Papers by Jürgen Schreiber
Non-Destructive Control and Diagnostics (Неразрушающий контроль и диагностика) № 4/2022, 2022
The challenging task for industrial application of Barkhausen noise technique is to obtain reliab... more The challenging task for industrial application of Barkhausen noise technique is to obtain reliable quantitative results of surface stresses. The solution of this task requires cumbersome, time and cost intensive calibration work. For these cases new approaches must be developed, either the industrial customers are not willing to spend time and money for calibration, or more seriously, reference material for the calibration is not available at all. Just this is the aim of the current investigation. The consideration will be restricted to calibration free stress determination for cases, where the microstructure is mainly fixed. The central point of the presented approach is the idea of autocalibration. Suggesting physically based calibration functions a quantitative estimation of the 2D-stress values is realized by adapting the Barkhausen noise amplitudes to the corresponding calibration functions. The Barkhausen measurements must be performed with the magnetizing field along the two perpendicular to each other stress directions. To proof that approach the stress in samples of four biaxial test experiments were analysed comparing the results of autocalibration with the reference values obtained by strain gauges or equilibrium conditions. The most surprising result was the near quantitative agreement of the stress values without using a fit parameter. The deviations found were due on the one hand to the differences in the measuring positions of strain gauges and magnetic sensors, and on the other hand to the influence of material areas close to the surface, which could not be detected by the two reference methods. The analysis of the considered biaxial experiments allows to draw the conclusion that the Barkhausen noise amplitude is not independent of the hydrostatic stress as it was assumed in a series of papers.
Spin Dependence of the Susceptibility and Curie Temperature of Amorphous Ferromagnets
JETP Letters
Chemically activated nanodiamonds as nanoagents for SHM-application: protective and smart coating for aluminium alloys
Aqeuous colloids of detonation synthesized nanodiamond particles - investigations of deaggregation and deagglomeration by means of mechanical methods
Curie Temperature and Susceptibility of an Amprphous Heisenberg Ferromagnet (High-temperature Expansion)
Jetp Letters - JETP LETT-ENGL TR, 1971
physica status solidi (b), 1975
Colloid & Polymer Science, 1996
Time domain Brillouin spectroscopy has been used as a definitive experimental approach to demonst... more Time domain Brillouin spectroscopy has been used as a definitive experimental approach to demonstrate the intrinsic nature of the thermal glass transition in Polyvinylacetate. The transition from the equilibrium liquid to the ideal glassy state appears at the ultimate temperature rg s. Key words Glass transition time dependent properties high performance Brillouin scattering Polyvinylacetate The current discussion of freezing processes in liquids concerns the thermal glass transition (TGT) as well as the dynamic glass transition (DGT) characterized by their transition temperatures Tg and T * well above Tg [-cf. 1-3].
On spin glass-like behaviour of UGaNi
Journal of Magnetism and Magnetic Materials, 1985
Pseudo-Spin Motion in Solid Solutions of the Type of the Type K(H1−xDx)2PO4
Physica Status Solidi (b), 1977
ABSTRACT
physica status solidi (b), 1976
The study of amorphous magnetism in itinerant electron models is necessary chiefly for transition... more The study of amorphous magnetism in itinerant electron models is necessary chiefly for transition metals (1). In many amorphous systems the width of the nearest neighbour maximum in the radial distribution function is much larger than the change of the averaged nearest neighbour separation in comparison to the crystal. Hence the fluctuations of the distances of atoms a r e very important and we have to include off-diagonal randomness. We want to discuss the influence of structure fluctuations on ferromagnetism (FM) within the lattice model starting with an idealized density of states (DS) for crystalline Ni (cf. (2) and see Fig. l a). In analogy to (3) we start with a Hartree-Fock approximation of Hubbard's Hamiltonian for a single tight-binding band and use the extended Lloyd model (4) for the treatment of the off-diagonal disorder problem. Thereby we apply the same notations a s in (3). In the extended Lloyd model the hopping integrals t.. fluctuate according to a Lorentzian distribution with the width A and the mean value to (3). In difference to (3) we include also fluctuations of the U. term in the spin dependent site energy Eid = Ei + Uin-d. We choose E i u a s a linear function of surrounding 1J 1 r 1 In this case the exact structure averaged Green's function<(;> is obtained by re-The DS is given by formula (5) placing t. .+ t in (3) if we substitute U-+U and distinguish between three cases: A in Gcrystal. i sign(A + Bn 1J 0-U A-+A+ Bn. In further discussions we choose t < 0 0'-d 0 case I , positive coupling (A, B > 1); case 11, only diagonal fluctuations (A + 0 , I MI,] BAI= const); case 111, negative coupling (A, B <-1).
The processes of plastic deformation and fracture of Ag and Ti thin films under thermal treatment... more The processes of plastic deformation and fracture of Ag and Ti thin films under thermal treatment and mechanical loading are studied. The evolution of the film surface topography is examined with atomic force and inverted incident-light microscopes. The plastic flow in thin metal films under both thermal and mechanical loading is found to have a similar nature. The processes of plastic deformation and fracture of the films under different external actions are shown to develop sequentially at different scale levels.
Metal Science and Heat Treatment, 2001
The mesorelief of the surface of plastically deformed specimens is characterized by a correlation... more The mesorelief of the surface of plastically deformed specimens is characterized by a correlation function. It makes it possible to determine the fractal dimension D c and the correlation length DL from surface images of the studied specimens obtained under light and scanning electron microscopes. It is shown that two modes of behavior of the correlation function can be distinguished for specimens of iron silicide and austenitic steel broken in the process of active stretching. In one mode D c and DL characterize the mesorelief of the surface at scale levels less than the grain size (D c1 , DL 1) and in the other they describe it at scale levels on the order of several grains (D c2 , DL 2). The behavior of D c1 , DL 1 , D c2 , and DL 2 is studied as a function of the distance from the head to the breakage place for specimens of iron silicide and as a function of the degree of plastic deformation for specimens of corrosion-resistant steel. The characteristics increase stage-by-stage with increase in the degree of plastic deformation until the specimen fails.
Self-Consistent Dynamical Theory for Heisenberg Spin Glasses
physica status solidi (b), 1985
ABSTRACT
On superconductivity in systems with non-linear electron-phonon coupling and structural instabilities
Journal of Physics: Condensed Matter, 1991
ABSTRACT
ndt.net
Abstract: Mass production in microelectronics and solar cell industry poses a problem of creating... more Abstract: Mass production in microelectronics and solar cell industry poses a problem of creating cheap and fast sensors being able to perform on-line quality testing of semiconductor wafers and bulk dielectric components in fab conditions. A challenging ...
Dislocation Motion in Compound Semiconductors
Solid State Phenomena, 1989
Second-order elasticity of liquid crystals within their nematic state at high frequencies
Physical Review E, 1995
ABSTRACT Within this work we present Brillouin and ultrasonic investigations performed on the liq... more ABSTRACT Within this work we present Brillouin and ultrasonic investigations performed on the liquid crystals p-methoxybenzylidene p-(n-butylaniline) (MBBA), p-azoxyanisol (PAA), 4-cyano-4-n-alkylbiphenyles (nCB), and 4-n-pentoxybenzylidene-4&#39;-n-octoaniline (5O.8). Special attention has been paid to the evolution of a significant splitting of the two longitudinal polarized acoustic modes within the nematic phase. Angle-resolving Brillouin spectroscopy allowed the determination of the complete stiffness tensors and hence a discussion of the propagation of quasitransverse polarized acoustic modes in the nematic state of liquid crystals. We analyze the behavior of the eigenvectors of the relevant acoustic modes and discuss their significance for the propagation of quasishear modes. For 5O.8 we report an acoustic instability within its nematic state. We confirm the existence of a universal thermal relaxation mechanism of weak activation energy for the nematic state of classical liquid crystals. The observed hypersonic anisotropy is discussed in terms of that relaxation mechanism and is compared with that of glass-forming liquid crystals.
Proposal on MEMS-based interferometric profiler for in-situ etching depth control
SPIE Proceedings, 2007
ABSTRACT An innovative instrument for fast and accurate surface profiling of three dimensional pa... more ABSTRACT An innovative instrument for fast and accurate surface profiling of three dimensional patterned microstructures and insitu plasma etching depth control is proposed. Several advantages of the design make it promising for in-situ metrology. First, the system constitutes a common-path interferometer with the spatial phase shift between the reference and the object beams, thus the vibration and improper positioning of an object have a minor impact on the system performance. Second, no mechanical translation of either object or sensor is required; instead, a digital micromirror array is used for scanning the surface. It results in a higher processing rate, better measuring reproducibility, and easy adaptation of the method to specifics of the fabrication technology or object under test. Third, recording a full fringe for a particular pair of object&#39;s pixels is done within a single frame of a CCD camera. Also, multiple fringes for the whole line of object pixels can be captured at once. Then only 1-D scan is required to recover the depth profile of a 2-D object area. The experimental setup has been constructed to verify major principles of the method and measurement of test samples have been realized and compared to alternative measuring methods.
<title>High-resolution Carbon/Carbon Multilayers</title>
X-Ray Mirrors, Crystals, and Multilayers II, 2002
To synthesize X-ray optical multilayers showing both high resolution and high reflectivity, space... more To synthesize X-ray optical multilayers showing both high resolution and high reflectivity, spacer and absorber materials with low absorption coefficients for the desired spectral range are required. Beside the well-known candidates the material system Carbon / Carbon is interesting because of its low absorption coefficient over a wide spectral range and the opportunity, to deposit C-layers with different modifications, i.e. different optical properties. Simulations of C/C multilayers with different period thicknesses d and single layer densities ρ show, that reflectivities R (Cu Kα ) > 80% and a resolution ΔΘ≈0.002° can be achieved for C/C layer stacks with d= 3 nm and N= 1000 periods. An advanced large area Pulsed Laser Deposition (LA-PLD) technology was used to deposit C/C multilayers on Si-substrates up to 4" diameter. The carbon film growth conditions for the spacer and absorber layers were optimised by the variation of selected laser parameters like pulse energy and ablation wavelength, to achieve a sufficient density contrast and smooth interfaces. C/C multilayers with period thickness d= 1.1...7.0 nm and more than 500 periods were deposited. The X-ray optical performance of the C/C multilayers was characterized by means of X-ray reflectometry. A reflectivity R > 50 % (CuKα) was measured for C/C multilayers with d= 17.2 nm and N= 106 periods. A peak resolution (Δλ/λ) ≈ 1.1 % was obtained for a C/C multilayer structure with N= 80 periods and a period thickness d= 1.1nm. Results of TEM investigations indicate a regular morphology as well as smooth interfaces in the C-C layer stacks. Low compressive stresses were determined in C/C multilayers with different period thicknesses using X-ray diffraction techniques.
<title>Improved mechanical properties of metallic micro-structures</title>
Testing, Reliability, and Application of Micro- and Nano-Material Systems II, 2004
ABSTRACT Properties of materials used in micro- and nano-technology are rather different from tho... more ABSTRACT Properties of materials used in micro- and nano-technology are rather different from those of bulk material and even to lateral macroscopic extended thin films. Designing MOEMs components, it has to be clarified how functionality and reliability of the micro-devices are influenced. Suitable tools are necessary to test the materials properties on micro- and submicro-scale. The application of Al- and Ti-layers in micro-mirror devices is discussed. Attempts to control and improve their mechanical properties in accordance with the application requirements for micro-mirror devices are described.
Uploads
Papers by Jürgen Schreiber