Determining Electron Spin-Transfer Mechanisms in Paramagnetic Ba2YMO6 (M = Mo, Re, Ru) Double Perovskites by Y-89 and Ba-137 MAS NMR Spectroscopy

作者：Michaelis Vladimir K; Greer Brandon J; Aharen Tomoko; Greedan John E; Kroeker Scott^*

来源：Journal of Physical Chemistry C, 2012, 116(44): 23646-23652.

DOI：10.1021/jp308214d

The spin-transfer mechanisms of three B-site ordered double perovskites, Ba2YMO6 (M = Mo, Re, and Ru), were determined using variable-temperature Y-89 and Ba-137 magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. On the basis of symmetry-compatible overlap and trends observed in the MAS NMR, spin polarization was determined to be the dominant mechanism at the Y sites and spin delocalization to be the operative mechanism at the Ba sites. The MAS NMR spectra display Y-89 and Ba-137 chemical shifts that far exceed those of other paramagnetic solids, appearing at up to -6402 and +12 200 ppm, respectively. Detection of additional resonances in Y-89 MAS NMR indicates a small degree of cation site mixing in two cases.

• 出版日期2012-11-8