In situ NMR approach of the local structure of molten materials at high temperature

Abstract

The developments of NMR spectroscopy at high temperature now allow us to study in situ a great number of molten materials. This technique is sensitive to local environment around the nucleus, and gives selective and quantitative information not limited by the disorder existing in liquids. NMR can thus provide a microscopic approach of the structure and dynamics of molten compounds by means of knowledge of different species existing in the melt, the average coordination, or nature of the first neighbors. We present high temperature NMR approach of molten fluoride systems of nuclear interest and description of the local structure around each nucleus, and its evolution with the composition.

Transport in molten LiF–NaF–ZrF4 mixtures: A combined computational and experimental approach

“…In molten fluorides, Raman [2] as well as classical NMR or EXAFS [3][4][5][6][7][8][9] studies have recently been undertaken by several groups, and proved to be efficient in determining the cationic environments in a wide range of melt compositions. On the contrary, matter transport is difficult to quantify with precision.…”

NMR parameters in alkali, alkaline earth and rare earth fluorides from first principle calculations

“…Unfortunately, there are some discrepancies between the 19 F δ iso values previously reported for these compounds. 1,[4][5][6]30,64,[93][94][95][96][97][98][99][100][101][102] In addition, these values are referenced relative to different fluorine standard (CFCl 3 , C 6 F 6 ) and thus need to be expressed with respect to CFCl 3 , the primary fluorine standard. Such conversion procedure was used in previous works 26,56 (some experimental values seem erroneously converted in the paper of Zheng et al 56 .…”

Evidence of dynamical local scale distribution heterogeneities in CsF-AF (A=Li, Na, K and Rb) molten salts

“…Recent structural studies on rare earth/actinide (and analogous cations) alkali fluoride mixtures have shown that the liquid behaves like a labile network. 39,40,41,42 On the reverse, molten alkali fluorides and their mixtures typify basic molten salts. Their viscosity is known to be of the same order of magnitude than liquid water, which means that these liquids are highly fluid.…”