| Popis: |
Chemical and biological agents continue to pose a threat to U.S. national security. The development of next generation of devices to sense, detect, filter, and remove these threats remains a priority of the U.S. Department of Defense. Zr(OH)4 is currently being developed as a decontaminant and is being engineered into suitable forms capable of removing chemical warfare agents. As such, having a detailed understanding of the local structure of amorphous Zr(OH)4 and heat treated ZrO2 analogs is a crucial step in developing these compounds as suitable countermeasures against chemical threats. In this study, zirconium hydroxide powders were calcined at various temperatures to study the effects of porosity, surface area, structure, and electronic properties as a function of temperature. Different characterization techniques were used to demonstrate that the surface area and porosity decreased as the material changed from an amorphous phase to a monoclinic crystal structure. Analysis of X-ray pair distribution function data provided a detailed representation of the local structure of amorphous Zr(OH)4 and its thermal decomposition into ZrO2. Impedance analysis showed both the dielectric constants and capacitance decreased by two orders of magnitude as crystallinity increased, correlating to a lowered concentration of defects, such as surface hydroxyl groups that contribute to leakage current. |
