Microwave hydrothermal synthesis and characterization of rare-earth stannate nanoparticles

Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate（Gd_2Sn_2O_7） nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7：Eu^（3＋） nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7（Ln = Y, La–Lu） nanocrystals were prepared by similar approaches.

Microwave-hydrothermal synthesis,characterization and upconversion luminescence of rice-like Gd(OH)_(3) nanorods

Rice-like Gd(OH)_(3)nanorods were successfully prepared through a facile and rapid microwave-hydrothermal synthesis method without using any surfactants or templates.X-ray diffraction(XRD),Fourier transform infrared(FTIR)spectroscopy,thermogravimetric analysis(TGA),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM),selected area electron diffraction(SAED)and energy-dispersive spectroscopy(EDS)were used to characterize the samples.Results show that the nanorods have an average length of 400 nm and an average diameter of 50 nm.The effects of reaction parameters such as reaction temperature and time on the preparation were briefly investigated.It is found that the crucial factor for the formation of rice-like Gd(OH)3nanorods is reaction time.When the rice-like Gd(OH)3nanorods was codoped with Yb^(3+)and Er^(3+),strong upconversion emissions could be observed under the excitation of 980-nm-laser,and the calculated CIE color coordinates falls within the yellow region,which may be potential candidate for optical materials.

Low temperature solid-state synthesis and characterization of uniform YF_3 submicroparticles

In this paper, submicro-scaled YF3 particles with uniform rice-like morphologies were facilely synthesized by reacting yttrium nitrate with tetrabutylammonium fluoride via a solid-state reaction process at 50 °C for 12 h.The phase confirmation and morphology of the as-prepared YF3 particles were investigated by X-ray powder diffraction（XRD） and scanning electron microscopy（SEM）.SEM results reveal that the YF3 submicroparticles are about 700 nm in length and 260 nm in width. Eu^3＋ and Tb^3＋ doped YF3 submicroparticles were also prepared with similar process and their photoluminescence properties were studied. Results demonstrate that the doping of Eu^3＋ and Tb^3＋ has slight effect on the morphologies of the product. Owing to the small average crystallite size or the low crystallinity of the product, the photoluminescence intensity of the Eu^3＋ and Tb^3＋ doped YF3 submicroparticles is very weak. Some characteristic peaks even cannot be observed in the emission spectrum.