Insulator-metal transition on heavily reduced TiO 2 (1 1 0) surface studied by high temperature-scanning tunnelling spectroscopy (HT-STS)

Abstract Scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) were used to study the electronic structure of the reduced TiO 2 (1 1 0) surface. At the occupied part of the spectra some states at energies of about 1.1 and 0.6 eV below the Fermi level were found. At the unoccupied part of the spectra, the presence of a surface state at an energy of about 0.6 eV above the Fermi level was observed. Their presence has been ascribed to the appearance of Ti 2 O 3 regions on the TiO 2 (1 1 0) surface. High temperature spectroscopy measurements indicated smooth insulator-metal transition (I-M) caused by bands overlap in Ti 2 O 3 , which takes place at elevated temperatures.

Studies of high temperature sliding wear of metallic dissimilar interfaces

The evolution of microstructures in the glaze layer formed during limited debris retention sliding wear of Nimonic 80A against Stellite 6 at 750 8C and a sliding speed of 0.314 m sK1 (7 N applied load, 4522 m sliding distance) was investigated using scanning electron microscopy (SEM), energy dispersive analysis by X-ray (EDX), X-ray diffraction (XRD), scanning tunnelling microscopy (STM) and transmission electron microscopy (TEM). The collected data indicate the development of a wear resistant nano-structured glaze layer. The process of ‘fragmentation’ involving deformation, generation of dislocations, formation of sub-grains and their increasing refinement causing increasing misorientation was responsible for the formation of nano-structured grains. The rapid formation of this glaze layer from primarily cobalt–chromium debris transferred from (and also back to) the surface of the Stellite 6, kept wear of both the Nimonic 80A and Stellite 6 to very low levels. However, increasing the sliding speed to 0.905 m sK1 (750 8C) suppressed glaze formation with only a patchy, unstable glaze forming on the Stellite 6 counterface and an absence of glaze development on the Nimonic 80A sample (the Nimonic 80A surface was covered with at most, a very thinly smeared layer of oxide). The high levels of oxide debris generated at 0.905 m sK1 instead acted as a loose abrasive assisting wear of especially the Nimonic 80A. This behaviour was attributed to a change in oxide chemistry (due to the dominance of nickel and chromium oxides generated from the Nimonic 80A) resulting in poor oxide sintering characteristics, in combination with increased mobility and reduced residency of the oxide debris at 0.905 m sK1

High-Temperature Scanning Tunnelling Spectroscopy of Transition Metal Oxides

In situ high-temperature scanning tunnelling spectroscopy measure-ments recorded on the heavily reduced TiO$\text{}_{2}$(110) surface which contains Ti$\text{}_{2}$O$\text{}_{3}$ regions showed disappearance of the energy gap accompanied by substantial decrease in amplitude of the band edge states with increasing temperature. It indicates smooth insulator-metal transition caused by bands overlap in Ti$\text{}_{2}$O$\text{}_{3}$, which takes place at elevated temperatures. In situ high-temperature scanning tunnelling microscopy and spectroscopy were used to study the influence of temperature on the electronic properties of Ni$\text{}_{x}$Mn$\text{}_{3-x}$O$\text{}_{3-δ}$ (0.4< x<1) thin films deposited by rf magnetron sputtering at three different oxygen/argon (2.5%, 10%, 15%) containing ambient. The morphology and distribution of the local density of states of the observed films did not show any difference for the films deposited at different conditions. The distribution of the local density of states was temperature dependent. The changes in the shape of the local density of states observed at 473 K were reversible with temperature implying that no permanent change of the electronic structure occurred

High-Temperature Scanning Tunnelling Spectroscopy of Transition Metal Oxides

In situ high-temperature scanning tunnelling spectroscopy measure-ments recorded on the heavily reduced TiO$\text{}_{2}$(110) surface which contains Ti$\text{}_{2}$O$\text{}_{3}$ regions showed disappearance of the energy gap accompanied by substantial decrease in amplitude of the band edge states with increasing temperature. It indicates smooth insulator-metal transition caused by bands overlap in Ti$\text{}_{2}$O$\text{}_{3}$, which takes place at elevated temperatures. In situ high-temperature scanning tunnelling microscopy and spectroscopy were used to study the influence of temperature on the electronic properties of Ni$\text{}_{x}$Mn$\text{}_{3-x}$O$\text{}_{3-δ}$ (0.4< x<1) thin films deposited by rf magnetron sputtering at three different oxygen/argon (2.5%, 10%, 15%) containing ambient. The morphology and distribution of the local density of states of the observed films did not show any difference for the films deposited at different conditions. The distribution of the local density of states was temperature dependent. The changes in the shape of the local density of states observed at 473 K were reversible with temperature implying that no permanent change of the electronic structure occurred

Management of riparian forests for good water quality in the Baltic Sea Region countries – current knowledge, methods and areas for development

201

Forest drainage and water protection in the Baltic Sea Region countries – current knowledge, methods and areas for development

201

Suojavyöhykkeet metsätalouden vesiensuojelussa Itämeren maissa – nykytietämys, menetelmät ja kehitystarpeet

201

Metsäojitus ja vesiensuojelu Itämeren maissa - nykytietämys, menetelmät ja kehitystarpeet

201