Crystal structure, morphology and luminescent properties of rare earth ion-doped SrHPO_4 nanomaterials

Undoped and rare earth ions （Eu3＋, Ce3＋, Tb3＋） doped β-SrHPO4 nanomaterials were successfully prepared by a facile hydrothermal method. The crystal structure, morphology and luminescent properties were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, photoluminescence （PL） spectra and lumi- nescence decay curves. The results indicated that the tmdoped and rare earth ions doped SrHPO4 nanomaterials （the doping concen- tration was not above 7%） were well crystallized, with the same crystal structure （^-SrHPO4）. Nevertheless, the doping of rare earth ions could lead to the changing of morphology from nanoflakes to nanocrystals. Under the excitation of UV light, rare earth ions （Eu3＋, Ce3＋, Tb3＋） doped I3-SrHPO4 nanocrystals exhibited the characteristic emission of Eu3＋, Ce3＋ and Tb3＋ ions, respectively. The luminescence decay curves of [3-SrHPO4：Eu3＋ and D-SrHPO4：Ce3＋,Th3＋ nanocrystals conformed to the double exponential fluores- cence decay, and the average lifetimes were 1.14 and 4.12 ms, respectively. The luminescence decay curve of 13-SrHPO4：Ce3＋ was fitted into a single exponential function, and the lifetime was about 0.78 ns.

Integration of nanoscale light emitters:an efficient ultraviolet and blue random lasing from NaYF_4:Yb/Tm hexagonal nanocrystals

Near infrared light-controlled release of payloads from ultraviolet-sensitive(UV-sensitive) polymer hydrogels or nanocarriers is one of the most promising strategies for biotherapy. Here, we propose the concept of light activation of NaYF_4:20%Yb, 2%Tm nanocrystals(NCs). NaYF_4:20%Yb, 2%Tm NCs are synthesized by a solvothermal method. Effective upconversion luminescence from NaYF_4:20%Yb, 2%Tm NCs excited by a continuous wave(CW) 980 nm laser is obtained. The NaYF_4:20%Yb, 2%Tm NCs are then used as a laser gain medium and sandwiched between Al and quartz reflectors to form laser microcavities. UV and blue upconverted random lasing is obtained from the laser microcavities. Hence, we verify explicitly that the NaYF_4:Yb, Tm NCs support UV and blue upconversion random lasing via a 980 nm nanosecond laser excitation. Our work provides what we believe is a new concept for precision and localized cancer therapy by external light excitation.