This three-year award supports U.S.-France cooperative research in condensed matter physics between Jean Toulouse of Lehigh University and Michel Rousseau, University of Maine in LeMans, France. The investigators will study structural phase transitions fluorides with perovskite structure. The objectives of their collaboration are to investigate the physical mechanism involved in structural phase transitions (SPT) and to understand the properties of these materials during the phase transitions. The Lehigh group brings to this collaboration a solid background in defect studies and experience in ultrasonic, dielectric and spectroscopic experimental techniques. This is complemented by the French investigators expertise in neutron scattering and x-ray studies and their ability to grow high quality crystals. Structural phase transition in mixed systems, especially oxides, is an area of considerable current interest. Mixed systems are important to the development of high Tc superconductors, optical materials and structural materials. Further knowledge about the effects of structural phase transition on the composition of materials could lead to the development of improved, high performance materials.
