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We present the nonlinear optical properties of CsPb(Br/I)3 perovskite quantum dots (QDs) with high crystallinity. The perovskite QDs show better two-photon absorption response than the traditional metal chalcogenide QDs. And, the photoluminescence peak of the halogen vacancies in perovskite nanocrystals was experimentally observed for the first time. [ABSTRACT FROM AUTHOR]

Hollow Gd2O3:Ln (Ln = Eu3, Sm3) microspheres were successfully fabricated by using carbon spheres as a template and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence spectroscopy as well as kinetic decays were used to characterize the samples. The results indicate that the as-prepared products can be indexed to pure cubic Gd2O3phase. The samples are composed of uniform hollow Gd2O3:Ln spheres with a mean particle size of about 300 nm. The possible mechanism of evolution from glucose to carbon microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. In particular, the urea-assisted precipitation process was carried out in aqueous solution without any organic solvent, and the hollow spheres formation process was achieved by simple calcination without using any etching agents. The hollow Gd2O3:Ln phosphors exhibit light emission under ultraviolet excitation, which may find promising applications in the fields of field emission displays (FED) and MRI contrast agents. [ABSTRACT FROM AUTHOR]

Hollow Gd2O3:Ln (Ln = Eu3+, Sm3+) microspheres were successfully fabricated by using carbon spheres as a template and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence spectroscopy as well as kinetic decays were used to characterize the samples. The results indicate that the as-prepared products can be indexed to pure cubic Gd2O3phase. The samples are composed of uniform hollow Gd2O3:Ln spheres with a mean particle size of about 300 nm. The possible mechanism of evolution from glucose to carbon microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. In particular, the urea-assisted precipitation process was carried out in aqueous solution without any organic solvent, and the hollow spheres formation process was achieved by simple calcination without using any etching agents. The hollow Gd2O3:Ln phosphors exhibit light emission under ultraviolet excitation, which may find promising applications in the fields of field emission displays (FED) and MRI contrast agents. [ABSTRACT FROM AUTHOR]