An Ultrawide-Line 139La Solid-State NMR Investigation of Layered La(OH)2NO3

Abstract

Layered rare earth hydroxides are new classes of functional materials. In this study, a layered La(OH)2NO3 compound having both ion-exchange capacity and non-linear optical property was studied by solid-state nuclear magnetic resonance (SSNMR) spectroscopy. The quadrupolar Carr-Purcell-Meiboom-Gill sequence (QCPMG) was used to acquire 139La SSNMR sub-spectra with variable offsets, from which the ultrawide-line spectrum was reconstructed by co-addition after applying a filtering function. The ultrawide-line spectrum consisted of both center and satellite transition line shapes, which were also simulated with the QUEST software. The 139La CQ and ηQ values measured by SSNMR experiments agreed well with those calculated with the Cambridge Sequential Total Energy Package (CASTEP). The 139La SSNMR results unambiguously indicated that the layered La(OH)2NO3 compound studied belongs to a non-centrosymmetric space group of P21.

Keywords

• 139la solid-state nmr
• ultrawide-line nmr spectrum
• quadrupole nucleus
• qcpmg pulse sequence
• layered compounds