The main goal of this work is to provide a general description the negative photoconductivity effect observed in Ag/AgO films grown by spray-pyrolysis technique. X-ray diffractograms display hybrid with high texturized AgO and metallic Ag phases. Scanning electron microscopy images show small particles on surface. Due its surface nature, photoelectron spectroscopy revealed predominance character 3d spectra as compared Ag2+. Negative photoresponse order seconds under several wavelengths...

The problems related to organic deposition on pipeline walls are well-known and have been challenging the petroleum industry since primordial days. Some can result in a decrease of production rate or rise pumping power. Motivated by these problems, present work tried understand influence magnetic fields paraffin crystallization reduction crude oil viscosity. A mixture (C15−C58) was diluted n-hexane, solvent evaporated slowly, under 0.3 T field, also naturally, without fields. micrographs...

Recently, some works showed that magnetic fields may reduce the paraffin crystallization and viscosity of types oil. This Article shows main results obtained in an attempt to determine factors responsible for oil interaction with fields, which caused rheological properties change crude samples. Under influence a field (1.3 T 1 min exposure), one six brazilian samples studied (sample 1) 39% reduction on its viscoelastic (loss modulus storage modulus). However, other five did not show any...

We investigated the negative photoconductivity (NPC) effect that was observed in a p-type Pb1-xSnxTe film for temperatures varying from 300 K down to 85 K. found this is consequence of defect states located bandgap which act as trapping levels, changing relation between generation and recombination rates. Theoretical calculations predict contributions NPC both conduction valence bands, are accordance with experimental observations.

Despite the widespread emergence of memory effects in solid systems, understanding basic microscopic mechanisms that trigger them is still puzzling. We report how ingredients state transport polycrystalline such as semiconductor oxides, become sufficient conditions for a memristive response points to natural memory, discernible under an adequate set driving inputs. The experimental confirmation these trends will be presented along with compact analytical theoretical picture allows discerning...

The utilization of nanostructured materials for development biosensors is a growing field in medical diagnostics. In this work glucose biosensor based on bioactive polyglycerol (PGLD) and chitosan dendrimers (CHD) was developed. PGLD CHD were bioconjugated with the enzyme oxidase (GOx) to obtain sensing properties. Polyaniline nanotubes (PANINT´s) used as electron mediator due their high ability promote electron-transfer reactions involving GOx. PGLD-GOx CHD-GOx entrapped PANINT´s during...

We investigated the persistent photoconductivity effect observed in p-PbTe:BaF2 and undoped p-PbTe films temperature range of T = 100–300 K. It was that PPC scales with there is a transition relaxation time behavior around ∼150 found caused by particular dynamics hole carries between energy barriers characterize traps originated from disorder present samples. The analysis performed comparing theory random potential experimental data revealed presence both local fluctuations localized states,...

We investigated the photoconductivity effect in $p$-type $\mathrm{P}{\mathrm{b}}_{1\ensuremath{-}x}\mathrm{E}{\mathrm{u}}_{x}\mathrm{Te}$ films for $x=0.01$, 0.02, 0.03, 0.05, and 0.06 at $T=300\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The measurements revealed a clear transition from negative to positive as Eu content $x$ is increased room temperature. This related metal-insulator that occurs due disorder originated introduction of atoms it an Anderson transition. Our investigation found...

We present here the magnetotransport experiment performed with a magnetic field up to 30 T on 10 nm-wide $p$-type PbTe quantum well. Pronounced Shubnikov--de Haas oscillations and integer Hall effect are clearly observed, demonstrating transport of confined two-dimensional hole gas negligible parallel conduction at low temperatures. The sequence filling factors can be explained by considering evolution Landau levels derived from two longitudinal one oblique occupied subbands taking Zeeman...

We investigated the photoconductivity effect in n-type PbTe/Pb0.88Eu0.12Te quantum wells for a temperature range of 300–10 K using infrared light. The measurements revealed that at high temperatures, photoresponse has small amplitude. As decreases to T ∼ 75 K, however, amplitude increases reaching maximum value 10 times higher than original before illumination. From Hall performed under dark and light conditions, we show this is result carrier concentration increase Unexpectedly, further...

In this work, we present the results of photoconductivity measurements performed in temperature range 12 K–300 K on a 150 nm-thick Bi2Te3 film grown by molecular beam epitaxy (111) BaF2 substrate. A transition from negative to positive is found occur around 125 K. Resistivity and Hall data measured under light dark conditions qualitatively elucidate observed phenomena. The Arrhenius plot recombination times obtained decay curves at different temperatures gives activation energy associated...

This work presents the results of magnetotransport measurements performed on a 156 nm-thick Bi2Te3 epitaxial film in temperature range 1.9–300 K, showing Shubnikov–de Haas oscillations for temperatures below 50 K. A detailed analysis as function provides main transport parameters, including Landé g-factor and cyclotronic masses. systematic fast Fourier transform, oscillations, indicates that origin oscillation pattern is not related to topological surface states but from Rashba splitting...

Abstract Chitin hydrogels of poly(vinylpyrrolidone) (VP) were prepared by means the hydrogen peroxide graft copolymerization process. The effect VP grafted chain on water diffusion through biopolymer was studied. Fourier transform infrared spectra VP‐g‐Ch showed an increase in intensities hydroxyl and carbonyl stretching bands indicating a reduction bonding chitin. An investigation undertaken regarding adsorption nickel(II) cadmium(II) ions from aqueous solutions chitin effects grafting...

We report on a large linear magnetoresistance effect observed in doped p-PbTe films. While undoped reveals sublinear magnetoresistance, films with BaF2 exhibit transition to nearly perfect behaviour that is persistent up 30 T. The slope ΔR/ΔB good approximation, independent of temperature. This agreement the theory Quantum Linear Magnetoresistance. also performed simulations using classical model magnetoresistance. found this fails explain experimental data. A systematic study doping...

Atualmente há uma crescente demanda no cenário mundial com relação ao tratamento de resíduos industriais, dentre estes o fenol e pilhas inutilizadas. Óxidos cerâmicas a base ferro, tais como ferritas são utilizadas catalisadores processo Fenton heterogêneo. Os processos foto-Fenton apresentam alta eficiência tóxicos utilizando ferro. Neste contexto foram desenvolvidas partir O uso destas é bastante interessante, vez que, materiais ferromagnéticos podendo ser recuperados final do campo...

Photo-Hall free electron concentrations were measured on molecular beam epitaxy grown silicon planar-doped GaAs samples, with nominal concentration ranging from 1.4×1012 to 8.8×1013 cm−2, as function of temperature. We found conclusive results showing competition between positive photoconductivity and negative persistent effects. At temperatures below a critical Tc, the effect is dominant, while above Tc dominates. also some evidence that related spatial charge separation DX center.

The electrical conductivity of poly(vinylalcohol)/polyaniline-iodine blend (PVA/PAN-I2) prepared by solution process was investigated. FTIR spectroscopy revealed a structural change both shape and intensity the polyaniline (PAN) bands after doping with iodine, indicating formation charge transfer complex. J-V curves for pure PAN; PAN-I2 PVA/PAN-I2 film obey ohm law at lower voltages, deviate from linear response higher voltages finally display breakdown behavior. exhibit photoconductivity...