In this paper, we investigate the propagation of electromagnetic wave in 12-fold symmetric quasiperiod structure employing finite difference time domain (FDTD) method. The quasiperiodic photonic crystal (QPC) consists of a dodecahedral lattice of air holes embedded in a dielectric background. Simulation on wave propagation through a wedge-shaped structure shows that negative refraction can occur at the interface between air and the quasicrystal sample. We further design QPC slab for performance of a high-quality flat lens. Simulation results reveal that non-near-field imaging can be achieved through the QPC slab. TM and TE modes are discussed and both the two modes exhibit the focusing effect. Since the air-hole type QPCs are more easily fabricated and integrated than the dielectric-rod type QPCs, our results might be important to the applications.

Direct-illumination CCDs find increasing use in coherent X-ray imaging due to their good spatial resolution and signal-to-noise ratio. These CCDs offer a high quantum efficiency for soft X-rays near the 3d transition metal L edges. We compare front- and back-illuminated CCDs and describe a method to obtain images with a large dynamic range (five orders of magnitude) and high spatial resolution. Back-illuminated CCDs are resistant to radiation damage at the soft X-ray energies and provide a true 13.5 μm pixel resolution. High quality diffraction images are obtained in magnetic studies from metallic multilayer structures in reflection geometry.

Thermodynamic and magnetic measurements of ternary compounds RCo9Si4 with R = Pr, Nd, and Sm were analyzed in order to estimate the magnetic entropy, specific heat jump and effective magnetic moments. The samples show a ferromagnetic behaviour at low temperature with T C varying from 10 to 35 K. The saturation magnetisation M s at 2 K with 6 T is found to be about 23.20, 24.94 and 10.70 emu/g for R = Pr, Nd, and Sm, respectively. The total effective magnetic moments μeff of RCo9Si4 for R = Pr , Nd, and Sm as obtained from the Curie constant C are estimated to be 4.94 μB , 5.26 μB , and 3.90 μB , respectively. The magnetic specific heat jump ΔC p at T C is found to be 12, 3.6, and 10.5 J/mol K for RCo9Si4 with R = Pr, Nd, and Sm, respectively. Magnetic entropy S M associated with the magnetic ordering in RCo9Si4 (R = Pr, Nd and Sm) were estimated to vary from 19.15 J/mol K and 14.90 J/mol K.

This paper deals with the application of schlieren techniques to the optical diagnostics of ultrasonic pulses, passing a grid target. We used bright field schlieren method with the image post-processing by 2-dimensional Fourier transform (2D FT). In case the basic wavelength of the pulse is larger than the grid spatial period, the ultrasonic wave does not resolve the grid and the corresponding modulation is absent in the schlieren images. However the pulse contains also the super-harmonics of its basic frequency, while their wavelengths, which are smaller than the grid period and capable therefore to resolve the target. The resulting modulation is hardly visible in the schlieren images, but could be easily revealed with the 2D FT. The quantitative interpretation of the schlieren images and their FT are presented in the paper as well.

Formation of different types of nanosized Al-containing oxide precipitates in an Fe-Cr-Al alloy (PM 2000) was studied by electron energy loss spectroscopy (EELS) using a transmission electron microscope (TEM). It was shown that Y3Al5O12 (garnet) and YAlO3 (perovskite) as well as $\gamma $ -Al2O3 and $\alpha $ -Al2O3 precipitates can be distinguished by analysing the O-K energy loss near-edge structure (ELNES). The formation of interface-specific phases on Al2O3/YAlO3, Al2O3/matrix and Y3Al5O12/matrix interfaces was also investigated by specially resolved EELS analysis. Applicability and sensitivity of the EELS method in the study of steel precipitates were discussed. A sharp pre-peak or “pre-shoulder” in the O-K edge was observed and studied by means of spatially resolved EELS of oxide inclusions. The intense pre-peak was found to be caused by radiation damage induced by the electron beam of the Al hydroxide phase inside Al2O3 inclusions. This phase formed due to the incorporation of hydrogen in the matrix during mechanical alloying in the hydrogen atmosphere. The “pre-shoulder” of the main O-K feature measured on the inclusion/matrix interface results from the formation of a thin Ti-O layer.

In this paper, the ceramic compositions ( $1-x$ )Pb1−w−y Law Sry (Zrz Ti $_{1-z})_{(1-w/4)}$ O3-xBaTiO3, where x = 0.15, 0.25, 0.35 and 0.45, fabricated through solid state reaction method were investigated for phase formation, microstructure, density, dielectric and piezoelectric properties. The combination of the two perovskite structured stoichiometric compositions (i.e., isovalent Sr2+ modified PLZT and BaTiO3) indicated that tetragonality enhanced further due to BaTiO3 concentration in PLSZT lattice. The BaTiO3 in PLSZT ceramics were homogeneously distributed within the two perovskite structured solid solutions. The dielectric characterization indicated that $\varepsilon _{RT}$ enhanced while $\tan\delta _{RT}$ and T c decreased with increasing BT additions into PLSZT perovskite. The maximum $\varepsilon _{RT}$ = 2986 and $\varepsilon _{T_c}$ = 21468 were found in 0.55PLSZT-0.45BT ceramic system. The piezoelectric properties were influenced by both BaTiO3 and Sr2+ modified PLZT perovskite. The influence of BT modified PLSZT ceramics showed significant variations that has been discussed. The piezoelectric properties remarkably enhanced with maximum ( $k_{p} = 0.541$ and $d_{33} = 518$ pC/N) values in the 0.55PLSZT-0.45BT composition and thus, could be a promising candidate among this series for possible capacitor, sensor and actuator applications.

Surface caesium content is known to greatly influence the negative ion yield during SIMS analyses. In NanoSIMS, a 16 keV ion probe of Cs+simultaneously performs the surface enrichment and the sample sputtering. To increase the surface caesium content and thus generate higher ion yields, it is suggested herein to significantly reduce the energy of the primary ions by biasing the sample with a positive voltage slightly smaller than the voltage of 8000 V that is used for primary ion acceleration. Then, once the typical bias voltages are restored, SIMS analysis may carried out with increased sensitivity right from the beginning of the sample erosion. The use of such a procedure may improve many types of SIMS investigations such as thin sections of biological samples, semiconductor wafers shallowly doped over very small areas and small meteorite samples.However, during deceleration close to the sample surface, the beam size is markedly enlarged unless the excitation of the objective lens is corrected. In this study, optics simulations are performed using Simion 8 in order to facilitate adjustment of the experimental setups. An objective lens excitation set at E0P = 0 V and E0S = +5930 V focuses a 100 eV caesium beam into an area 9.2 μm in diameter. Even for a final energy as low as 25 eV, 90% and 50% of the beam is confined to areas of 30 μm and 4 μm in diameter respectively (with electrodes E0Pand E0S set at 3150 and 5450 V and using a beam slightly limited in angle). The procedures being suggested will be confirmed by experimental studies soon to be submitted as complementary contribution. As predicted, caesium rich surfaces greatly improve ion yield and consequently localised SIMS analysis as well.

Carr-Purcell-Meiboom-Gill (CPMG) experiments were made upon sedimentary rock samples at different RF pulsation rates. A dispersion of the transversal relaxation rate was observed. The experiments revealed that due to the diffusional processes there is a diminution of the second moment of the absorption line with the delay time between the RF pulses and the echo time, with a complex evolution characterized either as a stretched exponential or a power-law behavior as a function of the echo time, with parameters dependent on the characteristic time of the experiment, i.e., the delay between RF pulses. Results show that the observed behavior is dependent on permeability and geometrical properties of the sedimentary rock.

Scheme of coaxial microwave gas-discharge plasma source based on a “plasma resonance” phenomenon is presented. Possibility of conditions realization at which energy of accelerated in the “resonance” electrons goes into ionization processes (in volume of chamber outside of “resonance” region) is discussed. Results of experimental investigation of a coaxial microwave plasmatron in which “resonance” mechanisms have been manifested are presented. A plasmachemical reactor based on a “resonance” plasmatron is described. The data on plasmachemical decomposition of CF2Cl2 are displayed.

The behavior of illuminated Pt/a-Si:H Schottky barrier has been studied by numerical calculations. The electric field, the electrons and holes currents, the charge space and the recombination rate where calculated as function of the position. The photocurrent, when the front of the barrier is illuminated by different wavelengths under lower reverse applied voltage, tends towards saturation. By comparing the number of collected carriers to the incoming photons, we remark that the collection of photogenerated carriers is partial for long wavelengths (λ ≥ 600 nm), in this case the collection efficiency is determined by the recombination in the bulk, and total when the short wavelengths (λ < 600 nm) are used and the recombination in the front layer seems to be an important carrier loss mechanism. This is mainly the consequence of the virtual cathode apparition that behaves against the carrier collection. This cathode moves to back contact and tends to disappear with increasing the reverse bias voltage.

This paper aims at investigating the influence of the dielectric support on the indications of single axis and three-axis low frequency electric field meters obtained during their calibration. The modification of the calibration field due to the dielectric support, experienced by the meter probe, is predicted by a Boundary Element model and experimentally compared with the actual probe indication, considering both a parallel plate set-up and a TEM cell for the generation of the reference field. The perturbing effect, estimated for different dielectric supports, is found to be greatly amplified and frequency dependent when considering lossy dielectric materials.

We characterized two samples consisting of photoresist layers on silicon with square arrays of square holes by spectroscopic ellipsometry (SE) and Mueller matrix polarimetry (MMP). Hole lateral dimensions and depths were determined by fitting either SE data taken in conventional planar geometry or MMP data in general conical diffraction configurations. A method for objective determination of the optimal measurement conditions based on sensitivity and parameter correlations is presented. When applied to MMP, this approach showed that for one of the samples the optimal incidence angle was 45°, much below the widely used 70° value. The robustness of the dimensional characterisation based on MMP is demonstrated by the high stability of the results provided by separated fits of the data taken at different azimuthal angles.