A compact, thermal-image furnace has been developed in conjunction with synchrotron radiation to collect in situ high-temperature powder diffraction data on selected oxide ceramics in air up to 2400 C. The experimental data is analysed and compared with theoretical predictions by the Rietveld crystallographic, profile fitting technique. The ultimate aim of this research project is to investigate detailed mechanisms of crystal structure changes involved in ferroelastic phase transformations in selected materials, using in situ synchrotron XRD, hot stage optical microscopy and TEM techniques. Specifically, phase transformations involving negligible or zero volume changes, but possibly some unit cell shape changes will be focused upon. Phase transformations in tantalum oxide (Ta2O5) and lanthanide tantalates (LnTaO4), as well as lanthanide aluminates will be studied. In this manner, the structure-property relationships of the materials could be better understood and tailored for application, e.g., in toughening mechanisms, large force actuation and shape memory ceramics. Preliminary studies will be made on some of the mechanical properties of key ferroelastic materials
This objective of this project is to undertake in-situ high-temperature studies of phase transformations in oxide ceramics, using our newly-invented, thermal-image furnace, capable of 2400 C in air, in conjunction with synchrotron radiation. The emphasis is on oxide materials exhibiting polymorphic phase transformations, especially of a ferroelastic nature, at elevated temperatures. This is inline with our on-going research efforts in identifying potential materials with new, energy absorbing mechanisms, which have applications in the design of tough, high-temperature composites. Furthermore, as a result of domain rearrangement by ferroelastic mechanisms, potential applications are possible in large force actuation and shape memory behavior.
