Ab initio study of vacancies in cubic zirconia

M.A. TAYLOR; R. E. ALONSO; L. ERRICO

Aarhus, Dinamarca

Workshop; Workshop QTS-5: Quantum Theory of Solids.; 2009

Universidad de Aarhus

.O {font-size:149%;} <!--.sld {left:0px !important; width:6.0in !important; height:10.66in !important; font-size:185% !important;} --> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Zirconia-based materials are in the focus of interest for many years because of their outstanding electrical and mechanical properties. They also show a rich variety of crystal structures depending on pressure, temperature, impurity/dopant content, growth conditions, etc. The addition of small amounts of impurities could stabilize the high temperature phases. These phases have applications ranging from solid oxide fuel cell electrolytes to catalyst substrates, and protective coatings.             ZrO2 has three polymorphs at atmospheric pressure: the low-temperature phase is monoclinic, and is transformed, on heating, to a tetragonal phase, and finally to a cubic phase. It is known that, cation-doped zirconia ZrO2 with aliovalent cations such as Y, Ca, Sc, both stabilized the high temperature cubic phase and increase the number of oxygen vacancies enhancing anion conductivity. In the present work, we have performed an ab initio density functional theory study of oxygen vacancies in cubic ZrO2. The equilibrium configuration and electronic structure of neutral and charged vacancies were calculated for one vacancy concentration (2%). . From the electric field gradient tensor (EFG) at the Zr-nucleus, we can evaluate the EFG distribution.