Domain needle-shaped

Figure 8.38. Structural parameters of an ensemble of needle-shaped soft domains in a poly(ether ester) as a function of elongation . D (open circles) is the average needle diameter, a/D (filled circles) is the relative standard deviation of the needle-diameter distribution. Square symbols demonstrate the lateral compressibility of the soft needles during elongation... 

When needle-shaped phases, such as the W 03 2 CS structures are considered, the fault planes run parallel to the needle axis. In addition, the needles are rarely homogeneous, and often consist of domains in which the planar defects are relatively well ordered, but oriented differently from domain to domain. It is this feature which has made these crystals so difficult to study by A -ray diffraction. No mechanism has been proposed in the literature to account for the formation of such materials, and so they will not be considered further here. 

Blackburn J, Salje EKH (1999a) Formation of needle shaped twin domains in cordierite A computer simulation study. J Appl Phys 85 2414-2422... 

Fig. 3 SPEM images cf pcrhydrotripenylene inclusion crystals with a dipolar guest molecule [l-(4-nitrophenyl)piperazine], thinned in three steps. A two-dimensional mapping of the pyroelectric response in the channel direction is shown for a constant modulation frequency of the heating laser source of 415 Hz. Color code red=positive current blue=negative current Low color intensity no current.Moving from the outer to the inner part of the needle-shaped crystal shows that at all depths, there are two main domains of opposite polarization althou somehow interpenetrating. In the middle cf the needle, a cone-shaped structure cf polarity distribution is seen, which is typical for a Markov-type growth in two dimensions. Qualitative agreement with stochastic simulations is obtained. (View this art in color at www.dekker.com.)...

An example of analysis in which a more elaborate data analysis was performed is the analysis of stretched samples of poly(etherester) (PEE) (73,74). This material consists of hard and soft domains. By stretching this material the soft domains elongate and become needle shaped. The analysis performed here is in the form of projections which are, in this case, integral operators that map fimc-tions onto subspaces of the domain in which they are defined. The most well known of these projections is the one that maps the scattered intensity onto a zero-dimensional subspace, ie, a number or scalar. For instance,... 

Figure 9. (a) Characterization of the ensemble of needle-shaped soft domains in Amitel E2000/60 as a function of elongation c. (b) Diameter distributions, hp (D), cf soft domain needles computed by numerical Mellin deconvolution of curves shown in fig 8(b). (Reproduced with permission from r erence [3] ( ) 1999 John Wiley.)... 

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