In order to efficiently recycle the Fe-Ni waste acid solution resulting from shadow mask processing, a spray pyrolysis process was used to fabricate the nano-sized Ni-ferrite powder with the average particle size below 100 nm. The properties of the nano-powder were investigated as function of reaction temperature, concentration and injection speed of raw material solution.As the reaction temperature increases from 800 to 1100 C, the average particle size of the powder increased accordingly, the microstructure of it gradually became solid which is close to the theoretical density, and the surface area of it decreased significantly. Along with the temperature rise, the formation rate of NiFe 2 O 4 phase also increased.As the concentrations of iron and nickel elements in waste solution increased, the average particle size became larger, the particle size distribution became more irregular, the surface area of the powder decreased. Along with the increase of the concentration, the formation rate of NiFe 2 O 4 phase increased significantly.As the air pressure increases up to 1 kg/cm 2 , the average particle size of the powder decreased slightly, yet the ratio of the Ni-ferrite phase kept almost unchanged. As the air pressure increases up to 3 kg/cm 2 , the average particle size and the ratio of the Ni-ferrite phase decreased significantly, yet the particle distribution size appears much more uniform.

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In this study, nano-sized indium oxide powder with average particle size below 50 nm is synthesized from indium chloride solution by a spray pyrolysis process. This study also examines influences of reaction factors on the properties of the synthesized powder. These factors include the reaction temperature, the inflow speed of the raw material solution and the inflow speed of the environmental air.As the reaction temperature increases from 850 to 1000 C, the average particle size of the generated powder increases from around 30 nm to 100 nm, the microstructure gradually becomes solid, the XRD peak intensity gradually increases and the specific surface area decreases.As the inflow speed of the raw material solution increases from 2 to 5 mL/min, the average particle size of the powder decreases. When the inflow speed is 10 mL/min, the average particle size is larger than that at 5 mL/min. When the inflow speed of solution is 50 mL/min, the average particle size is smaller and the microstructure of the powder is less solid than that at 10 mL/min. The variations of the XRD peak intensity and the specific surface area show the similar tendency to that of the average particle size.As the air pressure increases from 0.1 to 0.5 kg/cm 2 , the average particle size of the powder shows a not significant change from 90 nm to 100 nm. As the air pressure increases up to 1 kg/cm 2 and 3 kg/cm 2 , the average particle size decreases down to 50 nm and the XRD peak intensity decreases.

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In this study, a nano-sized ITO powder with the average particle size below 50 nm by using waste ITO target is generated by spray pyrolysis proces. This study also examines the influences of reaction parameters such as reaction temperature, concentration and inflow speed of raw material solution on the properties of the generated ITO powder.As the reaction temperature increases from 800 C to 1100 C, the average particle size of the generated ITO powder increases from 40 nm to 100 nm, the microstructure gradually becomes compact, the particle size distribution becomes increasingly irregular, the XRD peak intensity gradually increases, and the specific surface area decreases.When the concentration of the solution is at 50 g/L, the average particle size of the ITO powder is below 30 nm, and the particle size distribution appears comparatively uniform. As the concentration reaches 400 g/L, which is close to the saturated concentration, the particle size distribution appears extremely irregular, and the particles with the size ranging from 20 nm to 100 nm coexist. Along with the rise of concentration, the XRD peak intensity gradually increases, yet the specific surface area decreases.As the inflow speed of the raw material solution increases from 2 mL/min to 100 mL/min, the average particle size of the ITO powder increases from 30 nm to 90 nm, yet the particle size distribution becomes irregular, and individual particles appear in the distinct shape of polygon. Along with the rise of inflow speed, the XRD peak intensity gradually increases, and the specific surface area decreases.