Structure cristalline du nitrate de calcium trihydraté

Leclaire, A.

doi:10.1107/s0567740876002665

Cited by 8 publications

(5 citation statements)

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“…Enriched calcium nitrate, 43 Ca(NO 3 ) 2 Under normal atmospheric conditions, Ca(NO 3 ) 2 will freely absorb ambient water, with the most stable water solvate being the a-tetrahydrate, 125,126 although many other hydrated and solvated forms of calcium nitrate may be prepared. 127,128 The crystal structure for anhydrous calcium nitrate was determined approximately 90 years ago by XRD methods, 129 and does not appear to have been updated since 1931. 63 The crystal structure belongs to the cubic Pa% 3 space group, with calcium cations being positioned on high symmetry % 3 sites (Fig.…”

Section: Calcium Titanate Catiomentioning

confidence: 99%

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Widdifield

Moudrakovski

Bryce

2014

Phys. Chem. Chem. Phys.

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Calcium is the 5th most abundant element on earth, and is found in numerous biological tissues, proteins, materials, and increasingly in catalysts. However, due to a number of unfavourable nuclear properties, such as a low magnetogyric ratio, very low natural abundance, and its nuclear electric quadrupole moment, development of solid-state (43)Ca NMR has been constrained relative to similar nuclides. In this study, 12 commonly-available calcium compounds are analyzed via(43)Ca solid-state NMR and the information which may be obtained by the measurement of both the (43)Ca electric field gradient (EFG) and chemical shift tensors (the latter of which are extremely rare with only a handful of literature examples) is discussed. Combined with density functional theory (DFT) computations, this 'tensor interplay' is, for the first time for (43)Ca, illustrated to be diagnostic in distinguishing polymorphs (e.g., calcium formate), and the degree of hydration (e.g., CaCl2·2H2O and calcium tartrate tetrahydrate). For Ca(OH)2, we outline the first example of (1)H to (43)Ca cross-polarization on a sample at natural abundance in (43)Ca. Using prior knowledge of the relationship between the isotropic calcium chemical shift and the calcium quadrupolar coupling constant (CQ) with coordination number, we postulate the coordination number in a sample of calcium levulinate dihydrate, which does not have a known crystal structure. Natural samples of CaCO3 (aragonite polymorph) are used to show that the synthetic structure is present in nature. Gauge-including projector augmented-wave (GIPAW) DFT computations using accepted crystal structures for many of these systems generally result in calculated NMR tensor parameters which are in very good agreement with the experimental observations. This combination of (43)Ca NMR measurements with GIPAW DFT ultimately allows us to establish clear correlations between various solid-state (43)Ca NMR observables and selected structural parameters, such as unit cell dimensions and average Ca-O bond distances.

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Section: Calcium Titanate Catiomentioning

confidence: 99%

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Widdifield

Moudrakovski

Bryce

2014

Phys. Chem. Chem. Phys.

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“…However, the β-phases are metastable over the entire range of concentrations and temperatures. Besides, the solubilities of the corresponding α- and β-forms sometimes are quite close, which makes it difficult to interpret correctly the experimental data. , The existence of metastable crystal hydrates was revealed in the earliest studies on phase equilibria in the H 2 O–Ca(NO 3 ) 2 system and was reliably confirmed in further works on their crystal structures. − …”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Properties and Phase Equilibria in the H₂O–Ca(NO₃)₂ System

et al. 2021

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A comprehensive data set of thermodynamic and calorimetric properties of calcium nitrate aqueous solutions, including the heats of dilution, heat capacity, and phase equilibria in a wide temperature and concentration range is thoroughly collected and critically reviewed. A temperature-dependent Pitzer− Simonson−Clegg model is proposed to describe reliably the properties of liquid phase as well as solid−liquid (SLE) and vapor− liquid (VLE) equilibria, including metastable ones, over T = (243.15 to 425.75) K and up to x(Ca(NO 3 ) 2 ) = 0.3. Improved accuracy is obtained as compared to that of earlier models along with incorporating many diverse experimental data types simultaneously.

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“…In the first model, Ca 2+ cations are surrounded by five NO 3 − anions and by four H 2 O molecules, whereas in the second model, which is the same used in Ref. 6 for the crystalline phase of Ca͑NO 3 ͒ 2 ·3H 2 O, the cations are surrounded by six NO 3 − anions and by three H 2 O molecules. It was not possible to distinguish between these two models on the basis of the quality of fit to experimental data.…”

Section: Structurementioning

confidence: 99%

“…1,3 In this work, we are concerned with a prototype of these glass-forming liquids, namely, aqueous solution of calcium nitrate, Ca͑NO 3 ͒ 2 · nH 2 O, n = 4, 6, and 8, where n indicates concentration as the water to salt mole ratio. A large literature related to thermodynamics, 1,4,5 structural, [6][7][8][9][10] and dynamical properties 5,[11][12][13] investigated with many different techniques is available for Ca͑NO 3 ͒ 2 · nH 2 O. However, previous molecular dynamics ͑MD͒ simulations of aqueous solutions of nitrate salts have been reported mainly in the limit of dilute solution, [14][15][16][17] in which the most important issue is the equilibrium structure of the hydration shell around the ions.…”

Section: Introductionmentioning

confidence: 99%

Polarization effects in molecular dynamics simulations of glass-formers Ca(NO3)2⋅nH2O, n=4, 6, and 8

Ribeiro

2010

The Journal of Chemical Physics

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Monte Carlo simulation strategies for computing the wetting properties of fluids at geometrically rough surfaces J. Chem. Phys. 135, 184702 (2011) Semi-bottom-up coarse graining of water based on microscopic simulations J. Chem. Phys. 135, 184101 (2011) Hydrophobic interactions in presence of osmolytes urea and trimethylamine-N-oxide J. Chem. Phys. 135, 174501 (2011) Potential of mean force between identical charged nanoparticles immersed in a size-asymmetric monovalent electrolyte J. Chem. Phys. 135, 164705 (2011) Additional information on J. Chem. Phys. Thermodynamics, equilibrium structure, and dynamics of glass-forming liquids Ca͑NO 3 ͒ 2 · nH 2 O, n = 4, 6, and 8, have been investigated by molecular dynamics ͑MD͒ simulations. A polarizable model was considered for H 2 O and NO 3 − on the basis of previous fluctuating charge models for pure water and the molten salt 2Ca͑NO 3 ͒ 2 · 3KNO 3 . Similar thermodynamic properties have been obtained with nonpolarizable and polarizable models. The glass transition temperature, T g , estimated from MD simulations was dependent on polarization, in particular the dependence of T g with electrolyte concentration. Significant polarization effects on equilibrium structure were observed in cation-cation, cation-anion, and water-water structures. Polarization increases the diffusion coefficient of H 2 O, but does not change significantly the diffusion coefficients of ions. Viscosity decreases upon inclusion of polarization, but the conductivity calculated with the polarizable model is smaller than the nonpolarizable model because polarization enhances anion-cation interactions.

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Structure cristalline du nitrate de calcium trihydraté

Cited by 8 publications

References 2 publications

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Thermodynamic Properties and Phase Equilibria in the H₂O–Ca(NO₃)₂ System

Polarization effects in molecular dynamics simulations of glass-formers Ca(NO3)2⋅nH2O, n=4, 6, and 8

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Structure cristalline du nitrate de calcium trihydraté

Cited by 8 publications

References 2 publications

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration

Thermodynamic Properties and Phase Equilibria in the H2O–Ca(NO3)2 System

Polarization effects in molecular dynamics simulations of glass-formers Ca(NO3)2⋅nH2O, n=4, 6, and 8

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Thermodynamic Properties and Phase Equilibria in the H₂O–Ca(NO₃)₂ System