摘要
Polymorphism is crucial for unraveling crystallization mechanisms,predicting crystal structures and discovering novel materials.A new high-symmetry polymorph of Li_(2)TeMo_(3)O_(12),β-Li_(2)TeMo_(3)O_(12),was identified successfully by a spontaneous crystallization technique,and it exhibits improved thermal stability and crystallizes in the trigonal space group R3(No.148)in contrast to the metastable α-Li_(2)TeMo_(3)O_(12).Thermal analysis and variable-temperature X-ray diffraction powder patterns demonstrated an irreversible phase transition of Li_(2)TeMo_(3)O_(12)from α-Li_(2)TeMo_(3)O_(12)to β-Li_(2)TeMo_(3)O_(12).High-quality and centimetre-sized single crystals of β-Li_(2)TeMo_(3)O_(12)were extracted via a facile flux approach.Moreover,optical characterization showed that it has a large bandgap of 3.05 eV accompanied by high transparency from 0.34 to 5.4μm,encompassing a 3-5μm atmospheric window.Remarkably,the title compound features the intriguing merits of an intrinsically strong Raman shift located at 955 cm^(−1) and a narrow line width of 12.54 cm^(−1),which enable it to act as a stimulated Raman laser,making it a promising mid-infrared Raman crystal.Additionally,theoretical investigations are used to evaluate the fundamental relationships between the compound’s structure and optical properties.
基金
financially supported by the National Natural Science Foundation of China(Grant No.52002273,51972229,61835014 and 51890864)
National Key R&D Program of China(2021YFA0717800).
