Short range structural models of the glass transition temperatures and densities of 0.5Na2S + 0.5[xGeS2 + (1 - x)PS5/2] mixed glass former glasses.
نویسندگان
چکیده
The 0.5Na2S + 0.5[xGeS2 + (1 - x)PS5/2] mixed glass former (MGF) glass system exhibits a nonlinear and nonadditive negative change in the Na(+) ion conductivity as one glass former, PS5/2, is exchanged for the other, GeS2. This behavior, known as the mixed glass former effect (MGFE), is also manifest in a negative deviation from the linear interpolation of the glass transition temperatures (T(g)) of the binary end-member glasses, x = 0 and x = 1. Interestingly, the composition dependence of the densities of these ternary MGF glasses reveals a slightly positive MGFE deviation from a linear interpolation of the densities of the binary end-member glasses, x = 0 and x = 1. From our previous studies of the structures of these glasses using IR, Raman, and NMR spectroscopies, we find that a disproportionation reaction occurs between PS7/2(4-) and GeS3(2-) units into PS4(3-) and GeS5/2(1-) units. This disproportionation combined with the formation of Ge4S10(4-) anions from GeS5/2(1-) groups leads to the negative MGFE in T(g). A best-fit model of the T(g)s of these glasses was developed to quantify the amount of GeS5/2(1-) units that form Ge4S10(4-) molecular anions in the ternary glasses (∼ 5-10%). This refined structural model was used to develop a short-range structural model of the molar volumes, which shows that the slight densification of the ternary glasses is due to the improved packing efficiency of the germanium sulfide species.
منابع مشابه
IR, Raman, and NMR studies of the short-range structures of 0.5Na2S + 0.5[xGeS2 + (1-x)PS(5/2)] mixed glass-former glasses.
A nonlinear and nonadditive composition-dependent change of the ionic conductivity in mixed glass-former (MGF) glasses when one glass former, such as PS(5/2), is replaced by a second glass former, such as GeS2, at constant alkali modifier concentrations, such as Na2S, is known as the mixed glass-former effect (MGFE). Alkali ion conducting glasses are of particular interest for use as solid elec...
متن کاملStructural Investigation, Physical and Optical Properties of Mixed Alkali Bismuth Borate Glasses
Lead free, eco-friendly bismuth borate glasses doped with alkali oxides of composition xLi2O+(30-x)Na2O+55B2O3+15Bi2O3 (x = 5,10,15,20,25) were prepared by melt quenching technique. Amorphous nature of glasses was confirmed by X-ray diffraction. Density measurements were carried out at room temperature by standard principle of Archimedes with Xylene as an immersion liquid. The non-linear ...
متن کاملIonic Conductivity of Mixed Glass Former 0.35Na2O + 0.65[xB2O3 + (1 â•fi x)P2O5] Glasses
The mixed glass former effect (MGFE) is defined as a nonlinear and nonadditive change in the ionic conductivity with changing glass former fraction at constant modifier composition between two binary glass forming compositions. In this study, mixed glass former (MGF) sodium borophosphate glasses, 0.35Na2O + 0.65[xB2O3 + (1 – x)P2O5], 0 ≤ x ≤ 1, have been prepared, and their sodium ionic conduct...
متن کاملElectrical conductivity anomaly in silver vadadium-tellurite glasses at temperatures higher than a characteristic temperature: evidence for an ionic-nonadiabatic polaronic mixed conduction
Electrical conduction anomaly was observed in the mixed ion-polaron regime for xAg2O-40TeO2-(60-x)V2O5 glassy system with 0 ≤x≤ 50 mol%, which were prepared by common melt quenching method. For the understudied glasses, the temperature dependence of dc electrical conductivity was measured from a characteristic temperature to 380 K, which certified their semiconducting nature. The measured condu...
متن کاملOptical and Thermal Properties of Mixed Alkali Phosphate Based Glasses
Glassy samples with a composition of 40P2O5–30V2O5–(30-x)Li2O– xK2O, 0<x<30 (mol %) were prepared by the conventional melt quenching technique in two forms of bulk and blown film. X-ray diffraction patterns corroborated the amorphous feature of the samples. Density of samples was investigated by using Archimedes principle. Based on absorption and reflection spectra, indirect a...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The journal of physical chemistry. B
دوره 118 13 شماره
صفحات -
تاریخ انتشار 2014