Electrical conductivity and dielectric relaxation in Ag1-xLixNbO3

The broadband electrical properties of Ag1xLixNbO3 (ALNx) ceramics (x 0.1) together with AgNbO3 (AN) crystals were studied over a wide temperature interval of 20–800 K. For ALNx with x 0.05, a very diffused ferroelectric phase transition was observed. The position of the dielectric permittivity maximum in this phase transition is strongly frequency-dependent and is described well by the Vogel–Fulcher law. The freezing temperature decreases when the lithium concentration increases. Below the ferroelectric phase transition temperature, the dielectric dispersion is mainly caused by ferroelectric domain dynamics. Moreover, for ALN3 and ALN5 ceramics at very low temperatures (below 100 K), behavior typical of dipolar glasses is observed. At higher temperatures (above 650 K for ALN5), electrical conductivity effects become important. The DC conductivity increases with temperature according to the Arhenius law and the activation energy is highest in the antiferroelectric phase. Moreover, the activation energy is strongly dependent on the lithium concentration and it is greatest when x = 0.02

Crossover from Ferroelectric to Relaxor Behavior in Ba1−xCaxTiO3 (x = 0.17) System

The dielectric properties of Ba1xCaxTiO3 (x = 0.17) ceramics were studied in a wide frequency range of 20 Hz–53 GHz. Di used ferroelectric phase transition was revealed close to 339 K in the dielectric properties of ceramics. The behaviour of distributions of relaxation times in vicinity of the ferroelectric phase transition temperature is also typical for order-disorder ferroelectric phase transition. However, at lower temperatures (below 200 K), the most probable relaxation increased according to the Arrhenius law. At lower temperatures the maximum of the imaginary part of dielectric permittivity versus temperature strongly shifted to higher temperatures when the frequency increased (from 125 K at 1.21 kHz to 300 K at 33 GHz). This behaviour was attributed to the dynamics of Ti ions. The origin of the crossover from ferroelectric to relaxor behaviour of Ba1xCaxTiO3 (x = 0.17) ceramics is discussed in the paper

Transport mechanisms and dielectric relaxation of epoxy nanocomposites in DC to microwave range

Using several methods we measure the effective complex permittivity of epoxy composites realized by shear mixing and filled with carbonaceous carbon black (CB), single wall CNT (SWCNT), and multiwalled carbon nanotube (MWCNT) over nine decades of frequency. The spectral analysis of permittivity of these nanocomposites is in good agreement with Jonscher's modelling. We point out, taking these examples, that the experimental frequency dependence of the effective permittivity has a range of interesting properties. Likely transport mechanisms responsible for the dielectric relaxation in these samples can be modeled by the dipolar relaxation and anomalous low frequency dispersion (LFD) below and above percolation, respectively

DAMPAK BERMAIN GAME ONLINE DALAM MEMPERLUAS RELASI SOSIAL PADA PEMAIN GAME ONLINE DOTA 2

This research was conducted in order to find out the impact in social relations in DOTA online game players. The method used in this research is qualitative research methods using a phenomenological approach, namely research taken based on phenomena that exist in society. The researcher used interviews and observation as a method of retrieving data. The subjects of this study were 3 students of Soegijapranata Catholic University Semarang, playing online game Dota 2 and able to communicate well. The data analysis method that the researcher uses is inductive, which is an analysis of data based on the data that has been obtained, and then developed into general conclusions. The research results obtained, namely playing online games can have a positive impact on social relations such as expanding the social relations of the players. In addition, researchers also found that there was a negative impact from playing online games on social relations in the parent subject, namely the time to communicate was reduced. Keywords: online games, social relations, the impact of playing online games

Carbon-Coated Nickel Nanoparticles: Effect on the Magnetic and Electric Properties of Composite Materials

Nickel nanoparticles coated with few layers of carbon have been embedded into the polydimethylsiloxane (PDMS) matrix in concentrations up to 11 vol %. Dielectric and magnetic properties of composite materials have been studied in wide frequency (20 Hz–1 MHz) and temperature (130–430 K) ranges. It was demonstrated that the temperature behavior of dielectric properties is determined by glass transitions in the PDSM matrix below 200 K and the Maxwell–Wagner relaxation above room temperature. The possibility of using fabricated composites on the basis of the PDMS matrix for producing a wide range of passive electromagnetic components, such as frequency-selective filters, wide-band detectors/sensors of a bolometric type, and even electromagnetic “black holes” is also discussed

Electrical Conductivity and Dielectric Relaxation in Ag1−xLixNbO3

The broadband electrical properties of Ag1−xLixNbO3 (ALNx) ceramics (x ≤ 0.1) together with AgNbO3 (AN) crystals were studied over a wide temperature interval of 20–800 K. For ALNx with x ≤ 0.05, a very diffused ferroelectric phase transition was observed. The position of the dielectric permittivity maximum in this phase transition is strongly frequency-dependent and is described well by the Vogel–Fulcher law. The freezing temperature decreases when the lithium concentration increases. Below the ferroelectric phase transition temperature, the dielectric dispersion is mainly caused by ferroelectric domain dynamics. Moreover, for ALN3 and ALN5 ceramics at very low temperatures (below 100 K), behavior typical of dipolar glasses is observed. At higher temperatures (above 650 K for ALN5), electrical conductivity effects become important. The DC conductivity increases with temperature according to the Arhenius law and the activation energy is highest in the antiferroelectric phase. Moreover, the activation energy is strongly dependent on the lithium concentration and it is greatest when x = 0.02

Hot-melt adhesives based on co-polyamide and multiwalled carbon nanotubes

Composites of two hot melt adhesives based on co-polyamides, one high viscosity (coPA_A), the other low viscosity (coPA_B), and multiwalled carbon nanotubes (MWCNTs) were prepared using twin-screw extrusion via dilution of masterbatches. Examination of these composites across the length scales confirmed that the MWCNTs were uniformly dispersed and distributed in the polymer matrices, although some micron size agglomerations were also observed. A rheological percolation was determined from oscillatory rheology measurements at a mass fraction of MWCNTs below 0.01 for coPA_B and, between 0.01 and 0.02 for coPA_A. Significant increases in complex viscosity and storage modulus confirmed the “pseudo-solid” like behavior of the composite materials. Electrical percolation, determined from dielectric spectroscopy was, found to be at 0.03 and 0.01 MWCNT mass fraction for coPA_A and coPA_B based composites, respectively. Addition of MWCNTs resulted in heterogeneous nucleation and altered the crystallization kinetics of both copolymers. Indirect evidence from contact angle measurements and surface energy calculations confirmed that MWCNT addition enhanced the adhesive properties of coPA_B to a level similar to coPA_A

Weak Localization in Polycrystalline Tin Dioxide Films

The electrical and magnetotransport properties of nanocrystalline tin dioxide films were studied in the temperature range of 4–300 K and in magnetic fields up to 8 T. SnO2−δ films were fabricated by reactive direct current (DC) magnetron sputtering of a tin target with following 2 stage temperature annealing of synthesized samples. The nanocrystalline rutile structure of films was confirmed by X-ray diffraction analysis. The temperature dependences of the resistance R(T) and the negative magnetoresistance (MR) were explained within the frame of a model, taking into account quantum corrections to the classical Drude conductivity. Extracted from the R(T) and R(B) dependences electron dephasing length values indicate the 3D character of the weak localization (WL) in our samples