Al2O3-NaPO3 glass system [34]. Moreover, Al3+-ions, when added to phosphate glass, have been known to increase the degree of structural polymerization via forming the crosslinked P-O-Al structure within the glass networks. The substitution of AlPO4 for NaPO3 consumes both P-O-P and P-O-Na+ bonds to form P-O-Al bonds, which crosslink and shorten the P-O-P chains in the Al(PO3)3-Na(PO3) system [35,36]. On the other hand, it is believed that the area of NBO peak from Mg(PO3)2 means the forming of major P-O-Mg and V-O-Mg bonds, as well as the V-O-Ba and P-O-Ba bonds in 55V2O5-5ZnO-22BaO-3B2O3-Mg(PO3)2 (mol%). This trend can be described as a role of the alkaline earth within the glass. Generally, the incorporation of alkaline earth, such as MgO, CaO, SrO, and BaO, within the glass matrix results in depolymerization of glass structure. Indeed, it was reported that Mg2+-ions break the glass network and can take a position in the vanadate or phosphate chain within the MgO-V2O5 and MgO-P2O5 systems [26,27]. Consequentially, the trivalent Al-ion within the glass is well-known as a network intermediate which plays a role in increasing thermal/chemical stability, melting temperature, and viscosity, and reducing crystallization tendency [37]. Therefore, it could be assumed that Al3+-ions from Al(PO3)3 contributed to the enhancement of Tg by reducing the fraction of NBO by preferentially forming intermediate BOs, such as the P-O-Al and V-O-Al bonds [35]. As explained in Figure 3 and Figure 4, these results supported that the network bonding and connectivity being more strongly improved by trivalent Al(PO3)3 led to an increase in Tg and, in turn, the thermal stability.

4. Conclusions

The (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) incorporated with different M(PO3)n at various concentrations (where M = Mg, Al, n = 2, 3, respectively) was prepared to observe its aptness for fiber types of sealant. The thermal stability of the (70-x) V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system in x = 15 mol% (where M = Mg, Al, n = 2, 3 respectively, mol%) increased from 30.4 °C to 93.2 °C and 112.9 °C, respectively. Incorporation of Al(PO3)3 increased the degree of structural polymerization through forming crosslinked P-O-Al bonds. The Al(PO3)3 plays a role in increasing thermal stability and reducing crystallization tendency. The coefficient thermal expansion of the (70-x)V2O5-5ZnO-22BaO-3B2O3-xAl(PO3)3 glass system (mol%) (where x = 5~15, mol%) is in the range of 9.5–15.5 (×10−6/K). These developed glass compositions are tunable for matching the thermal expansion coefficient with DSSC panels having 9–10 (×10−6/K) of CTE. The considerable variation in the thermal stability and CTE with the substitution of Al(PO3)3 indicates that the network bonding and connectivity being more strongly improved led to an increase in the Tg and, in turn, the thermal stability. The Raman and XPS studies also confirm the network connectivity and bond strength with the substitution of Al(PO3)3 in the present system. The results clearly indicate that the 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3 glass system (mol%) is a potential candidate for the development of fiber types of sealant in laser sealing applications.

Author Contributions

Glass fabrication, analysis and original draft preparation, S.K. (Soyoung Kim) and K.H.; formal analysis, S.K. (Seonhoon Kim) and L.K.; writing—original draft preparation, J.C.; writing—review and editing, L.K. and J.K. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Technology Development Program (S2888597) funded by the Ministry of SMEs and Startups (MSS, Korea).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Wang, W.; Xiao, Y.; Wu, X.; Zhang, J. Optimization of laser-assisted glass frit bonding process by response surface methodology. Opt. Laser Technol. 2016, 77, 111–115. [Google Scholar] [CrossRef]
  2. Cruz, R.; da Cruz Ranita, J.A.; Maçaira, J.; Ribeiro, F.; da Silva, A.M.B.; Oliveira, J.M.; Mendes, A. Glass–Glass Laser-Assisted Glass Frit Bonding. IEEE Trans. Compon. Packag. Manuf. Technol. 2012, 2, 1949–1956. [Google Scholar] [CrossRef]
  3. Lee, K.; Ko, M.J. The Effect of Sealing Technology on the Long-Term Stability of Dye-Sensitized Solar Cell Module. Curr. Photovolt. Res. 2016, 4, 155–158. [Google Scholar] [CrossRef] [Green Version]
  4. Dietz, R.L. Optical fiber sealing with solder glass. In Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education; International Society for Optics and Photonics: Ottawa, ON, Canada, 2004; pp. 642–651. [Google Scholar]
  5. Daniel, H.S.; Moore, D.R.; Tekippe, V.J. Glass soldering improves photonic component packaging. Laser Focus World 1994, 30, 94. [Google Scholar]
  6. Kim, S.Y.; Park, J.; Kim, S.H.; Kadathala, L.; Baek, J.H.; Kim, J.H.; Choi, J.H. The Tuning Capability of CuO and Na2CO3 Dopant on Physical Properties for Laser Sealing Using Fiber Types of Sealant. Appl. Sci. 2020, 10, 353. [Google Scholar] [CrossRef] [Green Version]
  7. Morena, R. Phosphate glasses as alternatives to Pb-based sealing frits. J. Non-Cryst. Solids 2000, 263–264, 382–387. [Google Scholar]
  8. Sung, W.; Won, J.; Lee, J.; Kim, H. Properties and Structure of P2O5-V2O5-ZnO/B2O3 Glasses. Mol. Cryst. Liq. Cryst. 2009, 499, 234–241. [Google Scholar] [CrossRef]
  9. Naito, T.; Matsuda, A.; Shiojiri, D.; Aoyagi, T.; Sawai, Y.; Fujieda, T.; Yoshimoto, M. Yoshimoto. Influence of P2O5/TeO2 composition ratio on the physical properties of V2O5–P2O5–TeO2 glasses for lead-free low-temperature sealing. J. Ceram. Soc. Jpn. 2013, 121, 452–456. [Google Scholar] [CrossRef] [Green Version]
  10. Chung, W.J.; Kim, K.H.; Choi, Y.G.; Shin, D.W. Compositional Effect on the Electrical Properties of V2O5–P2O5–WO3 System. J. Am. Ceram. Soc. 2010, 93, 2292–2296. [Google Scholar] [CrossRef]
  11. Stachel, D.; Barz, A. Structure investigations of ultraphosphate glasses with some water content. J. Phys. Chem. Solids 2007, 68, 1021–1023. [Google Scholar] [CrossRef]
  12. Minami, T.; Mackenzie, J.D. Thermal Expansion and Chemical Durability of Phosphate Glasses. J. Am. Ceram. Soc. 1997, 60, 232–235. [Google Scholar] [CrossRef]
  13. Li, Y.; Yang, J.; Xu, S.; Wang, G.; Hu, L. Physical and thermal properties of P2O5-Al2O3-BaO-La2O3 glasses. J Mater Sci Technol. 2005, 21, 391–394. [Google Scholar]
  14. Mošner, P.; Vosejpková, K.; Koudelka, L.; Montagne, L.; Revel, B. Structure and properties of ZnO–B2O3–P2O5–TeO2 glasses. Mater Chem Phys. 2010, 124, 732–737. [Google Scholar] [CrossRef]
  15. Muñoz-Senovilla, L.; Muñoza, F. Behaviour of viscosity in metaphosphate glasses. J Non-Cryst Solids 2014, 385, 9–16. [Google Scholar] [CrossRef]
  16. Tsuchida, J.E.; Schneider, J.; Pizani, P.S.; Oliveira, S.L. Lead and Aluminum Bonding in Pb Al Metaphosphate Glasses. Inorg. Chem. 2008, 47, 690–698. [Google Scholar] [CrossRef]
  17. Sohn, I.; Min, D.J. A Review of the Relationship between Viscosity and the Structure of Calcium-Silicate-Based Slags in Ironmaking. Steel Res. Int. 2012, 83, 611–630. [Google Scholar] [CrossRef]
  18. Schneider, J.; Oliveira, S.L.; Nunes, L.A.O.; Bonk, F.; Panepucci, H. Panepucc. Short-Range Structure and Cation Bonding in Calcium−Aluminum Metaphosphate Glasses. Inorg. Chem. 2005, 44, 423–430. [Google Scholar] [CrossRef]
  19. Nascimento, M.L.F.; Souza, L.A.; Ferreira, E.B.; Zanotto, E.D. Can glass stability parameters infer glass forming ability? J. Non. Cryst. Solids 2005, 351, 3296–3308. [Google Scholar] [CrossRef] [Green Version]
  20. Mandlule, A.; Döhler, F.; van Wüllen, L.; Kasuga, T.; Brauer, D.S. Changes in structure and thermal properties with phosphate content of ternary calcium sodium phosphate glasses. J Non-Cryst Solids 2014, 392–393, 31–38. [Google Scholar] [CrossRef]
  21. Ahmed, A.A.; Ali, A.A.; Mahmoud, D.A.; El-Fiqi, A.M. Preparation and characterization of antibacterial P2O5-CaO-Na2O-Ag2O glasses. J. Biomed. Mater. Res. A 2011, 98, 132–142. [Google Scholar] [CrossRef]
  22. Amos, R.T.; Henderson, G.S. The effects of alkali cation mass and radii on the density of alkali germanate and alkali germano-phosphate glasses. J Non-Cryst Solids 2003, 331, 108–121. [Google Scholar] [CrossRef]
  23. Marzouk, M.A.; ElBatal, F.H.; ElBadry, K.M.; ElBatal, H.A. Optical, structural and thermal properties of sodium metaphosphate glasses containing Bi2O3 with interactions of gamma rays. Spectrochim. Acta A 2017, 171, 454–460. [Google Scholar] [CrossRef] [PubMed]
  24. Hollaway, D.G. The Physical Properties of Glass; Wykeham publications Ltd.: London, UK, 1973; pp. 36–41. [Google Scholar]
  25. Shelby, J.E. Introduction to Glass Science and Technology, 2nd ed.; The Royal Society of Chemistry United Kingdom: London, UK, 2005; p. 154. [Google Scholar]
  26. Khan, S.; Singh, K. Effect of MgO on Structural, Thermal and Conducting Properties of V2-xMgxO5-δ (x = 0.05–0.30) Systems. Ceram. Int. 2019, 45, 695–701. [Google Scholar] [CrossRef]
  27. Walter, G.; Vogel, J.; Hoppe, U.; Hartmann, P. Hartmann. Structural Study of Magnesium Polyphosphate Glasses. J. Non-Cryst. Solids 2003, 320, 210–222. [Google Scholar] [CrossRef]
  28. Bingham, P.A.; Hand, R.J.; Hannant, O.M.; Forder, S.D.; Kilcoyne, S.H. Effects of modifier additions on the thermal properties, chemical durability, oxidation state and structure of iron phosphate glasses. J. Non-Cryst. Solids 2009, 355, 1526–1538. [Google Scholar] [CrossRef] [Green Version]
  29. Brow, R.K. Review: The structure of simple phosphate glasses. J. Non-Cryst. Solids 2000, 263–264, 1–28. [Google Scholar] [CrossRef]
  30. Wang, P.W.; Zhang, L. Structural role of lead in lead silicate glasses derived from XPS spectra. J. Non-Cryst. Solids 1996, 194, 129–134. [Google Scholar] [CrossRef]
  31. Khattak, G.D.; Salim, M.A.; Wenger, L.E.; Gilani, A.H. X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of copper-vanadium phosphate glasses. J. Non-Cryst. Solids 2000, 262, 66–79. [Google Scholar] [CrossRef]
  32. Khattak, G.D.; Mekki, A.; Wenger, L.E. X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses. J. Non-Cryst. Solids 2009, 355, 2148–2155. [Google Scholar] [CrossRef]
  33. Majjane, A.; Chahine, A.; Et-tabirou, M.; Echchahed, B.; Do, T.O.; Mc Breen, P. X-ray photoelectron spectroscopy (XPS) and FTIR studies of vanadium barium phosphate glasses. Mater. Chem. Phys. 2014, 143, 779–787. [Google Scholar] [CrossRef]
  34. Brow, R.K.; Kirkpatrick, R.J.; Turner, G.L. Local Structure of xAl2O3·(I − x)NaPO3 Glasses: An NMR and XPS Study. J. Am. Ceram Soc. 1990, 73, 2293–2300. [Google Scholar] [CrossRef]
  35. Brow, R.K. Nature of Alumina in Phosphate Glass: I, Properties of Sodium Aluminophosphate Glass. J. Am. Ceram Soc. 1993, 76, 913–918. [Google Scholar] [CrossRef]
  36. Brow, R.K.; Kirkpatrick, R.J.; Turner, G.L. Nature of Alumina in Phosphate Glass: II, Structure of Sodium Aluminophosphate Glass. J. Am. Ceram Soc. 1993, 76, 919–928. [Google Scholar] [CrossRef]
  37. Wang, C.Y.; Chen, M.; Chen, J.H. (Eds.) Glass Making Techniques; Chemical Industry Press: Beijing, China, 2006; Chapter 4. [Google Scholar]
Applsci 11 04603 g001 550
Figure 1. Thermal profile of (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%), and inset depicts photographs of glass samples.
Figure 1. Thermal profile of (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%) (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%), and inset depicts photographs of glass samples.
Applsci 11 04603 g001
Applsci 11 04603 g002 550
Figure 2. Variation of (a) Density and (b) Molar volume with respect to M(PO3)n concentration in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (where M = Al, Mg, n = 3, 2, respectively, mol%) glass system.
Figure 2. Variation of (a) Density and (b) Molar volume with respect to M(PO3)n concentration in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (where M = Al, Mg, n = 3, 2, respectively, mol%) glass system.
Applsci 11 04603 g002
Applsci 11 04603 g003 550
Figure 3. Effect of M(PO3)n concentration on thermal properties in V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (where M = Al, Mg, Na mol%, n = 3, 2, 1, respectively) glass system. (a) DSC curves, (b) glass transition temperature (Tg), crystallization onset temperature (Tx) and peak crystallization temperature (Tp).
Figure 3. Effect of M(PO3)n concentration on thermal properties in V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (where M = Al, Mg, Na mol%, n = 3, 2, 1, respectively) glass system. (a) DSC curves, (b) glass transition temperature (Tg), crystallization onset temperature (Tx) and peak crystallization temperature (Tp).
Applsci 11 04603 g003
Applsci 11 04603 g004 550
Figure 4. Variation of thermal stability with respect to xM(PO3)n concentration (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%).
Figure 4. Variation of thermal stability with respect to xM(PO3)n concentration (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n glass system (mol%).
Applsci 11 04603 g004
Applsci 11 04603 g005 550
Figure 5. Variation of coefficient of thermal expansion (CTE) in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, n = 3, 2, respectively, mol%) glass as a function of metaphosphate concentration.
Figure 5. Variation of coefficient of thermal expansion (CTE) in (70-x)V2O5-5ZnO-22BaO-3B2O3-xM(PO3)n (mol%) (where M = Al, Mg, n = 3, 2, respectively, mol%) glass as a function of metaphosphate concentration.
Applsci 11 04603 g005
Applsci 11 04603 g006 550
Figure 6. Comparison of the Raman spectra in 55V2O5-5ZnO-22BaO-3B2O3-15M(PO3)n (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glass system and 70V2O5-5ZnO-22BaO-3B2O3 glass system. Refer to Table 1.
Figure 6. Comparison of the Raman spectra in 55V2O5-5ZnO-22BaO-3B2O3-15M(PO3)n (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glass system and 70V2O5-5ZnO-22BaO-3B2O3 glass system. Refer to Table 1.
Applsci 11 04603 g006
Applsci 11 04603 g007 550
Figure 7. Comparison of the XPS spectra of (a) 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3, and (b)55V2O5-5ZnO-22BaO-3B2O3-15Mg(PO3)2.
Figure 7. Comparison of the XPS spectra of (a) 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3, and (b)55V2O5-5ZnO-22BaO-3B2O3-15Mg(PO3)2.
Applsci 11 04603 g007
Table
Table 1. Chemical composition of the present glasses, (Al(PO3)3 = xAP, Mg(PO3)2 = xMP and NaPO3 = xNP (where x = 2.5, 5, 7.5, 10, 12.5, 15) (mol%).
Table 1. Chemical composition of the present glasses, (Al(PO3)3 = xAP, Mg(PO3)2 = xMP and NaPO3 = xNP (where x = 2.5, 5, 7.5, 10, 12.5, 15) (mol%).
GlassesV2O5ZnOBaOAl(PO3)3B2O3
VZBB7052203
AP2.567.55222.53
AP5.06552253
AP7.562.55227.53
AP10.060522103
AP12.557.552212.53
AP15.055522153
GlassesV2O5ZnOBaOMg(PO3)2B2O3
MP2.567.55222.53
MP5.06552253
MP7.562.55227.53
MP10.060522103
MP12.557.552212.53
MP15.055522153
GlassesV2O5ZnOBaONaPO3B2O3
NP2.567.55222.53
NP5.06552253
NP7.562.55227.53
NP10.060522103
NP12.557.552212.53
NP15.055522153
Table
Table 2. Ratio between charge, ionic radius, and cation field strength in Na, Mg, and Al [17].
Table 2. Ratio between charge, ionic radius, and cation field strength in Na, Mg, and Al [17].
Cation (M)Charge (Z)Ionic Radius (α)Ratio (Z/α)Cation Field Strength (Z/α2)
Na11.02 Å0.980 Å−10.961 Å−2
Mg20.72 Å2.778 Å−13.858 Å−2
Al30.53 Å4.615 Å−110.679 Å−2
Table
Table 3. Assignment of observed Raman bands of V2O5-5ZnO-22BaO-M(PO3)x-3B2O3 (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glasses.
Table 3. Assignment of observed Raman bands of V2O5-5ZnO-22BaO-M(PO3)x-3B2O3 (where M = Al, Mg, Na, n = 3, 2, 1, respectively, mol%) glasses.
Raman Vibrational Bands (cm−1)Attributed Vibrational Modes
VZBBVA#1-6VM#1-6VN#1-6
291275289279Bending modes of PO4 tetrahedra units or bending vibrations of V3–O, V–O–V, and V=O bonds
399491494496Bending modes of PO4 tetrahedra units or stretching vibration of V3–O bonds
665-626633Stretching vibrations of V–O–V, V–O–P, P–O–P bonds
799706685689Stretching vibrations of V–O–V, V–O–P, P–O–P bonds
1154991984979V=O vibrations in VO4 tetragonal pyramid or PO4 vibrations of Q0 units
-1120-1127PO2 symmetric stretching in O–P–O groups of corner sharing PO4 tetrahedra
-13261327Symmetric stretching modes of P=O bonds of Q3 units
Table
Table 4. Peak positions and area from the curve fitting of O 1s core levels for 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3 and 55V2O5-5ZnO-22BaO-3B2O3-15Mg(PO3)2 glasses (mol%).
Table 4. Peak positions and area from the curve fitting of O 1s core levels for 55V2O5-5ZnO-22BaO-3B2O3-15Al(PO3)3 and 55V2O5-5ZnO-22BaO-3B2O3-15Mg(PO3)2 glasses (mol%).
15 mol% Al(PO3)315mol% Mg(PO3)2
Area (%)Centroid (eV)Area (%)Centroid (eV)
NBO27.3530.0936.49529.97
BO40.24531.1729.55531.07
BO32.46532.5533.95532.24
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Kim, S.; Han, K.; Kim, S.; Kadathala, L.; Kim, J.; Choi, J. Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications. Appl. Sci. 2021, 11, 4603. https://doi.org/10.3390/app11104603

AMA Style

Kim S, Han K, Kim S, Kadathala L, Kim J, Choi J. Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications. Applied Sciences. 2021; 11(10):4603. https://doi.org/10.3390/app11104603

Chicago/Turabian Style

Kim, Soyoung, Karam Han, Seonhoon Kim, Linganna Kadathala, Jinhyeok Kim, and Juhyeon Choi. 2021. "Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications" Applied Sciences 11, no. 10: 4603. https://doi.org/10.3390/app11104603

APA Style

Kim, S., Han, K., Kim, S., Kadathala, L., Kim, J., & Choi, J. (2021). Strengthening Thermal Stability in V2O5-ZnO-BaO-B2O3-M(PO3)n Glass System (M = Al, Mg) for Laser Sealing Applications. Applied Sciences, 11(10), 4603. https://doi.org/10.3390/app11104603

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop