Nano-sized BaNd2Ti5O14 powders were prepared by the spray pyrolysis process. Sucrose used as the organic additive enabled the formation of nano-sized BaNd2Ti5O14 powders. The powders prepared from the spray solution without sucrose had a spherical shape, dense structure and micron size before and after calcination. However, the precursor powders prepared from the spray solution with sucrose had a large size, and hollow and porous morphology. The precursor powders had an amorphous crystal structure because of the short residence time of the powders inside the hot wall reactor. The complete decomposition of sucrose did not occur inside the hot wall reactor. Therefore, the precursor powders obtained from the spray solution with sucrose of 0.5M had a carbon content of 39.2wt.%. The powders obtained from the spray solution with sucrose of 0.5M had a slightly aggregated structure of nano-sized primary powders of BaNd2Ti5O14 crystalline phase after calcination at 1000˚C. The calcined powders turned into nano-sized BaNd2Ti5O14 powders after milling. The mean size of the BaNd2Ti5O14 powders was 125 nm.

Fe powders with elongated and aggregated structure as heat pellet material for thermal battery applications were prepared by spray pyrolysis under various preparation conditions. The precursor powders with spherical shapes and hollow morphologies turned into Fe powders after reduction at a temperature of 615˚C under 20% H2/Ar gas. The powders had pure Fe crystal structures irrespective of the preparation conditions of the precursor powders in the spray pyrolysis. The morphologies and mean sizes of the Fe powders are affected by the preparation conditions of the precursor powders in the spray pyrolysis. Therefore, the ignition sensitivities and the burn rates of the heat pellets formed from the Fe powders prepared by spray pyrolysis are affected by the preparations of the precursor powders. The Fe powders prepared under the optimum preparation conditions have a BET surface area of 2.9 m2g1. The heat pellets prepared from the Fe powders with elongated and aggregated structure have a good ignition sensitivity of 1.1W and a high burn rate of 18 cms1.

Ni-GDC (gadolinia-doped ceria) composite powders, the anode material for the application of solid oxide fuel cells, were prepared by a solution reduction method using hydrazine. The distribution of Ni particles in the composite powders was homogeneous. The Ni-GDC powders were sintered at 1400˚C for 2 h and then reduced at 800˚C for 24 h in 3% H2. The percolation limit of Ni of the sintered composite was 20 vol%, which was significantly lower than these values in the literature (30-35 vol%). The marked decrease of percolation limit is attributed to the small size of the Ni particles and the high degree of dispersion. The hydrazine method suggests a facile chemical route to prepare well-dispersed Ni-GDC composite powders.

Blue-emitting BAM:Eu phosphor powders were formed by post-treatment of precursor powders with hollow or dense morphologies. The morphologies of the precursor powders obtained by spray pyrolysis were controlled by changing the preparation conditions and by changing the type of spray solution. The effects of the morphologies of the precursor powders on the characteristics of the BAM : Eu phosphor powders reacted with AlF3 flux were investigated. Precursor powders with a spherical shape and a hollow morphology produced BAM : Eu phosphor powders with a plate-like morphology, a fine size and a narrow size distribution. On the other hand, precursor powders with a spherical shape and dense morphology produced BAM : Eu phosphor powders with a plate-like morphology and a large size. AlF3 flux improved the photoluminescence intensities of the BAM : Eu phosphor powders. The photoluminescence intensity of the fine-sized BAM : Eu phosphor powders with a plate-like morphology was 90% of the commercial product under vacuum ultraviolet conditions.

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of Ca8Mg(SiO4)4Cl2:Eu2+ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The Ca8Mg(SiO4)4Cl2:Eu2+ phosphor powders prepared at temperatures that were lower and higher than 700˚C had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of Ca2SiO4. The optimum flow rates of the carrier gas in the preparation of the Ca8Mg(SiO4)4Cl2:Eu2+ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

Green-emitting Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders under long-wavelength ultraviolet light were prepared via high-temperature flame spray pyrolysis from spray solutions with and without NH4Cl flux. The effects of the temperature of the diffusion flame and the NH4Cl flux on the morphologies, crystal structures and photoluminescence intensities of the Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders were investigated. The phosphor powders obtained from the spray solution with the NH4Cl flux had higher photoluminescence intensities compared to phosphor powders obtained from the spray solution without the flux. The photoluminescence intensity of the phosphor powders obtained from the spray solution without the flux decreased as the flow rate of the fuel gas increased. On the other hand, the photoluminescence intensity of the phosphor powders obtained from the spray solution with the flux increased as the flow rate of the fuel gas increased. The difference of in the phase purity and morphology of the powders affected the photoluminescence intensities of the phosphor powders.