Synthesis of tetragonal phase stabilized nano and submicron sized nanoparticles
View Patent ↗Novel, monodispersed, spherical ZrO 2 particles in the size range of approximately 10 to approximately 600 nm exhibiting metastable tetragonal crystal structure at room temperature and novel methods of preparation. The ZrO 2 particles are approximately 100% in the tetragonal phase at room temperature and can be pure and free of foreign oxides. The novel method can include mixing zirconium-alkoxide and an alcohol, forming preparation one, followed by separately dissolving completely de-ionized water and a polymeric steric stabilizer in an alcohol forming preparation two. Next the preparations can be mixed with vigorous stirring while subjecting the materials to hydrolysis and condensation reactions with very slow stirring. Next, there is waiting for the formation of a sol from the mixture, followed by drying at approximately 80 degrees C. to form resultant material followed by crushing the resultant material.
1. A method for preparing monodispersed, spherical ZrO 2 particles, pure and free of foreign oxides, comprising the steps of:
preparing equal parts of an alcohol solution wherein a first part is mixed with deionized water and a second part is mixed with a zirconium-alkoxide using an R-value of 5 to get approximately 500 nm to approximately 600 nm ZrO 2 particles, wherein the R-value comprises the ratio of molar concentrations of water to the zirconium-alkoxide;
adding a polymeric steric stabilizer to the first part of an alcohol solution with deionized water, wherein the stabilizer is in a concentration of approximately 1.0 to approximately 2.0 g/L and stirring over time forming solution one;
dissolving the zirconium-alkoxide in the second part of the alcohol solution and forming solution two;
mixing the solution one and the solution two together;
stirring the mixture for approximately 4 hours;
holding the stirred solution under static conditions for approximately 24 hours to form a resultant material;
crushing the resultant material; and
calcining the crushed material at a temperature of approximately 400 to approximately 600 degrees C. to prepare spherical zirconium oxide particles exhibiting approximately 100% metastable tetragonal structure at room temperature.
2. The method, as in claim 1 , wherein said polymeric steric stabilizer is an organic polymer containing —OH groups or ether groups.
3. The method, as in claim 2 wherein said polymeric steric stabilizer is one of the group consisting of HPC polymer, polyvinylalcohol, ethylene glycol, and hexamethyldisilazane.
4. The method in claim 3 , wherein said polymeric steric stabilizer is HPC polymer.
5. The method, as in claim 4 wherein HPC is added in a concentration of approximately 1.0 g/L.
6. The method, as in claim 4 wherein said HPC polymer has a molecular weight of approximately 80,000 to approximately 1,000,000 g/mol.