New Fluoride and Oxyfluoride Materials – Targeting Magnetic and Optical Properties

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

Non-Technical Materials containing different chemical elements exhibit a wide range of useful, everyday properties and are found in devices as basic as LED light bulbs. The properties, which include optical and magnetic behavior, are found especially in materials containing fluorine and are used for many applications that require the emission of light for them to function. Examples include coatings in LED light bulbs, radiation detectors for homeland security, and scanners for medical x-rays. For many optical applications it is necessary to obtain the materials in the form of single crystals. The research, supported by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, therefore, targets the crystal growth of new fluoride materials by developing new methods to grow such crystals and by optimizing the chemical compositions to obtain materials with the desired properties. The basic research focus is on the crystal growth of new fluorine-containing materials that are designed to exhibit specific properties, such as light emission, which can find widespread applications and can benefit the nation. As part of this research, numerous students are trained in the chemical sciences by involving a wide range of students, including those from underrepresented groups, in a materials chemistry research laboratory experience. Furthermore, a summer program for undergraduates allows the involvement of underrepresented minorities in research and teaches them about the chemistry of materials with the goal of recruiting them specifically into the University of South Carolina chemistry graduate program. Technical Summary The concept of materials discovery via crystal growth is applied to substantially increase the number of new fluoride and oxyfluoride material families to develop new functional materials. It is well known that complex fluoride materials are important for applications that rely on their optical properties, such as luminescence and scintillation, while the ability to obtain fluoride and oxyfluoride structures exhibiting magnetic frustration is of general interest for understanding spin-liquid and spin-ice behavior. The research project is centered around the development of new approaches to systematically synthesize and characterize new classes of fluoride and oxyfluoride materials and to study their optical and magnetic behavior. Specifically, the optimization of the crystal growth of new fluoride and oxyfluoride materials is carried out via three different synthetic routes (mild hydrothermal, supercritical hydrothermal, and flux crystal growth) to produce new magnetic and optical materials. Properties are controlled via the selection and incorporation of transition and lanthanide elements into the new fluoride and oxyfluoride structures, where those containing transition and lanthanide metals are used to study magnetic behavior and those containing lanthanides are used to study optical properties. As part of this research, numerous students are trained in the chemical sciences by involving a wide range of students, including those from underrepresented groups, in a materials chemistry research laboratory experience. Furthermore, a summer program for undergraduates allows the involvement of underrepresented minorities in research and teaches them about the chemistry of materials with the goal of recruiting them specifically into the University of South Carolina chemistry graduate program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.