Author : Ranjith Kumar Thanneeru
Publisher :
ISBN 13 :
Total Pages : 82 pages
Book Rating : 4.:/5 (946 download)
Book Synopsis Vacancy Engineered Doped and Undoped Nanocrystalline Rare Earth Oxide Particles for High Temperature Oxidation Resistant Coatings by : Ranjith Kumar Thanneeru
Download or read book Vacancy Engineered Doped and Undoped Nanocrystalline Rare Earth Oxide Particles for High Temperature Oxidation Resistant Coatings written by Ranjith Kumar Thanneeru and published by . This book was released on 2007 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rare earth oxides with trivalent lattice dopants have been of great interest to researchers in the recent years due to its potential applications in catalysis and high temperature protective coatings. The ability to store oxygen in rare earths is the basis for catalysis because of the ability to change valence states which causes the presence of intrinsic oxygen vacancies in the crystal lattice. Although, several doped-rare earth oxide systems in micron scale have been investigated, the doping effect in cerium oxide nanoparticles with well characterized particle size has not been studied. The doping of ceria at that small size can be very beneficial to further improve its catalytic properties and alter the high temperature phases in alloy systems. Cost effective room temperature chemical methods are used in the current work to synthesize uniformly distributed undoped and doped (dopants: La, Nd, Sm, Gd, Y and Yb) rare earth oxide nanoparticles. In the present study, the variation of the properties in nanocrystalline ceria (NC) synthesized by microemulsion method is studied as a function of dopant size and its concentration. To further understand, the role of dopant (cation) size on the oxygen vacancy concentration, doped nanocrystalline oxide powders were analyzed by Raman Spectroscopy, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). XRD studies showed that lattice parameter change in nanocrystalline oxide by doping trivalent rare earth elements is largely depending on size of trivalent ions. It showed that by doping larger cations (Gd3+ and Y3+) compare to Ce3+ causes lattice expansion where as smaller cations (Yb3+) leads to lattice contraction. It also showed that the lattice expansion or contraction is directly proportional to dopant concentration.