TY - JOUR

T1 - Ultrasonic studies of alkali-rich hydrous silicate glasses

T2 - Elasticity, density, and implications for water dissolution mechanisms

AU - Liu, Bohan

AU - Liu, Qiong

AU - Li, Baosheng

AU - Behrens, Harald

AU - Lange, Rebecca A.

N1 - Funding Information: We thank Xiaoli Li for his support on microprobe analysis and Xinjian Bao for technical assistance in the high-pressure and high-temperature laboratory at Peking University. We thank George Morgan and Youxue Zhang for their helpful suggestions on the conditions for electron microprobe analysis. We also acknowledge Wim Malfait and an anonymous reviewer for the constructive comments and Daniel Neuville for handling our manuscript. This study was supported by the National Natural Science Foundation of China (Grant Nos. 41672036 and 40972028).

PY - 2023/4/3

Y1 - 2023/4/3

N2 - The acoustic velocities of three series of alkali-rich hydrous silicate glasses were determined at ambient conditions using ultrasonic interferometry. The sound velocities and calculated elastic properties are nearly linear functions of dissolved water content. The water content derivatives of both compressional [d(VP)/d(XH2O)] and shear wave velocity [d(VS)/d(XH2O)] decrease with increasing Na2O content, which suggests that increasing sodium content might weaken the effect of water on acoustic velocities. For each glass series, the shear modulus decreases with increasing water content, whereas the adiabatic bulk modulus (KS) varies little with water content. By comparing our results of KS to previously published data on hydrous alkalic (rhyolite, phonolite, and trachyte) glasses, we speculate that H2O may have a negligible effect on the compressibility of alkalic glasses/melts. The measured densities of each series of glasses were converted to molar volumes and extrapolated to the hypothetical pure water component to derive the partial molar volume of water V ¯ H 2 O. $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right).$The resulting V ¯ H 2 O $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right)$at room pressure and temperature was found to be independent of composition for the three series of glasses, with a value of 10.4 ± 0.5 cm3/mol, whereas the partial molar bulk modulus (KS) of water is composition-dependent, suggesting that V ¯ H 2 O $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right)$may depend on composition at elevated pressures. Furthermore, the Poisson's ratio (ν) increases linearly with increasing water content for all three composition series. Therefore, the similar behavior of Al-free and Al-bearing glasses implies that water depolymerizes melts in both systems. The decrease of water content derivative of the Poisson's ratio [d(ν)/d(XH2O)] with increasing Al/(Al+Si) indicates that water interaction with Al-O bonds to produce Al-OH depolymerizes peralkaline silicate melts less effectively than with Si-O bonds to form Si-OH. Hence, we speculate that water prefers to interact with Si-O bonds rather than Al-O bonds in peralkaline silicate systems. The dissolution mechanisms of water between peraluminous and peralkaline melts might be different, which merits further research.

AB - The acoustic velocities of three series of alkali-rich hydrous silicate glasses were determined at ambient conditions using ultrasonic interferometry. The sound velocities and calculated elastic properties are nearly linear functions of dissolved water content. The water content derivatives of both compressional [d(VP)/d(XH2O)] and shear wave velocity [d(VS)/d(XH2O)] decrease with increasing Na2O content, which suggests that increasing sodium content might weaken the effect of water on acoustic velocities. For each glass series, the shear modulus decreases with increasing water content, whereas the adiabatic bulk modulus (KS) varies little with water content. By comparing our results of KS to previously published data on hydrous alkalic (rhyolite, phonolite, and trachyte) glasses, we speculate that H2O may have a negligible effect on the compressibility of alkalic glasses/melts. The measured densities of each series of glasses were converted to molar volumes and extrapolated to the hypothetical pure water component to derive the partial molar volume of water V ¯ H 2 O. $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right).$The resulting V ¯ H 2 O $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right)$at room pressure and temperature was found to be independent of composition for the three series of glasses, with a value of 10.4 ± 0.5 cm3/mol, whereas the partial molar bulk modulus (KS) of water is composition-dependent, suggesting that V ¯ H 2 O $\left({{{\bar{V}}}_{{{H}_{2}}O}} \right)$may depend on composition at elevated pressures. Furthermore, the Poisson's ratio (ν) increases linearly with increasing water content for all three composition series. Therefore, the similar behavior of Al-free and Al-bearing glasses implies that water depolymerizes melts in both systems. The decrease of water content derivative of the Poisson's ratio [d(ν)/d(XH2O)] with increasing Al/(Al+Si) indicates that water interaction with Al-O bonds to produce Al-OH depolymerizes peralkaline silicate melts less effectively than with Si-O bonds to form Si-OH. Hence, we speculate that water prefers to interact with Si-O bonds rather than Al-O bonds in peralkaline silicate systems. The dissolution mechanisms of water between peraluminous and peralkaline melts might be different, which merits further research.

KW - alkali-rich

KW - dissolution mechanisms

KW - elastic properties

KW - hydrous silicate glasses

KW - the partial molar volume of water

KW - Ultrasonic interferometry

KW - water speciation

UR - http://www.scopus.com/inward/record.url?scp=85151846598&partnerID=8YFLogxK

U2 - 10.2138/am-2022-8451

DO - 10.2138/am-2022-8451

M3 - Article

AN - SCOPUS:85151846598

VL - 108

SP - 744

EP - 753

JO - American mineralogist

JF - American mineralogist

SN - 0003-004X

IS - 4

ER -