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Open access

Lovdeep Singh, Jagjeet Malhotra, Charanjeet Singh, S. Bindra Narang and Madhu Chandra

Abstract

Microwave characteristics of M-type hexagonal ferrite, Ba0.5Sr0.5CoxZrxFe(12-2x)O19 (x = 0.0 to 1.0 in steps of 0.2), have been investigated as a function of frequency and substitution at X-band. The microwave absorption has been investigated using absorber testing device method. The static I-V characteristics have been studied as a function of substitution. The results show maximum microwave absorption at higher substitution. The static current exhibits ohmic behavior from 0 to 3 V and exponential trend from 3 to 4.8 V. The microstructure influences both microwave and electrical properties. The ferrite compositions for different electromagnetic applications are also suggested by measuring the microwave absorbed, transmitted and reflected power.

Open access

P. Kula, W. Szymański, Ł. Kołodziejczyk, R. Atraszkiewicz, K. Dybowski, J. Grabarczyk, R. Pietrasik, P. Niedzielski, Ł. Kaczmarek and M. Cłapa

In this work, the growth mechanisms of chemical vapor deposited and metallurgical graphene and their selected mechanical and electrical properties were investigated. The study revealed the influence of the growth mechanisms on monoand poly-crystalline nanostructures of synthesized graphene monolayers. The structure of flake boundaries greatly affects both the mechanical and electrical properties. The key factors are overlapping of the graphene flakes, their degree of mismatch and the presence of π type bonds. All of these issues should be taken into account when developing industrially scaled technologies for graphene manufacturing.

Open access

A. Zafar, Z. Imran, M. Rafiq, S. Shah and M. Hasan

Abstract

We investigated electrical properties of nanostructured La1−x SrxFeO3 (0 ≤ x ≤ 1) from 300 K–400 K. The nanostructured La1−x SrxFeO3 (0 ≤ x ≤ 1) was synthesized by citrate gel method requiring no pH control. X-ray diffraction pattern showed that single phase LaFeO3 with an orthorhombic structure was formed. The structure changed into rhombohedral for x = 0.5 and it became cubic for x = 1.0. For x ≤ 0.5, our material showed non-linear current-voltage characteristics and for x > 0.5 it showed linear current-voltage characteristics. Poole Frenkel type conduction mechanism was found to be operative in LaFeO3 from 300 K–400 K. The experimental values of field-lowering coefficient were by 2.56–6.41 times higher than the predicted value and were attributed to the presence of localized fields. The increase in conductance with Sr content was due to formation of Fe4+ ions in addition to Fe3+ with the increase in Sr content. Impedance spectroscopy and ac conductivity analysis of La1−x SrxFeO3 (0 ≤ x ≤ 1) was also carried out in the temperature range from 300 K–400 K and frequency was varied from 20 Hz - 2 MHz. The ac conduction followed the correlated barrier hopping model in La0.9Sr0.1FeO3.

Open access

G. Boczkal, P. Marecki and M. Perek-Nowak

The Influence of Soldering Conditions on Conductivity, Structure and Strength of Cu/Sn96Ag4 Solders

In the paper the electrical properties of the Cu/Sn96Ag4 solders were studied. The studied solders were produced at 200, 220 and 250°C and within time range 3 to 90 s. Soldering temperatures were chosen to assure the best soldering conditions for the Cu/Sn96Ag4 alloy. The most appropriate temperature of 200°C is the one just above the melting point. The temperature of 250°C is the maximal one recommended by producers, which can be applied for the electronic elements during soldering. The studies have shown that the best electrical properties and tensile strength Rm have samples soldered at times 3 and 30 s, while the highest specific resistance together with the lowest Rm value are observed for samples soldered at the time of 10 s. The soldering temperature have small influence on the strength of the connection/bond however it shows significant affect on the electrical properties.

Open access

D. Wójcik-Grzybek, K. Frydman and P. Borkowski

Abstract

The correlation between the microstructure of Ag-C, Ag-WC-C and AgWC composites and their switching properties was investigated. Two methods were used to manufacture the starting powder mixtures, namely classical milling and mechanical alloying . The arc erosion, contact resistance and welding forces of the contact materials obtained by different methods were measured using model devices. This paper presents the results achieved for the tested materials. It was found that weight loss was lower for the contacts produced by high energy milling

Open access

Ömer Güllü and Abdulmecit Türüt

Abstract

In this work, we prepared an ideal Cu/DNA/n-InP biopolymer-inorganic Schottky sandwich device formed by coating a n- lP semiconductor wafer with a biopolymer DNA. The Cu/DNA/n-InP contact showed a good rectifying behavior. The ideality factor value of 1.08 and the barrier height (Φb) value of 0.70 eV for the Cu/DNA/n-InP device were determined from the forward ias I-V characteristics. It was seen that the Φb value of 0.70 eV obtained for the Cu/DNA/n-InP contact was significantly larger tan the value of 0.48 eV of conventional Cu/n-InP Schottky diodes. Modification of the interfacial potential barrier of Cu/n-InP iode was achieved using a thin interlayer of DNA biopolymer. This was attributed to the fact that DNA biopolymer interlayer increased the effective barrier height by influencing the space charge region of InP.

Open access

M.M. Ibrahim, S.A. Fayek, G.A.M. Amin and D.M. Elnagar

Abstract

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott’s condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the γ-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices.

Open access

W. Głuchowski, Z. Rdzawski, J. Sobota and J. Domagała-Dubiel

Abstract

The aim of this work was to study the microstructure and functional properties of CuNi2Si1 alloy. The material was prepared classically by melting, casting, hot rolling and cold rolling. The obtained strips were processed with combined operations of supersaturation, ageing and one of the intensive deformation method - repetitive corrugation and straightening. The efficiency of RCS operation in shaping of functional properties in precipitation hardened copper alloys depends not only on tool geometry and operating parameters but also on whether and at what stage of strip production the supersaturation operation was applied. Application of the supersaturation before RCS operation broadens the potential to shape the set of functional properties. Comparable functional properties of the precipitation hardened copper alloy strips can be reached without application of the supersaturation operation in their manufacturing processes. The process of RCS applied after annealing, and the potentially slightly lower mechanical properties would be compensated by higher electrical conductivity.

Open access

W. Głuchowski, Z. Rdzawski, J. Domagała-Dubiel and J. Sobota

Abstract

In the study microstructure and properties of composite multifibre copper-base wires are presented. A decision was made to produce wires with “soft” fibres (Al) and “hard” fibres (Fe). In the study the phenomenon occurring on the border of Al-Cu was also analysed. The produced Cu-Al and Cu-Fe composites presented ordered microstructure with the fibres uniformly distributed in the copper matrix. The composites underwent plastic consolidation to the degree which provided satisfactory mechanical and electrical properties. During the drawing the fibres deformed proportionally with copper matrix therefore their content in the cross section remained unchanged.

Open access

Sandeep Kumar, Anal K. Jha and K. Prasad

Abstract

Single phase silver aluminum titanate (Ag1/2Al1/2)TiO3, later called AAT, nanoceramic powder (particle size 2 to 7.5 nm) was synthesized by a low-cost, green and reproducible tartaric acid gel process. X-ray, FT-IR, energy dispersive X-ray and high resolution transmission electron microscopy analyses were performed to ascertain the formation of AAT nanoceramics. X-ray diffraction data analysis indicated the formation of monoclinic structure having the space group P2/m(10). UV-Vis study revealed the surface plasmon resonance at 296 nm. Dielectric study revealed that AAT nanoceramics could be a suitable candidate for capacitor applications and meets the specifications for “Z7R” of Class I dielectrics of Electronic Industries Association. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were performed using the impedance data. Electric modulus studies supported the hopping type of conduction in AAT. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in AAT. The ac conductivity data were used to evaluate the density of states at Fermi level and minimum hopping length of the compound.