A planar antenna operating at 13.56 MHz is presented for potential applications in plasma processing. It consists of interconnected elementary resonant meshes composed of inductive and capacitive elements. Due to its structure, the antenna exhibits a set of resonant modes associated with peaks of the real input impedance. Each mode is defined by its particular distribution of current and voltage oscillating at the frequency of the mode. A rectangular antenna of 0.55 m×0.20 m has been built and first results obtained with argon plasmas are presented. Efficient plasma generation is shown by plasma densities above 3 × 10 ¹⁷ m ⁻³ at 2000 W with reasonable uniformity over the antenna area. The plasma couples inductively with the resonating currents flowing in the antenna above a threshold power of about 60 W. The real input impedance at antenna resonance avoids the problem of strong reactive currents and voltages in the matching box and RF power connections associa...

Magneto-impedance measurements on iron whiskers with ⟨1 0 0⟩ growth direction were performed at room temperature as a function of the applied longitudinal magnetic field and frequency of the applied current. A maximum magneto-impedance ratio of more than 60% was observed under the chosen experimental conditions. Calculations based on the standard skin effect formalism permit the determination of the complex values of the effective circumferential permeability and the skin depth. The observations on the particularly simple model system allow a very detailed analysis of the magneto-impedance contributions not having been possible for the much more complex systems studied.

La _0.7Sr _0.3MnO ₃/BaTiO ₃ (LSMO/BTO) bilayer films were grown on (0 0 1) oriented SrTiO ₃ (STO), LaAlO ₃ (LAO) and (LaAlO ₃) _0.3(SrAl _0.5Ta _0.5O ₃) _0.7 (LSAT) substrates by pulsed laser deposition. The bilayer deposited on the LSAT substrate presented the best ferromagnetic properties due to the smallest lattice mismatch between LSAT and LSMO. However, the best ferroelectric properties and strongest magnetoelectric (ME) effect existed in the bilayer on the STO substrate due to the minimal compressive strain in the BTO film. All these showed similar frequency-dependent ME behaviour from 0.1 to 100 kHz, and the largest value of ME voltage coefficient (α _E ) was obtained on the STO substrate. The values of α _E were around 263 mV cm ⁻¹ Oe ⁻¹, 202 mV cm ⁻¹ Oe ⁻¹ and 169 mV cm ⁻¹ Oe

Unintentionally doped and Y-doped SnO thin films were prepared and characterized by x-ray diffraction, spectroscopic ellipsometry, and Hall-effect measurements. SnO-based thin-film transistors were also fabricated and investigated. Preferred (0 0  l) grain orientation present in the undoped films is alleviated by Y doping, inducing the deterioration of crystallinity as well as the decrease in Hall-effect and saturation field-effect mobilities. However, both the films and the transistor devices always possess p-type characteristics in this study. As the Y content increases, the optical band gap, the real part of the dielectric constant of the films and the on/off current ratio of the devices increase. Moreover, the threshold voltage was observed to shift towards the positive direction as more yttrium content is introduced. These results give evidence that the yttrium element is incorporated into the SnO lattice successfully and higher hole concentration can be generated.

To improve thermoelectric (TE) efficiency, the physical phenomenon of TE effect is revisited. The important TE figure of merit (FOM) is expressed in terms of powers, and it is mapped by two fundamental quantities. One is the electronic TE efficiency, which is purely determined by a probability distribution function of electron transport. Furthermore, electronic TE efficiency plays an important role in the upper limit of TE FOM, which is an important index to judge the quality of a TE device. For any TE device with FOM more than one, its electronic TE efficiency must be greater than 0.5. For demonstration purpose, the TE properties of silicon nanowire are investigated.

The point defect structure of As-implanted ZnO crystals was investigated using diffuse x-ray scattering and spectroscopic methods. A dynamic picture regarding the defect structure transformation was revealed. The defect type, size and combination state experienced obvious changes during annealing. Before annealing the point defects distributed isolatedly and coexisted with dislocation loops. After annealing, As _O disappeared and other point defects either aggregated into large clusters or formed defect complexes including As _Zn–2V _Zn whose ionization energy was measured and which was discerned as the main origin of p-type conductivity.

The production of NO radicals by an atmospheric pressure plasma jet has been investigated by means of absorption spectroscopy in the mid-infrared region (IR) and optical emission spectroscopy (OES) in the ultraviolet (UV) part of the spectrum. The plasma jet investigated here operates in argon with air admixtures up to 1%. The study shows that OES can be used to characterize the relative NO production at small air admixtures. The Production of NO radicals can be controlled by variation of air admixture. Important to note—especially for operation in ambient conditions—is that a small addition of water vapour strongly affects the production of NO radicals especially at higher air admixtures (greater than 0.2%).

The controlled metal transfer process (CMT) is a variation of the gas metal arc welding (GMAW) process which periodically varies wire feeding speed. Using a short-arc burning phase to melt the wire tip before the short circuit, heat input to the workpiece is reduced. Using a steel wire and a steel workpiece, iron vapour is produced in the arc, its maximum concentration lying centrally. The interaction of metal vapour and welding gas considerably impacts the arc profile and, consequently, the heat transfer to the weldpool. Optical emission spectroscopy has been applied to determine the radial profiles of the plasma temperature and iron vapour concentration, as well as their temporal behaviour in the arc period for different mixtures of Ar, O ₂ and CO ₂ as shielding gases. Both the absolute iron vapour density and the temporal expansion of the iron core differ considerably for the gases Ar + 8%O ₂, Ar + 18% CO ₂ and 100% CO ₂ respec...

Indentation tests on epitaxial GaN thin films, grown by metalorganic chemical vapour deposition on Si (1 1 1) substrate, were conducted at temperatures of 23, 100 and 180 °C. The first pop-in events were statistically analysed with Schuh's model and resulted in thermal activation energy of 850 ± 36 meV, activation volume of 10.8 ± 1.6 Å ³ and frequency factor of 4.23 × 10 ²¹ m ⁻³ s ⁻¹. In addition, the experimental results show that the critical force at the first pop-in event and the measured shear strength depend on the indenter tip radius.

A comparative analysis of the efficiency of approaches based on the exposure of reacting gas to resonance laser radiation to enhance combustion in a supersonic flow of H ₂–air mixture is conducted. The kinetic processes responsible for the intensification of chain reactions in premixed and non-premixed H ₂–air flows upon photodissociation of O ₂ molecules by 193.3 nm laser radiation, excitation of these molecules to the singlet sigma state by laser photons with 762.346 nm wavelength and heating the mixture by laser radiation are analysed in a detailed manner. It is shown that both photochemical methods, photodissociation and excitation of O ₂ molecules, are much more effective in shortening the ignition delay length than merely heating the mixture. For the premixed flow, the photodissociation of O ₂ molecules ensures a slightly higher reduction in the ignition delay than the laser-induced excitation of molecular oxygen to the sing...