Giant Second Harmonic Generation from Metastable BaTi2O5

Giant second harmonic generation (SHG) was observed while metastable α-BaTi2O5 crystallized from BaTi2O5 glass. The observed SHG confirmed that α-BaTi2O5 had a large polarization and a non-centrosymmetric structure. The optical anomaly suggested that the alignment of polar nanocrystals of α-BaTi2O5 was the cause of the observed giant dielectric response. Furthermore, the giant SH intensity of α-BaTi2O5 could be obtained at room temperature by quenching the crystallized α-BaTi2O5. The thermal stability of α-BaTi2O5 was evaluated by in situ monitoring of the SH intensity above the crystallization temperature. These results demonstrate that α-BaTi2O5 is a promising material for electro-optical applications, even at high temperatures.