Synthesis of Yttrium Oxide Nanocrystal via Solvothermal Process

Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-re-crystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460℃for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to the Y2O3 nanocrystal.

Preparation of Sn-doped In_2O_3 nanopowders by a solvothermal process

Sn-doped In2O3（ITO） nanopowders in square shape were prepared in ethylene solvent by a solvothermal process,using In（4N） and SnCl4·5H2O as starting materials.The effects of solvothermal temperature and coprecipitation pH on the products were investigated using XRD,XPS,and TEM.Mixtures of InOOH crystals and In4Sn3O12 crystals were prepared at 210°C or 230°C and ITO nanopowders with cubic structure were obtained at 250°C or above 250°C.When the coprecipitation pH was 6,the product was ITO with impurity Sn3O4.When the pH was 9,the product was single phase ITO.

Optical Spectroscopy Properties of KMgF_3 :Eu^(2+) Nanocrystals and Powder Synthesized by Microemulsion and Solvothermal Process

Nanocrystals and powders of KMgF3 doped with Eu^2＋ were synthesized by the microemulsion method and the selvothermal process, respectively. The emission and excitation spectra of KMgF3： Eu^2＋ phosphors were measured and compared with those of the samples synthesized through a solid state reaction, Bridgman-Stockbarger method, and mild hydrothermal technique. The KMgF3： Eu^2＋ samples synthesized by means of the microemulsion method and the solvothermal process show only a sharp emission peak located at 360 nm in the emission spectra, which arises from the f→f（ ^6P7/2→^8S7/2 ） transition of Eu^2＋ The broad emission bands appear at 420 nm, which arises from Eu^2＋←O^2- cannot be observed（ in the mild hydrothermal and single crystal samples, the emission peak at 420 nm besides the emission of Eu^2＋ at 360 nm is observed）. In the excitation spectrum of the KMgF3 ： Eu^2＋ samples synthesized by the microemulsion method and the solvothermal process, the excitation peaks show an intensive blue shift. The blue shift can be attributed to the lower oxygenic content in the KMgF3 ： Eu^2＋ samples synthesized by the microemulsion method and the selvothermal process.

Application of the Solvothermal Process in the Synthesis of High-performance Ag/γ-Al_2O_3 Catalysts

Ag/γ-Al2O3 is a kind of promising catalyst with the relatively lower cost compared with those using noble metals,good resistance against catalytic poisoning and excellent behaviour for NOx removal.In the present study,Ag/γ-Al2O3 catalysts were synthesized by the solvothermal process and characterized by XRD,TG?DTA,TEM,UV?Vis and FT?IR.It was found that high-performance Ag/γ-Al2O3 catalysts could be synthesized by properly selecting starting materials,controlling the composition of solvent and other reaction conditions.The microstructure evolution of the catalysts was also discussed.

Photocatalytic properties of hierarchical BiOXs obtained via an ethanol-assisted solvothermal process

In this study, bismuth oxyhalide（Bi OXs（X_Cl, Br, I）） semiconductors were prepared by a simple solvothermal method, with ethanol serving as solvent and a series of tetrabutylammonium halide surfactants as halogen sources. Under identical synthetic conditions, Bi OBr was more readily constructed into regular flower-like hierarchical architectures. The photocatalytic properties of the materials were studied by monitoring the degradation of rhodamine B（Rh B）,with visible light absorption, and colorless salicylic acid（SA）. It was found that both Rh B and SA were rapidly degraded on the surface of Bi OBr. Bi OCl was rather active for the degradation of Rh B,but ineffective toward the degradation of SA. However, neither Rh B nor SA could be degraded effectively in the case of Bi OI. Further experiments such as UV–visible spectroscopy and detection of U OH and O2 Uradicals suggest that the electronic structure of the Bi OX photocatalysts is responsible for the difference in their activities.

One-step solvothermal synthesis of indium oxide as liquefied petroleum gas sensor

A liquefied petroleum gas （LPG） sensor with high selectivity, sensitivity and low power consumption has been developed based on indium oxide with very low resistance. Nanocrystalline In203 gas sensing materials were directly synthesized through a one-step controllable solvothermal process at 210 ℃ for 24 h, using InCI3.4H2O as the starting material, cetyltrimethyl ammonium bromide （CTAB） as additive and ethanol as the solvent. The obtained samples were characterized by X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. The results showed that indium oxide takes on uniform cubic shape with range size of 10~30 nm and fine dispersivity. Gas sensitivity was measured in a mixing static gas. The results indicated that 3.0 V is the best working voltage of the sensor to LPG. Sensitivity is 12.6. The response-time and recovery-time are 3 s and 10 s respectively. Power consumption is only around 200 mW.

Solvothermal preparation and characteristics of Sn-doped In_2O_3

Sn-doped In2O3 (ITO) nanopowders were prepared in ethanol solvent by solvothermal process. The effects of the solvothermal temperature, coprecipitation pH value and SnO2 content on the products phase and microwave absorption were investigated by X-ray diffractometry and microwave reflectance. ITO nanopowders with cubic structure can be respectively prepared at 250 and 270 ℃ for 6 h. The prepared product is InOOH or the mixture of InOOH and In3Sn4O12 when the solvothermal temperature is below 250℃. With rising solvothermal temperature and prolonging time, the absorption of the ITO powders gradually decreases. The products are ITO nanopowders by coprecipitating at pH=9 or 11, but ITO powders with Sn3O4 at pH=6. The absorption of powders prepared at pH=6 is better than that at any other pH value. The products are all ITO nanopowders and crystal size reduces with increasing SnO2 content. The microwave absorption of ITO nanopowders with SnO2 content of 8% (mass fraction) is the best among samples with different SnO2 contents.

Noble Metal-Doped In_2O_3 for Enhancing Response to H_2

Nanocrystalline In_2O_3 was synthesized through a controllable solvothermal process in one-step at 210℃for 24 h. Gas sensing properties were tested by mixing gas in air in static state.At 268.5℃,the nanocrystal showed high sensitivity to LPG but lower sensitivity to H_2 and CO.In order to enhance the sensitivities to H_2 and CO,0.5 mass % Au and Pd were doped by an impregnation process.The sensitivities to H_2 and CO were increased under different working temperature.Au-doped In_2O_3 was superior to Pd-doped In_2O_3 whatever to H_2 or CO;the sensitivity was increased with the increase of working temperature;gas sensing properties to H_2 overmatched to CO.

Key synthesis of magnetic Janus nanoparticles using a modified facile method

Inorganic/organic poly（methylmethacrylate-acrylic acid-divinylbenzene） iron oxide Janus magnetic nanoparticles（P（MMA-AA-DVB）/Fe3O4） with strong magnetic domains and unique surface functionalities were prepared using a solvothermal process.The P（MMA-AA-DVB） nanoparticles were prepared via soapfree emulsion polymerization and used as a precursor for preparing Janus nanoparticles.The morphology and magnetic properties of the magnetic Janus nanoparticles formed were characterized using a laser particle size analyzer,transmission electron microscopy,Fourier transform infrared spectroscopy,vibrating sample magnetometry,and thermogravimetric analysis.The synthesized P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were characterized by a Janus structure and possessed a stable asymmetric morphology after being dually functionalized.The particle size,magnetic content,and magnetic domain of the P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were 200 nm,40%,and 25 emu/g,respectively.The formation mechanism of the Janus nanoparticles was also investigated,and the results revealed that the reduction of Fe3＋ ions and growth of Fe3O4 took place on the surface of the P（MMA-AA-DVB） polymeric precursor particles.The size of the Janus particles could be controlled by narrowing the size distribution of the P（MMA-AA-DVB） precursor nanoparticles.

Large-Scale Self-Assembled Ag Nanotubes

A high yield of silver nanotubes with large aspect ratio were conveniently synthesized via an organic-assist solvothermal preparation technique using polyvinyl pyrrolidone （PVP） as a capping reagent and architecture soft-template. The molecular ratio between the repeating unit of PVP and AgNO3 plays a crucial role in determining the geometric shape of the product. Such novel-type Ag nanotubes were self-assembled by Ag nanoparticles, which had largely similar crystallographic orientation, forming a texture. The fact that nanoparticles without anisotropic crystal structures can form such superstructures by self-assembly may open a window for understanding a range of nanotube formation processes.