Superposition model for isotropic chemical shift in ionic fluorides: from basic metal fluorides to transition metal fluoride glasses

Bureau, Bruno; Silly, Gilles; Buzaré, Jean‐Yves; Eméry, J.

doi:10.1016/s0301-0104(99)00253-0

Cited by 89 publications

(136 citation statements)

References 29 publications

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“…6 The value of d, which most likely depends on the Ba-Sr-configuration regarded, plays a crucial role in the calculation. In the 52 The theoretically predicted value of 68.9 ppm obtained by using a periodic structure model 52 is in good agreement with the experimental one found here (66 ppm) which is identical to that probed by Bureau et al 50 For comparison, the value calculated for BaLiF 3 using the empirical superposition model turned out to be 91 ppm indicating the uncertainty of the estimated values.…”

Section: à3supporting

confidence: 89%

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

et al. 2011

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Highly metastable Ba 1Àx Sr x LiF 3 (0 < x # x max z 0.4) with an inverse perovskite structure analogous to that of BaLiF 3 was synthesized by soft mechanical treatment of BaF 2 and LiF together with SrF 2 at ambient temperature. Ex as well as in situ X-ray powder diffraction (XRPD) measurements show that heat treatment at 393 K initiates the decomposition of the mixed phase into BaLiF 3 , LiF and (Sr,Ba)F 2 . Structural details of the metastable compound (Ba,Sr)LiF 3 were investigated by ultrafast 19 F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. Interestingly, five magnetically inequivalent F sites were identified which correspond to fluorine anions coordinated by a variable number of Ba and Sr cations, respectively. Details from XRPD and NMR spectroscopy are discussed with respect to the formation mechanisms and thermal stability of the as prepared fluorides. Impedance spectroscopy is used to characterize (long-range) ionic transport properties. Results are compared with those obtained recently on mechanosynthesized BaLiF 3 .

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Section: à3supporting

confidence: 89%

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

et al. 2011

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“…In the case of organic molecules and H or C nuclei a set of empirical rules are already established and routinely applied. 2 However, for other (heavier) nuclei, or larger molecules and in particular for solids such rules are more difficult to build [3][4][5][6][7][8] and the interpretation of the experimental data is more complicated task. [9][10][11] The interpretation procedure can be aided by ab-initio calculations provided that the computed spectra can properly reproduce the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Assessment of DFT functionals with NMR chemical shifts

2013

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Density-functional theory (DFT) calculations of the magnetic shielding for nuclear magnetic resonance (NMR) in solids provide an important contribution for understanding the experimentally observed chemical shifts. It is known that the calculated NMR shielding parameters for a particular nucleus in a series of compounds correlate well with the experimentally measured chemical shifts; however, the slope of a linear fit often differs from the ideal value of 1.0. Focusing on a series of ionic compounds (fluorides, oxides, bromides, and chlorides), we show that the error is caused by the generalized gradient approximation (GGA) to the exchange-correlation functional and it is related to the well-known band-gap problem. In order to devise an ab initio approach that would correctly reproduce the variation of the shifts within a series of compounds, we test various DFT based approaches. A simple GGA + U scheme with the orbital field acting on the cation d states does not work in a general way. Also, the popular hybrid functionals (including the screened versions), which contain some fixed amount of exact exchange, lead to a large overestimation of the necessary slope correction. Surprisingly, the best solution to this problem is offered by a semilocal potential designed by Becke and Johnson to reproduce the optimized exact exchange potential in free atoms. Density functional theory (DFT) calculations of the magnetic shielding for nuclear magnetic resonance (NMR) in solids provide an important contribution for understanding the experimentally observed chemical shifts. It is known that the calculated NMR shielding parameters for a particular nucleus in a series of compounds correlate well with the experimentally measured chemical shifts, however, the slope of a linear fit often differs from the ideal value of 1.0. Focusing on a series of ionic compounds (fluorides, oxides, bromides and chlorides), we show that the error is caused by the generalized gradient approximation (GGA) to the exchange correlation functional and it is related to the well known band-gap problem. In order to devise an ab-initio approach that would correctly reproduce the variation of the shifts within a series of compounds, we test various DFT based approaches. A simple GGA+U scheme with the orbital field acting on the cation d-states does not work in a general way. Also the popular hybrid functionals (like HSE or YS-PBE0), which contain some fixed amount of exact exchange, leads to a large overestimation of the necessary slope correction. Surprisingly, the best solution to this problem is offered by a semi-local potential designed by Becke and Johnson to reproduce the optimized exact exchange potential in free atoms.

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“…Although several computational approaches have been proven to be very successful in the investigations of 19 F magnetic shielding constants of organic fluorides (see, for examples, Refs 6-12), few theoretical investigations have been performed on metal fluorides. 3,13 -17 Recently, Bureau et al 3 calculated the 19 F magnetic shielding constants of several series of metal fluorides using two empirical methods. Ramsey's theory 18,19 was used to calculate 19 F chemical shifts with molecular orbitals obtained by Löwdin's orthogonalization method.…”

Section: Introductionmentioning

confidence: 99%

“…The resulting 19 F chemical shifts of mixed-metal fluorides deviated from experimental results. 3 Both methods have the major disadvantage that the empirical parameters must be estimated from NMR data.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on ¹⁹F magnetic shielding constants of some metal fluorides

Cai

Zhong

et al. 2003

Magnetic Reson in Chemistry

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using the DFT/GIAO method. The aug-cc-pVTZ basis set was used for the fluorine atom under investigation and LanL2DZ for the remaining fluorine atoms. The 3-21G(2d) basis set was used for the aluminum atom and CRENBL for the other metal atoms. When appropriate cluster models were employed, the theoretical results obtained from the B3LYP/GIAO calculations are in good agreement with experimental measurements and may be better than those obtained from empirical calculations. The correlation coefficient and the slope of the fitting line between our theoretical predictions and the experimental observations are close to unity.

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Superposition model for isotropic chemical shift in ionic fluorides: from basic metal fluorides to transition metal fluoride glasses

Cited by 89 publications

References 29 publications

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

Assessment of DFT functionals with NMR chemical shifts

Theoretical study on ¹⁹F magnetic shielding constants of some metal fluorides

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Superposition model for isotropic chemical shift in ionic fluorides: from basic metal fluorides to transition metal fluoride glasses

Cited by 89 publications

References 29 publications

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

Access to metastable complex ion conductors via mechanosynthesis: preparation, microstructure and conductivity of (Ba,Sr)LiF3 with inverse perovskite structure

Assessment of DFT functionals with NMR chemical shifts

Theoretical study on 19F magnetic shielding constants of some metal fluorides

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Theoretical study on ¹⁹F magnetic shielding constants of some metal fluorides