Chemical shift and quadrupole coupling of the 27Al NMR spectra of LiAIO2 polymorphs

Application of27Al NMR techniques to structure determination in solids

“…The quadrupolar interaction can be sufficiently large that second-order quadrupolar effects must be considered. For general m and t/ quite involved expressions exist (see [15] ), but for the central transition these effects may be written as 9C2 [9(3 -/~cos~9)2sin4L % vt~ z ----144v ~ -12(6 + ~/2 _ 5rq 4rq (10) This gives rise to a characteristic powder pattern (Fig. 2c) which if clearly resolved can be used to deduce Cq and r/, the latter clearly having a marked influence on the lineshape (Fig.…”

“…However the more complicated angular variafion of the second-order perturbation 0Eq. (10)) means that MAS at v r can only produce partial narrowing. Under rotation at an angle t3 to the applied magnetic field the laboratory components of the efg can be written down in terms of a double angular transformation: Such transformations have been used to calculate second-order quadrupolar perturbed spectra from rotating solids [19][20][21][22][23][24].…”

“…As illustration, consider the polymorphs [3-and ~/-LiAIO2 where at 6.35 T their peak positions differ by around 10 ppm, which cannot be explained on the basis of any structural influences on 61s o. This difference is almost entirely due to quadrupole effects (vide infla), which are different for the two materials (Table 4), and when suitably corrected for gives a difference in ~1so of only -1 ppm [10]. The following two sections are devoted to a discussion of the quadrupolar interaction and its influence on the NMR spectrum before proceeding to the applications of solid state 27Al NMR.…”

Local electronic structure in aLiAlO2single crystal studied withLi7Indris1, Heitjans2, Uecker3 et al. 2006Phys. Rev. B251330View full textAdd to dashboardCite

“…5 First NMR measurements were performed on powder samples to determine structure-dependent parameters like electric field gradients and chemical shifts at the Al sites. 6 For the analysis of the 7 Li NMR spectra and their angular dependencies, the Hamiltonian for an I =3/2 nucleus system is…”

NMR and Impedance Spectroscopy Studies on Lithium Ion Diffusion in Microcrystallineγ-LiAlO2

“…Figure 3a shows the 27 Al MAS NMR spectrum of -LiAlO 2 with the central transition positioned at 80 ppm. This chemical shift corresponds to tetrahedrally coordinated Al-O [24]. The two small signals marked by asterisks are side bands caused by spinning.…”