Bridgman growth and characterization of langanite (La₃Ga_5.5Nb_0.5O₁₄, LGN) single crystal

As a promising optical and piezoelectric crystal, efficient growth of LGN single crystal is crucial for its practical applications. Herein, a langanite (La₃Ga_5.5Nb_0.5O₁₄, LGN) crystal with high quality was successfully grown by the Bridgman method along the Z direction. In order to prepare high-purity polycrystalline precursors for LGN crystal growth, the sintering conditions of LGN polycrystalline precursors were studied in detail. The melting point of LGN was also measured to provide a reference for the crystal growth temperature. For the [001] oriented wafer, the full width at half maximum (FWHM) value of the high-resolution X-ray diffraction (HRXRD) analysis is 38.52″, demonstrating that the LGN crystal exhibits excellent crystalline quality. In addition, we also measured the thermal properties and transmission spectrum of the as-grown LGN crystal. It is found that the absorption peak at 1.85 μm of the LGN crystal grown in air using the Bridgman method disappears compared with previous reports (grown in N₂ + (1–3) vol% O₂ atmosphere), which is attributed to the oxygen-enriched growth environment. Similar phenomenon also occurs in other LGS-type disordered crystals. It is believed that these findings may expand the potential applications of LGS series crystals at 1.85 μm.