Search Results

21 - 30 of 261 items :

  • "Measurement" x
  • Nanomaterials x
Clear All
Effect Y substitution on the microstructure, transport and magnetic proprieties of Bi2Sr2Ca1Cu2O8+δ superconducting ceramics

force balances the Lorentz force. Moving of vortices causes thermal dissipation which may destroy superconductivity. Near Tc, the resistive transition corresponds to the “flux flow” dissipative regime [ 6 , 7 ] where the Lorentz force dominates [ 1 ]. Thermal dissipation is possible also when the pinning force dominates and is caused by “flux creep” [ 8 ] which is more evident in magnetic measurements [ 4 , 5 ]. On the other hand, doping by cation has been intensively studied in order to understand the mechanism of high Tc superconductivity and to improve the

Open access
Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

to determine the lattice parameters of the samples, with CuKα radiation in the range of 3° ≤2θ≤70° at a scan speed of 2°/min. Phase structure and lattice parameters were obtained by using Bruker-EVA version analyzing program with ICDD PDF2-2002 library. The mean values of lattice parameters of the Bi 1.8 Sr 2 Ca 2 Cu 3.2-x Zn x O 10+δ samples were determined from the high angle (0 0 1) peaks of the XRD measurements. Leo EVO-40 VPX scanning electron microscope was used to determine the surface morphology of the samples. Hereafter, the produced samples were

Open access
FMR study of samples obtained by nitriding and nitrides reduction of nanocrystalline iron

because of its relevance, for instance, in catalysis processes. The nitriding process as well as nitrides reduction process were investigated in our group by making use of a differential tubular reactor equipped with thermogravimetric measurements. Details of the processes have been presented in the literature [ 11 – 13 ]. During nitriding process a chain of reactions occurs: nitriding reaction, penetration of the chemisorbed atomic nitrogen to the bulk of the lattice of iron (α-Fe(N)), phase transition to iron nitride γ ′ -Fe 4−x N and next, to ε-Fe x N when a

Open access
Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate

Renishaw inVia micro-Raman system. As an excitation source, a 488 nm wavelength from ion argon laser was used. The spectral range was chosen from approximately 1000 cm -1 to 1800 cm -1 . Two types of polarized RS were collected in the scattering geometry VV and VH. Motorized stages were used to perform Raman surface mapping measurements. The laser beam was focused on the sample by a Leica microscope objective (magnification × 100) with numerical aperture (NA) equal to 0.85. Those parameters correspond to laser spot diameter about 1 μm. To prevent any damages caused by

Open access
Microstructural, optical and electrical properties of Cl-doped CdTe single crystals

Nikon infrared camera. To characterize the optical properties of the samples, spectroscopic ellipsometry (SE, J.A. Woollam Co., photon energy: from 1.1 eV to 6.5 eV) measurements at room temperature (RT) were performed. Finally, electrical measurements were performed by using a Keithley 4200 semiconductor characterization system. 3 Results and discussion Fig. 2 shows XRD measurement results for the samples from four ingots with different Cl doping concentrations (undoped, 4.97 × 10 19 cm −3 , 9.94 × 10 19 cm −3 and 1.99 × 10 20 cm −3 ) chosen from top

Open access
Influence of ion irradiation on temperature dependent electrical transport behavior of thin graphite flakes

flakes. After several times of repeated peeling-off, thin graphite flakes were identified by using an optical microscope and were transferred on the substrate. Silver paste was used to deposit electrical contacts which were then annealed at 200 °C to lower the contact resistance. Gallium (Ga + ) ions were irradiated on the thin graphite flake for 30 s. This was performed inside the chamber with focused ion beam (FIB). Low-and room-temperature electrical transport measurements were performed using cryo-cooler (helium compressor unit) in which the temperature could be

Open access
Influence of plasma treatment on wettability and scratch resistance of Ag-coated polymer substrates

. Thin films were deposited with a rate of ca. 3.3 Å/s and their thickness was equal to 50 nm. During evaporation of silver thin films the power was equal to ca. 60 W. The voltage of the ion gun was 6 kV, while the current was 10 mA. Immediately after plasma treatment the surface properties of polymers and thin films deposited on modified samples were analyzed by contact angle measurement. Surface wettability was assessed by a Theta Lite tensiometer (Attension). Liquid used for the contact angle determination was deionized water with a conductivity of 0.05 μS

Open access
Optical properties of porous Si/PECVD SiNX:H reflector on single crystalline Si for solar cells

. Fig 1 Thickness vs. etching time of PS grown at a constant current density of 100 mA ·cm −2 on a polished p + substrate. The optimum thickness for the PS (BR) was obtained by varying the anodization time in the range of 1.3 to 10 s; the weighted average value for the measured total reflectivity was calculated in the range of 800 to 1200 nm ( Table 1 ), The values of the thickness for each layer were determined from the spectroscopic ellipsometry (SE) measurements and SEM images. The results show that the maximum reflectivity is equal to 55 % for the

Open access
High accuracy computational methods for behavioral modeling of thick-film resistors at cryogenic temperatures

(T) characteristics, from very low up to room temperature (–190 °C ≤ T ≤ 25 °C or even higher) are very important for the analysis of possible conduction mechanisms in such composites [5 - 13] . However, such models are not recommended for designers and users of electronic circuits because of their complexity [14] . The mathematical models, worked out on the basis of measurements, are a good solution to this situation. Therefore, the aim of this paper was to elaborate two-dimensional mathematical (behavioral) modeling method for thick-film resistors working in low

Open access
Optical and electrical characterization of BixSe1−x thin films

hot-probe experiment was used to distinguish between n-type and p-type semiconductors using a hot probe and a standard multimeter. Positive voltage read out was obtained for n-type semiconductor whereas for a p-type semiconductor, negative voltage was measured. Thin film samples were deposited on glass substrates in a co-plannar configuration, with Au electrode separated by ~0.15 cm gap for DC conductivity measurements. The measurements were carried out under controlled equilibrium conditions in the temperature range of 209 K to 313 K (glass transition temperature T

Open access