What can NMR tell us about the local structure of NaNbO3 and (Na,Bi)TiO3-BaTiO3 (NBT-BT) electroceramics?

In this contribution, I will overview the key aspects of solid-state nuclear magnetic resonance spectroscopy of sodium (23Na NMR) regarding functional ceramics. This technique explores interactions between the nucleus and its... [ view full abstract ]

In this contribution, I will overview the key aspects of solid-state nuclear magnetic resonance spectroscopy of sodium (²³Na NMR) regarding functional ceramics. This technique explores interactions between the nucleus and its close surroundings to provide insight into the structure at the atomic scale. After a brief introduction, two examples of the application of ²³Na NMR to the study of the local structure in perovskite oxides will be discussed.

In the first example, the grain size-induced transition between the antiferroelectric P and ferroelectric Q polymorphs of NaNbO₃ is analyzed with ²³Na NMR.^[1] This technique is used to quantify the relative amount of each phase and determine the critical grain size for the transition to the ferroelectric polymorph to occur.

The second example deals with the characterization of local structure disorder in (100‑x)(Na_1/2,Bi_1/2)TiO₃‑xBaTiO₃ (NBT-BT) relaxor ferroelectrics. I will highlight its relation to the tilting of oxygen octahedra and discuss its role in the composition-driven ferroelectric-to-relaxor transition observed between rhombohedral and tetragonal phases of this solid-solution.^[2]

[1] Grain-size-induced ferroelectricity in NaNbO₃,   J. Koruza, P. Groszewicz, H. Breitzke, G. Buntkowsky, T. Rojac, B. Malič , Acta Materialia, 126 (2017) 77-85.

[2] Reconciling Local Structure Disorder and the Relaxor State in (Bi_1/2Na_1/2)TiO₃-BaTiO₃,    P.B. Groszewicz, M. Gröting, H. Breitzke, W. Jo, K. Albe, G. Buntkowsky, J. Rödel,  Scientific Reports, 6 (2016) 31739.