Phase transformation crystals

Careful control of the surfactant-water content and the rate of condensation of silica at high alkalinity resulted in hollow tubules 0.3 to 3 pm in diameter.[292] The wall of the tubules consisted of coaxial cylindrical pores, nanometers in size, that are characteristic of those of MCM-41. The formation of this higher-order structure may take place through a liquid-crystal-phase transformation mechanism involving an anisotropic membrane-to-tubule phase change. 

Takahashi Y, Matsubara Y, Tadokoro H (1982) Mechanisms for crystal phase transformations by heat treatment and molectdar motion in poly(vinylidene fluoride). Macromolecules 15 334... 

This chapter discusses the topics of crystallinity detection and measurement, the morphology of polymer crystalline aggregates at different levels of size and the kinetics of melt-crystal phase transformation. Chapter 3 presents thermodynamic aspects of crystallinity in polymers. The treatment is intended to provide a broad... 

Since the EFG is a very sensitive function of the molecular and crystal structure, the resonance frequencies and band shapes are specific to each compound, and NQR data can be used for determining unambiguous sample identification, local electronic structure, atomic arrangement, order/disorder phenomena, and crystal phase transformations. In addition, molecular dynamics in the solid state can be studied. Furthermore, since NQR data are sensitive to changes in temperature and pressure, there is the possibility of obtaining strain information. 

A chiral compound, dissolved in a nematic liquid crystal phase, transforms this phase into a chiral phase that is very often a chiral nematic - cholesteric -phase. Under the same condition of concentration and temperature two enantiomers induce helical structures with the same pitch but of opposite sign. The helical pitch p is for low concentrations of the dopant a linear function of mole fraction x. The molecular measure for the chiral induction is the helical twisting power (ITTP) ... 

In a recent paper (63], it was indicated that deactivation could occur by a crystal phase transformation during the process however, the initial activity could be restored by hearing the catalyst in the presence of O2. 

CRYSTAL-LIQUID CRYSTAL PHASE TRANSFORMATION OF SYNTHETIC BIMOLECULAR MEMBRANES... 

The afor nentioned structural changes occurring diving uniaxial elongation at 300 K are additionally superimposed by a crystal phase transformation. Several authors have shown that under conditions of stress the orthorhombic... 

Fig. 22 a and b. The stress-induced crystal phase transformation in PTMT a conformation of the aliphatic chain segments in the relaxed and strained modification ... 

Figure 11 The single-crystal to single-crystal phase transformation observed in a subUmed crystal of 2 after soaking in vinyl bromide for 15 min. The phase transition involves a concurrent relative shift of adjacent bilayers and results in a change from ab/cd to ab/ab packing. (Reproduced with permission from Ref. 84. American Association for the Advancement of Science, 2002.)...

The liquid crystal to liquid crystal phase transformations and the liquid crystal to isotropic liquid transition (clearing... 

Fig. 39.3 (a) The discrete void of 235 A enclosed within bilayer arrangement of 2. (b) Single crystal to single crystal phase transformation observed in 2b after immersion in vinyl bromide (Reproduced with permission from Refs. [21, 22] Copyright 2002, and 2007 AAAS and Royal Society of Chemistry)... 

S. Gorer, G. Hodes, Y. Sorek, R. Reisfeld, Crystal phase transformation in sol-gel films of nanocrystalline CdSe and CdS, Mater. Lett. 31 (1997) 209-214. 

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