Structural Study of Cu/Co Multilayer by Anomalous Small-Angle X-ray Scattering

The diffraction peaks in the small-angle region due to a long period of a Cu/Co multilayer were observed with the anomalous small-angle x-ray scattering in reflection geometry. These peaks appear to be enhanced because of a large negative value of the real part of the anomalous. dispersion term of Co just below the Co K-absorption edge. By comparing the relative integrated intensities of these peaks with the theoretical values calculated from a trapezoidal concentration model, the concentration profile along the surface normal in this multilayer has been determined

Structural Investigation of Amorphous and Quasicrystalline Al-based Alloys by the Anomalous X-ray Scattering (AXS) Method

An attempt has been made in this paper to present the current information about the atomic structures of both amorphous and icosahedral Al_Cu_V_ alloys and icosahedral Al_Cu_Fe_ alloy determined by the anomalous x-ray scattering (AXS) method as well as the ordinary x-ray diffraction. Characteristic features of their intensity profiles are observed, and the structural parameters of coordination numbers and interatomic distances determined from the RDF analysis clearly indicate the presence of the icosahedral short-range ordering clusters in the as-quenched amorphous sample and other annealed amorphous samples, which are similar to the fundamental atomic distribution constructing the icosahedral phase. The AXS measurements at the Cu and Fe K-absorption edges also provide the possible interpretation about the distribution of these components in the icosahedral short-range ordering clusters

Primordial Non-Gaussianity and Analytical Formula for Minkowski Functionals of the Cosmic Microwave Background and Large-scale Structure

We derive analytical formulae for the Minkowski Functions of the cosmic microwave background (CMB) and large-scale structure (LSS) from primordial non-Gaussianity. These formulae enable us to estimate a non-linear coupling parameter, f_NL, directly from the CMB and LSS data without relying on numerical simulations of non-Gaussian primordial fluctuations. One can use these formulae to estimate statistical errors on f_NL from Gaussian realizations, which are much faster to generate than non-Gaussian ones, fully taking into account the cosmic/sampling variance, beam smearing, survey mask, etc. We show that the CMB data from the Wilkinson Microwave Anisotropy Probe should be sensitive to |f_NL|\simeq 40 at the 68% confidence level. The Planck data should be sensitive to |f_NL|\simeq 20. As for the LSS data, the late-time non-Gaussianity arising from gravitational instability and galaxy biasing makes it more challenging to detect primordial non-Gaussianity at low redshifts. The late-time effects obscure the primordial signals at small spatial scales. High-redshift galaxy surveys at z>2 covering \sim 10Gpc^3 volume would be required for the LSS data to detect |f_NL|\simeq 100. Minkowski Functionals are nicely complementary to the bispectrum because the Minkowski Functionals are defined in real space and the bispectrum is defined in Fourier space. This property makes the Minksowski Functionals a useful tool in the presence of real-world issues such as anisotropic noise, foreground and survey masks. Our formalism can be extended to scale-dependent f_NL easily.Comment: 16 pages, 5 figures, accepted for publication in ApJ (Vol. 653, 2006

Structural Study of Icosahedral Al_<65>Cu_<20>TM_<15> (TM= Fe, Ru, and Os) and Decagonal Al_<75>Fe_<15>Ni_<10> Alloys by Anomalous X-ray Scattering((B)Quasicrystals)

The structural study has been carried out in fully annealed quasi-crystalline Al_Cu_TM_ (TM=Fe, Ru and Os) and as-quenched decagonal Al_Fe_Ni_ alloys by anomalous x-ray scattering (AXS) and ordinary x-ray scattering techniques. The environmental radial distribution functions (RDFs) for Cu and Os atoms in the Al_Cu_Os_ alloy and those of Fe and Ni atoms in the Al_Fe_Ni_ alloy were determined and compared with the ordinary RDF which represents the average structure of the system. Environmental structures for Cu and Os atoms are quite different in the Al_Cu_Os_ alloy, which implies that Cu and Os atoms occupy different sites in icosahedral clusters. By comparing the ordinary RDFs of the three Al_Cu_TM_ (TM=Fe, Ru and Os) alloys, their fundamental atomic structure is found to be identical. The environmental RDFs for Fe and Ni atoms in the decagonal Al_Ni_Fe_ alloy resemble each other and also the ordinary RDF, which contrasts to the environmental RDFs for Cu and Os atoms in the Al_Cu_Os_ alloy. These results suggest that Ni and Fe atoms share their atomic sites in the decagonal Al_Fe_Ni_ structure

Structural Study of Amorphous Alloys with a Wide Supercooled Liquid Region by the Anomalous X-ray Scattering (AXS) Method

The atomic structures of new kinds of as-quenched La_Al_Ni_ and Zr_Al_Ni_ amorphous alloys exhibiting a wide supercooled liquid region and a high reduced glass transition temperature have been studied with the anomalous x-ray scattering (AXS) method in combination with the ordinary x-ray diffraction. The environmental structures around certain constituent elements in the alloys were determined with the AXS method. The atomic structures of these amorphous alloys annealed in the super-cooled liquid region were also investigated. The systematic structural studies revealed a structural feature common to these amorphous alloys. Namely, the environment around a certain element in the amorphous sample is very different from that in the crystallized sample. Such as, Ni atoms around La atoms in La_Al_Ni_ and Al atoms around Zr atoms in Zr_Al_Ni_. In other words, quite a large change of the environments around a certain element is required for the crystallization, which controls the crystallization in these amorphous alloys. Consequently, This may provide a high thermal stability of these amorphous alloys

Ammattikorkeakoulut ja yrityselämä

Yritysten on menestyäkseen ja kilpailussa pärjätäkseen kehityttävä jatkuvasti. Yritykset tarvitsevat kehitystyössään innovaatiovalmiuksia ja sparraavaa tukea. Oulun seudulla on luotu yhteistyöfoorumeita ja kehitetty valmiuksia vastata yritysten tunnistamiin kehittämistarpeisiin. Ammattikorkeakoulujen palvelutarjonta yrityksille on nykyisellään laajaa. Palvelut voivat olla muun muassa koulutus- ja kehittämispalveluja, testaus-, mallinnus- ja tuotekehityspalveluja, yrittäjyyteen liittyviä hautomopalveluja ja tutkimuspalveluja. Ammattikorkeakoulussa eri alojen opiskelijoiden yhteen saattaminen jo opiskeluaikana mahdollistaa innovaatioiden kehittymisen ja laaja-alaisen asioiden tarkastelemisen hallinnolliset raja-aidat ylittäen. Myös kansainvälistymisen lisäämiseen tarvitaan sekä pk- että ammattikorkeakoulusektoreilla lisää innovatiivisia avauksia. Yrityksen voivat myös hyödyntää kansainvälistymisessä ammattikorkeakouluilla jo valmiiksi olevia kansainvälisiä verkostoja. Tuntevatko pk-yritykset riittävästi ammattikorkeakoulujen yrityksille tarjoamia mahdollisuuksia esimerkiksi kehittämistoiminnan kautta? Onko palvelujen käyttämisen kynnys riittävän matala ja ovatko palvelut mahdollisimman helposti saatavilla

Structural Study of SiO_x Amorphous Thin Films by the Grazing Incidence X-ray Scattering (GIXS) Method

Atomic structures of SiO_x amorphous thin films of 200 nm thick were analyzed by the grazing incident x-ray scattering (GIXS) method. The radial distribution functions (RDFs) were experimentally determined in two SiO_x amorphous thin films grown in the atmosphere with and without N_2 gas. The SiO_x amorphous film grown with N_2 gas forms the network structure consisting of SiO_4 tetrahedra which are connected each other by oxygen atoms at their vertices. This network structure is similar to the one observed in SiO_2 glass. On the other hand, in the SiO_x amorphous film grown without N_2 gas, the atomic distance of Si-O pairs is a few percent longer and the coordination number of O-O pairs is smaller than the other. This suggests that some of oxygen atoms in a SiO_4 tetrahedron are not connected to a next neighboring tetrahedron. Namely, some part of the network structure is disconnected in the SiO_x amorphous film grown without N_2 gas. Due to this imperfection of the network structure, it is expected that the SiO_x film grown without N_2 gas would be inferior to the other one grown with N_2 gas in some electrical properties as an insulator