Ramanspektroskopische Untersuchungen an KJO3-Kristallen
Abstract
Raman signals given by single crystals of ferroelectric KIO3 are strongly dependent on the directions of phonon-propagation. The anti-Stokes frequencies, measured using different experimental arrangements, are correlated with the optical indicatrix. The ferroelectric phase transitions at 72.5°C and 212°C are accompanied by a “soft-mode” behaviour of some transversal modes, as predicted earlier. The temperature dependencies of the valence constants of I–O and K–O bonds thus calculated, show that the biggest differences in the bond energies of the ferroelectric β and γ phases must be attributed to K–O interaction. Moreover, the bonds of the IO6-complex are weakened during the transition in the high-temperature phase. The interatomic distances, estimated using the method of central-field approximation and the coordinates of normal modes given by Salje (1973), agree with the structural data. The phonon spectra of the phases α, β, and γ are compatible with the point group symmetries R[unk]m, Pm and P 1 with 2, 4 and 4 molecules in their respective unit cell. A decrease in the scattering frequencies is observed in Raman experiments in which a small quasi-momentum transfer is involved. This is due to polariton dispersion. The coupling parameters, calculated using polariton frequencies, indicate strong photon-phonon interactions for all wave vectors near the origin of the Brillouin zone.
Artikel in diesem Heft
- The crystal structure of jordanite, Pb28As12S46*
- Crystal structure of a synthetic lithium zeolite
- The crystal structure of synthetic MgIV mica
- Die Molekular- und Kristallstruktur des Zimtsäurepyrrolidids C13H15ON*
- Verfeinerung der Kristallstruktur von Cerussit, PbCO3
- Verfeinerung der Kristallstruktur von K2Cu(C2O4)2 · 2 H2O
- Die Kristallstruktur von Caesium-Kupfer(II)-Oxalat-Dihydrat, Cs2Cu(C2O4) · 2H2O
- Zur Entwicklung des Begriffs “Gitterkomplex”
- Zur Definition des Punktlagen- und Gitterkomplex-Begriffes
- Eine Definition des Begriffs “Gitterkomplex”
- Röntgenographische Bestimmung der fehlgeordneten Schichtfolgen in Graphit-FeCl3-Einlagerungsverbindungen
- Atomic vibrations and thermal expansion of some silicates at high temperatures
- Ramanspektroskopische Untersuchungen an KJO3-Kristallen
- Lattice parameters and space group of plumbagin
Artikel in diesem Heft
- The crystal structure of jordanite, Pb28As12S46*
- Crystal structure of a synthetic lithium zeolite
- The crystal structure of synthetic MgIV mica
- Die Molekular- und Kristallstruktur des Zimtsäurepyrrolidids C13H15ON*
- Verfeinerung der Kristallstruktur von Cerussit, PbCO3
- Verfeinerung der Kristallstruktur von K2Cu(C2O4)2 · 2 H2O
- Die Kristallstruktur von Caesium-Kupfer(II)-Oxalat-Dihydrat, Cs2Cu(C2O4) · 2H2O
- Zur Entwicklung des Begriffs “Gitterkomplex”
- Zur Definition des Punktlagen- und Gitterkomplex-Begriffes
- Eine Definition des Begriffs “Gitterkomplex”
- Röntgenographische Bestimmung der fehlgeordneten Schichtfolgen in Graphit-FeCl3-Einlagerungsverbindungen
- Atomic vibrations and thermal expansion of some silicates at high temperatures
- Ramanspektroskopische Untersuchungen an KJO3-Kristallen
- Lattice parameters and space group of plumbagin
