The development of flat panel display devices such as field emission displays (FEDs) and vacuum fluorescent displays (VFDs) requires thermally stable, high luminous, radiation resistant, fine particle size and multi-color powders. The demand for these newer properties has produced a search for new materials and synthesis techniques to improve the performance of phosphors.
Combustion synthesis is a novel technique that has been applied to prepare novel oxides containing dopant elements, low-temperature compounds and cermets which are difficult to synthesize by conventional methods in the past few years. And this process is one of the simplest powder preparation processes. The process involves very rapid exothermic reactions between a metal salt as an oxidizer and an organic fuel, such as urea $(CH_{4}N_{2}O)$, carbohydrazide $(CH_{6}N_{4}O)$, glycine $(C_{2}H_{5}NO_{2})$, and citric acid $(C_{6}H_{8}O_{7})$.
The orange-emitting $SnO_{2}:Eu^{3+}$ phosphor has been studied for multicolor display applications such as VFDs in the past few years. And it has been reported that there is a relatively large separation among the three strongest emission lines, which are assigned to the $^{5}D_{o} → ^{7}F_{1}$ magnetic dipole transitions. And it corresponds to a large $^{7}F_{1}$ level splitting.
In this study, the orange-emitting $SnO_{2}:Eu^{3+}$ phosphor was prepared by the combustion method using a citric acid as a fuel and the conventional solid-state reaction, respectively. Both particle size and morphology of the resultant powders showed the very different characteristics from each other. The smaller-sized $(> 100 nm)$ $SnO_{2}:Eu^{3+}$ phosphor particles has been obtained from the combustion method. And the shape of particles has generally been spherical in the case of $SnO_{2}:Eu^{3+}$ phosphor prepared by combustion method.
The cathodoluminescence (CL) intensities of the $SnO_{2}:Eu^{3+}$ phosphor prepared by the combustion method strongly depended on the amount of citric acid and the atmosphere of the reaction. And the CL intensities of the $SnO_{2}:Eu^{3+}$ phosphor synthesized by the combustion method were lower than those of the phosphor synthesized by the solid-state reaction. When as-pyrolysized $SnO_{2}:Eu$ powder obtained after the combustion reaction was fired in oxidizing atmosphere, its CL intensity was improved up to about 30 %. But particle size has also increased in the case of calcination in oxidizing atmosphere.
In adding $HNO_{3}$ as an oxidizer, the CL intensity increased up to about 50 %. And the particle size of as-pyrolysized $SnO_{2}:Eu$ powder has become more smaller than those of prepared by combustion method using only citric acid. And the crystallinity of $SnO_{2}:Eu$ powder also increased. The CL intensities have strongly depended on the ratio of fuel/oxidizer.
