Synthesis, structure and properties of high pressure and ambient pressure ternary vanadium oxides

Transition metal oxides have been extensively studied during past decades. The purpose of this research was to synthesize new or little characterised transition metal oxides using high-pressure/high-temperature (HPHT) techniques. Various ternary vanadium oxides have been synthesised at ambient and high pressure conditions. All compounds have been studied by neutron and laboratory X-ray powder diffraction and magnetisation measurements. In some cases resistivity and synchrotron X-ray powder diffraction measurements were also carried out. The MnVO3 perovskite containing localized 3d5 Mn2+ and itinerant 3d1 V4+ states has been synthesised at 8 GPa and 1100°C. MnVO3 crystallises in Pnma space group (a = 5.2741(6) Å, b = 7.4100(11) Å, and c = 5.1184(8) Å at 300 K) and is metallic at temperatures of 2 – 300 K and at pressures of up to 67 kbar. Synchrotron X-ray powder diffraction study on the combined sample of several high pressure products showed slight variation in the stoichiometry of MnVO3. Incommensurate Mn spin order was discovered in the neutron powder diffraction measurements, which reveal a (0.29 0 0) magnetic vector below the 46 K spin ordering transition, and both helical and spin density wave orderings are consistent with the diffraction intensities. Electronic structure calculations show large exchange splittings of the Mn and V 3d bands, and (kx 0 0) crossings of the Fermi energy by spin up and down V 3d bands may give rise to Ruderman-Kittel-Kasuya-Yosida coupling of Mn moments, in addition to their superexchange interactions. The new compound CoVO4 has been discovered in a high pressure synthesis experiment. Magnetic susceptibility measurement, synchrotron X-ray and neutron powder diffraction studies were carried out. Refinements of the synchrotron X-ray and neutron data show CoVO4 to crystallise in space group Pbcn (a = 4.5012(2) Å, b = 5.5539(3) Å, and c = 4.8330(2) Å at 300 K (synchrotron X-ray data)). The magnetic susceptibility measurement reveals that Co3+ is most likely in a low spin state in CoVO4. Monoclinic brannerite type CoV2O6 was synthesised in ambient pressure. Neutron powder diffraction measurements were carried out and an antiferromagnetic order with an a x b x 2c supercell was observed below TN = 15 K. High spin Co2+ moments of magnitude 4.77(4) μB at 4 K lie in the ac plane and are ferromagnetically coupled within chains of edge-sharing CoO6 octahedra parallel to b axis. No structural transition is observed down to 4 K, but a magnetostriction accompanying antiferromagnetic order at TN = 15 K was discovered. A field-induced 1/3 magnetisation plateau and corresponding changes in the magnetic structure were studied by carrying out neutron powder diffraction measurements at 2 K in applied magnetic fields of 0, 2.5 and 5.0 T. Three collinear magnetic phases were observed as field increases; the above antiferromagnetic state with propagation vector (0 0 ½), a ferrimagnetic (¯⅓ 1 ⅓) phase, and a (0 0 0) ferromagnetic order. Co2+ moments of 4.4 - 5.0 μB have a large orbital component and are aligned close to the c-axis direction in all cases. Spin-lattice coupling leads to a magnetostriction and volume expansion as field increases. The ferrimagnetic phase accounts for the previously reported 1/3 magnetisation plateau, and demonstrates that monoclinic CoV2O6 behaves as an accidental triangular antiferromagnetic lattice in which further frustrated orders may be accessible. Orthorhombic columbite-type NiV2O6 and CoV2O6 compounds were synthesised at 6 GPa and 900°C. Metamagnetism and magnetic transitions were found in magnetic measurements. Powder neutron diffraction studies in zero and applied field were carried out. Both compounds were refined in space group Pbcn and the following lattice parameters were obtained at 300 K, CoV2O6: a = 13.4941(20) Å, b = 5.5736(9) Å, and c = 4.8082(8) Å and NiV2O6: a = 13.3725(17) Å, b = 5.5344(7) Å, and c = 4.8162(7) Å. Neutron powder diffraction studies in zero field did not reveal any magnetic peaks for either of the compounds but magnetic order emerges in applied fields between 1 and 4 T

Incommensurate spin order in the metallic perovskite MnVO3

Incommensurate Mn spin order has been discovered in the perovskite MnVO3 containing localized 3d5 Mn2+ and itinerant 3d1 V4+ states. This phase has a distorted Pnma crystal structure (a = 5.2741(6) Å, b = 7.4100(11) Å, and c = 5.1184(8) Å at 300 K) and is metallic at temperatures of 2-300 K and at pressures of up to 67 kbar. Neutron scattering reveals a (0.29 0 0) magnetic vector below the 46 K spin ordering transition, and both helical and spin density wave orderings are consistent with the diffraction intensities. Electronic structure calculations show large exchange splittings of the Mn and V 3d bands, and (kx 0 0) crossings of the Fermi energy by spin up and down V 3d bands may give rise to Ruderman-Kittel-Kasuya-Yosida coupling of Mn moments, in addition to their superexchange interactions. © 2011 American Physical Society

Incommensurate spin order in the metallic perovskite MnVO₃

Incommensurate Mn spin order has been discovered in the perovskite MnVO3 containing localized 3d(5) Mn2+ and itinerant 3d(1) V4+ states. This phase has a distorted Pnma crystal structure (a = 5.2741(6) angstrom, b = 7.4100(11) angstrom, and c = 5.1184(8) angstrom at 300 K) and is metallic at temperatures of 2-300 K and at pressures of up to 67 kbar. Neutron scattering reveals a (0.29 0 0) magnetic vector below the 46 K spin ordering transition, and both helical and spin density wave orderings are consistent with the diffraction intensities. Electronic structure calculations show large exchange splittings of the Mn and V 3d bands, and (k(x) 0 0) crossings of the Fermi energy by spin up and down V 3d bands may give rise to Ruderman-Kittel-Kasuya-Yosida coupling of Mn moments, in addition to their superexchange interactions

Comparison of the Finnish translations of C.S. Lewis’s The Screwtape Letters

In this thesis the two Finnish translations of C.S. Lewis’s The Screwtape Letters are compared and reasons for the retranslation are suggested. The translations of the whole text are compared, and the “erroneous” words and passages found are classified into two groups according to Pym’s “Binary error vs. non-binary error” -classification. Within these groups the “incorrect” translations are sorted into the following sub-groups: 1) Binary error with incorrect meaning in the translation 2) Binary error with an unidiomatic translation 3) Binary error with an incorrect translation of an idiomatic expression 4) Non-binary error with a slightly unidiomatic translation 5) Non-binary error with a slightly inaccurate translation and 6) Non-binary error with interference in translation. The numbers of different errors are compared. The style and structure of the translations are compared. The introduced theoretical background include the following items: concepts of domestication and foreignization; retranslation hypothesis; effects of earlier translations on retranslation; differences between retranslation and revision; different approaches to literary translation; politics, authority and institutional aspects related to (re)translation; influence of norms and ideologies on (re)translations; aging of translations; translation evaluation and error classification; and language transfer in translation. In Tuulio’s translation 107 binary errors and 54 non-binary errors were found while in Junttila’s translation only three binary errors and two non-binary errors were spotted. The number of errors in Tuulio’s translation seem to be the only reason and motive for the retranslation. Other possible reasons such as changes in the ideological contexts or social norms or in the relationship between British and Finnish cultures do not apply here

Do Car Drivers Respond Earlier to Close Lateral Motion Than to Looming?

It is essential to understand drivers’ responses to visual stimuli when analyzing or reconstructing driver behavior in critical traffic situations. In a controlled experiment, drivers’ on-road glances relevant to a situation may however be obscured by the presence of check glances which are not induced by the visual input that the experiment intends to study. The purpose of this work is to compare five methods to reduce the influence check glances may have on the results in studies of drivers’ glance responses. We apply the methods to a comparison of driver glance response times in a critical lead vehicle brake event (characterized by strong looming) and a non-critical close cut-in event (characterized by a distinct lateral motion), using data from a previously conducted driving simulator experiment. Without the noise added to the analysis from the check glances, our study shows that drivers look back towards the road in front earlier when exposed to close lateral motion, than when exposed to looming. We conclude that a careful data selection process aiming to minimize the influence of potential check glances is important to ensure relevance of the results in glance response studies