论文部分内容阅读
LiErF4 was commonly used as a dipolar-coupled antiferromagnet,and was rarely considered as a luminescent material.Herein,we achieved the strong red upconversion emission of LiErF4 simply by an inert shell coating,i.e.,LiErF4@LiYF4.Owing to the unique and intrinsic ladder-like energy levels of EP ions,this LiErF4 core-shell nanostructures present red emission (～ 650 nm) under multi-band excitation in the near-infrared (NIR) region (～ 808,～ 980,and ～ 1,530 nm).A brighter and monochromic red emission can be further obtained via doping 0.5％ Tm3+ into the LiErF4 core,i.e.,LiErF4∶ 0.5％ Tm3+@LiYF4.The enriched Er3+ ions and strong monochromic red emission natures make LiErF4∶ 0.5％ Tm3+@LiYF4 nanocrystals very sensitive for trace water probing in organic solvents with detection limit of 30 ppm in acetonitrile,50 ppm in dimethyl sulfoxide (DMSO),and 58 ppm in N,N-dimethylformamide (DMF) under excitation of 808 nm.Due to their superior chemical and physical stability,these nanoprobes exhibit excellent antijamming ability and recydability,offering them suitable for real-time and long-term water monitoring.