A transmission electron microscopic study of the electrochromic material bis(phthalocyaninato) ytterbium

Abstract Transmission electron microscopy has been used to characterize thin solid films of bis(phthalocyaninato) ytterbium which were prepared by subliming powder, in vacuo, onto unheated carbon-coated glass substrates. The films are found to consists of three main growth forms: (i) highly crystalline monocrystals in the form of rectangular parallelopipeds, (ii) less perfect, thinner rectangular-shaped monocrystals than type (i), and (iii) very small, finely distributed molecular ckusters and strings. The crystalinity of types (i) and (ii) is degraded by electron irradiation, but the use of low-dose methods has enabled the following crystallographic parameters to be determined from the microcrystals by means of both lattice images and electron diffraction: crystal system: face-centered tetragonal, unit cell parameters: a = b = 28.02 ± 0.48 A , c = 6.92 ± 0.10 A . Variations of cell parameters outside the error limits are shown to be statistically significant and are believed to indicate the presence of a structural variant. Several forms of crystals defect have been imaged and identified.