The goals of this project are to understand the fundamental principles that govern the formation and function of novel nanoscale and nanocomposite materials. Specific scientific issues being addressed include: design and synthesis of complex molecular precursors with controlled architectures, controlled synthesis of nanoclusters and nanoparticles, development of robust two or three-dimensionally ordered nanocomposite materials with integrated functionalities that can respond to internal or external stimuli through specific molecular interactions or phase transitions, fundamental understanding of molecular self-assembly mechanisms on multiple length scales, and fundamental understanding of transport, electronic, optical, magnetic, catalytic and photocatalytic properties derived from the nanoscale phenomena and unique surface and interfacial chemistry for DOE's energy mission.
Fine powders of calcium zirconate (CaZrO{sub 3}, CZ) and calcium titanate (CaTiO{sub 3}, CT) were synthesized using a nonaqueous oxalate co-precipitation route from Ca(NO{sub 3}){sub 2}{center_dot}4 H{sub 2}O and group(IV) n-butoxides (Ti(OBu{sup n}){sub 4} or Zr(OBu{sup n}){sub 4}). Several reaction conditions and batch sizes (2-35 g) were explored to determine their influence on final particle size, morphology, and phase. Characterization of the as-prepared oxalate precursors, oven dried oxalate precursors (60-90 C), and calcined powders (635-900 C) were analyzed with TGA/DTA, XRD, TEM, and SEM. Densification and sintering studies on pressed CZ pellets at 1375 and 1400 C were also performed. Through the developed oxalate co-precipitation route, densification temperatures for CZ were lowered by 125 C from the 1500 C firing temperature required for conventional mixed oxide powders. Low field electrical tests of the CZ pellets indicated excellent dielectric properties with dielectric constants of {approx}30 and a dissipation factor of 0.0004 were measured at 1 kHz.