Localization and transfer of charge carriers in CuO nanopowder by impedance spectroscopy

Abstract

Particular electro-physical characteristics of CuO nanopowder were investigated by impedance spectroscopy using a sensor based on interdigitated structure in the frequency range from 1 Hz to 100 MHz. The results of investigation were considered. Simulation of impedance spectra by equivalent electric circuits was carried out for numerical approximations of the frequency dependences of the dielectrical permittivity and conductivity. Electric charge accumulation of on the boundaries of nanoparticles and near the metal electrodes of the sensor was revealed. It was shown that a double electric layer is formed near the electrodes, which leads to the appearance of anomalously large values of dielectrical permittivity and an increase in the conductivity in the low-frequency region. The obtained results can be explained by proton conductivity in the nanopowder caused by moisture which is adsorbed on the surface of the nanoparticles. It was shown that after high-temperature annealing of CuO nanopowders, accumulation of electric charges was not observed. It was established that hopping or polaron conductivity occurs in the annealed CuO samples, which increases with increasing electric field frequency according to the power law with a fractional exponent.

Исследование магнитоимпедансных свойств наночастиц CuO, полученных в плазме дугового разряда низкого давления

“…Видно, что диэлектрическая проницаемость (ε ′ ) остается почти постоянной до 60 K, а затем быстро увеличивается в диапазоне температур 100−300 K. Увеличение диэлектрической проницаемости (ε ′ ) составляет до трех порядков. Наблюдение очень высокой диэлектрической проницаемости (ε ′ ) порядка 10 4 при 500 Hz для наночастиц CuO в данном случае соответствует результату, полученному нами ранее [22]. Как упоминалось выше, АФМ состояние наночастиц CuO наблюдается при 230 K. Это обеспечивает " пиннинг" подрешеточных носителей заряда, что приводит к снижению диэлектрической проницаемости.…”

Synthesis and chemoresistive sensitivity to hydrogen of nanostructured CuO films

“…The background of this study was investigation of the copper oxide nanopowders by impedance spectroscopy performed by the authors earlier [6]. As it turned out later, significant variation in electrical resistance of powders annealed in air at 300 • C relative to the resistance of as−fabricated ones cannot be explained only by excluding the proton conductivity.…”

Синтез и хеморезистивная чувствительность к водороду наноструктурированных пленок CuO

“…Предпосылками настоящей работы послужили исследования нанопорошков оксида меди методом импедансной спектроскопии, проведенные ранее авторами [6].…”