Herein we demonstrate the specifics of using positron annihilation lifetime spectroscopy (PALS) method for study free volume changes in functional ceramic materials. Choosing technological modification nanostructured MgAl2O4 spinel as an example, show that ceramics with well-developed porosity is revealed through two channels: trapping channel and ortho-positronium decay. Positron free-volume defects described by second component spectra decay process single or multiple components, depending...

Methodological possibilities of positron annihilation lifetime (PAL) spectroscopy applied to characterize different types nanomaterials treated within three-term fitting procedure are critically reconsidered. In contrast conventional analysis based on admixed positron- and positronium-trapping modes, the process nanostructurization is considered as substitutional positron-positronium trapping same host matrix. Developed formalism allows estimate interfacial void volumes responsible for...

The radiation properties and the electronic structure of hybrid composites based on suspension polystyrene (PS) nanocrystals BaZrO3 (BZO) (d < 50 nm) have been studied using luminescent spectroscopy x-ray analysis. A strong cathodoluminescence (CL) in BZO-nanocrystals is observed temperature range 80–293 K. It modified BZO-PS composites: both low- a high-energy bands (near 4 eV) appear, together with significant reduction CL intensity. decrease lattice parameter for BZO phase...

The surface topology and fractal dimension of ultrathin silver gold films have been investigated utilizing atomic force microscopy. These were formed at the early stages metal deposition through thermal evaporation pre-percolation thicknesses. They contain both metallic insulating (void) phases, making them metal–dielectric composites. We identified main parameters microstructure, such as size particles roughness, well dependence these on film thickness substrate parameters. Approaches to...

'Cold' crystallization in 80GeSe2-20Ga2Se3 chalcogenide glass nanostructurized due to thermal annealing at 380°C for 10, 25, 50, 80, and 100 h are probed with X-ray diffraction, atomic force, scanning electron microscopy, as well positron annihilation spectroscopy performed lifetime Doppler broadening of line modes. It is shown that changes defect-related component the fit experimental spectra nanocrystallized glasses testify favor structural fragmentation larger free-volume entities into...

Free volume and pore size distribution in functional micro macro-micro-modified Cu0.4Co0.4Ni0.4Mn1.8O4 ceramics are characterized by positron annihilation lifetime spectroscopy comparison with Hg-porosimetry scanning electron microscopy technique. Positron results interpreted terms of model implication trapping ortho-positronium decaying. It is shown that free traps the same type for macro modified ceramics. Classic Tao-Eldrup spherical approximation used to calculation nanopores smaller...

Nanostructured silver films are studied using computational and experimental methods. Surface plasmon resonance-related phenomena emphasized. Resonant optical absorption band changes due to the influence of noxious gases investigated. Amplification light at film surface local electromagnetic field enhancement nanoscale is discussed based on finite difference time domain calculations.

Systematic evaluation of the influence radiation on electrical response hybrid nanocomposites obtained by adding multi-walled carbon nanotubes into poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonate) host matrix is presented. Variations resistance conductivity depending volume fraction in matrix, ionizing dosage, temperature are analyzed.

The water-vapor sorption processes in nanoporous MgO-Al2O3 ceramics are studied with positron annihilation lifetime (PAL) spectroscopy employing trapping and positronium (Ps)-decaying modes. It is demonstrated that the longest-lived components four-term reconstructed PAL spectra characteristic lifetimes near 2 60-70 ns can be, respectively, attributed to ortho-positronium (o-Ps) traps nanopores 0.3- 1.5-1.8-nm radii. first o-Ps decaying process includes "pick-off" "bubbles" of liquid water,...

Mathematical models of degradation-relaxation kinetics are considered for jammed thick-film systems composed screen-printed spinel Cu0.1Ni0.1Co1.6Mn1.2O4 and conductive Ag or Ag-Pd alloys. Structurally intrinsic nanoinhomogeneous ceramics due to diffusing agents embedded in a phase environment shown define governing thermally induced degradation under 170 °C obeying an obvious non-exponential behavior negative relative resistance drift. The characteristic stretched-to-compressed exponential...

Technologically modified spinel ceramics are prepared from Al2O3 and 4MgCO3×Mg(OH)2×5H2O powders at 1200, 1300 1400 oC. The influence of sintering temperature on porous structure exploitation properties obtained humidity-sensitive MgO-Al2O3 studied. It is shown that increasing preparing 1200 to oC result in transformation pore size distribution tri- bi-modal including the open macro- mesopores with sizes tem hundreds nm nanopores until a few nm. studied ceramic elements electrical...

Multilayered temperature-/humidity-sensitive thick-film p - i + structures based on spinel-type semiconducting ceramics of different chemical composition (Cu 0.1 Ni Co 1.6 Mn 1.2 O 4 with -type electrical conductivity and Cu 0.8 0.2 1.9 conductivity) magnesium aluminate MgAl 2 ceramics, as well temperature-sensitive p-p -p were prepared studied. It is shown that increasing the quantity layers (from two to three) results in improvement temperature sensitivity structures. Humidity-sensitive...

BaGa2O4 ceramics doped with Eu3+ ions (1, 3 and 4 mol.%) were obtained by solid-phase sintering. The phase composition microstructural features of investigated using X-ray diffraction scanning electron microscopy in comparison energy-dispersive methods. Here, it is shown that undoped Eu3+-doped are characterized a developed structure grains, grain boundaries pores. Additional phases mainly localized near creating additional defects. evolution defect-related extended free volumes due to the...

Abstract Extended defects in insulating nanoporous MgAl 2 O 4 spinel‐type ceramics which trap positrons are characterized by positron annihilation lifetime spectroscopy before and after water‐immersion treatment. It is shown that both cases the same type of traps prevails, but trapping near grain boundaries occurs more efficiently water‐moistened ceramics. perfect structure ceramics, considerable changes occur parameters (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Temperature sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition Cu 0.1 Ni Co 1.6 Mn 1.2 O 4 (with p + -types electrical conductivity), 0.8 0.2 1.9 p-types conductivity) and their multilayer -p structures were fabricated studied.These thick-film elements possess good electrophysical characteristics before after long-term ageing test at 170 • C. It is shown that degradation processes connected with diffusion metallic Ag into film grain...

Temperature sensitive thick films based on spinel-type NiMn2O4-CuMn2O4-MnCo2O4 manganites with p- and p+-types of electrical conductivity their multilayer p+-p structures were studied. These thick-film elements possess good electrophysical characteristics before after long-term ageing test at 170 °C. It is shown that degradation processes connected diffusion metallic Ag into film grain boundaries occur in one-layer p-and p+-conductive films. Some part the high stability, relative drift being...

Temperature-sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition Cu 0.1 Ni Co 1.6 Mn 1.2 O 4 (with p + -types electrical conductivity), 0.8 0.2 1.9 p-types and their multilayers -p p-p structures were fabricated studied. These thick-film elements possess good electrophysical characteristics before after long-term ageing test at 170 °C. It is shown that degradation processes connected with diffusion metallic Ag into grain boundaries occur in...

The new transition-metal manganite Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics for temperature sensors with improved functional reliability are first proposed. It is established that the amount of additional NiO phase in these extracted during sintering play a decisive role. This effect well revealed only having character fine-grain microstructure, while monolithization caused by great transferred thermal energy reveals an opposite influence. process monolitization from position evolution grain-pore...