Nanocomposites for Novel Sensing Systems

The work performed under the National Research Program of Latvia and presented here is about advanced, chemical stimuli responsive materials. Sensor materials are produced on the basis of metallophthalocyanines or zirconia nanocrystals with the purpose of detecting small size molecular compounds like NH3, O2 and O3. Polymer/nanostructured carbon composite is produced to detect large size molecular compounds like organic vapour. Basic gaseous compound sensing principles are discussed within this paper.

Optimization of thermal coefficient of electrical resistivity of Co-Ti-Si thin films due to laser-induced chemical reactions

The CO2 laser induced optimization of the thermal coefficient of electrical resistivity in Co-Ti-Si thin films is realized. The X-ray diffraction studies of the annealed Co- Ti-Si films confirm that the changes of electrical properties are related to forming a small structure of crystalline compounds Ti5Si3 and CoSi2 in an amorphous matrix.

Laser-Calorimetric Study of Fundamental Absorption Edge in Pb,La(ZrTi)O3 (PLZT) Perovskite Ceramics

The values of the light absorption coefficient of PLZT 10/65/35 ceramics at selected wavelengths have been obtained by laser calorimetric measurements. The absorption coefficient of the PLZT ceramics is an exponential function of the photon energy. Two values of characteristic Urbach energy have been found ΔE1 = 106 meV and ΔE2 = 238 meV. The first one is a characteristic of the potential of electron-phonon interaction of the optically excited transitions from the valence band to the conduction band and does not depend on lattice defects or admixtures. The other characterises the electron-phonon interaction at optical transitions between two localized electron states in the energy gap separ…

<title>Laser-pulse-induced chemical reactions and surface patterning in Co-Si and Co-Ti-Si films: investigations by x-ray diffraction and atomic force microscopy</title>

X-ray diffraction patterns reflected from the laser treated crystalline CoSi2 layer, the measurements of surface electrical resistance and atomic force microscopy micrographs confirm the 'generation-diffusion-deformational instabilities' model of formation of defect ordered structures of various types. The CO2 laser induced decrease of the thermal coefficient of resistance to zero in Co-Ti-Si films is realized. X-ray diffraction studies of the treated films confirm that the obtained (alpha) changes with number of laser pulses are caused due to solid phase reaction Co + 2Si equals CoSi2 and 5Ti + 3Si equals Ti5Si3.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Do…

Alternating-Current Properties of Elastomer-Carbon Nanocomposites

Polyisoprene-carbon black nanocomposites as tensile strain and pressure sensor materials

Abstract Electrically conductive polymer composites (ECPC) are shown as prospective large-size flexible pressure and stretch sensors for detecting of dangerous deformations and vibrations of vehicle parts. Reversible change of resistance dependent on stretch and pressure is obtained in electro-conductive polymer nanocomposites. At certain concentrations of carbon nano-particles a change of electrical resistance by more than four orders is observed at 40% relative stretch. The maximum sensitivity of nanocomposites is observed in the vicinity of the transition of electro-conductive percolation. Nanocomposites exhibit a very weak semiconductor-like temperature dependence of resistance. The ten…

CO2 laser-induced structure changes in lead zirconate titanate Pb(Zr0.58Ti0.42)O3 sol–gel films

Based on absorption spectra of lanthanum modified lead zirconate titanate Pb0.9La0.1(Zr0.65Ti0.35)O3 (PLZT10/65/35) ferroelectric ceramics an idea of local and selective treatment of lead zirconite titanate Pb(ZrXTi1−X)O3 (PZT) sol–gel film in the multi-layer structure by CO2 laser radiation was formulated. The possibility to obtain PZT perovskite film on the SiO2/Si substrate by irradiation with CO2 laser was shown experimentally. X-ray studies revealed the PZT perovskite structure ratio growth at the expenses of pirochlore structure with an increased power density of laser radiation.

PVA Hydrogel Electrolyte and Porous Polyisoprene Carbon Nanostructure Composite Based Pressure Sensitive Supercapacitor

Special gratitude is in order to Raimonds Orlovs for temperature dependent resistance measurements. Financial support of project 1.1.1.1/16/A/013, “Hybrid energy harvesting systems” is greatly appreciated.

Hybrid Tribo-Piezo-Electric Nanogenerator with Unprecedented Performance Based on Ferroelectric Composite Contacting Layers

This research was supported by the European Regional Development Fund within the project ‘‘Hybrid energy harvesting systems’’ 1.1.1.1./16/A/013.

Nanostructure carbon black-polyisoprene composites as prospective strain sensor materials: macro- and nanoscale studies

Nanostructured carbon black-polyisoprene composite is prepared and investigated. A giant reversible tensoresistive effect -- dependence of electrical resistance vs. uniaxial tension deformation - is found. A new application of the conductive atomic force microscope for the carbon black network mapping in a nonconducting matrix is reported.