Bipolar conduction

Biederman, J., Faraone, S.V., Wozniak, J., and Monuteaux, M.C. (2000) Parsing the associations between bipolar, conduct, and substance use disorders a familial risk analysis. Biol Psychiatry 48 1037-1044. 

Adachi, C., Baldo, M.A., and Forrest, S.R. (2000) Electroluminescence mechanisms in organic light emitting devices employing a europium chelate doped in a wide energy gap bipolar conducting host. Journal of Applied Physics, 87, 8049-8055. 

Figure 3. Schematic of electrohydrodynamic conditions in unipolar and bipolar conduction.

Nitrobenzene - An example of a homocharge bipolar conduction process... 

Fig, 12. Transient Kerr electro-optic field mapping measurements at 5000 frames/second with crossed polarizers in nitrobenzene (E 12 kV/cm) showing bipolar conduction when a stepped... 

LeSuer, R. J., Fan, F.-R. R, Bard, A. J. Scanning electrochemical microscopy, 52. Bipolar conductance technique at ultramicroelectrodes for resistance measurements. Anal Chem 2004, 76, 6894—6901. 

Let us first conduct this discussion in semiquantitative form. Here we place the am-bipolar conductivity even though it is dependent on fiza in front of the integral and correct the error caused by regarding the expression in brackets as the corresponding mean value. 

It is also possible to measure the stationary oxygen permeation flux (see Chapter 6) instead of the cell voltage- This provides us with information concerning the am-bipolar conductivity and, hence, concerning the conductivity of the minority charge carrier (e.g. [Pg.417]

Some of tliese problems are avoided in heterojunction bipolar transistors (HBTs) [jU, 38], tlie majority of which are based on III-V compounds such as GaAs/AlGaAs. In an HBT, tlie gap of tlie emitter is larger tlian tliat of tlie base. The conduction and valence band offsets tliat result from tlie matching up of tlie two different materials at tlie heterojunction prevent or reduce tlie injection of tlie base majority carriers into tlie emitter. This peniiits tlie use of... 

The bipolar plate material of the PAFC is graphite. A portion of it has a carefully controlled porosity that sei ves as a resei voir for phosphoric acid and provides ffow channels for distribution of the fuel and oxidant. The plates are elec tronically conductive but impervious to gas crossover. 

The anode material in SOF(7s is a cermet (rnetal/cerarnic composite material) of 30 to 40 percent nickel in zirconia, and the cathode is lanthanum rnanganite doped with calcium oxide or strontium oxide. Both of these materials are porous and mixed ionic/electronic conductors. The bipolar separator typically is doped lanthanum chromite, but a metal can be used in cells operating below 1073 K (1472°F). The bipolar plate materials are dense and electronically conductive. 

Ion chromatography (see Section 7.4). Conductivity cells can be coupled to ion chromatographic systems to provide a sensitive method for measuring ionic concentrations in the eluate. To achieve this end, special micro-conductivity cells have been developed of a flow-through pattern and placed in a thermostatted enclosure a typical cell may contain a volume of about 1.5 /iL and have a cell constant of approximately 15 cm-1. It is claimed15 that sensitivity is improved by use of a bipolar square-wave pulsed current which reduces polarisation and capacitance effects, and the changes in conductivity caused by the heating effect of the current (see Refs 16, 17). 

Composite structures that consist of carbon particles and a polymer or plastic material are useful for bipolar separators or electrode substrates in aqueous batteries. These structures must be impermeable to the electrolyte and electrochemical reactants or products. Furthermore, they must have acceptable electronic conductivity and mechanical properties. The physicochemical properties of carbon blacks, which are commonly used, have a major effect on the desirable properties of the conductive composite structures. Physicochemical properties such as the surface... 

A third approach, not yet fully demonstrated at the limit of dispersed catalysts, is the induction of electrochemical promotion without an intermediate conductive phase (Fig. 12.3). This approach will be discussed in Section 12.3 in relation to the concept of the bipolar design. 

During the last year a bipolar particular cell has been described (Fleischmann et al., 1971d). The cell shown in Fig. 18 consists of a packed bed of mixed conducting and non-conducting particles a d.c. potential is applied between two feeder electrodes situated at the ends... 

Fig. 18. Bipolar particulate cell. conducting particles, o non-conducting glass beads.

The micro structured platelets, hold in a non-conducting housing, were realized by etching of metal foils and laser cutting techniques [69]. Owing to the small Nemst diffusion layer thickness, fast mass transfer between the electrodes is achievable. The electrode surface area normalized by cell volume amounts to 40 000 m m". This value clearly exceeds the specific surface areas of conventional mono- and bipolar cells of 10-100 m m. ... 

Figure 3.16 Schenatic diagran of a Hall electrolytic conductivity detector with an expanded view of the bipolar pulsed differential conductivity cell.

---