Ab initio piezoelectricity and energy landscape of Y0.375Al0.625N
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesisAlternative title
Ab initio piezoelektricitet och energilandskap för Y0.375Al0.625N (Swedish)
There is high industrial demand for materials with a high piezoelectrical response which are stable at high temperatures. A recent study on ScAlN has explained the microscopic origin of the increased piezoelectric response in the alloy and its effect on the energy landscape. Y is a promising candidate to observe the same phenomena.
The ab initio DFT-GGA calculations for Y0.375Al0.625N, using a 128 atom SQS model, show a less pronounced increase of the piezoelectric response. The Y0.375Al0.625N energy landscape shows a flattening due to competition between the parent wurtzite phase of AlN and the hexagonal phase of YN. The flattening causes softening of the C33 elastic constant, while the piezoelectric constant e33 is only slightly increased. This slight increase can be explained by the quite stable local tetrahedral environment in Y0.375Al0.625N, which is related to the big volume mismatch between the parent YN and AlN. In summary we conclude the importance of the volume matching to obtain high piezoelectric response via phase competition.
Place, publisher, year, edition, pages
2011. , 64 p.
IdentifiersURN: urn:nbn:se:liu:diva-67642ISRN: LITH-IFM-A-EX--11/2457--SEOAI: oai:DiVA.org:liu-67642DiVA: diva2:413075
2011-04-05, Mott, Fysikhuset Linköpings universitet, Linköping, 11:34 (English)
UppsokPhysics, Chemistry, Mathematics
Tasnadi, Ferenc, Assistant Professor
Abrikosov, Igor, Professor