Local electronic structure in aLiAlO2single crystal studied withLi7

Abstract

The local electronic structure of a ␥-LiAlO 2 single crystal was investigated with 7 Li nuclear magnetic resonance measurements. We observed different sets of spectra which originate from the four crystallographically equivalent but magnetically inequivalent Li sites per unit cell. We find a coupling constant e 2 qQ / h = 115.1± 0.6 kHz and an asymmetry parameter = 0.69± 0.01. The directions of the principal axes of the electric field gradient tensor at the sites of the Li nuclei have also been determined. We compared these experimental results with quantum chemical calculations at density-functional level and found good agreement.

Single-crystal neutron diffraction on γ-LiAlO2: structure determination and estimation of lithium diffusion pathway

“…Single crystals of γ-7 LiAlO 2 were prepared as described before [11,12]. Diffraction experiments were performed at FRM II (MLZ, Garching b. München, Germany).…”

“…Because the crystals for diffraction were also used for nuclear magnetic resonance studies, they have been synthesized from isotopically pure lithium-7 reagents [11,12]. It is safe to assume that isotope effects on the crystal structure -caused by substitution of the 7.59(4)% of naturally abounding lithium-6 [25] -are negligible.…”

“…It is built of a three dimensional network consisting of pairs of one nearly ideal AlO 4 and one distorted LiO 4 tetrahedron, manifesting itself, e.g., in a highly anisotropic electric field gradient tensor [11]. In these pairs, each corner is shared by two further tetrahedra.…”

Lithium Diffusion in Ion-Beam Sputtered Amorphous LiAlO2

“…However, there exist comprehensive studies on nanocrystalline LiAlO 2 [15] and on -LiAlO 2 single crystals based on impedance spectroscopy, while the latter paper gives additional nuclear magnetic resonance spectroscopy measurements [2,16]. In order to realize tracer diffusion studies for Li containing solids, stable tracers have to be used.…”

Diffusion Pathways and Activation Energies in Crystalline Lithium-Ion Conductors

“…γ-LiAlO 2 (tetragonal, P4 1 2 1 2/P4 3 2 1 2; see Figure 8) is an example of an ultra-slow threedimensional lithium conductor -densely packed and lacking structural cation defects. It was investigated in different forms with a variety of techniques, such as NMR and impedance/conductivity spectroscopy on micro-to nanocrystalline [42] or amorphous powders [43], as well as on differently oriented single crystals [44][45][46]. Even dynamic mechanical analysis (DMA) has been performed [47].…”