Capacitively coupled electrolyte-conductivity sensor based on high-k material of barium strontium titanate
| Autor: | Patrick Wagner, Willi Zander, Matthias Bäcker, Christina Huck, Arshak Poghossian, V.K. Begoyan, S. Chaudhuri, Michael J. Schöning, Jürgen Schubert, V.V. Buniatyan |
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| Rok vydání: | 2014 |
| Předmět: |
Materials science
Metals and Alloys Oxide Analytical chemistry Electrolyte Conductivity Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials Pulsed laser deposition chemistry.chemical_compound chemistry Electrode Materials Chemistry Electrical and Electronic Engineering Instrumentation Layer (electronics) High-κ dielectric Perovskite (structure) |
| Zdroj: | Sensors and Actuators B: Chemical. 198:102-109 |
| ISSN: | 0925-4005 |
| Popis: | A miniaturized capacitively coupled contactless conductivity detection (C 4 D) sensor based on high-k perovskite oxide of barium strontium titanate (BST) has been implemented for the first time. The BST films (∼120 nm thick) of Ba 0.25 Sr 0.75 TiO 3 composition were prepared on a p-Si-SiO 2 -Pt structure by pulsed laser deposition technique using BST targets fabricated by the self-propagating high-temperature synthesis method. The Pt electrodes were buried into the SiO 2 layer to obtain a planar structure. For comparison, contact-mode electrolyte-conductivity (EC) sensors without the protective BST layer were also fabricated. To study the influence of the protective BST layer, both sensors were characterized in electrolyte solutions with various conductivities using two- and four-electrode operation modes. The impedance spectra were recorded in a frequency range from 1 Hz to 1 MHz. An equivalent circuit of the C 4 D sensor is discussed as well. Both, the EC and C 4 D sensor, demonstrate nearly identical sensor characteristics. The obtained results clearly show the benefits of the use of the BST-based C 4 D sensor in a four-electrode configuration for contactless conductivity measurements. A linear dependence between the measured conductance and the electrolyte conductivity is obtained in a wide range of electrolyte conductivity from 0.3 mS/cm to 50 mS/cm. Moreover, typical problems associated with contact-mode EC detection such as the effect of possible redox processes, contamination and fouling of electrodes during continuous measurements can be minimized, thus, enhancing the life-time of conductivity sensors considerably. |
| Databáze: | OpenAIRE |
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