Structural characterization and Thermal Behavior of ...

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Jun 7, 2017 - mol%, while the molar volume of glass TNS4 and TNS5 decreased with increasing of Sm. 3+ content,this behaviorcan be explained as the. Sm.
Mawlud S. et of al./ZJPAS: 2017,Applied 29(2): 32-42 ZANKO Journal Pure and Science The official scientific journal of Salahaddin University-Erbil ZJPAS (2017), 29 (2); 32-42 http://dx.doi.org/10.21271/ZJPAS.29.2.4

Structural characterization and Thermal Behavior of Sm3+ Ions Doped Sodium Tellurite Glasses 1,2

Saman Q. Mawlud, 1Mudhafar M. Ameen, 2Md. Rahim Sahar, 1,2Kasim F. Ahmed

1

Department of Physics, College of Education, University of Salahaddin, Erbil, Kurdistan Region, Iraq. Advanced Optical Material Research Group, Department of Physics, Faculty of Science, University of Technology Malaysia, Skudai, Johor, Malaysia.

2

A RT I C L E I N FO ArticleHistory: Received:27/08/2016 Accepted:20/11/2016 Published:07/06/2017 Keywords: Tellurite glass, Rare Earth, Glass transition, FTIR, Raman spectra *CorrespondingAuthor: Saman Q. Mawlud Email: [email protected]

A B ST R AC T The influence of Sm+3 ions concentration doped sodium tellurite glasses on structural characterizationand thermal parameters have been investigated. Glass samples with molar composition (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 glasses (x=0, 0.3, 0.6, 1, 1.2, 1.5) are prepared by conventionalmelt quenching technique.Crystallization temperature (T c ), melting temperature (T m ) and glass transition temperature (T g ) are measured by using differential thermal analysis (DTA),it is found that the stability factor (ΔT) of the glassincreases from (58.5to97.8) ºC with the increasingSm 2 O 3 . The amorphous phase nature of the glass samplesare observed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysisspectrometer are applied to study the structural properties of the glass samples. Values of Thedensity (ρ), molar volume (V M ), and ionic packing density (V t ) were calculated for each of the glass compositions.The effect of the Sm 2 O 3 on the glass structure has been investigated by using Fourier transform infrared (FTIR)and Raman spectroscopies, the FTIR spectra are characterized by a band of 637 cm-1 for the telluride glass, high frequency peak at 668 cm-1 presented by Raman spectra which indicates that these glasses network arebasically consists of TeO 4 and TeO 3 /TeO 3+1 structural units. The Raman spectra of shows the presence of Sm-O bond, Na-O bond, Te-O-Te bridging configurations, vibrations of Te-O-Te bonds and stretching modes of non-bonding oxygen found on the TeO 3 /TeO 3+1 structural unit.

1. INTRODUCTION Under normal quenching conditions tellurium dioxide (TeO 2 ) does not possess the ability of forming a glassy network without

theaidof the secondary material component which is called a network modifier.This specific feature makes TeO 2 a conditional glass former (El-Mallawany, 2011;

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 Çelikbileket al., 2011).Manystudies indicate that heavy metal oxide (HMO) glasses have been found to be more promising convenient glassy materials especially for photonic applications with acceptable low phonon energies (Sun et. al., 2006;Pan et. al., 1996),their wide advantages of tellurite glasses makes them to be represented as a more attractive structure among the HMO glasses such as low temperature of melting, good corrosion resistance, excellent chemical durability, low glass transition temperature T g , better thermal stability, high thermal expansion coefficient, low phonon energy, wide optical transmission region (especially in the infrared region) (0.36μm–6.3μm), high refractive index and required rare earth concentration in the matrices (Xuet al., 2005).Basically, the structure of TeO 2 glasses contains of three dimensional network of TeO 4 trigonal bipiramids (tpb) units having two each of oxygen at two equatorial and axial sites with one other equatorial site being occupied by a lone pair of electrons, once the modifier is introduced to the structure, the three dimensional network will break down with the conversion of TeO 4 units into TeO 3+1 and TeO 3 units (Kiefferet al., 2006; Radaet al. 2011). In addition to the glass former conditionality and fast quenching requirements properties of tellurite glasses, they are also counted as a good host for the formation of rare earth doped glasses.The Te– O bonds are weak and canbe broken easilyby addingheavy metal and the rare earth atoms (Muraliet al., 2005). In the literature there are relatively few reports on structural of glasses doped with Sm 3 O ions (Bolundutet al., 2015;Yusoffet al. 2015). Accordingly the present work aims to investigate the influence of Sm3+ ion on the structural and thermal properties of TeO 2 -Na 2 O glasses. The thermal modification of the glass system were analyzed by DTA technique and the structure

of the Sm 2 O 3 doped glasses has been studied through Raman and FTIR Spectra. 2. MATERIALS AND METHODS TeO 2 -Na 2 O-Sm 2 O 3 glass samples possessing compositions(80-x) TeO 2 with 20Na 2 O-xSm 2 O 3 (x=0,0.3,0.6,1,1.2,1.5)are prepared using melt quenching techniquewhich is essentially the amorphous solid can be formed by the continuous hardening (namely increase in viscosity) of the melt,, glasses code of the samples and their molar ratio of the compositions are listed in Table 1.High purity 99.9% of raw materials from Sigma Aldrichwith an appropriate amounts of chemicals for 15gm batch were weighed by using electronic balance Precisa 205A SCS model with accuracy ±0.001gm,the chemical compositions were mixed well by using a milling machine. Platinum crucible of about 30ml capacity containing the batch was used and preheated at 250ºC for about minutes for reducing the batch blanket coverage on the top of the glass and enlarges the free non coverage glass melt surface(Saharat al., 2007).Then the batch is melted at 900 ºC for 40 min by a controlled electric furnace. The melts are poured on to a stainless steel mold and annealed at 250 ºC for 3hours, then the sample cooled down tothe room temperature, sample powder of the glass prepared and used for characterizing each of T g , T c and T m by Pyris Dymond TG/DTA technique at a heating rate 50°C-1000°C at 10°C/min.To analysis the amorphous state of the samples an advanced powder XRD Bruker D8 were used, the CuKα radiation specification was (1.54A°) at 40 kV, 100mA and scanning angel 2θ ranges between 10°-80°. A Perkin– Elmer FTIR double beam spectrometer over the range 400-4000 cm-1 are used for studying the transmission measurements, the spectra resolution of 4 cm-1at room temperature made by using KBr pelletswere investigated.Raman analysisis performed using a confocal Horbia

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 Jobin Yvon (Model HR800 UV) with Argon ion laser (excitation wavelength 514.55 nm) operates at 20 mW in the range of 100-900 cm-1. Relatively fine glass powders are used for Raman and FTIR measurements. Traditional Archimedes method is used for determining the density of the glass sample after measuring the weight of the sample by using a sensitive analytical balance PrecisaXT220A, toluene ( =0.8669 gcm-3)is used as an immersed liquid.Thedensity iscalculatedusingtheexpression (Azmiet al., 2015):

WhereW a and Wt are weightoftheglasssampleinairand in toluene respectively, is the density of air and is the density of the toluene. The molar volume (V M ) of the glasses was calculated from density values according to (Yusoff and Sahar, 2015):

where M is the molar weight and ρ is the density of the glass. The ionic packing density (V t ) is calculated using Makishima and Mackenzie approach (Yusoff and Sahar, 2015; kareemet al., 2011),

glass samplesis shown in Figure 1, it can be seen thatthe density of TNS glass system increasesfrom 4.903 gcm-3 for x=0 mol% to 5.019g cm-3 forx=1.2 mol% of Sm3+ion. Higher molecular mass of Sm 3 O 2 (348.74 g mol-1) andthose for TeO 2 (159.60 g mol1 )might be responsible for increase its density [15]. The decrease in density at x=1.5mol% might be caused by Sm3+ ions which participatein the structure of glass and make the density decreased(Yusoff and Sahar, 2016).A molar volume of the TNS glassagainst Sm 2 O 3 % is plotted in the Figure1, it reveals that the molar volumeof glass increased from TNS1 to TNS3 as the Sm3+content increased from 0 mol% to 0.6 mol%, while the molar volume of glass TNS4 and TNS5 decreased with increasing of Sm3+ content,this behaviorcan be explained as the Sm3+mole friction content increased the structure of glasses willget more compact due to increase in packing density of oxygen (Yusoff and Sahar, 2016), thisis indicate that the structureof TNS glasses changed, this manners of molar volume is in consistent with the increasing behavior of rigidity and compactness of glass samples(Hajeret al., 2014).

Density (gm cm-3)

where x i is the mole fraction (mol%) and V i is packing density parameter (m3/mol). For an oxide glass of the form M x O Y , the value of V i yields (Yusoff and Sahar, 2015):

29.0

ρ VM

5.00

28.9 28.8

4.98

28.7

4.96

28.6

4.94

28.5

4.92

28.4

4.90 -

whereN A is Avogadro’s number (mol ), r M and r o are the Shannon’s ionic radius of metal and oxygen, respectively. Table 1represents the glass sample code and their molar ratio effect on each of the density, molar volume and ionic packing density.The effect of Sm 2 O 3 %on both of the density and molar volume for each composition of the 1

0.0

0.3

0.6 0.9 1.2 Sm2O3 (mol%)

1.5

28.3

Molar Volume (cm3mol-1)

5.02

Figure 1: Density and molar volume of the glasses (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 as a function of Sm 2 O 3 mol%.

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 Table 1: Glasses sample code and calculated density, molar volume and ionic packing density. Sample Code TNS1 TNS2 TNS3 TNS4 TNS5 TNS6

TeO 2 % 80 79.7 79.4 79 78.8 78.5

Na 2 O % 20 20 20 20 20 20

Sm 2 O 3 % 0 0.3 0.6 1 1.2 1.5

3. RESULTS AND DISCUSSION 3.1 XRD Analyses In order to check the non-crystalline nature of the glass samples, the XRD measurement is performed for all samples and the result can be seen in Figure 2. The presence of a broad hump between 25 − 35° without any sharp crystallization peaks confirms the amorphous nature of the prepared glass samples. It can be seen thatthe results did not reveal any kinds of sharp peaks, therefore,proving the amorphous nature structure of the present glass.In this study, no sharp characteristic peak of Sm is evidenced due to its small concentration in the samples.

Figure 2: Typical XRD pattern of (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 glasses (x=0, 0.3, 0.6, 1, 1.2, 1.5)glasses. 3.2 SEM-EDX Spectra

M g mol-1 140.07 140.64 141.21 141.97 142.34 142.91

Vt 0.4012 0.4017 0.4019 0.4051 0.4092 0.4025

VM cm3 mol-1 28.571 28.623 28.700 28.593 28.359 28.919

ρ g cm-3 4.903 4.914 4.920 4.965 5.019 4.942

The EDX spectra evaluate the amount of eachelement present in the glasses.It is important to mark that EDX measured elements by calculating the area under the peak of each identified element(Noran, 1999).SEM-EDX investigations were performed on the (80-x) TeO 2 -20Na 2 OxSm 2 O 3 with (x=1)% molefraction glasses in order to identifychangesinmorphologyandchemicalco mposition.The typical EDX spectrum of TNS4 glass sample from selected area as shown in Figure 3 exhibits Te, O, Na, Na and the weak Sm peak which is attributed to the elemental traces in the glass matrix surrounding.The presence of detected elements confirms the successfulpreparation of the desired glass samples. A quantitative analysis of the EDX spectra are listed in Table 2. It shows theelements with their respective weight% and atomic%. K, L and M represent the innershell electrons. The intense peak located at 0.5 keV isconnected with the domination of oxygen (O) in the sample. However, there is a discrepencies between the experimental and calculatedpercentages (weight% and atomic%) of elements. This discrepencies is due to EDXanalyses which quantify elements by calculating the area under the peak of eachidentified element(Fultz and Howe, 2013) SimilarresultswereobtainedforallinvestigatedT eO 2 -Na 2 O-Sm 2 O 3 glass samples.

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 SEM micrograph in Figure 3 for the glass containing 1% mole of Sm 2 O 3 has shownhomogeneous glassy phase. Both dimensions show irregular shape of grains

and this structure can be observed for other glass samples. This confirmed homogeneous and amorphous nature of the prepared glasses (Pal et al., 2011) .

Table 2: Calculated and EDX-measured weight of elements for sample containing 1 mol % Sm 2 O 3 (TNS4 glass). Experimental Calculated Element Line Weight% Atomic% Weight% Atomic% O K 30.28 71.35 31.17 72.56 Na K 6.01 9.86 6.81 10.26 Te L 62.79 18.55 65.79 19.88 Sm L 0.92 0.23 0.98 0.28

Figure 3: EDX spectra and SEM micrograph of TNS4 sample. 3.3 DTA Spectral Analysis The DTA thermogram for (80-x) TeO2-20Na 2 O-xSm 2 O 3 glasses sample are shown in Figure4. The endothermic peaks due to the glass transition and melting point andthe exothermic peak due to the crystallization are clearly observed.The T g value of 80TeO 2 -20Na 2 O have been determined to be 265.8°C and by adding 0.3

mol% Sm 2 O 3 into the composition,the T g value wasincreased to 267.6 °C. Obtained results indicate that by increasing the amount of mol% Sm 2 O 3 , the T g of the samples also increases, the small increase of T g in these glasses shows that the structure is strongly and progressively modified(Pereira et al., 2016). The thermal stabilities ΔT of the TNS reference glass and Sm+3: TNS glass have

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 (Saddeeket al., 2008). A large ΔT indicates strong inhibition of nucleation and crystallization (Özen et al., 2001).

been evaluated from their T g , T c and T m values, the results are listed in the table 2. ΔT is generally used as a rough measure of glass thermal stability and it is desirable for a glass host to have ΔT as large as possible

Table 3: Thermal parameters of (80-x) TeO2-20Na2O-xSm2O3 derived from the DTA profiles. Sample Name TNS1 TNS2 TNS3 TNS4 TNS5 TNS6

0 0.3 0.6 1 1.2 1.5

265.8 267.6 269.1 273.8 281.7 273.1

323.6 334.1 343.5 350.4 362.2 370.6

489.5 57.8 0.349 490.2 66.5 0.426 486.9 74.3 0.518 486.4 76.6 0.563 478.6 80.6 0.692 483.0 97.5 0.868 Figure5 shows the effect of increasing % Sm 2 O 3 onΔT,T c , T g , T m and Hruby’s parameter (H) (Kavaklıoğlu et al., 2015).

Figure 4: DTA traces of the (80-x) TeO 2 20Na 2 O-xSm 2 O 3 glasses at a heating rate is 10°C/min. The ΔT of present glasses are calculated to be in the range of (58.5-97.8) ºC, it is noted that the ΔT increases with increasing % Sm 2 O 3 to the composition, this results indicate that the present glass possesses good thermal stability and anticrystallization ability. Another factor to determine the tendency of the system to become a glass rather than a crystal is Hruby’s parameter which can be defined by (Sidek et al., 2006). Hruby’s parameter also calculated by using eq. (5), the greater values of the Hruby’s parameter indicate thehigher glass forming tendency, andthe values of H in our glasses increased with the addition of the Sm 2 O 3 .

Figure 5: Effect of Sm 2 O 3 % on each of the on ΔT, T c , T g , T m and Hruby’s parameter. 3.4 FTIR Spectral Study In order to understand the structural units of glasses, FTIR transmission spectra of TNS glasses and pure KBr have been recorded in the range of 400-4000 cm–1 as shown in Figure6. This range was used in order to study the fundamental vibrations and associated rotational-vibrational structure. From Figure 6 it can be seen there are seven

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 important absorption peaks appear in the FTIR transmission spectra. The identical peaks assignments are listed in Table 3. For better clarity about the FTIR spectra, the

FTIR spectra is divided into three regions: 400-900 cm-1, 1000-2500 cm-1 and 25004000cm-1as shown in Figure7,Figure 8 and Figure 9respectively.

Table 4: Peaks position (in cm-1) in the FTIR spectra of (80-x) TeO 2 -20Na 2 OxSm 2 O 3 glass . Sample Code Pure KBr TNS1 TNS2 TNS3 TNS4 TNS5 TNS6

Sm 2 O 3 (mol%) 0 0.3 0.6 1 1.2 1.5

Na-O

TeO 4

TeO 3

M-OH

471.80 472.19 473.30 478.36 475.12 476.65

637.51 637.21 635.9 637.31 619.19 636.42

759.61 760.20 765.61 759.35 759.95 759.63

1637.53 1633.99 1627.15 1629.76 1630.26 1623.00 1632.26

Figure 6: FTIR spectra of (80-x) TeO 2 20Na 2 O-xSm 2 O 3 glass in the range of 4004000cm-1. Figure7representthree bands at optical visible range759.6, 637.5 and 471.8 cm–1and are assigned to stretching vibrations of TeO 3 or TeO 3+1 , TeO 4 structural units and bending vibrations of Te-O-Te or O-Te-O linkages with Na-O respectively.The change in sodium tellurite structure can be predicted as the shift in the position is attributed to the change in the bonding length predicting (Sarithaet al., 2008; Saharet al., 1997).The shifts in the stretching vibration of TeO 4 and TeO 3 towards 637.5 and 759.6 cm-1are observed by increasingthe Sm3+ion concentration up to 1 mol %.This shift in the transmission bands is attributed to the deformation of TeO 4 group into TeO 3 throughTeO 3+1 intermediate coordinate formation (Radaet al., 2011; Upenderet al., 2009).The ratio of

Hydrogen Bonding 2855.22 2851.32 2853.64 2855.22 2768.96 2848.98 2848.92

Hydrogen Bonding 2933.75 2923.83 2923.07 2922.24 2927.44 2915.79 2921.24

OHGroup 3447.77 3443.73 3389.21 3395.65 3400.04 3382.01 3370.68

759.6/637.5cm-1represents the relative concentrations of the TeO 3 and TeO 4 structural units, which is absolutely dependent on the glass composition. According to the electronegativity theory, which is a measure of the tendency of an atom to attract a bonding pair of electrons, the covalency of the bond will become stronger with decreasing of the difference of electronegativity between cation and anion ions. From the periodic Table (Emsley, 1989) since the values of electronegativity for Te, Na, Sm and O elements are 2.1, 0.9, 1.17 and 3.5, respectively, the covalency of Te-O are stronger than Na-O and Sm-O, respectively (Radaet al., 2011). As a result, the higher affinity of the tellurium ions to attract oxygen atoms yields the apparition of TeO 4 structural units (Hager and El-Mallawany, 2010). These three bands are not exist in the pure KBr spectra.

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42

Figure 7: FTIR spectra of (80-x) TeO 2 20Na 2 O-xSm 2 O 3 glass in the range of 4001000cm-1. Figure8 shows the hydroxyl-metal (MOH) stretching vibrations bond which is observed at 1637.53 cm-1. This band is shifted to 1632.26 cm-1 with increasing amount of Sm3+ concentration. This shift might be due to the addition of rare earth in the host matrix of glasses that slightly increase the IR transmission and shift it to longer wavelength (Nazabalet al., 2003). M-OH stretching vibration peaks also appeared for pure KBr sample spectra.

Figure 8:FTIR spectra of (80-x)TeO 2 20Na 2 O-xSm 2 O 3 glass in the range of 10002500cm-1. The IR transmission bands occur around 2900 and 3400 cm-1 belong to stretching vibration of the hydroxyl group and hydrogen bond (Kumaret al., 2010). This is observed clearly in Figure 9, the band ranges 2768.96-2927.44 cm-1 and 3400.04-3447.77 cm-1 which correspond to hydroxyl group and hydrogen bond, respectively.

Figure 9:FTIR spectra of (80-x)TeO 2 20Na 2 O-xSm 2 O 3 glass in the range of 25004000cm-1.

3.5 Raman Spectra One of the most well-known types of vibrational spectroscopy is an energy sensitive method Raman spectroscopy. It is considered as a finger print about structural information of the glass. The Raman spectra of TNS glass series in the frequency range of 100-900 cm-1is shown in Figure10, and the de-convoluted of the Raman spectra for sample TNS2 is presented in Figure11.The observed spectrum is then fitted to Gaussian peaks andto get four distinct solid line peaks named by (A, B, C and D).The sum of these picks are represented by a dotted line which is well coincide with the obtained solid line from the Raman spectra.These peaksare centered at 294.43 (A), 471.09 (B), 668.33 (C) and 760.52 (D) cm-1.The corresponding absorption peak shifts are listed in Table(4).It can be observed that the shift is dominant by all band regions around 279.4-306.63 cm-1, 465.11-473.45 cm-1, 668.33-684.12 cm-1 and 759.06-773.3 cm-1. The Raman band in the region around 279.4-306.63 cm-1 can be assigned to both Sm3+-O and TeO3 tp which indicate thatthe presence of rare earth ions might significantly change the Te-O networking structure in

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 unit through TeO 3+1 intermediate coordination, this has been satisfied by Raman band shift at the certain region (Som and Karmakar, 2010).

Intensity (arb. unit)

3000

Figure 10: Raman spectra of (80-x) TeO 2 20Na 2 O-xSm 2 O 3 glass system. theglasses(Plotnichenkoet al., 2000; Som and Karmakar, 2010). TheRaman shift corresponding to the band in the range of 465.11-473.45 cm-1 is due to Te-O-Te linkages vibration (Jaba et al., 2005). Meanwhile, the Raman peaks shift in the range of 668.33-684.12 cm-1 and 759.06773.3 cm-1 are corresponding to TeO 3 bp unit and TeO 4 tbp unit respectively. It can also be observed that by adding the Sm3+ ions from 0 to 1.5 mol % into the TNS glass will turn the glass structure to transform slightly byperturbation of TeO 4 tbp unit into TeO 3 tp

2500 C

2000

D

1500 1000

A

B

500 300 400 500 600 -1 700 800 900 Raman Shift (cm )

Figure 11: The de-convoluted Raman spectra into Gaussian peak for sample TNS2. Moreover, it was observed that the intensity of Raman peaks around 668.33684.12 cm-1 and peaks around 759.06-773.3 cm-1 are increased by the increasing of the concentration of Sm3+ ions as shown in Figure 10, This is may be due to the creation of TeO 3 tp unit by perturbation of TeO 4 . It is asserted that the addition of Sm3+ ions in TNS glasses creates more number of TeO 3 tp units.

Table 5: Raman shift peaks position in cm-1 for (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 . Raman Shifts/ cm-1

Sample Code

% Sm 2 O 3

A

B

C

D

TNS1

0

284.34

473.17

671.8

759.06

TNS2

0.3

294.43

471.09

668.33

760.52

TNS3

0.6

289.74

473.45

671.01

767.81

TNS4

1

303.549

467.33

682.23

770.37

TNS5

1.2

306.63

465.11

684.12

773.3

TNS6

1.5

276.94

467.54

677.61

773.02

4. CONCLUSIONS In this study, glass formation range of (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 system isprepared by melt quenching method.The XRD results shows that all samples are amorphous innature since bump distributed in

a wide range of 2θ instead of high intensity narrower peaks obtained.The physical parameters such as glass density, molar volume and ionic packing density were found to be (4.903-5.019) g cm-3, (28.359-28.919) cm-3mol-1 and (0.4012-0.4092) respectively.

Mawlud S. et al./ZJPAS: 2017, 29(2): 32-42 Thermal and structural properties are investigated by DTA, FTIR and Raman spectroscopies. The thermal characteristics reveal that the glass transition temperature and stability factor increases with the increasing of Sm 2 O 3 mol%content. This is due to the increase in bond number per unit volume which is an indication of change in packing density in the structure.The vibrational spectra of the glass system suggested that the glass network consists of TeO4, TeO 3 /TeO 3+1 , Na 2 O and Sm 2 O 3 units.Raman spectra for the (80-x) TeO 2 -20Na 2 O-xSm 2 O 3 glasses showed that the TeO 4 tbps convert to TeO 3 tps with increasing of Sm 2 O 3 % mol fraction.The Raman shifts due to the structural units TeO4 and TeO3 have almost equal to the intensities in these glasses and overlapped to each other. Acknowledgments The authors gratefully acknowledge the financial support from Ministry of Higher Education, RMC, UTM and University of Salahaddin/Ministry of Higher Education/KRG through the research grant (vote 4B182) are highly appreciated. References Azmi, S.A.M., Sahar, M.R., Ghoshal, S.K. and Arifin, R., 2015. Modification of structural and physical properties of samarium doped zinc phosphate glasses due to the inclusion of nickel oxide nanoparticles. Journal of Non-Crystalline Solids, 411, pp.53-58. Bolundut, L., Culea, E., Borodi, G., Stefan, R., Munteanu, C. and Pascuta, P., 2015. Influence of Sm3+: Ag codoping on structural and spectroscopic properties of lead tellurite glass ceramics. Ceramics International, 41(2), pp.2931-2939. Çelikbilek, M., Ersundu, A.E., Solak, N. and Aydin, S., 2011. Investigation on thermal and microstructural characterization of the TeO 2 -WO 3 system. Journal of Alloys and Compounds, 509(18), pp.5646-5654. El-Mallawany, R.A., 2011. Tellurite glasses handbook: physical properties and data. CRC press. Emsley, J., 1989. The elements. Clarendon press.

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