A photoemission study of molybdenum hexacarbonyl adsorption and decomposition on TiO2(1 1 0) surface

The adsorption and decomposition of molybdenum hexacarbonyl on (1 1 0) TiO₂ surfaces were studied using both core levels and valence band photoemission spectroscopies. It was found that after an adsorption at 140 K, when going back to room temperature, only a small part of molybdenum compounds, previously present at low temperature, remained on the TiO₂ surface. This indicates that the desorption temperature on such a surface is lower than the decomposition one. The use of photon irradiation to decompose the hexacarbonyl molecule was also studied. It was shown that during such a decomposition molecular fragments were chemisorbed on the surface allowing a higher amount of metal to remain on the surface. It was also shown that it was possible to get rid of adsorbed subcarbonyl groups and to organize the metal atoms by thermal treatments at temperatures as low as 400 K, i.e. much lower than the one needed to obtain the same structures using physical vapour deposition (PVD). Moreover, due to lower used temperatures, this chemical way of deposition allows a better control of the interface than during PVD growth.     

Propagation of thickness-twist waves in a multi-sectioned piezoelectric plate of 6 mm crystals

We study thickness-twist vibrations and waves in an unbounded, multi-sectioned piezoelectric plate of crystals with 6 mm symmetry or polarized ceramics. An exact solution from the three-dimensional equations of piezoelectricity is obtained. Basic vibration and wave propagation characteristics are calculated based on the solution. The results are useful in the understanding and design of plate resonators, filters and acoustic wave sensors of ZnO, AlN and polarized ceramics.     

On the law of corresponding states for thermodynamic properties of a crystal

To study thermodynamic similarity of the properties of crystalline substances, we propose an approach connected with engaging of the metastable state region. Internal pressure and specific volume on the crystal’s stability boundary at T = 0 K are used as characteristic scales of thermodynamic variables. A semiempirical method of calculation of the stability boundary by the thermodynamic data related to the stable states region of a solid body is described. In the cases of argon and natrium, the stability boundary is calculated for a wide range of temperatures and pressures. Analysis of the properties of neon, argon, krypton, and xenon crystals in these variables indicates that the law of corresponding states holds for these substances.     

Fabrication of magnetic composite nanofibers of poly(ε-caprolactone) with FePt nanoparticles by coaxial electrospinning

In this article, composite nanofibers of poly(ε-caprolactone) (PCL) with iron–platinum (FePt) nanoparticles were successfully fabricated via coaxial electrospinning. The structure and morphology of FePt/PCL composite nanofibers were observed using transmission electron microscope and scanning electron microscope, respectively. The magnetic behavior of FePt/PCL composite nanofibers was investigated by alternating gradient magnetometer at room temperature.     

Micromagnetic analysis of transition noise for high-density perpendicular recording

In this paper, specific issues related to high-density perpendicular magnetic recording processes, such as transition noise properties and cross-track correlation lengths, were investigated with the help of micromagnetic analysis. The effects of media parameters were taken into consideration, including intergranular exchange coupling, and exchange distribution, irregular grain shapes, magnetization saturation distribution, and anisotropy distribution. The micromagnetic simulation results showed that the effect of anisotropy distribution on transition noise is more significant than magnetization saturation distribution, and it is crucial to reduce this effect to achieve a high signal-to-noise ratio. Additionally, a new method to further estimate the partial erasure threshold was proposed to approximate the partial erasure effects, and the relation between the microtrack jitter and total track jitter was investigated.     

Control of the temperature hysteresis and diffuse dielectric anomaly in the temperature range of the ferroelectric-antiferroelectric phase transition in PbZr1 − x TixO3 (0.03 ≤ x ≤ 0.05) ceramics

The magnitudes of the temperature hysteresis and diffuse dielectric anomaly corresponding to the transition from the antiferroelectric phase to the ferroelectric phase in PbZr_{1 ? x} Ti_xO₃ (0.03 ≤ x ≤ 0.05) ceramics can be reversibly changed by varying the temperatures of heating and cooling in the course of thermocycling. The results obtained indicate that the antiferroelectric-ferroelectric transition in the PbZr_{1 ? x} Ti_xO₃ ceramics materials is a smeared first-order phase transition.     

An observation on realcompact spaces

We give a characterization of realcompact spaces in terms of nets. By using the technique of this characterization we give easy proofs of the Tychonoff Theorem and the Alaoglu Theorem.

     

Mössbauer effect study of the decagonal quasicrystal Al65Co15Cu20

The ⁵⁷Fe Mössbauer effect study at 5.0 K and in an external magnetic field of 9.0 T on a high-quality stable decagonal quasicrystal Al₆₅Co₁₅Cu_19.9Fe_0.1 is presented. It is shown that the iron atoms are located in two distinct classes of sites. The values of the principal component of the electric field gradient tensor and the asymmetry parameter at these sites are, respectively, ?1.90(10)?×?10²¹ V/m², 0.97(15) and ?3.95(12)?×?10²¹ V/m², 0.00(17).     

Structure transition of single-texture CoSi2 nanolayer grown by refractory-interlayer-mediated epitaxy method

In this investigation, the crystalline structure of a nanometric CoSi₂ layer, formed in heat treated Co/W_xTa_(1−x)/Si(1 0 0) systems, has been studied by XRD analysis. Careful measurements of the diffraction intensities revealed that temporary formation of a metastable diamond cubic structure of CoSi₂ phase, rather than its usual CaF₂ structure, was occurred. It has been shown that formation of this metastable structure depends on the kind of the applied interlayer in addition to the annealing temperature. Among the studied systems with x = 0, 0.25, 0.5, 0.75 and 1, the second and the last systems resulted in growing a (1 0 0) single-texture CoSi₂ layer with the preferred usual CaF₂ structure, a strained lattice parameter, and the best thermal stability (900-1000 °C).