A novel mesoscopic model
Modelling is critical to efficient and effective design in all fields. Controlling strain effects in multifunctional crystalline materials enables harnessing resulting signals (e.g.: magnetisation and polarisation) to engineer novel devices with optimal properties. Unfortunately, the mesoscopic (intermediate scale) models of the crystal lattice behaviours are lacking.To bridge the ‘micron gap’ of missing length and time scales, EU-funded scientists initiated the project 'Mesoscopic framework for modeling physical processes in multiphase materials with defects' (MESOPHYSDEF). The model they developed is universally applicable to materials with a given reference crystal structure (or space group symmetry) exhibiting a cubic to tetragonal phase transition.Parameters for the model are taken from first principles or atomistic calculations and the model predicts macroscopic behaviours. Unlike finite element models, it retains the details of the discrete nature of the lattice. The user specifies the position and nature of a point defect in the crystal lattice and the model describes the deformation of the lattice.Comparing model predictions to experimental measurements of depolarisation or demagnetisation enables us to understand the physical mechanisms underlying observed effects. This general model is conceptually simple yet physically correlated, accounting for numerous materials of the same class. Project activities have paved the way to determine structure-property relationships in crystalline multiphase materials at all length and time scales. This opens the door to rapid knowledge-based design and development of novel devices with tailor-made properties such as resistance to fatigue or radiation damage.
Keywords
Mesoscopic, model, crystalline, lattice, strain, magnetisation, macroscopic, phase transition, atomistic
