Under solvent-free conditions (at 130 degrees C), zirconium and hafnium amine tris(phenolate) alkoxides are extremely active, well-controlled, single-site initiators for the ring-opening polymerization of rac-lactide, yielding highly heterotactic polylactide.

The Hf-O system has been modeled by combining existing experimental data and first-principles calculations results through the CALPHAD approach. Special quasirandom structures of α and β hafnium were generated to calculate the mixing behavior of oxygen and vacancies. For the total energy of oxygen, vibrational, rotational and translational degrees of freedom were considered. The Hf-O system was...

The paper discusses the design aspects of capacitive RF MEMS Symmetric Toggle Switch (STS) with particular emphasis on device compactness, reliability, and improvement in isolation & insertion loss by incorporating hafnium dioxide (HfO2) as a dielectric material. The major impact of the change from SiO2 to HfO2 having dielectric constant of 20, is the reduction in overall dimensions of the swit...

We present an infrared spectroscopy and X-ray diffraction study of hafnium oxide gate dielectric films deposited from hafnium tetra–tertbutoxide, Hf(OC(CH3)3)4. We characterize the crystal phase as a function of thickness and detect the chemical state of impurities in this high-permittivity (high) material. The HfO2 films are composed of monoclinic crystallites in an amorphous matrix. The cryst...

Hafnium and zirconium oxide films were prepared by atomic layer deposition (ALD) from dialkylamido precursors. Water was used as the oxygen source. Nanolaminates of hafnium, zirconium and aluminum oxide were also prepared. Atomic force microscopy was used to characterize the surface morphology of 10–100 nm thick films grown from 501C to 3001C. X-ray diffraction was used to characterize the film...

Graphite is widely used in technology because of its unique properties. A drawback of graphite is its low heat resistance in oxidizing atmospheres. To increase its heat resistance, Nb-Hf protective coatings were synthesized. Electrodeposition of niobium coatings on graphite with subsequent precise surface alloying of niobium with hafnium was studied. Electrochemical synthesis of Nb-Hf coatings ...

Raman spectra of monoclinic hafnium oxide HfO2 were measured at temperatures up to 1100 K. Raman peak shifts and broadenings are reported. Phonon dynamics calculations were performed with the shell model to obtain the total and partial phonon density of states, and to identify the individual motions of Hf and O atoms in the Raman modes. Correlating these motions to the thermal peak shifts and b...