p.1
p.44
p.59
p.107
p.144
Network Former Mixing (NFM) Effects in Ion-Conducting Glasses - Structure/Property Correlations Studied by Modern Solid-State NMR Techniques
Abstract:
Glassy solid electrolytes are important integral components for all-solid-state devices for energy storage and conversion. The use of multiple network formers is an important part of their design strategy for specific applications. In many glass systems the interaction between the different network formers results in strongly non-linear variations in physical properties (network former mixing (NFM) effects), requiring a detailed understanding on a structural basis.The issues to be addressed involve both the structural organization and connectivities within the framework, the local environments and spatial distributions of the mobile ions, and the dynamical aspects of ion transport, to be discussed in relation to possible phase separation or nano-segregation effects. Besides Raman and X-ray photoelectron spectroscopies, solid state nuclear magnetic resonance (NMR) methods are particularly useful for providing detailed answers to such issues. The present review introduces the basic principles of modern solid state NMR methods and their applications to glass structure, with a particular focus on the characterization of network-former mixing effects in the most common lithium and sodium conducting oxide and chalcogenide glass systems. Based on the current state of the literature reviewed in the present work, some emerging general principles governing structure/property correlations are identified, to be tested by further experimenteation in the future.
Info:
Periodical:
Pages:
144-193
Citation:
Online since:
February 2016
Authors:
Keywords:
Price:
Сopyright:
© 2015 Trans Tech Publications Ltd. All Rights Reserved
Citation:
[1] T. Minami, A. Hayashi, M. Tatsimusago, Recent progress of glass and glass-ceramics as solid electrolytes for lithium secondary batteries, Solid State Ionics, 177 (2006).
[2] W. H. Zachariasen, The atomic arrangement in glass. J. Am. Chem. Soc. 54 (1932).
[3] M. Schuch, R. Christensen, C. Trott, P. Maass, S. W. Martin, Investigation of the structures of sodium borophosphate glasses by reverse Monte Carlo modelling to examine the origins of the mixed glass former effect, J. Phys. Chem. C 116 (2012).
DOI: 10.1021/jp2085654
[4] K. Funke, C. Cramer, Amorphous materials: Frequency dependent ionic conductivity, Reference Module in Materials Science and Materials Engineering, Elsevier 2015, pp.1-9. K. Funke, R. Banhatti, D. M. Laughman, L.G. Badr, M. Mutke, A. Santic, W. Wrobel, E. M. Fellberg, C. Biermann, First and second universalities: Expeditions towards and beyond, Z. Phys. Chem. 224 (2010).
[5] H. Eckert, Short and medium range order in ion conducting glasses studied by modern solid state NMR techniques, Z. Phys. Chem. 224 (2010).
[6] R. DeHoff, Thermodynamics in Materials Science, CRC Press, Taylor & Francis Group Boca Raton, Fl, USA, (2006).
[7] M. Schuch, C. Trott, P. Maass, Network forming units in alkali borate and borophosphate glasses and the mixed glass former effect, RSC Adv. 1 (2011).
DOI: 10.1039/c1ra00583a
[8] A. Abragam, Principles of Nuclear Magnetism, Oxford Science Publications 1983; C.P. Slichter, Principles of Magnetic Resonance, Springer Series in Solid-State Sciences, 1990; M. H. Levitt, Spin Dynamics, Wiley (2008).
[9] K. Schmidt-Rohr, H. W. Spiess, Multi-dimensional NMR and Polymers, Elsevier (Amsterdam), 1994; M. Duer, Introduction to Solid State NMR spectroscopy, Wiley-Blackwell (2005).
[10] R. Boehmer, K. R. Jeffrey, M. Vogel, Solid-state Li NMR with applications to the translational dynamics in ion conductors. Prog. Nucl. Magn. Reson. 50 (2007), 87-174.
[11] S. M. Lee, Y. H. Kim, C.H. Song, S. J. Yoon, H. S. Kim, Y. S. Yang, Y. H. Rim, Dielectric and conduction behaviors of lithium germanium silicate glasses, J. Korean Phys. Soc. 58 (2011), 616-621.
DOI: 10.3938/jkps.58.616
[12] L. F. Maia, A. C. M. Rodrigues, Electrical conductivity and relaxation frequency of lithium borosilicate glasses, Solid State Ionics 168 (2004), 87-92.
[13] X. Wu, A. K. Varshneya, R. Dieckmann, Sodium Tracer Diffusion in glasses of the type (Na2O)0. 2[B2O3)y(SiO2)1-y]0. 8, J. Non-Cryst. Solids 357 (2011).
[14] S. P. Szu, C.T. Wu, Impedance study of 22. 2Na2O-(66. 7-x)B2O3-xSiO2 glasses, Mater. Chem. Phys. 100 (2006), 361-365.
[15] M. Tatsumisago, K. Yoneda, N. Machida, T. Minami, Ionic conductivity of rapidly quenched glasses with high concentration of lithium ions, J. Non-Cryst. Solids 95-96 (1987), 857-864.
[16] A.C.M. Rodrigues, R. Keding, C. Rüssel, Mixed former effect between TeO2 and SiO2 in the Li2O-TeO2-SiO2 system, J. Non-Cryst. Solids 273 (2000), 53-58.
[17] T. Tsuchiya, T. Moriya, Anomalous behavior of physical and electrical properties in borophosphate glasses containing R2O and V2O5, J. Non-Cryst. Solids 38-39 (1980), 323-329.
[18] A. Magistris, G. Chiodelli, M. Villa, Lithium borophosphate vitreous electrolytes, J. Power Sources 14 (1985), 87-91.
[19] R.V. Salodkar, V. K. Deshpande, K. Singh, Enhancement of the ionic conductivity of lithium borophosphate glass: a mixed glass former approach, J. Power Sources 25 (1989), 257-263.
[20] S. Kumar, P. Vinatier, A. Levasseur, K. J. Rao, Investigations of structure and transport in lithium and silver borophosphate glasses, J. Solid State Chem. 177 (2004), 1723-1727.
[21] P.S. Anantha, K. Hariharan, Structure and ionic transport studies of sodium borophosphate glassy system, Mater. Chem. Phys. 89 (2005).
[22] D. Zielniok, C Cramer, H. Eckert, Structure/property correlations in ion-conducting mixed network former glasses: solid state NMR studies of the system Na2O-B2O3-P2O5, Chem. Mater. 19 (2007), 3162-3170.
DOI: 10.1021/cm0628092
[23] T. D. Tho, R. P. Rao, S. Adams, Structure property correlation in lithium borophosphate glasses, Eur. Phys. J. E 35: 8 (2012), 1-11.
[24] D. Larink, H. Eckert, M. Reichert, S. W. Martin, The mixed network former effect in ion-conducting alkali borophosphate glasses: structure/property correlations in the system [M2O]1/3[(B2O3)x(P2O5)1-x]2/3 (M = Li, K, Cs), J. Phys. Chem. C 126 (2012).
DOI: 10.1021/jp307085t
[25] R. Christensen, G. Olson, S.W. Martin, Ionic conductivity of the mixed glass former 0. 35 Na2O+0. 65(xB2O3 + (1-x)P2O5) glasses, J. Phys. Chem. B 117, (2013), 16577-16586.
DOI: 10.1021/jp409497z
[26] M. Storek, R: Böhmer, S. W. Martin, D. Larink, H. Eckert, J. Chem. Phys. 137 (2012), 124507.
[27] B. Raguenet, G. Tricot, G. Silly, M. Ribes, A. Pradel, The mixed glass former effect in twin-roller quenched lithium borophosphate glasses, Solid State Ionics 208 (2012), 25-30.
[28] S. Kumar, K.J. Rao, Lithium ion transport in germanophosphate glasses, Solid State Ionics 170 (2004), 191-199.
[29] P. Balaya, P.S. Goyal, Non-Debye conductivity relaxation in a mixed glassformer system, J. Non-Cryst. Solids 351 (2005), 1575-1576.
[30] A. C. M. Rodrigues, J. Duclot, Lithium conducting glasses: the Li2O-B2O3-TeO2 system, Solid State Ionics 28-30 (1988), 729-731.
[31] A. Shaw, A. Ghosh, Dynamics of lithium ions in borotellurite mixed network former glasses: correlation between the characteristic length scales of mobile ions and glass network structural units, J. Chem. Phys. 141 (2014), 164504.
DOI: 10.1063/1.4899282
[32] D. Larink, H. Eckert, Mixed network former effects in tellurite glass systems: structure/property correlations in the system (Na2O)1/3(2TeO2)x(B2O3)1-x)2/3, J. Non-Cryst. Solids 426 (2015), 150-158.
[33] D. Larink, M. T. Rinke, H. Eckert, Mixed network former effects in tellurite glass systems: structure/property correlations in the system (Na2O)1/3(2TeO2)x(P2O5)1-x)2/3, J. Phys. Chem. C 119 (2015), 17539-17551.
[34] M. Tatsumisago, H. Yamashita, A. Hayashi, H. Morimoto, T. Minami, Preparation and structure of amorphous solid electrolytes based on lithium sulfide, J. Non-Cryst. Solids 274 (2000), 30-38.
[35] K. Minami, F. Mizuno, A. Hayashi, M. Tatsumisago, Structure and properties of the 70 Li2S – (30-x)P2S5 – x P2O5 oxysulfide glasses and glass ceramics, J. Non-Cryst. Solids 354 (2008), 370-373.
[36] Y. Kim, J. Saienga, S. W. Martin, Anomalous conductivity increase in Li2S + GeS2 + GeO2 glasses, J. Phys. Chem. B 110 (2006).
[37] V. K. Deshpande, A: Pradel, M. Ribes, The mixed glass former effect in the Li2S: SiS2: GeS2 system, Mater. Res. Bull. 23 (1988), 379-384.
[38] A. Pradel, N. Kuwata, M. Ribes, Ion transport and structure in chalcogenide glasses, J. Phys. Cond. Matter, 15 (2003), S1561-S1571.
[39] J. H. Kennedy, Z. Zhang, Preparation and electrochemical properties of the SiS2-P2S5-Li2S glass conformer system, J. Electrochem. Soc. 136 (1989), 2441-2443.
DOI: 10.1149/1.2097416
[40] Z. Zhang, J. H. Kennedy, Synthesis and characterization of the B2S3-Li2S, the P2S5-Li2S, and the B2S3-P2S5-Li2S glass systems, Solid State Ionics 38 (1990), 217-224.
[41] D. Larink, H. Eckert, S. W. Martin, Structure and ionic conductivity in the mixed network former chalcogenide glass system [Na2S]0. 67[(B2S3)x(P2S5)1-x]0. 33, J. Phys. Chem. C 116 (2012), 22698-22710.
DOI: 10.1021/jp3068365
[42] K. Minami, F. Mizuno, A. Hayashi, M. Tatsumisago, Structure and properties of the 70 Li2S(30-x)P2S5 x P2O5 oxysulfide glasses and glass ceramics, J. Non-Cryst. Solids 354 (2008), 370-373.
[43] S. W. Martin, C. Bischoff, K. Schuller, Composition dependence of the Na+ ion conductivity in 0. 5 Na2S + 0. 5[xGeS2 + (1-x)PS5/2 mixed glass former glasses: a structural interpretation of a negative mixed glass former effect, J. Phys. Chem. B 2016, in press.
[44] A. Hayashi, R: Araki, R: Komiya, K. Tadanaga, M. Tatsumisago, T. Minami, Thermal and electrical properties of rapidly quenched Li2S-SiS2-Li2O-P2O5 oxysulfide glasses, Solid State Ionics 113-115 (1998), 733-738.
[45] A. Navrotsky, Thermodynamics, Miscibility, and Phase Diagrams; http: /neat. ucdavis. edu/pages/oru/news/Thermo%20crash%20course%204%20%20Phase%20Diagrams%202-09. pdf. Figure 3 was taken from the website of the IIT Delhi, http: /nptel. ac. in/courses/116102010/23.
[46] M. Schuch, C. Trott, P. Maass, Network forming units in alkali borate and borophosphate glasses and the mixed glass former effect, RSC Adv. 1 (2011), 1370-1382.
DOI: 10.1039/c1ra00583a
[47] J. J. Hudgens, R. K. Brow, D. R. Tallant, S.W. Martin, Raman Spectroscopy Study of the Structure of Lithium and Sodium Ultraphosphate Glass, J. Non-Cryst. Solids 223 (1998).
[48] W. L. Konijendijk, J. M. Stevels, Structure of borate glasses studied by Raman scattering, J. Non-Cryst. Solids 18 (1975).
[49] T. Furukawa, K. E. Fox, W. B. White, Raman spectroscopic investigation of the structure of silicate glasses. III. Raman intensities and structural units in sodium silicate glasses, J. Chem. Phys. 75 (1981), 3226.
DOI: 10.1063/1.442472
[50] J. Heo, D. Lam, G. Sigel, E. Mendoza, D. Hensley, Spectroscopic analysis of the structure and properties of alkali tellurite glasses, J. Am. Ceram. Soc. 75 (1992).
[51] Y. Kim, J. Saienga, S. W. Martin, Glass formation in and structural investigation of Li2S + GeS2 +GeO2 composition using Raman and IR spectroscopy, J. Non-Cryst. Solids 351 (2005), 3716-3724.
[52] A. Mekki, D. Holland, K.A. Ziq, C. F. McConville, Structural and magnetic properties of sodium iron germanate glasses, J. Non-Cryst. Solids 272 (2000), 179-190.
[53] R. Gresch, W. Müller-Warmuth, H. Dutz, X-ray photoelectron spectroscopy of sodium phosphate glasses, J. Non-Cryst. Solids 34 (1979), 127-136.
[54] R. Brückner, H. U. Chun, H. Goretzki, Photoelectron spectroscopy (ESCA) on alkali silicate and soda alumosilicate glasses, Glastechn. Ber. 51 (1978), 1-7.
[55] B. M. J. Smets, T. P. A. Lommen, The structure of germanosilicate glasses, studied by X-ray photoelectron spectroscopy, J. Non-Cryst. Solids 29 (1981), 21-32.
[56] Y. Himei, Y. Miura, T. Nanba, A. Osaka, X-ray photoelectron spectroscopy of alkali tellurite glasses, J. Non-Cryst. Solids 211 (1997).
[57] M. T. Rinke, L. Zhang, H. Eckert, Structural integration of tellurium oxide into mixed-network former glasses: Connectivity distribution in the System NaPO3-TeO2, Chem. Phys. Chem. 8 (2007).
[58] Y. Miura, H. Kusano, T. Nanba, S. Matsumoto, X-ray photoelectron spectroscopy of sodium borosilicate glasses, J. Non-Cryst. Solids 290 (2001), 1-14.
[59] D. Foix, H. Martinez, A. Pradel, M. Ribes, D. Gonbeau, XPS valence band spectra and theoretical calculations for investigations on thiogermanate and thiosilicate glasses, Chem. Phys. 323 (2006), 606-616.
[60] E. R. Andrew, Bradbury and Eades, Nuclear magnetic resonance spectra from a crystal rotated at high speed. Nature. 182 (1958), 1659.
DOI: 10.1038/1821659a0
[61] H. Maekawa, T. Maekawa, K. Kawamura, T. Yokokawa, The structural groups of alkali silicate glasses determined from29Si MAS-NMR, J. Non-Cryst. Solids 127 (1991), 53-64.
[62] R. K. Brow, R. J. Kirkpatrick, G. L. Turner, The short. -range structure of sodium phosphate glasses. I. MAS-NMR Studies, J. Non-Cryst. Solids 116 (1990), 39-45.
[63] S. Kroeker, J. F. Stebbins, Three-coordinated boron-11 chemical shifts in borates, Inorg. Chem. 40 (2001), 6239-6246.
DOI: 10.1021/ic010305u
[64] D. Holland, J. Bailey, G. Ward, B. Turner, P. Tierney, R. Dupree, R. A. 125Te and 23Na NMR Investigation of the structure and crystallization of sodium tellurite glasses, Solid State Nucl. Magn. Reson. 27 (2005).
[65] H. Eckert, Z. Zhang and J. H. Kennedy, Glass-formation in non-oxide chalcogenide systems. Structural elucidation of Li2S-SiS2-LiI solid electrolytes by quantitative 29Si, 6Li and 7Li high resolution solid state NMR methods, J. Noncryst. Solids, 107 (1989).
[66] H. Eckert, Z. Zhang and J. H. Kennedy, Structural transformation of non-oxide chalcogenide glasses. The short-range order of Li2S-P2S5 glasses studied by quantitative 31P and 6, 7Li high-resolution solid-state NMR, Chem. Mater. 2 (1990).
DOI: 10.1021/cm00009a017
[67] D. B. Raskar, M. T. Rinke, H. Eckert, The mixed-network former effect in phosphate glasses: XPS and NMR Studies of the connectivity distribution in the glass system (NaPO3)1-x(B2O3)x, J. Phys. Chem. C 112 (2008), 12530-12539.
DOI: 10.1021/jp8035549
[68] J. Ren, H. Eckert, Quantification of short- and medium range order in mixed network former glasses of the system GeO2-NaPO3: A combined NMR and XPS study, J. Phys. Chem. C, 116 (2012), 12747-12763.
DOI: 10.1021/jp301383x
[69] F. Behrends, H. Eckert, Mixed network former effects in oxide glasses: Structural studies in the system (M2O)1/3[(Ge2O4)x(P2O5)1-x]2/3 by solid state NMR spectroscopy, J. Phys. Chem. C 118 (2014), 10271-10283.
[70] D. Freude, J. Haase, Quadrupole effects in solid state nuclear magnetic resonance, NMR- Basic Principles and Progress, 29 (1993), 1-90.
[71] S. P. Brown, M. Pérez-Torralba, D. Sanz, R. M. Claramunt, L. Emsley, Determining hydrogen-bond strengths in the solid state by NMR: the quantitative measurement of homonuclear J couplings, Chem. Commun. 7 (2002).
DOI: 10.1039/b205324a
[72] A. Lesage, M. Bardet, L. Emsley, Through-Bond Carbon−Carbon Connectivities in Disordered Solids by NMR, J. Am. Chem. Soc. 121 (1999), 10987-10993.
DOI: 10.1021/ja992272b
[73] T. Gullion, Rotational echo double resonance NMR, G. A. Webb (ed. ), Modern Magnetic Resonance, Springer Verlag 2008, 713–718, and references therein. T. Gullion , Magn. Reson. Rev. 17 (1997) 17, 83.
[74] T. Gullion, J Schaefer, Rotational echo double resonance NMR, J. Magn. Reson. 81 (1989), 196-200.
[75] A. Naito, K. Nishimura, S. Tuzi, H. Saitô, Inter- and intra-molecular contributions of neighboring dipolar pairs to the precise determination of interatomic distances in a simple [13C, 15N]-peptide by 13C, 15N-REDOR NMR spectroscopy, Chem. Phys. Lett. 229 (1994).
[76] M. Bertmer, H. Eckert, Dephasing of spin echoes by multiple dipolar interactions in rotational echo double resonance NMR experiments, Solid State Nucl. Magn. Reson. 15 (1999), 139-152.
[77] J. C. C. Chan, M. Bertmer, H. Eckert, Site connectivities in amorphous materials studied by double resonance NMR of quadrupolar nuclei: high resolution 11B « 27Al spectroscopy of aluminoborate glasses, J. Am. Chem. Soc., 121 (1999) 5238-5248.
DOI: 10.1021/ja983385i
[78] J. C. C. Chan, H. Eckert, Dipolar coupling information in multi-spin systems: Application of a compensated REDOR NMR approach to inorganic phosphates, J. Magn. Reson., 147 (2000), 170-178.
[79] J. H. van Vleck, The dipolar broadening of magnetic resonance lines in crystals. Phys. Rev. 74 (1948), 1168-1183.
[80] S. Elbers, W. Strojek, L. Koudelka, H. Eckert, Site connectivities in silver borophosphate glasses: New results from 11B{31P} and 31P{11B} rotational echo double resonance NMR Spectroscopy, Solid State Nucl. Magn. Reson. 27 (2005).
[81] J. S. Waugh, E. I. Fedin. Determination of hindered-rotation barriers in solids. Soviet Physics-Solid State, 4 (1963) 1633-1636.
[82] J. Jeener and P. Broekaert, Nuclear magnetic resonance in solids: Thermodynamic effects of a pair of rf pulses, Phys. Rev. 157 (1976), 232-240.
[83] R. Böhmer, Multiple-time correlation functions for spin-3/2 solid state NMR spectroscopy, J. Magn. Reson. 147 (2000), 78-88.
[84] R. Böhmer and F. Qi, Spin relaxation and ultra-slow Li motion in an aluminosilicate glass ceramic, Solid State Nucl. Magn. Reson. 34 (2007).
[85] A. Heuer, S. C. Kuebler, U. Tracht, H. W. Spiess, Multidimensional NMR experiments to observe the nature of non-exponential relaxation in glasses, Appl. Magn. Reson. 12 (1997), 183-191.
DOI: 10.1007/bf03162185
[86] M. Vogel, C. Brinkmann, H. Eckert, A. Heuer, Silver dynamics in silver iodide/silver phosphate glasses studied by multi-dimensional 109Ag NMR, Phys. Chem. Chem. Phys. 4 (2002).
DOI: 10.1039/b200619g
[87] B. Raguenet, G. Tricot, B. Silly, M. Ribes, A. Pradel, Revisiting the mixed glass former effect, in ultra-fast quenched borophosphate glasses by advanced 1D/2D NMR, J. Mater. Chem. 21 (2011), 17693-17704.
DOI: 10.1039/c1jm12350e
[88] Tricot, B: Raguenet, G. Silly, M. Ribes, A. Pradel, H. Eckert, P-O-B3 linkages in borophosphate glasses evidenced by high-field 11B/31P correlation NMR; Chem. Comm. 51 (2015), 9284-9286.
DOI: 10.1039/c5cc01992c
[89] L. Funke, H. Eckert, Charge compensation in sodium borophosphate glasses studied by 11B{23Na} and 31P{23Na} rotational echo double resonance spectroscopy, J. Phys. Chem. C 2016, in press.
[90] J. W. Zwanziger, Structure and chemical modification in oxide glasses, Int. Rev. Phys. Chem. 17 (1998), 65-90; J. C. Mc. Laughlin, S. L Tagg, J. W. Zwanziger, The structure of alkali tellurite glasses J. Phys. Chem. B 105 (2001), 67-75.
DOI: 10.1021/jp0025779
[91] A. Bunde, K. Funke, M. Ingram, Ionic glasses: history and challenges, Solid State Ionics 105 (1998), 1-13.
[92] B. Gee, H. Eckert, 23Na nuclear-magnetic-resonance spin-echo decay spectroscopy of sodium-silicate glasses and crystalline model compounds, Solid State Nucl. Magn. Reson. 5 (1995), 113-122.
[93] J. D. Epping, W. Strojek, H. Eckert, Cation Environments and Spatial distribution in Na2O-B2O3 Glasses: New results from Solid State NMR, Phys. Chem. Chem. Phys. 7 (2005).
DOI: 10.1039/b502265g
[94] S. H. Lee, K. I Cho, J. B. Choi, D. W. Shin, Phase separation and electrical conductivity of lithium borosilicate glasses for potential thin film solid electrolytes, J. Power Sources 162 (2006).
[95] X. Wu, R. Youngman, R. Dieckmann, Sodium tracer diffusion and 11B NMR study of glasses of the type (Na2O)0. 17[BO1. 5)x(SiO2)1-x]0. 83, J. Non-Cryst. Solids 378 (2013), 168-176.
[96] R. Martens, W. Müller-Warmuth, Structural groups and their mixing in borosilicate glasses of various compositions – an NMR study, J. Non-Cryst. Solids 265 (2000), 167-175.
[97] S. Wegner, L. van Wüllen, G. Tricot, The structure of phosphate and borosilicate glasses and their structural evolution at high temperatures as studied with solid state NMR spectroscopy: Phase separation, crystallisation and dynamic species exchange, Solid State Sci. 12 (2010).
[98] S. Wang, J. F. Stebbins, Nature of Silicon−Boron mixing in sodium borosilicate glasses: A high-resolution 11B and 17O NMR study, J. Non-Cryst. Solids 231 (1998).
[99] L.S. Du, L. Peng, J. F. Stebbins, Germanosilicate and alkali germanosilicate glass structure: New insights from high-resolution oxygen-17 NMR J. Non-Cryst. Solids 353 (2007), 2910-2918.
[100] Y. Kim, J. Saienga, S. W. Martin, Glass formation in and structural investigation of Li2S + GeS2 +GeO2 composition using Raman and IR spectroscopy, J. Non-Cryst. Solids 351 (2005), 3716-3724.
[101] M. Tatsumisago, K. Hirai, T. Hirata, M. Takahashi, T. Minami, Structure and properties of lithium conducting oxysulfide glasses prepared by rapid quenching, Solid State Ionics 86-88 (1996).
[102] A. Pradel, C. Rau, D. Bittencourt, P. Armand, E. Philippot, M. Ribes, Mixed glass former effect in the system 0. 3Li2S-0. 7[(1-x)SiS2-xGeS2]: A structural explanation., Chem. Mater. 10 (1998), 2162-2166.
DOI: 10.1021/cm980701j