Parametric crystalline characterization of Anatase/Rutile polymorphic ceramic

A Radhi and V Iacobellis and K Behdinan, APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 129, 295 (2023).

DOI: 10.1007/s00339-023-06562-9

The investigation of Anatase and Rutile structure is of great importance to certain the reliability of such polymorphs to operate during designated operations. In particular, Anatase is considered a metastable polymorph of Titania that has unique electrical properties and is often used in solar cells, electrical sensors/semiconductors and other photocatalytic applications. Anatase is prone to revert to Rutile under elevated temperature, exposing a debilitating performance at high thermal environment. The work here aims to investigate the structural changes of such polymorphs. The transition of material lattice from sub- atomic to macroscale is essential to understand the continuum behavior of a structure from the nanoscale. This is the very definition of a multiscale behavior, where a material response heavily depends on the atomic characteristics and environmental factors. These factors have high influence on the atomic structure in a spatial and temporal perspective, where atomistic simulation methods require high computational power in order to observe certain response features. Moreover, crystalline characterization methods in such approaches are highly limited to either simplified structures or largely complex factors. The introduced Predominant Common Neighborhood Parameter (PCNP) and Cumulative Common Neighborhood Parameter (CCNP) parameters are put to use in order to investigate the phase transition between two titania polymorphic phases (Rutile and Anatase). The work was done on a temperature range from 100 to 1300 K in a localized MD simulation in order to ascertain the phase transition mechanics. It is found that CCNP showed a better performance in obtaining such transition along the critical planes of the transformation phase. A subsequent nanoindentation simulation was conducted to obtain the mechanical property of the final structure using a new dynamic formulation of the Bridging Cell Method (BCM).

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