Influence of sputtering atmosphere on hopping conductance in granular nanocomposite (FeCoZr)x(Al2O3)1−x films

Abstract

The present paper investigates conductivity r for a wide temperature range of 2 K < T < 300 K in the nanocomposite (FeCoZr) x (Al 2 O 3 ) 1Àx films (1-6 lm thicknesses, 0.30 < x < 1.00) which were sputtered on glass-ceramic substrates from the compound target in vacuum chamber filled with Ar (set 1 films) or Ar + O 2 gas mixture (set 2 films). TEM and HRTEM images revealed that granular films of set 1 containing nanosized crystalline metallic bcc a-FeCo-based nanoparticles embedded in the amorphous Al 2 O 3 matrix. In case of Ar + O atmosphere of deposited a-FeCo-based crystalline ''cores'' with stabilized sizes were covered with an amorphous FeCo-based oxide ''shells''. The r(T) dependences were found to be in agreement with this phase structure. They show transition of the set 1 films r(T) curves with x from tunneling (hopping) behavior below the percolation threshold x < x C % 0.46 to metallic one for x > x C . Moreover, as opposed to such behavior, for the set 2 films hopping mechanism of r(T) was revealed far beyond x C due to the formation of semiconducting FeCo-based oxide ''shells'' separating electrically contacting FeCoZr cores.

Structural and mechanical properties of NbN and Nb-Si-N films: Experiment and molecular dynamics simulations

“…Nanostructured films [4][5][6] are widely used as wear-protection coating on cutting tools due to high hardness, good corrosion stability and low friction coefficient [7]. Among these films, nanostructured NbN-based films are of increasing interest.…”

Arc-Evaporated Nanoscale Multilayer Nitride-Based Coatings for Protection Against Wear, Corrosion, and Oxidation

“…While nitrides of single elements are studied well enough, their multilayer modifications need study that is more detailed [26][27][28][29][30][31][32][33][34][35]. Therefore, the study of features of structure, elemental and phase composition of multilayer coatings depending on the deposition conditions is an important task in solid-state physics and materials science [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51].…”

Dielectric Response and Transport Properties of Pb2Sr2CaCu2O9 [Lead Strontium Calcium Copper Oxide]

“…18 The total ceramic impedance in perosvkites gets mainly a®ected by grain impedance and grain boundary impedance. Hence, impedance data can be presented as a basic equivalent circuit consisting of two parallel resistors-capacitor (RC) elements connected in series.…”

“…17 The investigations performed into electrical properties of ceramic composites at alternating currents have con¯rmed that current conduction within a certain frequency range is realized by hopping exchange of electrons. [18][19][20] The objective of the present work is to study the dielectric and electrical impedance properties of the sample Pb 2 Sr 2 CaCu 2 O 9 in the range of frequencies (42 Hz-1 MHz) at di®erent temperatures with a view to understand the conductivity mechanisms involved in this new material.…”