Structural transformations in KNbF6 and KTaF6

Low-temperature phase transitions in KNbF6 and KTaF6 were detected for the first time by the NMR relaxation method on ZF nuclei. The probable mechanism of the phase transitions may be related to the rotation of polyhedra - the cotahedral NbF6 and TaF6 anions. A characteristic feature of the crystals...

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Veröffentlicht in:	J. Struct. Chem. (Engl. Transl.); (United States) 1986-03, Vol.27 (2), p.221-224
Hauptverfasser:	Gabuda, S. P., Kozlova, S. G., Kriger, Yu. G., Goncharuk, V. K.
Format:	Artikel
Sprache:	eng
Schlagworte:	360602 - Other Materials- Structure & Phase Studies 360603 - Materials- Properties ALKALI METAL COMPOUNDS ANIONS CALORIMETRY CHARGED PARTICLES COHERENT SCATTERING COOLING COUPLING CONSTANTS CRYSTAL LATTICES CRYSTAL STRUCTURE CRYSTAL-PHASE TRANSFORMATIONS CUBIC LATTICES DIAGRAMS DIELECTRIC PROPERTIES DIFFRACTION DIFFUSION ELECTRICAL PROPERTIES FLUORIDES FLUORINE 19 FLUORINE COMPOUNDS FLUORINE ISOTOPES HALIDES HALOGEN COMPOUNDS INTERMEDIATE MASS NUCLEI IONS ISOMERIC TRANSITION ISOTOPES ISOTOPES LIGHT NUCLEI LINE BROADENING MATERIALS SCIENCE NIOBIUM 93 NIOBIUM COMPOUNDS NIOBIUM FLUORIDES NIOBIUM ISOTOPES NMR SPECTRA NUCLEAR QUADRUPOLE RESONANCE NUCLEI ODD-EVEN NUCLEI PHASE DIAGRAMS PHASE TRANSFORMATIONS PHYSICAL PROPERTIES POTASSIUM COMPOUNDS POTASSIUM FLUORIDES QUADRUPOLE MOMENTS RADIOISOTOPES REFRACTORY METAL COMPOUNDS RELAXATION RELAXATION TIME RESONANCE SCATTERING SPECTRA SPIN-LATTICE RELAXATION STABLE ISOTOPES TANTALUM COMPOUNDS TANTALUM FLUORIDES TEMPERATURE DEPENDENCE TETRAGONAL LATTICES TRANSITION ELEMENT COMPOUNDS X-RAY DIFFRACTION YEARS LIVING RADIOISOTOPES
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Beschreibung
Zusammenfassung:	Low-temperature phase transitions in KNbF6 and KTaF6 were detected for the first time by the NMR relaxation method on ZF nuclei. The probable mechanism of the phase transitions may be related to the rotation of polyhedra - the cotahedral NbF6 and TaF6 anions. A characteristic feature of the crystals studied is their tendency to undergo a strong supercooling with the formation of several phases, which are stable for a prolonged time (more than 10 h). Data were obtained confirming that some of the supercooled phases can be considered disproportional.
ISSN:	0022-4766 1573-8779
DOI:	10.1007/BF00751728