The glass transition temperature of mixed glass former 0.35Na2O+0.65[xB2O3+(1−x)P2O5] glasses

Christensen, Randilynn; Byer, Jennifer; Olson, Garrett; Martin, Steve W.

doi:10.1016/j.jnoncrysol.2011.12.068

Cited by 40 publications

(74 citation statements)

References 24 publications

(43 reference statements)

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“…The maximum deviation from linearity occurs at x = 0.3 for all phosphorous SRO structural units and at x = 0.4 for all borate SRO structural units. This is the same compositional region where the conductivity [27] and the glass transition temperature (T g ) [27] go through maximum values and indicates that the maximum in the conductivity and the T g may be associated with the same factor that caused the density maximum, the decreasing volumes of the various structural groups.…”

Section: Molar Volume Modelmentioning

confidence: 63%

“…(10) and the density is at a maximum suggests that the second factor affecting the ionic conductivity, the collective and many-body long range columbic forces acting between the mobile cations, Na + , and the anions, NBO in the P 2 , P 1 , and B 2 groups, and the BO of the B 4 groups in the glasses must be a more important factor. We will explore this hypothesis further in future reports on the behavior of the ionic conductivity in theses glasses [27].…”

Section: Free Volume and Ionic Conductivitymentioning

confidence: 92%

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The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

Christensen

Byer

Olson

et al. 2012

Journal of Non-Crystalline Solids

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Section: Molar Volume Modelmentioning

confidence: 63%

Section: Free Volume and Ionic Conductivitymentioning

confidence: 92%

The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

Christensen

Byer

Olson

et al. 2012

Journal of Non-Crystalline Solids

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“…48 The number of BOs present in a glass was compared to the composition dependence of the T g of the glasses and found to be in excellent agreement. The trend in the number of B 4 units in the "atomic fraction SRO model" with composition was found to have a strong relationship to the number of BOs.…”

mentioning

confidence: 88%

Structural Studies of Mixed Glass Former 0.35Na₂O + 0.65[xB₂O₃ + (1 – x)P₂O₅] Glasses by Raman and ¹¹B and ³¹P Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopies

2013

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The mixed glass former (MGF) effect (MGFE) is defined as a nonlinear and nonadditive change in the ionic conductivity with changing glass former composition at constant modifier composition. In this study, sodium borophosphate 0.35Na2O + 0.65[xB2O3 + (1 -x)P2O5], 0 ≤ x≤ 1, glasses which have been shown to exhibit a positive MGFE have been prepared and examined using Raman and 11B and 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Through examination of the short-range order (SRO) structures found in the ternary glasses, it was determined that the minority glass former, B for 0.1 ≤ x ≤ 0.7 and P for 0.7 ≤ x ≤ 0.9, is "overmodified" and contains more Na+ ions than would be expected from simple linear mixing of the binary sodium borate, x = 1, and sodium phosphate, x = 0, glasses, respectively. Changes in the intermediate range order (IRO) structures were suggested by changes in the NMR spectral chemical shifts and Raman spectra wavenumber shifts over the full composition range x in the Raman and MAS NMR spectra. The changes observed in the chemical shifts of 31P MAS NMR spectra with x are found to be too large to be caused solely by changing sodium modification of the phosphate SRO structural groups, and this indicates that internetwork bonding between phosphorus and boron through bridging oxygens (BOs), P-O-B, must be a major contributor to the IRO structure of these glasses. While not fully developed, a firstorder thermodynamic analysis based upon the Gibbs free energies of formation of the various SRO structural units in this system has been developed and can be used to account for the preferential formation of tetrahedral boron groups, B4, by the reaction of B3 with P2 groups to form B4 and P3 groups, respectively, where the superscript denotes the number of BOs on these units, in these glasses. This preference for B4 units appears to be a predominate cause of the changing modifier to glass former ratio with composition x in these ternary MGF glasses and appears to be associated with the large negative value of the Gibbs free energy of formation of this group. Disciplines Materials Science and Engineering | Physical Chemistry CommentsReprinted with permission from The Journal of Physical Chemistry B 117 (2013) P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Through examination of the short-range order (SRO) structures found in the ternary glasses, it was determined that the minority glass former, B for 0.1 ≤ x ≤ 0.7 and P for 0.7 ≤ x ≤ 0.9, is "overmodified" and contains more Na + ions than would be expected from simple linear mixing of the binary sodium borate, x = 1, and sodium phosphate, x = 0, glasses, respectively. Changes in the intermediate range order (IRO) structures were suggested by changes in the NMR spectral chemical shifts and Raman spectra wavenumber shifts over the full composition range x in the Raman and MAS NMR spectra. The changes observed in the chemical shifts of 31 P MAS NMR spectra with x are found to be too large to be ...

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“…An excellent review of the structures of these and related glasses in relation to the MGFE is available, 17 see also Ref. 56. Therefore, here we will focus on the most important structural changes that are occurring for the present glass system.…”

Section: B Correlation Of Transport With the Composition Dependence mentioning

confidence: 99%

“…Hence in the absence of other P groups, the fraction of the electrically neutral metaphosphate, P (3) , groups is {P (3) } = 1 − {P (2) } = 0.5. As P 2 O 5 is substituted by B 2 O 3 , x > 0, it was found 12,48,56 that all of the added B is incorporated into the glass in the form of B (4) units even though the base binary glass 0.33Li 2 O + 0.67B 2 O 3 (x = 1) is found to consist of ∼45% B (4) units, ∼45% B (3) , and ∼10% B (2) . 58 The formation of B (4) units in the ternary glasses can be thought to arise from the reaction of a neutral B (3) unit with a P (2) unit.…”

Section: B Correlation Of Transport With the Composition Dependence mentioning

confidence: 99%

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Storek

Böhmer

Martin

et al. 2012

The Journal of Chemical Physics

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Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li 2 O + 0.67[xB 2 O 3 + (1 -x)P 2 O 5 ]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li 2 P 4 O 11 to pure glassy Li 2 B 4 O 7 has been examined while keeping the molar fraction of Li 2 O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure.

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The glass transition temperature of mixed glass former 0.35Na2O+0.65[xB2O3+(1−x)P2O5] glasses

Cited by 40 publications

References 24 publications

The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

Structural Studies of Mixed Glass Former 0.35Na₂O + 0.65[xB₂O₃ + (1 – x)P₂O₅] Glasses by Raman and ¹¹B and ³¹P Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopies

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

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The glass transition temperature of mixed glass former 0.35Na2O+0.65[xB2O3+(1−x)P2O5] glasses

Cited by 40 publications

References 24 publications

The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

The densities of mixed glass former 0.35 Na2O+0.65 [xB2O3+(1−x)P2O5] glasses related to the atomic fractions and volumes of short range structures

Structural Studies of Mixed Glass Former 0.35Na2O + 0.65[xB2O3 + (1 – x)P2O5] Glasses by Raman and 11B and 31P Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopies

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

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Structural Studies of Mixed Glass Former 0.35Na₂O + 0.65[xB₂O₃ + (1 – x)P₂O₅] Glasses by Raman and ¹¹B and ³¹P Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopies