Structural rules of phase separation in alkali silicate melts analyzed by high-temperature Raman spectroscopy

Maehara, Terutaka; Yano, Tetsuji; Shibata, Shuichi

doi:10.1016/j.jnoncrysol.2005.10.003

Cited by 26 publications

(26 citation statements)

References 22 publications

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“…The light intensifier can be driven by a high voltage (opaque or transparent depending on the voltage) and constitutes an optical door integrated to the detector. These ICCDs today appear as the best solution for the time-resolved Raman measurements, and they are used by several groups by the world [56,[71][72][73][74][75][76][77][78]. Goncharov et al [71], who have used them for simultaneous high P and high T measurements feel that ICCDs could allow the Raman scattering up to huge temperatures (5000 K).…”

Section: Specific Instrumentationmentioning

confidence: 99%

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

Polian

Simon

Pagès³

2010

Thermodynamic Properties of Solids

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This chapter aims to show how optical spectroscopies contribute to the study of vibrational properties under extreme conditions. Now, what do we mean by extreme conditions? We can take it in the other way and mention that ambient conditions have nothing more special as to permit life on earth -that is already not bad! From the point of view of physics, no particular property occurs at ambient conditions. On the contrary, most of the matter in the universe is under extreme pressure (P) and temperature (T), as it is in planets, stars, and more exotic objects. Studies at high pressure and high temperature are hence only the study of matter in its normal conditions. The reason why geoscientists are much interested in such studies is self-explanatory, but other fields are widely studied. The application of high pressure and high temperature enables to explore the repulsive part of the potential energy (fundamental physics), to provoke phase transformations thereby leading to new structures eventually metastable at ambient conditions (materials sciences), to orient chemical reactions in requested directions (chemistry), and even to crystallize proteins, that otherwise would not happen by using other techniques (biology). Another interest to work under variable conditions is that, obviously, more insight is given into the considered phenomenon, in that the pressure and/or temperature derivatives of the phenomenon become available, thus offering a more complete picture to achieve optimum understanding and/or modeling.There are mainly five experimental methods to probe the vibrational properties of matter: optical spectroscopies (of main interest here), ultrasonics (US), inelastic neutron scattering (INS, cf. Chapter 3), more recently inelastic X-ray scattering (IXS, cf. Chapter 4) -that was made possible due to the introduction of third generation synchrotron radiation facilities -and picosecond (PS) acoustics.INS and IXS are used to determine the dispersion of vibration modes, that is, acoustical as well as optical ones, over the whole Brillouin zone (BZ). The most stringent limitations are the needed sources (national-size ones, i.e., a nuclear reactor for INS and a monochromatized X-ray beam as delivered by a synchrotron for IXS), and a limitation to small momentum transfer (q < 0.1q BZB , where q is the magnitude of the wavevector and BZB is the BZ boundary). An additional limitation for INS is

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Section: Specific Instrumentationmentioning

confidence: 99%

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

Polian

Simon

Pagès³

2010

Thermodynamic Properties of Solids

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“…Some of these can reproduce crystal structures and its elastic properties [12], and were used for silicate melts [13]. However, these previous models which can reproduce only qualitative pressure dependence of viscosity seem not to reproduce temperature dependence of Q-species [14]. Q-species are the chemical species of silicon and 'n' in Q n denotes the number of bridging oxygen around silicon atom.…”

Section: Inter-atomic Potential Modelmentioning

confidence: 99%

Molecular dynamics simulation and electrical conductivity measurement of Na2O•3SiO2 melt under high pressure; relationship between its structure and properties

Noritake¹,

Kawamura²,

Yoshino³

et al. 2012

Journal of Non-Crystalline Solids

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“…Therefore, in order to express the thermodynamic properties of liquids as a function of temperature and composition, previous studies have attempted to calculate the configurational entropy of mixing of liquids using fictive chemical [13][14][15]58,59] or quasichemical models [16][17][18][19]; followed by optimization of H Mix, α Romero-Serrano et al [19] Wu et al [17] system with components M x O (M = divalent or univalent cation) and SiO 2 , the quasi-chemical model assumes that M and Si mix substitutionally in a quasi-lattice, obeying short-range ordering described by the equilibrium…”

Section: Comparison With Quasi-chemical Modelmentioning

confidence: 99%

“…In the case of the Na 2 O-SiO 2 liquid, the compositional dependence of S Mix,α L is likely to be attributed to the topological variation in the melt structures. Mysen [14] and Maehara et al [15] considered that the entropy of mixing can be described by the random distribution of Q n -species, measured by high-temperature Raman spectroscopy as follows:…”

Section: Comparison With Spectroscopic Datamentioning

confidence: 99%

“…Previous studies have calculated the configurational entropies of mixing of Na 2 O-SiO 2 these liquids by assuming the chemical speciation [13][14][15] or structure [16][17][18][19] of liquids. Then, the enthalpies of mixing of these liquids have been determined on the basis of calculated entropy, liquidus phase relations, and activity data, and they are expressed as functions of temperature and composition.…”

Section: Introductionmentioning

confidence: 99%

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