17O NMR in room temperature phase of La2Mo2O9 fast oxide ionic conductor

✍ Scribed by Joel Emery; Dominique Massiot; Philippe Lacorre; Yvon Laligant; Kasik Conder

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 380 KB
• Volume: 43
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1555

✦ Synopsis

A room temperature 17 O NMR study of La 2 Mo 2 O 9 , a fast oxide ionic conductor exhibiting a phase transition at 580 • C between a low-temperature a-phase and a high-temperature b-phase, is presented. Four partly overlapping quasi-continuous distributions of oxygen sites are evidenced from 1D magic angle spinning (MAS) and 2D triple quantum MAS NMR experiments. They can be correlated with the three oxygen sites O1, O2 and O3 of the high-temperature crystal structure. The low-temperature phase is characterized by two distributed sites of type O1, which proves that the symmetry is lower than in the cubic hightemperature phase. Two-dimensional experiments show that there is no dynamic exchange process, on the NMR time-scale, between the different oxygen sites at room temperature, which agrees well with conductivity results.