Nano-sized Y2O3 powders were prepared via a sol-gel method starting with Y(NO3)3·6H2O (Yttrium(III) nitrate hexahydrate) and water with ethanol as a cosolvent. Y2O3 is an important rare earth oxide and has been considered for use in nuclear applications, such as ceramic materials, due to its excellent optical and refractory characteristics. It has been used as a chemically stable substrate, a crucible material for melting reactive metals, and a nozzle material for jet casting molten rare earth-iron magnetic alloys. Oxalic acid (C2H2O4) has been adopted as a chelating agent in order to control the rate of hydrolysis and polycondensation, and ammonia was added in order to adjust the base condition. The synthesized Y2O3 powder was characterized using TG/DTA, XRD, FE-SEM, BET and Impedance Analyzer analyses. The powder changed its properties in accordance with the pH conditions of the catalyst. As the pH increases according to the FE-SEM, the grain grew and it showed that the pore size decreased while confirming the effect of the grain size. The nano-material Y2O3 powders demonstrated that the surface area was improved with the addition of oxalic acid with ammonium hydroxide.

We carried out to better understand calcium behavior in plant growing in media with different calcium levels, deficiency (3), normal (1), and surplus (3). Growth of cucumber plants did not appear significant difference among calcium levels by 7 days after transplanting, but growth rate at 14 days was the highest in normal and followed deficiency and surplus. Increase in calcium concentration treated resulted in not only an excessive Ca uptake of plant but also a proportional decrease in Mg contents. In addition, excessive absorbed Ca was preferentially accumulated in stem and root to avoid leaf damage. Oxalate playing a role as a mediator of excessive Ca through Ca-oxalate crystal formation in cell was analyzed. Oxalate content in leaves was proportionally increased with an increase in calcium level in media, and the correlation coefficient was 0.94(>0.001), while Ca and oxalate in stem and roots did not show significant relation. Ca-oxalate crystal isolated from different Ca-treated leaves and stem was observed using SEM-EDX. Large amount of Ca-oxalate crystal was formed with an increase in Ca concentration. This means that excessive Ca in cell is immobilized through the formation of Ca-oxalate crystal with oxalate bio-synthesized.