Thermally stimulated current TSC

which is also referred to as thermally stimulated depolarisation (TSD) in the literature, is a technique with capabihties similar to those of DMA and DEA. However, TSC is superior to these two in its sensitivity to the investigation of the fine molecular structure of polymers and hence its abihty to find relationships between this and physical properties that may have eluded the other techniques. 

The principle of TSC is to orient the dipoles in molecules by applying a high voltage field to a material at a high temperature and then quenching the material to freeze in the orientation created by the electric field. The external field is then removed and the sample heated at a constant rate. At temperatures that are associated with specific relaxations the sample will 

Because of this high sensitivity, TSC is ideally suited to investigating the detailed structure in blends and copolymers that have not been characterised satisfactorily by DMA and DEA [111, 112]. 

A significant increase in the precision of TSC was achieved when Lacabanne [113] developed the method of windowing polarisation, and this in turn enables the process known as relaxation map analysis to be applied to polymer systems [114, 115]. This also enables fine detail within a polymer to be elucidated and a thorough description of the technique and its capabilities has been provided by Ibar [116]. 

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In order to study the chaiged photoexcitalions in conjugated materials in detail their contribution to chaige transport can be measured. One possible experiment is to measure thermally stimulated currents (TSC). Next, we will compare the results of the TSC-expcrimenls, which are sensitive to mobile thermally released charges trapped after photoexcilation, to the temperature dependence of the PIA signal (see Fig. 9-17) which is also due to charged states as discussed previously. 

Fig. 4. Energy below the conduction band of levels reported in the literature for GaP. States are arranged from top to bottom chronologically, then by author. At the left is an indication of the method of sample growth or preparation liquid phase epitaxy (LPE), liquid encapsulated Czochralski (LEC), irradiated with 1-MeV electrons (1-MeV e), and vapor phase epitaxy (VPE). Next to this the experimental method is listed photoluminescence (PL), photoluminescence decay time (PLD), junction photocurrent (PCUR), photocapacitance (PCAP), transient capacitance (TCAP), thermally stimulated current (TSC), transient junction dark current (TC), deep level transient spectroscopy (DLTS), photoconductivity (PC), and optical absorption (OA).

Some recent thermally stimulated current (TSC) data obtained by Martin and Bois (1978) are shown in Fig. 8. Here the maximum occurs at 264°K, giving Ei0 0.61 eV,forcrBj 10-1S cm2. Evidently, a was not varied in this experiment. Note that the dark current begins to increase rapidly near room temperature in these data. Here our analysis must break down since capture... 

The interaction of MH nanoparticles with the PP matrix across their enhanced surface area resulted already at low loading level (2.5%) in Tg (determined by thermally stimulated current [TSC] method) shifting from -12°C to 8°C and heat release rate reduced as shown in Figure 13.2. For achieving V-0 rating (according to UL-94) inclusion of 50% nano-MH was needed in PP, while the reference system required 65% loading of commercial micro-MH. 

The presence of cooperative motion of chain segments present in intercalated polymer chains can be examined using various analytical techniques such as Differential Scanning Calorimetry (DSC), thermally stimulated current (TSC) and dielectric spectroscopy. DSC measurements on an intercalated PEO, (Mw= 100,000)/montmorillonite hybrid (20 wt. % polymer), indicated the absence of... 

By thermally stimulated-current (TSC) techniques, Slowik (1976) measured a zero-field activation energy of 0.60 eV for PVK, slightly lower than the 0.65 eV reported by Gill (1972). The technique used by Slowik is based on an... 

Another way of investigating the depth in energy to which charges are trapped (a measure of the stability towards thermal decay) may be obtained by thermally stimulated currents (TSC). In this technique, electrodes on the two sides of the electret are connected via a sensitive current meter and the specimen is then heated at a constant, slow rate (1 Cmin-1, say). Discrete current peaks are observed as a function of temperature as successively more deeply trapped charges are released (Fig. 7.22). Dipolar relaxation may also give peaks in the TSC spectrum (van Turnhout, 1975). 

Thermally stimulated currents (TSC) have been used to probe the carrier generation mechanism in a dual-layer photoreceptor with an azo-pigment-based CGL and hydrazone-based CTL. It appears that this technique may be a useful tool in understanding the carrier generation process in organic photoreceptors [21]. 

We describe here a relatively new form of dielectric spectroscopy known as thermally stimulated current (TSC) spectroscopy that has to date been applied to the study of inorganic materials (insulators, semiconductors) and organic macromolecules (collagen or elastin) (8) but does not appear to have been applied extensively to small organic molecules (9). 

Thermally Stimulated Current (TSC). This relatively straightforward method has been used for years as a method of thermal analysis comparable in some aspects to Thermal Mechanical Analysis (TMA). For example, TSC is able to detect many of the same transitions as seen by the mechanical methods. The advantages of TSC include its extremely high sensitivity and its low... 

The techniques of thermally stimulated capacitance (TSCAP) and thermally stimulated current (TSC) are the simplest methods for surveying the... 

Saffell, J.R., Matthiesen, A., McIntyre, R. et al. 1991. Comparing thermal stimulated current (TSC) with other thermal analytical methods to characterize the amorphous phase of polymers. Thermochim. Acta 192 243-264. 

Thermally stimulated current (TSC) spectroscopy is used to characterize the relaxation processes and structural transitions occurring in samples that have been polarized at a temperature greater than the temperature where molecular motion in the sample is enhanced and subsequently quenched so that the high mobility state is frozen. On heating the sample at a controlled rate, depolarization of the polymer electrets (molecular or ionic dipoles, trapped electrons, mobile ions) occurs and the oriented dipoles, frozen in the quenched sample, relax to a state of thermal equilibrium. This relaxation process is observed as a depolarization current, which is typically of the order of picoamperes, and is referred to as the thermally stimulated current. 

Thermally stimulated current (TSC) Electric current observed following the depolarization of a sample through heating. The sample is initially poled in an electric field at a temperature greater than the glass transition or melting temperature and subsequently quenched. 

Technical Analysis Description 3.1 Thermally Stimulated Current (TSC)... 

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