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A remanent polarization of 130Ϯ3 mC/m 2 , large among the values reported for organic materials, and rectangular D -E hysteresis curves were realized in synthesized vinylidene fluoride ͑VDF͒ oligomer ͓CF 3 (CH 2 CF 2 ) 17 I͔ film evaporated onto a platinum surface around liquid nitrogen temperature. The results suggested that the VDF oligomer film has an extremely high crystallinity, and the electric dipoles arrange almost perfectly perpendicular to the film surface, and that a Lorentz local field factor of ferroelectric VDF oligomer crystals is nearly zero. Moreover, the obtained value of the coercive field, which was larger than those of ferroelectric polymers, might be attributed to the steric hindrance arising from the existence of iodine atoms at the VDF oligomer chains.

Structures and crystal transformation of the newly synthesized vinylidene fluoride (VDF) oligomer with large electric dipoles evaporated on KCl (001) at various substrate temperatures have been investigated by an energy dispersive–grazing incidence x-ray diffraction system, Fourier transform infrared spectroscopy, and atomic force microscope (AFM). It was revealed that the molecules grow epitaxially and are influenced greatly by forces of the crystal surface field in terms of van der Waals or electrostatic potentials, and found that the phase transformation from form II (α phase) to form I (β phase) is induced by raising the temperature of the substrate from 50 to 80 °C, accompanying the alternation in the crystal axes on the substrate from the a axis of form II to the polar b axis of the form I crystal. This fact suggests that the molecular chain of VDF oligomers aligns their c axes along the 〈110〉 row of K+ or Cl− with the aid of electrostatic interaction under enough thermal movement. Moreover, in the transformation process, a pair of “rod-like” crystals, suggesting ferroelectric activity, were observed by AFM.

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Molecular orientations during physical vapor deposition of various linear long-chain compounds are interpreted on the basis of a simple model for the initial stage of anisotropic crystal growth. In this model, the initial stage involves adsorption from vapor, surface migration, reevaporation from the substrate, capture into a cluster, re-evaporation from a cluster, and reorientation, where the anisotropy of the molecules are considered. In addition, two fundamental orientations of initial small nuclei are assumed to be under thermal equilibrium. The set of dierential equations for the individual elementary processes can be solved numerically. The calculated results agree well with actual orientational phenomena of long-chain molecules at various substrate temperatures, i.e., a higher substrate temperature results in a higher degree of normal orientation.