IntroductionYttria nanoparticles gained on interest in recent years due to unique properties of doped yttria luminescent particles. The efficiency of luminescence phenomena depends on morphology, particle size, crystallinity... [ view full abstract ]
Introduction
Yttria nanoparticles gained on interest in recent years due to unique properties of doped yttria luminescent particles. The efficiency of luminescence phenomena depends on morphology, particle size, crystallinity of the nanopowder. Solution combustion synthesis (SCS), which is based on the high energy reaction between the metal nitrates and reducing agent, is a promising method for fabrication of nanopowders. Unlike sol-gel or precipitation technique it is less time consuming and requires less technological steps, as the synthesis by-products undergo thermal decomposition.
In the work the relationship between the reaction path with four various reducing agents added in stoichiometric amounts on the morphology of the obtained yttria nanopowder was investigated.
Methods
Thermogravimetric analysis was carried out using thermal analyser TG449 F1 Jupiter (Netzsch Gerätebau GmbH, Germany) in alumina crucibles in argon flow. The powders microstructure was characterized by means of scanning electron microscopy (Nova NanoSEM 200, FEI Company).
Results
Glycine, urea, malonic acid and citric acid were tested as reducing agent for fabrication of nY2O3. In Fig. 1-4 the results of thermal analysis and micrographs of the obtained powders are presented.
Powders produced with malonic and citric acid have highly porous structure (Fig. 1, 2). After calcination the powder remain in a shape of agglomerates. Reaction of yttrium nitrate with urea (Fig. 3) leads to production of powder in form of platelet. After calcination at temperature of 1100°C nanosized grains are reviled.
Only reaction with glycine (Fig. 4) leads to fabrication of Y2O3 without calcination step. Thus obtained powder has highly porous microstructure. After calcination at temperature of 1100°C nanosized grains are visible.
Discussion
All reactions are connected with evolution of big amounts of gases (about 30 molgas/1 molprod.) which is supposed to destroy the internal structure of produced oxide to nanopowders. Utilization of substances with carboxyl groups which can create complex compounds with yttrium ion lead to fabrication of porous and spongy (“sponge-like”) structures. Using urea, which interaction in the solution with yttria ion is less significant, powders of platelet-like structure are obtained.
Acknowledgement
This work was funded by the Polish Ministry of Science and Higher Education.
