1. bookVolume 34 (2016): Issue 4 (December 2016)
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2083-134X
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16 Apr 2011
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Spectroscopic investigations of polycrystalline InxSb20−xAg10Se70 (0 ⩽ × ⩽ 15) multicomponent chalcogenides

Published Online: 19 Dec 2016
Volume & Issue: Volume 34 (2016) - Issue 4 (December 2016)
Page range: 794 - 799
Received: 16 Feb 2016
Accepted: 05 Sep 2016
Journal Details
License
Format
Journal
eISSN
2083-134X
First Published
16 Apr 2011
Publication timeframe
4 times per year
Languages
English
Abstract

The composition dependence of physical properties of chalcogenides has recently been studied for their phase change properties and energy conversion. In the present work, we report the structure, composition, optical and Raman spectroscopy results for bulk polycrystalline InxSb20−xAg10Se70 (0 ⩽ × ⩽ 15) samples. The phase quantification and composition have been studied by using XRD and EDX techniques. The alloy composition up to 5 at.% of indium resulted in crystallization of AgSbSe2, while further increase in In content favored the formation of another chalcopyrite AgInSe2 phase yielding the solid solutions for this alloy system. A decrease in band gap up to x = 5 followed by its increase with an increase in indium concentration has been observed. The variations in shape and position of characteristic Raman bands has been used for understanding the structural modifications of the network with the variation in indium content.

Keywords

Introduction

Chalcogenide glasses are very attractive because of their potential applications in passive and active solid state and optical devices, such as thermal imagining, memory switching, IR-photodetectors, photovoltaic systems and photoreceptors, etc. [16]. Se based chalcogenide alloys have emerged as a promising material due to their large potential applications in holography, e-beam recording and digital X-ray imaging [7, 8]. The reported physical characteristics have been improved by alloying Se with other elements. Sb2Se3 is an important photoconductive semiconductor which crystallizes in orthorhombic system [9, 10]. An addition of a third element usually affects the properties of chalcogenide semiconductors by creating compositional and configurational disorder in the material with respect to binary alloys [11]. Ag–Sb–Se is a narrow band gap p-type semiconducting system which crystallizes to AgSbSe2 with a cubic NaCl type structure [12]. Further, the incorporation of indium in Sb–Se system is expected to make it more suitable for reversible optical recording having less erase time [13]. However, an addition of Ag into the Sb–Se system increases its ionic conductivity and causes a large change in resistance with minute change in volume during crystallization to a single crystalline phase [14, 15]. The indium based chalcogenide alloys have also found applications as active material in non-volatile memory which uses the reversible phase transition of chalcogenide resistors [16]. The alloying of indium in the Ag–Sb–Se system might modify the lattice and optical properties what plays an important role in the fabrication of new devices. Thus, the present system is basically a quaternary or pseudo-ternary chalcogenide alloy system and is of interest for the development of new materials having improved efficiency, being less toxic and highly reproducible.

The chalcogenide glassy alloys have very useful properties which are strongly dependent on composition and various compositional thresholds viz. rigidity percolation threshold and chemical threshold for these network systems [17, 18]. Since the parent Ag10Sb20Se70 ternary system has an average coordination number 〈r〉 = 2.20 (<2.40), the system belongs to the floppy network [19]. Therefore, the isovalent substitution does not alter average coordination number of In–Sb–Ag–Se system. In this study, we have separated the effect of variation of 〈r〉 or composition from the nature of additive which is important for elaborating the further glassy systems. The crystalline structure of InxSb20−xAg10Se70 (0 ⩽ x ⩽ 15) system has been investigated using optical and Raman spectroscopy. Modification of the structure caused by relative variation of In/Sb ratio or concentration of different cluster units with composition have been used for discussing the results.

Experimental

Bulk samples of InxSb20−xAg10Se70 (0 ⩽ x ⩽ 15) system were prepared by conventional melt quenching technique. High purity (5N) elements in appropriate amounts were weighed and sealed in quartz ampoules under vacuum of ~10−2 Pa. The ampoules were kept in a vertical furnace at 970 °C for 48 hours. Each ampoule was inverted at regular intervals of time to ensure a homogeneous sample and finally air quenched to get the bulk material. The quenched material was separated from the quartz ampoule by using HF + H2O2 for approximately 48 hours. The as-prepared bulk was further taken for characterization by using different techniques. The amorphous/crystalline phases in the as-prepared samples were studied by using X-ray diffractometer (D8 FOCUS, Bruker, Germany) with CuKα (λ = 1.5405 Å) line. The Raman spectra were studied by using an argon ion laser at a wavelength of 514 nm (Renishaw in via Reflex Micro Raman Spectrometer) and 2400 lines per mm diffraction grating having a suitable filter. Chemical composition was studied by EDX (Oxford Instrument, UK) equipped with FESEM (Supra 55, Carl Zeiss, Germany). Diffuse reflectance measurements were carried out by using UV-Vis-NIR spectrophotometer (UV-3600, Shimadzu, Japan).

Results and discussion
Composition and crystalline phases

The elemental composition of each bulk sample was determined by energy dispersive X-ray spectroscopy (EDS) and the EDS spectra are shown in Fig. 1. The atomic percentages of all elements present in the bulk alloys are given in Table 1. These results suggest that the samples are nearly stoichiometric with those of the initial compositions used for the synthesis.

EDS spectra of InxSb20−xAg10Se70 chalcogenide alloys.

Compositions of as-prepared bulk InxSb20−xAg10Se70 (0 ⩽ x ⩽ 15) chalcogenide alloys obtained by using EDS spectroscopy.

xat.%
SeSbAgIn
072.6618.049.300.00
572.1013.759.564.59
1072.429.858.958.77
1574.704.538.5712.20

The structural analysis of devitrified glassy alloys and their phases is important for furthering the science of chalcogenide alloys. Fig. 2 shows the X-ray diffraction patterns of InxSb20−xAg10Se70 chalcogenide alloys. The existence of sharp diffraction peaks for different phases in the multicomponent chalcogenide alloys reveals their polycrystalline nature. The crystalline phases are indexed to tetragonal phases of AgSbSe2 (JCPDF Card No. 12-0379) and AgInSe2 (JCPDF Card No. 75-0118) having a body centered lattice. The structural analysis of Se70Sb20Ag10 reveals the devitrification of single phase AgSbSe2 [12] without denomination of other phases due to their large intensity. The addition of small amount of indium additive (x = 5) results in a decrease in the intensity of diffraction peaks of AgSbSe2 without forming new phases. However, further increase in x (10 at.%) favors the appearance of new diffraction peaks with increased intensity for AgInSe2 phase, accompanied with peaks of decreased intensity for AgSbSe2 phase.

X-ray diffraction patterns for InxSb20−xAg10Se70 chalcogenide alloys.

Further addition of indium (x = 15) results in an increase in the AgInSe2 phase and decrease in AgSbSe2 phase.

Raman spectroscopy

Raman spectra yield valuable information about the dynamics and structure at the molecular level. The Raman spectra have been shown in Fig. 3. The Raman spectrum for the parent Sb20Ag10Se70 chalcogenide alloy exhibits three dominant peaks at 82 cm−1, 188 cm−1 and 252 cm−1, and two weak bands at 117 cm−1 and 371 cm−1. The Raman spectra of In–Ag–Sb–Se systems have been discussed by considering AgSbSe2 and AgInSe2 basic structural units. For simplifying the discussion, the R-value has been defined as a ratio of covalent bonding possibility of chalcogen atoms to the covalent bonding possibility of the non-chalcogen atoms [20]. The value of R = 1 represents the case of existence of only hetero-nuclear bonds in a given system which unequivocally indicates the occurrence of the chemical threshold. Since the R-value is 1.75 for the present system it suggests Se rich material having heteropolar bonds and chalcogen-chalcogen bonds. The heteropolar bonds are also more favorable than homopolar bonds due to their larger bond energies. The weak bands up to 136 cm−1 are reported to be of mixed character with identical contributions from Ag, Se and In atoms [21]. Therefore, the observation of weak band can be ascribed to the contributions from Se and Ag atoms in the parent ternary system. Holubova et al. [22] have assigned the peak at 194 cm−1 to heteropolar Sb–Se bond vibrations in SbSe3/2 pyramids so, the peak observed at 188 cm−1 can be ascribed to Sb–Se bond vibrations of AgSbSe2 structural units due to the incorporation of Ag in this ternary system. However, the broadening of this peak with indium content can be ascribed to the replacement of Sb by In in AgSbSe2 structural units. The peak at 252 cm−1 may correspond to the homopolar Sb–Sb bonds in Se2Sb–Se2Sb structural units [23]. The band at 369 cm−1 has been ascribed to the bond bending modes of Se [24]. Therefore, the band at 371 cm−1 can be assigned to this mode. The observed shift may be due to the presence of Sb or Ag. This band was found to fade with the increase in the indium concentration due to breaking of Se chains.

Raman spectra of InxSb20−xAg10Se70 chalcogenide alloys.

The peak at 82 cm−1 has been found to broaden for all the concentrations, while the band at 117 cm−1 broadens for x = 5 and disappears for x = 10 and 15 at.%. The intensity ratio for 188 cm−1 and 252 cm−1 peaks have been found to increase up to x = 5, and thereafter, this value decreased with the appearance of new band at 238 cm−1 for x = 10 sample. The B2 mode of AgInSe2 chalcopyrite structure has been reported at 230 cm−1[25] and therefore, the shift can be ascribed to the presence of Sb atoms in this system. It has further been observed that when the In content increases (x = 15), the intensity for 238 cm−1 peak increases as compared to the intensity of 252 cm−1 peak, indicating a decrease of the homopolar Sb–Sb bonds and increase in the heteropolar In–Se bonds. The relative decrease in the intensity for the 252 cm−1 peak at higher In content can be ascribed to the segregation of AgInSe2 phase. Also, the new weak band at 142 cm−1 can be assigned to the B2 mode corresponding to the antiphase motion between In and Se atoms of AgInSe2 chalcopyrite structure [25].

Optical spectroscopy

The relation between absorption coefficient and diffuse reflectance has been given by Kubelka-Munk [26]: α=ks=(1R)22R $$\alpha {\rm{ = }}\frac{{{\rm{ k}}}}{{\rm{s}}}{\rm{ = }}\frac{{{{{\rm{(1 - }}{{\rm{R}}_\infty }{\rm{)}}}^{\rm{2}}}}}{{{\rm{2}}{{\rm{R}}_\infty }}} $$

where s and k are the scattering and absorption coefficients. Fig. 4 shows the variation of (αhv)2 versus photon energy (E) for the present system.

The variation (αhv)2 versus photon energy (E) for bulk polycrystalline InxSb20−xAg10Se70 chalcogenide alloys.

The band gap can also be calculated by the following equation [27]: α=B(hvEg)hvn $$\alpha = B{\frac{{( hv - Eg)}}{{hv}}^n} $$

where B is a constant, Eg is the band gap and n = 1/2 corresponds to the allowed direct transitions [28]. The parameter B depends upon the transition probability, the inverse of which is known as tailing parameter describing the disorder in the network systems [29, 30]. Fig. 4 reveals direct band transitions for InxSb20−xAg10Se70 alloys. The values of band gap and tailing parameter are summarized in Table 2. The value of Eg for Sb20Ag10Se70 alloy is 1.59 eV and decreases to 1.30 eV for 5 at.% of indium with the increase in tailing parameter. This can be correlated with the decrease in disorder of the system. The dominant contribution for the states near the band edge of the chalcogenide alloys comes from their lone pair p-orbital [31]. The electronegativity of Sb, Ag, Se and In are 2.05, 1.93, 2.55 and 1.78 respectively [32]. When Sb atom is replaced by the electropositive In atom, the energy of lone pair of electrons gets enhanced and hence, the valence band edge moves towards the forbidden gap to cause an increase in the tailing parameter and decrease in the optical gap for this system [33]. Further addition of In have been found to increase the band gap to 1.71 and 2.06 eV for x = 10 and 15, respectively. This can be explained by considering the bond formation energies. For hetero-nuclear bonds, the bond energy (BE), EA−B has been calculated by using the relation [34]: EA - B=(EA - A×EB - B)1/2+30(χA - χB)2 $${E_{A{\text{ - }}B}}\; = \;{{\text{(}}{E_{A{\text{ - }}A}}\; \times \;{E_{B{\text{ - }}B}})^{1/2}}\; + \;30{({\chi _A}\;{\text{ - }}\;{\chi _B}{\text{)}}^{\text{2}}} $$

Optical band gap (Eg) and tailing parameter (B−1) of the as-prepared InxSb20−xAg10Se70 chalcogenide alloys.

CompositionEgB−1
(x)[eV][× 10−4 cm−1 ⋅eV−1]
01.59137.5
51.30138.7
101.7169.4
152.0654.1

where EA-A and EB-B are the BE of the homonuclear bonds and χA, χB are the electronegativities of the atoms respectively. The calculated bond energies are Se-Se (44.02 kcal/mol), Sb–Sb (30.02 kcal/mol), In-In (24.2 kcal/mol), Sb–Se (40.15 kcal/mol), Sb–In (30.72 kcal/mol) and In–Se (47.33 kcal/mol) [35]. According to the chemically ordered network model, an atom combines preferably with the atoms of different kind as compared with the same atoms and the bonds are formed in the sequence of the BE [2]. The increase in In and decrease in Sb lead to the relative increase in AgInSe2 phase at the expense of AgSbSe2 phase or replacing the weaker Sb–Se and Sb–In bonds by stronger In–Se bonds in this system. Therefore, the band gap is found to decrease for lower indium concentrations where the system forms the solid solutions. Similar effects associated with the incorporation of In on the electrical properties have been observed in Se90_x>Te5Sn5lnx glassy alloys [36]. The XRD studies have also revealed the increase in the relative increase in AgInSe2 phase at the expense of AgSbSe2 phase as earlier discussed. This leads to an increase in the average bond energy and hence, an increase in the optical gap for this system.

Conclusions

Bulk samples of InxSb20_xAg10Se70 chalcogenides have been synthesized by conventional melt quenching technique and found to be polycrystalline with the formation of tetragonal AgSbSe2 and AgInSe2 phases. The composition of the bulk samples have been found to be close to those taken for the synthesis. The main Raman band at 188 cm−1 have been assigned to Sb–Se vibrations in the SbSe3/2 pyramids, a basic structural unit of AgSbSe2 phase, and the 252 cm−1 band for the homopolar Sb–Sb bonds in Se2Sb–Se2Sb structural units for the x = 0 sample. The value of intensity ratio for 188 cm−1 and 252 cm−1 bands have been found to increase up to x = 5, and thereafter, this value decreased with the appearance of the new band at 238 cm−1 corresponding to B2 mode of AgInSe2 chalcopyrite structure for x = 10 sample. The weak band at 142 cm−1 corresponds to antiphase motion between In and Se for the AgInSe2 chalcopyrite structure with 15 at.% of In. The direct optical band gap has been found to decrease up to x = 5 and thereafter, the value was found to increase having inverse relation with the tailing parameter. The variations in the optical properties have been discussed by considering the electronegativity of the additive, change in average bond energy and the structural modifications of the network.

EDS spectra of InxSb20−xAg10Se70 chalcogenide alloys.
EDS spectra of InxSb20−xAg10Se70 chalcogenide alloys.

X-ray diffraction patterns for InxSb20−xAg10Se70 chalcogenide alloys.
X-ray diffraction patterns for InxSb20−xAg10Se70 chalcogenide alloys.

Raman spectra of InxSb20−xAg10Se70 chalcogenide alloys.
Raman spectra of InxSb20−xAg10Se70 chalcogenide alloys.

The variation (αhv)2 versus photon energy (E) for bulk polycrystalline InxSb20−xAg10Se70 chalcogenide alloys.
The variation (αhv)2 versus photon energy (E) for bulk polycrystalline InxSb20−xAg10Se70 chalcogenide alloys.

Compositions of as-prepared bulk InxSb20−xAg10Se70 (0 ⩽ x ⩽ 15) chalcogenide alloys obtained by using EDS spectroscopy.

xat.%
SeSbAgIn
072.6618.049.300.00
572.1013.759.564.59
1072.429.858.958.77
1574.704.538.5712.20

Optical band gap (Eg) and tailing parameter (B−1) of the as-prepared InxSb20−xAg10Se70 chalcogenide alloys.

CompositionEgB−1
(x)[eV][× 10−4 cm−1 ⋅eV−1]
01.59137.5
51.30138.7
101.7169.4
152.0654.1

Studentyak I.P., Kutsyk M.M., Buchuk M.Y., Rati Y.Y., Neimet Y.Y., Izai V.Y., Kokenyesi S., Nemec P., Opt. Mater., 52 (2016), 224StudentyakI.P.KutsykM.M.BuchukM.Y.RatiY.Y.NeimetY.Y.IzaiV.Y.KokenyesiS.NemecP.Opt. Mater.52201622410.1016/j.optmat.2015.12.030Search in Google Scholar

Elliot S.R., Physics of amorphous materials, Longman Publication, London, 1991.ElliotS.R.Physics of amorphous materialsLongman PublicationLondon1991Search in Google Scholar

Fritzsche H., J. Phys. Chem. Solids, 68 (2007), 878.FritzscheH.J. Phys. Chem. Solids68200787810.1016/j.jpcs.2007.01.017Search in Google Scholar

Pattanayak P., Ashokan S., Euro. Phys. Lett., 75 (2006), 778.PattanayakP.AshokanS.Euro. Phys. Lett.75200677810.1209/epl/i2006-10173-xSearch in Google Scholar

Hamann H.F., Boyle M.O., Martin Y.C., Rooks M., Wickramasinghe H.K., Nat. Mater., 5 (2006), 383.HamannH.F.BoyleM.O.MartinY.C.RooksM.WickramasingheH.K.Nat. Mater.5200638310.1038/nmat162716604077Search in Google Scholar

Balitska V., Shpotyuk O., Altenburg H., J. Non-Cryst. Solids, 352 (2006), 4809.BalitskaV.ShpotyukO.AltenburgH.J. Non-Cryst. Solids3522006480910.1016/j.jnoncrysol.2006.01.111Search in Google Scholar

Stronski A., Achimova E., Paiuk O., Meshalkin A., Abashkin V., Lytvyn O., Sergeev S., Prisacar A., Triduh G., Nanoscale Res. Lett., 11 (2016), 39.Stronskia.achimovaE.PaiukO.MeshalkinA.AbashkinV.LytvynO.SergeevS.PrisacarA.TriduhG.Nanoscale Res. Lett.1120163910.1186/s11671-016-1235-x472971926815608Search in Google Scholar

Afifi M.A., Abd El-Wahabb E., Bekheet A.E., Atyia H.E., J. Mater. Sci., 41 (2006), 7969.AfifiM.A.Abd El-WahabbE.BekheetA.E.AtyiaH.E.J. Mater. Sci.412006796910.1007/s10853-006-0868-zSearch in Google Scholar

Zheng W.X., Xie Y., Zhu Y.L., Jiang X.C., Jia Y.B., Sun Y.P., Inorg. Chem., 41 (2002), 455.ZhengW.X.XieY.ZhuY.L.JiangX.C.JiaY.B.SunY.P.Inorg. Chem.41200245510.1021/ic010707211825071Search in Google Scholar

Yu Y., Wang R.H., Chen Q., Peng L., J. Phys. Chem. B, 110 (2006), 13415.YuY.WangR.H.ChenQ.PengL.J. Phys. Chem. B11020061341510.1021/jp061599d16821864Search in Google Scholar

Abdel-Rahim M.A., Hafiz M.M., Shamekh A.M., Physica B, 369 (2005), 143.Abdel-RahimM.A.HafizM.M.ShamekhA.M.Physica B369200514310.1016/j.physb.2005.08.007Search in Google Scholar

Soliman H.S., Abdel-Hady D., Ibrahim E., J. Phys. Condens. Mat., 10 (1998), 847.SolimanH.S.Abdel-HadyD.IbrahimE.J. Phys. Condens. Mat.10199884710.1088/0953-8984/10/4/013Search in Google Scholar

Kaur G., Komatsu T., J. Mater. Sci., 36 (2001), 4531.KaurG.KomatsuT.J. Mater. Sci.362001453110.1023/A:1017951307399Search in Google Scholar

Wojciechowski K., Tobola J., Schmidt M., J. Phys. Chem. Solids, 69 (2010), 2748.WojciechowskiK.TobolaJ.SchmidtM.J. Phys. Chem. Solids692010274810.1016/j.jpcs.2008.06.148Search in Google Scholar

Wang K., Steimer C., Wuttig M., J. Optoelectron. Adv. M., 9 (7) (2007), 2008.WangK.SteimerC.WuttigM.J. Optoelectron. Adv. M.9720072008Search in Google Scholar

Al-Ghamdi A.A., Khan S.A., Al-Henti S., Alagel F.A., Zulfequar M., Curr. Appl. Phys., 11 (2011), 315.Al-GhamdiA.A.khanS.A.Al-HentiS.AlagelF.A.ZulfequarM.Curr. Appl. Phys.11201131510.1016/j.cap.2010.07.025Search in Google Scholar

Mott N.F., Davis E. A., Electronic Processes in NonCrystalline Materials, Oxford Press, Clarendon, 1979, p. 132.MottN.F.DavisE. A.Electronic Processes in NonCrystalline MaterialsOxford PressClarendon1979132Search in Google Scholar

Boolchand P., Georgieb D.G., Goodman B., J. Optoelectron. Adv. M., 3 (2001), 703.BoolchandP.GeorgiebD.G.GoodmanB.J. Optoelectron. Adv. M.32001703Search in Google Scholar

Thorpe M.F., J. Non-Cryst. Solids, 57 (1983), 355.ThorpeM.F.J. Non-Cryst. Solids57198335510.1016/0022-3093(83)90424-6Search in Google Scholar

Kumar P., Thangaraj R., J. Non-Cryst. Solids, 352 (2006), 2288.KumarP.ThangarajR.J. Non-Cryst. Solids3522006228810.1016/j.jnoncrysol.2006.02.041Search in Google Scholar

Kopytov A.V., Kosobutsky A.V., Phys. Solid State, 51 (2009), 2115.KopytovA.V.KosobutskyA.V.Phys. Solid State512009211510.1134/S1063783409100217Search in Google Scholar

Holubova J., Cernosek Z., Cernoskova E., J. Optoelectron Adv. M., 1 (2007), 663.HolubovaJ.CernosekZ.CernoskovaE.J. Optoelectron Adv.M.12007663Search in Google Scholar

Ivanova Z.G., Cemoskova E., Vassilev V.S., Boycheva S.V., Mater. Lett., 57 (2003), 1025.IvanovaZ.G.CemoskovaE.VassilevV.S.BoychevaS.V.Mater. Lett.572003102510.1016/S0167-577X(02)00710-3Search in Google Scholar

Ohta N., Scheuermann W., Nakamata K., Solid State Commun., 27 (1978), 1325.OhtaN.ScheuermannW.NakamataK.Solid State Commun271978132510.1016/0038-1098(78)91563-6Search in Google Scholar

Jin Y., Tang K., An C., Huang L., J. Cryst. Growth, 253 (1–4) (2003), 429.JinY.TangK.AnC.HuangL.J. Cryst. Growth2531–4200342910.1016/S0022-0248(03)00997-7Search in Google Scholar

Marfunin A.S., Egogrova N., Mischhenko A., Physics of Minerals and Inorganic Materials: An Introduction, Springer, Berlin, 1979.MarfuninA.S.EgogrovaN.MischhenkoA.Physics of Minerals and Inorganic Materials: An IntroductionSpringerBerlin197910.1007/978-3-642-67044-2Search in Google Scholar

Pankove J.I., Optical processes in semiconductors, Dover Publications, New York, 1971.PankoveJ.I.Optical processes in semiconductorsDover PublicationsNew York1971Search in Google Scholar

Kamatsu A., Takei S., Mizuhata M., Thin Solid Films, 359 (1) (2000), 55.KamatsuA.TakeiS.MizuhataM.Thin Solid Films359120005510.1016/S0040-6090(99)00684-7Search in Google Scholar

Kumar P., Thangaraj R., Sathiaraj T.S., Phys. Status Solidi A, 208 (4) (2011), 838.KumarP.ThangarajR.SathiarajT.S.Phys. Status Solidi A2084201183810.1002/pssa.201026537Search in Google Scholar

Tauc J., Amorphous and Liquid Semiconductors, Plenum Press, New York, 1974, p. 569.TaucJ.Amorphous and Liquid SemiconductorsPlenum PressNew York197456910.1007/978-1-4615-8705-7Search in Google Scholar

Kastner M., Adler D., Fritzsche H., Phys. Rev. Lett., 37 (1976), 1504.KastnerM.AdlerD.FritzscheH.Phys. Rev. Lett.371976150410.1103/PhysRevLett.37.1504Search in Google Scholar

Pauling L., The Nature of Chemical Bond, Cornell University, New York, 1976.PaulingL.The Nature of Chemical BondCornell UniversityNew York1976Search in Google Scholar

Sharda S., Sharma N., Sharma P., Sharma V., Def. Diff. Forum, 45 (2011), 316.ShardaS.SharmaN.SharmaP.SharmaV.Def. Diff. Forum45201131610.4028/www.scientific.net/DDF.316-317.45Search in Google Scholar

Katyal S.C., Verma R.C., J. Phys. Condens. Mat., 5 (1993), 3469.KatyalS.C.VermaR.C.J. Phys. Condens. Mat.51993346910.1088/0953-8984/5/21/011Search in Google Scholar

Amer H.H., Zekry A.E.H., El Araby S.M.S., Ghareeb K.E., Elshazly A.A., Arab. J. Nuc. Sci. Appl., 45 (3) (2012), 256.AmerH.H.ZekryA.E.H.El ArabyS.M.S.GhareebK.E.ElshazlyA.A.Arab. J. Nuc. Sci. Appl.4532012256Search in Google Scholar

Ram I.S., Kumar S., Singh R.K., Singh P., Singh K., AIP Adv., 5 (2015), 087164.RamI.S.KumarS.SinghR.K.SinghP.SinghK.AIP Adv.5201508716410.1063/1.4929577Search in Google Scholar

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