Lattice Dynamics of Calcite

Cowley, E. R.; Pant, A. K.

doi:10.1103/physrevb.8.4795

Cited by 53 publications

(27 citation statements)

References 14 publications

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“…Early computational activity, [44][45][46] focused on lattice dynamics and using solid-state force fields, 1 concerned primarily carbonates of divalent metals, because of their role in mineralogy and geophysics. 6-9 Density functional computations for the structure, lattice dynamics and energetics of metal carbonate crystals 47,48 are relatively recent developments.…”

Section: A Modelling Approachesmentioning

confidence: 99%

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

et al. 2017

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Interfaces between molten carbonates M 2 CO 3 (M=Li, Na and K) and planar metal walls have been investigated by molecular dynamics based on a rigid-ions force field (Janssen and Tissen, Mol. Simul. 5, 83-98, (1990)). Simulations cover the temperature range 1200 K ≤ T ≤ 1500 K at a moderate (∼ 15 kbar) overpressure to compensate for a slight overestimate of the system volume by the force field model. Most of the simulations represent neutral electrodes, but shorter computations have been carried out for systems with a low surface charge distribution on the metal side of the interface. The results provide an intriguing view of the interplay among ion packing, oscillating screening, anisotropic correlations and ion dynamics at the interface. The mass and charge density profiles display prominent peaks at contact, and tend to their constant bulk values through several oscillations, whose amplitude decays exponentially moving away from the interface.Oscillations in the charge density profile, in particular, limit the value of the interfacial dipole, and increase the capacitance of the interface. Ion-ion correlations are enhanced in proximity of the metal surface, but retain the exponentially-decaying oscillatory form of their bulk counterpart.Diffusion is slower in the molecularly thin layer of ions next to the interface than in the bulk.The analysis of interfaces is completed by the computation of structural properties of bulk phases, and by the estimate of transport coefficients such as self-diffusion, electrical conductivity, and especially thermal conductivity, which is seldom computed by simulation. All together, the results of our simulations for homogeneous and inhomogeneous molten carbonates provide crucial insight on systems and properties relevant for advanced devices such as fuel cells, that, in turn, might play a prominent role in future power generation strategies.

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Section: A Modelling Approachesmentioning

confidence: 99%

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

et al. 2017

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“…Table 3. Frequencies (cm À1 ) relative to the phonon dispersion curves of calcite along the c axis (values of the wavevector q given as fractions of c*) The observed data are those taken from Cowley & Pant (1973). For q = 1.5 two Á 1 branches as well as one Á 2 and one Á 3 branch coincide.…”

Section: Analysis Of Results and Discussionmentioning

confidence: 99%

“…calcite, magnesite, dolomite and aragonite) plus those of quartz, a few silicates such as some members of the olivine group (forsterite Mg 2 SiO 4 and monticellite CaMgSiO 4 ), andalusite Al 2 SiO 5 , diopside CaMgSi 2 O 6 and some oxides containing Al or Be, such as corundum, chrysoberyl and bromellite. Most of these data are Raman-and IR-active frequencies obtained by different authors (Hellwege et al, 1970;Cowley & Pant, 1973;Frech et al, 1980; for additional details, and reference to the sources for data on noncarbonates, see Pilati, Demartin, Cariati et al, 1993, Pilati et al, 1990c, 1994, 1995. The lowest branches of the phonon dispersion curves were included when available, as for calcite, quartz, forsterite and andalusite.…”

Section: Analysis Of Results and Discussionmentioning

confidence: 99%

“…Besides accurate measurements of a.d.p. 's for some members in this group (Effenberger et al, 1983;Maslen et al, 1993a,b), there are also reliable measurements of some of the lowest phonon dispersion curves of calcite (Cowley & Pant, 1973), as well as excellent experimental measurements of the Raman- Villiers, 1971;Dal Negro & Ungaretti, 1971;Jarosch & Heger, 1986), as well as Raman and IR data, are available (Bhagavantham & Venkatarayudu, 1939;Couture, 1947;Yamamoto et al, 1974;Frech et al, 1980), we included this substance in our study in order to check whether our results for carbonates could be extended outside the calcite group.…”

Section: Introductionmentioning

confidence: 99%

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Lattice-Dynamical Estimation of Atomic Displacement Parameters in Carbonates: Calcite and Aragonite CaCO₃, Dolomite CaMg(CO₃)₂ and Magnesite MgCO₃

Pilati¹,

Demartin²,

Gramaccioli³

1998

Acta Crystallogr B Struct Sci

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Using crystallographic information and empirical potentials derived from ®tting the vibrational frequencies of all the substances under study, together with those of a group of silicates and oxides, a Born±von Karman rigidion lattice-dynamical model has been applied to the whole Brillouin zone in calcite, aragonite ( -andCaCO 3 , respectively), magnesite (MgCO 3 ) and dolomite [CaMg(CO 3 ) 2 ]. The Raman and IR spectra are satisfactorily reproduced and interpreted by these calculations; there is also very good agreement with atomic anisotropic displacement parameters (a.d.p.'s) derived from accurate crystal structure re®nement by various authors and with the experimental values of thermodynamic functions over a wide range of temperatures. On these vibrational grounds, the stability of calcite with respect to aragonite at high temperature can be accounted for.

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“…In Figure 14 we show measurements of the dispersion curves for calcite, CaCO 3 , measured along the 3-fold axis of the rhombohedral space group [15] (the [111] direction in the rhombohedral setting of the unit cell, or the [001] direction in the hexagonal setting). Calcite has 2 formula units in the unit cell, hence z = 10.…”

Section: More Complex Crystalsmentioning

confidence: 99%

Introduction to the theory of lattice dynamics

Dove

2011

JDN

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Abstract. We review the theory of lattice dynamics, starting from a simple model with two atoms in the unit cell and generalising to the standard formalism used by the scientific community today. The key component of the theory is the force between atoms, and we discuss how this can be computed from empirical or quantum mechanical models. The basic model is developed to link the amplitudes of vibrations to thermodynamics. The major method for measuring lattice dynamics is inelastic scattering of beams of neutrons and x-rays. We develop a simplified theory of inelastic scattering of radiation beams, and show how this can be used in instrumentation. Several examples are used to illustrate the theory.

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Lattice Dynamics of Calcite

Cited by 53 publications

References 14 publications

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Lattice-Dynamical Estimation of Atomic Displacement Parameters in Carbonates: Calcite and Aragonite CaCO₃, Dolomite CaMg(CO₃)₂ and Magnesite MgCO₃

Introduction to the theory of lattice dynamics

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Lattice Dynamics of Calcite

Cited by 53 publications

References 14 publications

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Lattice-Dynamical Estimation of Atomic Displacement Parameters in Carbonates: Calcite and Aragonite CaCO3, Dolomite CaMg(CO3)2 and Magnesite MgCO3

Introduction to the theory of lattice dynamics

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Lattice-Dynamical Estimation of Atomic Displacement Parameters in Carbonates: Calcite and Aragonite CaCO₃, Dolomite CaMg(CO₃)₂ and Magnesite MgCO₃