Nanosized Metal Clusters: Challenges and Opportunities

This article presents challenges and opportunities to control the microstructure in nanostructured coatings using a nanocluster source. The cluster size distribution is monodisperse and the kinetic energy of the clusters during deposition can be varied. Interestingly, the clusters are grown in extreme non-equilibrium conditions leading to metastable structures of metals and alloys. Because one avoids the effects of nucleation and growth on a specific substrate, one may tailor the properties of the films by choosing the appropriate preparation conditions.

Electron Microscopic Study on Catalytic Carbonization of Biomass Carbon: I. Carbonization of Wood Charcoal at High Temperature by Al-Triisopropoxide

Currently, carbonized materials from wood or waste have been focused upon as raw materials for carbons. These carbons are important for the production of artificial graphite. First hand observation was done on the growth of long parallel graphite structures in wood charcoal. A comparison is made between graphitization in pure biomass carbon and catalytic graphitization in biomass carbon suspended in Al-triisopropoxide. Both types of samples were carbonized during 5 min under an argon pressure of 50 MPa at temperatures up to 2500 Kelvin. Catalytic graphitization was developed by formation and dissociation of plate like Al4C3, but only at temperatures higher than 2000 K.

Electron microscopic study on catalytic carbonization of biomass carbon: I. Carbonization of wood charcoal at high temperature by Al-triisopropoxide

Currently, carbonized materials from wood or waste have been focused upon as raw materials for carbons. These carbons are important for the production of artificial graphite. First hand observation was done on the growth of long parallel graphite structures in wood charcoal. A comparison is made between graphitization in pure biomass carbon and catalytic graphitization in biomass carbon suspended in Al-triisopropoxide. Both types of samples were carbonized during 5 min under an argon pressure of 50 MPa at temperatures up to 2500 Kelvin. Catalytic graphitization was developed by formation and dissociation of plate like Al4C3, but only at temperatures higher than 2000 K

Comparison between carbonization of wood charcoal with Al-triisopropoxide and alumina

A comparison was made between the catalytic carbonization of biomass carbon suspended in Al-triisopropoxide and in biomass carbon mixed with 40 µm sized Al2O3 particles. Both types of samples were plasma sintered during 5 min under an argon pressure of 50 MPa at temperatures up to 2200 °C. Plate-like catalytic graphitization develops by formation and dissociation of plate-like Al4C3. Plasma sintering under the proper CO partial pressure and heat treatment temperature is instrumental in forcing the Al2O3 to react with the carbon, forming first Al4C3 and subsequently graphite. The difference between Al-triisopropoxide and Al2O3 is a matter of intensity of the graphite reaction versus the size of the graphite patches.

Ultrasoft Magnetic Films Investigated with Lorentz Tranmission Electron Microscopy and Electron Holography

As a tribute to the scientific work of Professor Gareth Thomas in the field of structure-property relationships this paper delineates a new possibility of Lorentz transmission electron microscopy (LTEM) to study the magnetic properties of soft magnetic films. We show that in contrast to the traditional point of view, not only does the direction of the magnetization vector in nano-crystalline films make a correlated small-angle wiggling, but also the magnitude of the magnetization modulus fluctuates. This fluctuation produces a rapid modulation in the LTEM image. A novel analysis of the ripple structure in nano-crystalline Fe-Zr-N film corresponds to an amplitude of the transversal component of the magnetization ΔMy of 23 mT and a longitudinal fluctuation of the magnetization of the order of ΔMx=30 mT. The nano-crystalline (Fe99Zr1)1-xNx films have been prepared by DC magnetron reactive sputtering with a thickness between 50 and 1000 nm. The grain size decreased monotonically with N content from typically 100 nm in the case of N-free films to less than 10 nm for films containing 8 at%. The specimens were examined with a JEOL 2010F 200 kV transmission electron microscope equipped with a post column energy filter (GIF 2000 Gatan Imaging Filter). For holography, the microscope is mounted with a biprism (JEOL biprism with a 0.6 mm diameter platinum wire).