Silver Paint Electrodes

The conductivity measurements were made by a.c. methods (silver paint electrodes) and by d.c. methods (hydrogen molybdenum bronze electrodes). The measurements were made in the temperature range from —10 °C to 85 °C. In the lower part of the temperature range, the Arrhenius plots show linear behaviour. In the upper part (30-85 °C), the Arrhenius law was not obeyed. 

Measurement Technique. Rectangular stripes of silver paint are applied to the surface of each sample at regularly spaced intervals to form electrical contacts. Wires are attached to the samples by spring-loaded metal clips placed on the silver-paint electrodes. A comparison of two-point and four-point measurements showed that contact resistance between the sample and the silver-paint electrodes can be significant, especially for composites close to the percolation threshold. All measurements reported here are made with a four-point technique [72] in the linear (ohmic) range of the resistance versus voltage characteristic, and shpw no significant time dependence. 

To learn how to make electrical contacts to electrodes, e.g. with conductive silver paint. 

Figure 9.2 Schematic diagram showing how an electrical contact is fixed with silver paint to the conductive side of an optically transparent electrode. The outer layer of epoxy resin is necessary to impart strength, to insulate the silver paint from the analyte solution and to stop analyte solution seeping between the paint and the conductive layer.

Hi) (Following from (ii)) The silver electrode contact itself is not strong, so solution can seep between the silver paint and the electrode, thus destroying all chance of reproducibility. A protective over-layer prevents such seepage. 

Electrical contact between the electrode and connecting wires can be made with solder if the electrode is a refractory metal, while lower-melting-point metals such as lead, and reactive metals such as magnesium, should be joined to a connection lead with commercially available conductive silver paint . Contact to ITO-coated electrodes will similarly require this conductive paint. 

Contact materials and confignrations nsed in TSC experiments vary widely and depend on the particnlar application. Metal electrodes can be attached to the sample by evaporation or by application of condnctive pastes (silver paint or epoxy) or metal-organic compounds. Typical contact configurations are shown in Fig. 1.5. 

Rotating optically semii-transparent electrodes for spectroelectro-chemical or photoelectrochemical studies can be fabricated by vapour deposition techniques on a quartz substrate. In this way, tin oxide, platinum and gold electrodes, amongst others, can be made. Electrical contact is with silver paint. 

Following deposition, the Ti02 coated plates were subjected to a reduction treatment under H2 at 600°C for 2 hours. After verification of a good electrical contact at the back surface of the Ti sheet, a copper plate with an electrode lead was attached to the electrode back with silver paint. The electrode back and edges were covered with silicone rubber adhesive (GE RTV 108). 

Electrodes usually consist of fired-on silver paint with a small glaze content. It may be necessary to remove a high-resistivity surface layer from the ceramic before silvering. The contacts formed in this way are unlikely to be ohmic, but... 

After the sintering stage, electrodes are applied, usually either by electroless nickel plating or by painting or screening on specially adapted silver paint. Leads are then soldered to the electrodes when, for many applications, the device is complete in other cases it may be encapsulated in epoxy or silicone resins. Examples are illustrated in Fig. 4.15. 

The main problem in accurate measurement of resistivity is one of contact resistance between the measurement electrodes and the specimen. This is clearly the case for samples with low resistivity, but can also be a problem for more resistive samples if either the contact resistance is high or the contact is non-ohmic. Contact resistance may be reduced by painting electrodes directly on to the surface of the specimen instead of relying on pressure contact with metal plates or foils. Suitable paints are silver dispersions or Aquadag (an... 

The ceramic circular discs (1cm diameter, 0.1cm thick) were prepared by pressing the powder, using a pressure of 8 MPa, with adding in 8 % PVA solution as binder, and sintering at 1 300 °C for 2 hours. Then the ceramic samples were prepared by electroding the sintered disc with silver paint. 

Surface resistivity. One side of the specimen is coated with a circle of silver paint surrounded by a ring of silver paint. The uncoated distance between the circle and the ring is an effective length on which surface resistivity is measured. The other surface of the specimen is fully coated with silver paint. Current and voltage are measured and surface resistivity calculated. If samples contain internal or external antistatics, the measurement is performed under a controlled atmosphere to eliminate the influence of temperature and relative humidity. Also, specimen conditioning is used to account for migration of the antistatic to the surface. The surface of specimen containing antistatics is not coated with silver paint, but electrodes are... 

The reaction was carried out in a quartz ozonizer having an electrode length of 12 inches and an electrode separation of 8 mm. The electrodes consisted of fired-silver paint—one electrode coating the inside of the inner (high voltage) tube, and the other coating the outside of the outer (ground) tube. 

Sample Preparation. Inner and outer electrodes were applied using conductive silver paint. 

DIN 53482 uses methods similar to some of those in lEC 93, using silver or graphite painted electrodes for volume resistivity. A different electrode system was suggested for the measurements of surface and volume resistivity. A narrow guard gap of 1 mm makes it difficult to avoid short-circuiting the electrodes. 

The typical polymer LED structure is shown in Figure 7.3. In order to fit in the quartz finger dewar which is inserted in the microwave cavity (see Section 1.3.1 below), the width of the devices was limited to 4.5 mm. They were all fabricated on ITO-coated glass, which was the positive electrode. The active area of the devices was 7 mm. PPV layers were deposited by spin coating the appropriate precursor and thermally converting it CN-PPV was spin-cast directly from solution [3]. The deposition of the polymers was followed by evaporation of the metal electrode from which electrons were injected into the devices [3,9,25,26,28,29]. In the case of the PPV- and PPE-based devices, that electrode was Al-encapsulated Ca, which yielded a higher device efficiency than an A1 electrode [9,25,26,28,29]. The thickness of the emissive PPV and PPE layers was 600 and 300 nm, respectively. Derivatives of PPE dissolved in toluene were spin-coated onto the ITO substrates, followed by e-beam or thcnnal evaporation of A1 or Ca/Al electrodes in a base chamber pressure of 10 torr. The PPV/CN-PPV diodes used A1 as the electron-injecting electrode [3], The thickness of the PPV layer was 120 nm, and that of the CN-PPV layer was 100-200 nm. Finally, copper wires were bonded to the A1 and no layers with silver paint. 

Dip the end of this strand into a solution of conducting silver paint and immediately insert the wire into the stem end of the electrode. Push the wire inward, toward the electrode tip, so that the conducting paint-coated end of the strand makes contact with the carbon fiber and presses it against the glass (see Fig. 2B) Apply a drop of cyanoacrylate glue to the stem end of the electrode to secure the wire... 

Another variation of making an electrode connection is shown in Fig. 3.2. In this case, bare copper wire is inserted into a glass tube and coiled at the end. The coiled wire is attached to the back side of the sample using silver paint and allowed to dry at 80 °C for 20-30 min. The entire assembly is then encased in epoxy and annealed at 80 °C for 2 h. 

Fig. 3.2 Connecting an electrode with Cu wire. Bare Cu wire is inserted into a glass tube and coiled at the end to increase surface area (a). The back side of the sample (b) is connected to the Cu coil using silver paint, followed by the addition of HYSOL 9462 epoxy (c) to encase the entire assembly. The finished product is shown in (d)...

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