A5055463009- Gas Sensing Nanomaterials and Sensors
- Analytical Chemistry and Sensors
- ZnO doping and properties
- Electronic and Structural Properties of Oxides
- Luminescence Properties of Advanced Materials
- Catalytic Processes in Materials Science
- Ammonia Synthesis and Nitrogen Reduction
- Advanced Chemical Sensor Technologies
- Graphene research and applications
- Advanced Photocatalysis Techniques
- Electrochemical sensors and biosensors
- Nanomaterials for catalytic reactions
- Carbon Nanotubes in Composites
- Metal and Thin Film Mechanics
- Advanced Semiconductor Detectors and Materials
- Plasma Diagnostics and Applications
- Ga2O3 and related materials
- Advanced Sensor Technologies Research
- Transition Metal Oxide Nanomaterials
- Laser-Ablation Synthesis of Nanoparticles
- Copper-based nanomaterials and applications
- Photorefractive and Nonlinear Optics
- Near-Field Optical Microscopy
- Electrohydrodynamics and Fluid Dynamics
- Surface and Thin Film Phenomena
University of Tartu
2009-2023
Competence Centre on Health Technologies (Estonia)
2006
Abstract The Raman spectroscopy method was used for structural characterization of TiO2 thin films prepared by atomic layer deposition (ALD) and pulsed laser (PLD) on fused silica single-crystal silicon sapphire substrates. Using ALD, anatase were grown substrates at temperatures 125–425 °C. At higher temperatures, mixed rutile phases grew these Post-growth annealing resulted in anatase-to-rutile phase transitions 750 °C the case pure films. that contained chlorine residues amorphous their...
Graphene in its pristine form has demonstrated a gas detection ability an inert carrier gas. For practical use ambient atmosphere, sensor properties should be enhanced with functionalisation by defects and dopants, or decoration nanophases of metals or/and metal oxides. Excellent behaviour was found for two types single layer graphenes: grown chemical vapour deposition (CVD) transferred onto oxidized silicon (Si/SiO₂/CVDG), the epitaxial graphene on SiC (SiC/EG). Both samples were...
Graphene has been recognized as a promising gas sensing material. The response of graphene-based sensors can be radically improved by introducing defects in graphene using, e. g., metal or oxide nanoparticles. We have functionalised CVD grown, single layer applying pulsed laser deposition (PLD) V2O5 which resulted thin on with average thickness ~0.6 nm. According to Raman analysis, PLD process also induced graphene. Compared unmodified graphene, the obtained chemiresistive sensor showed...
Miniature and low-power gas sensing elements are urgently needed for a portable electronic nose, especially outdoor pollution monitoring. Hereby we prepared chemiresistive sensors based on wide-area graphene (grown by chemical vapor deposition) placed Si/Si3N4 substrates with interdigitated electrodes built-in microheaters. Graphene of each sensor was individually functionalized ultrathin oxide coating (CuO-MnO2, In2O3 or Sc2O3) pulsed laser deposition. Over the course 72 h, heated were...
Graphene as a single-atomic-layer material is fully exposed to environment and has therefore great potential for creating of sensitive gas sensors. However, in order realize this different polluting gases, graphene be functionalized - adsorption centers type with high affinity target gases have created at its surface. In present work, modification by small amounts laser ablated materials introduced purpose versatile precise tool. The approach was demonstrated two very chosen pulsed...
In this study we investigated the interaction of atmospheric-pressure helium (He) and He/H2 pulsed-discharge plasma with different water solutions. We developed a synthetic path to obtain fairly uniform, small (~2 nm), surfactant-free silver (Ag) nanoparticles (NPs) treatment an AgNO3 solution bipolar pulsed discharge. The colloidal solutions containing Ag NPs are stable for months do not show any agglomeration (the measured zeta potential is −41 mV at pH ~8). adsorption negatively charged...
Host luminescence excitation spectra and reflection of crystals at low temperatures have been measured in the energy region 4-30 eV using synchrotron radiation. High-efficiency host is connected to radiative decay self-trapped cation excitons. It shown that also multiplication, e.g. if larger than twice band gap , relaxation process core excitons are formed. However, recombination hole electrons (band-band excitation) does not give rise luminescence.
Some nanocrystalline TiO2 materials are notorious for their photoluminescence (PL), which exhibits a pronounced sensitivity to ambient oxygen and has potential optical gas sensing. Here, we utilized pulsed laser deposition obtain thin (70 nm) anatase films containing 1–2 atom % of either samarium (Sm) or neodymium (Nd) impurity ions. The highly porous nanostructure consisted quite regular, interconnected nanopillars with wall thickness 15–20 nm, fully exposing the material environment. PL...
The firing voltage (FV) of gas discharge in a test cell plasma display materials was investigated for standard protective layers MgO deposited by electron beam, and ternary BaY2O4 BaGa2O4 oxides grown pulsed laser deposition on the special dielectric coated glass substrates. determined FVs (160 V), (210 V) (257 lead to conclusion that replacement these is not expedient panels. Using results from luminescence spectroscopy, values energy gap Eg ≈ 6.2 5.8 eV were estimated BaGa2O4,...
Abstract A new p-type thin film material for gas sensing was prepared and investigated CO response. The films of CoW O 4 were fabricated by pulsed laser deposition (PLD) characterised XRD, XRR, XPS SEM. substrate temperature oxygen pressure in PLD chamber varied order to examine the relations between parameters, structure sensitivity. Conductometric response measured at 150–350 ∘ C found be highest relatively low temperatures, 200–250 depending on relative humidity or annealing time...
Rare earth oxycarbonates are potential candidate materials for constructing simple and low-cost chemiresistive sensors monitoring carbon dioxide (CO 2 ) gas in the living working environment personal comfort health reasons. Also, measurement of CO concentrations is needed many industrial processes. Specifically, sol-gel made nanoparticles Nd La have been studied previously as novel sensor materials. In this paper, pulsed laser deposition oxycarbonate (La O 3 thin films was structural...
Gas sensing properties of Co-oxide thin films were investigated and modelled. The cubic Co3O4 structure with thickness between 20-150 nm fabricated by pulsed laser deposition. response dc-conductivity to different gases (CO, NO2, CH4) was tested at temperatures 240 - 400 °C, oxygen pressures. conductivity changes due O2 test gas found be almost independent. commonly used ionosorption model, which assumes reactions adsorbed ions, failed describe the dataset obtained CO Alternative mechanisms...
Chemiresistive gas sensors were produced by functionalizing graphene with a ~3 nm layer of mixed oxide xCu2O⸱yMnO using pulsed laser deposition (PLD) from hopcalite CuMn2O4 target. Sensor response time traces recorded for strongly oxidizing (NO2, O3) and reducing (NH3, H2S) poisonous gases at ppb ppm levels, respectively. The morphology the MOX was modified growth temperature during PLD, resulting in optimization sensor response. Differences decomposition or oxidation rates on catalytically...
Abstract A comparison of excitation spectra photostimulated and ordinary luminescence enabled us for the first time to determine experimentally framework energy gap value E g = 6.5 eV 12CaO · 7 Al 2 O 3 (C12A7). The most short‐wavelength band (peaked at ∼4.5 eV) detected 10 K can be interpreted either as intrinsic excitations or recombination electrons, captured in sub‐nanometer sized cages C12A7 crystal structure, with holes valence band. main peak thermostimulated (134–137 K) is composed...
The resistance of an \ensuremath{\alpha}-tungsten film was measured in the temperature range 0.35--30 K and magnetic field up to 2.5 T. obtained dependences magnetoresistance are interpreted terms Maki-Thompson-Larkin superconducting fluctuation effect; however, magnitude exceeds theoretical value by order magnitude. From data dephasing scattering length determined contributions impurities, electron-electron, electron-phonon scatterings were extracted. experimental electron-electron lengths...