铌磷酸盐化合物的93Nb和17O核磁共振化学位移
93Nb and 17O NMR chemical shifts of niobiophosphate compounds.
作者信息
Flambard A, Montagne L, Delevoye L, Steuernagel S
机构信息
Unité de Catalyse et Chimie du Solide, UMR CNRS 8181, Ecole Nationale Supérieure de Chimie de Lille, Université des Sciences et Technologies de Lille, BP 108, 59652 Villeneuve d'Ascq Cedex, France.
出版信息
Solid State Nucl Magn Reson. 2007 Oct;32(2):34-43. doi: 10.1016/j.ssnmr.2007.07.001. Epub 2007 Jul 10.
Niobiophosphate compounds with a large range of niobium and oxygen environments were studied with (93)Nb and (17)O solid-state NMR. (93)Nb isotropic chemical shift of pure niobate Nb(ONb)(6), pure phosphate Nb(OP)(6) and mixed phosphate-niobate Nb(OP)(x)(ONb)((6-x)) (1<or= x<or=5) sites were measured at a high magnetic field (18.8T). (93)Nb chemical shifts were found to be sensitive to the variation of local charge on Nb, but not to the local bond geometry (i.e. crystallographic site and edge or corner connectivity). A systematic shift to high field of the (93)Nb chemical shift is measured when x increases. Then, (17)O NMR spectra of a series of enriched samples provided the chemical shift and quadrupolar parameters for 4 types of oxygen environment (P-O-P, P-O-Na, P-O-Nb and Nb-O-Nb). Finally, Nb-O-Nb sites were characterized by a large (17)O chemical shift anisotropy.
利用(^{93}Nb)和(^{17}O)固态核磁共振技术研究了具有多种铌和氧环境的铌磷酸盐化合物。在高磁场（(18.8T)）下测量了纯铌酸盐(Nb(ONb)_6)、纯磷酸盐(Nb(OP)_6)以及混合磷酸盐 - 铌酸盐(Nb(OP)x(ONb){(6 - x)})（(1\leq x\leq5)）位点的(^{93}Nb)各向同性化学位移。发现(^{93}Nb)化学位移对铌上局部电荷的变化敏感，但对局部键几何结构（即晶体学位点以及边或角的连接性）不敏感。当(x)增加时，测量到(^{93}Nb)化学位移向高场有系统的移动。然后，一系列富集样品的(^{17}O)核磁共振谱提供了四种氧环境（(P - O - P)、(P - O - Na)、(P - O - Nb)和(Nb - O - Nb)）的化学位移和四极参数。最后，(Nb - O - Nb)位点的特征是具有较大的(^{17}O)化学位移各向异性。
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