The Preparation And Properties Exploration Of Sm（OH）₃ And Sm₂O₃ Micro/Nanocrystallites

Lanthanide compounds exhibit unique optical, electritical, magnetical and chemical properties arising from their 4f electrons, which aroused widely exploration interesting in recent years. Sm(OH)3 and Sm2O3 as the typical lanthanide hydroxide and oxide materials, the synthesis method and properties exploration of them are the main theme of our research.Sm(OH)3 nanocrystallites were successfully synthesized by hydrothermal and uniform precipitation method by using diethylenetriamine(DETA) as alkaline source and Sm(NO3)3·6H2O as samarium source. The phase composition, morphology, specific surface area and optical properties of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2-sorption BET surface area and UV-vis diffuse reflectance spectroscopy. The influence of reaction temperature, the concentration of Sm3+ and the addition amount of DETA on the microstructure of Sm(OH)3 nanocrystallites were investigated in the hydrothermal systerm. The photocatalytic activities of the Sm(OH)3 nanorods with different sizes were evalued; The influence of different alkine sources and aging temperatures on the microstructure and photocatalytic activities of Sm(OH)3 nanocrystallites were studied in the precipitation system; In addition, the influence of different synthesis methods on the morphologies and photocatalytic activities of Sm(OH)3 nanocrystallites were studied. The results show that pure hexagonal Sm(OH)3 nanocrystallites were prepared at reaction temperature of 100~180 °C,the Sm3+ concentrations of 0.025~1.0 mol·L-1,the addition amount of DETA of 0.27~1.08 Vol% by hydrothermal reaction for 24 h. The sample prepared at CSm3+= 0.025 mol·L-1, VDETA= 0.66 Vol% at 160 °C with small and uniform size exhibits good photocatalytic activity; Sm(OH)3 nanocrystallites prepared by uniform precipitation method using DETA as alkine source with good dispersibility and uniform size exhibit better photocatalytic activity. With the increase of aging temperature, the size of Sm(OH)3 nanorods was increased, whose photocatalytic activity was reduced; In comparision of the microstructure and photocatalytic activity of the samples prepared by hydrothermal and uniform precipitation method, the better photocatalytic activity of the Sm(OH)3 nanorods prepared by the precipitation method may originate from the amorphous particles wrapped on the Sm(OH)3 nanorods.Sm2O3 nanocrystallites were synthesized with the assist of different templates using Sm(NO3)3·6H2O and diethylenetriamine as main raw materials under the condition of hydrothermal and thermal treatment. The influences of different templates(HMTA, PVP and CTAB) on the phase composition, morphologies and optical properties of the samples were investigated. The results show that strip-like Sm2O3 nanocrystallites were prepared with HMTA as template. Size controlled Sm2O3 nanocrystallites with rod-like microstructure were prepared with PVP or CTAB as template or without template. Different templates have different effects on the structure, size and optical properties of the samples. When HMTA was used as template, the energy gap of the strip-like Sm2O3 nanocrystallines is only 4.775 e V.Sm2O3 micro/nanocrystallites with different morphologies were prepared under the condition of hydrothermal and thermal treatment, using Sm(NO3)3·6H2O as samarium source, Na2CO3, urea and hexamethylenetetramine as alkaline sources, respectively. The influences of different alkine sources, the different Sm3+ and alkine molar ratios on the microstructure and the property of the sample were investigated. Cubic Sm2O3 micro/nanocrystallites with mesorporous octahedron morphology, rod-assembled dumbbell morphology, nanoparticles with irregular shapes, flower-like structure assembled by nano-flakes and cluster shapes assembled by nanorods were prepared at appropriate molar ratios of Sm3+ and alkaline source. The prepared Sm2O3 micro/nanocrystallines with different morphologies exhibit good UV absorption abilities. The energy gap of the prepared samples is decreased with the decrease of the size or microstructure size of the samples.