Crystallographic analysis of complex multiphase powder systems: A synthesis of theory and experiment.

摘要

X-ray and neutron based crystallographic analysis of structurally complex materials has typically been achieved using high intensity pure-phase single crystal refinements. Often, however, single crystals are unable to be acquired for analysis and powder refinements of the materials must be attempted. The 'least-squared' nature of powder refinement makes analysis of complex materials extremely difficu moreover single phase powder samples are frequently unavailable. This thesis develops methods which lay a groundwork for the investigation of multiphase complex powder samples by the incorporation of theoretically calculated thermal factors in the initial experimental structural model. As thermal data for powder refinements is typically acquired from single crystal analysis, this proves to be a novel and significant innovation. Developing the structural model via observations from Attenuated Total Reflection Infrared Spectroscopy is also investigated, and demonstrated to allow fast and effective confirmation of suggested structural models. The technique is illustrated for the components of a new calcium phosphate based bioactive ceramic consisting of a silicon stabilized calcium phosphate and calcium apatite.