ChemInform Abstract: COULOMB INTERACTIONS AND OPTICALLY ACTIVE VIBRATIONS OF IONIC CRYSTALS. II. COULOMB INTERACTIONS AND OPTICALLY ACTIVE VIBRATIONS OF CALCITE-TYPE CARBONATES

Abstract The Madelung contribution to the lattice energy of simple binary crystal structures and lanthanide oxide fluorides with different types of disorder has been calculated by summation of Coulomb interactions and additional consideration of surface effects. In the case of NaCl, CsCl, ZnS and CaF2 the agreement with mathematically exactly calculated values is better than 1 %. For the cubic high temperature modification of YOF it could be shown that a structure with long range order and short range disorder is more favourable from the energetic point of view than a stochastic distribution of the anions over all anion sites of the crystal.

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PIEZOELECTRICITY IN INSULATORS

International Journal of Modern Physics B ◽

10.1142/s0217979291000997 ◽

1991 ◽

Vol 05 (15) ◽

pp. 2531-2549 ◽

Cited By ~ 1

Author(s):

G.D. MAHAN

Keyword(s):

Long Range ◽

Dielectric Function ◽

Short Range ◽

Microscopic Theory ◽

Ionic Crystals ◽

Sensitive Test ◽

Coulomb Interactions ◽

Dipole Term ◽

Theory And Experiment ◽

Piezoelectric Constants

A microscopic theory is presented for the piezoelectric constants of zincblende. The theory is valid for ionic crystals. The constants have several contributions: one from long-range Coulomb interactions, and several from short range forces. The long-range term is given only by the dielectric function. The short-range terms are also large and nearly cancel the long-range terms: the largest is from the deformation-dipole term. The agreement between theory and experiment is a sensitive test of theories of short-range polarization in solids.

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Structure-property relationships of PE/PP sandwiched films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126998 ◽

1987 ◽

Vol 45 ◽

pp. 454-455

Author(s):

J. Petermann ◽

G. Broza ◽

U. Rieck ◽

A. Jaballah ◽

A. Kawaguchi

Keyword(s):

Mechanical Tests ◽

Polymer Materials ◽

Ionic Crystals ◽

Structure Property ◽

Polymer Systems ◽

Structure Property Relationships ◽

Oriented Films ◽

Materials Used ◽

Polymer Laminates ◽

Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

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