Crystal Growth and Dielectric Study of the Niobate Series K3Sr2RNb10O30 (R = Lanthanide) of Tungsten Bronze Structure

A. Lahmar; S. Ganschow; J. Doerschel; K. Tsuzuku; M. Couzi; B. Elouadi

doi:10.18321/ectj407

Authors

A. Lahmar Laboratoire d'Elaboration, Analyse Chimique et Ingenierie des Materiaux (LEACIM), Universite de La Rochelle, avenue Michel Crepeau, 17042 La Rochelle Cedex 01, France
S. Ganschow Institut fur Kristallzuchtung, Max Born-Stor. 2, D-12489 Berlin, Germany
J. Doerschel Institut fur Kristallzuchtung, Max Born-Stor. 2, D-12489 Berlin, Germany
K. Tsuzuku R&D Materials Departement, General R&D Laboratorises, Taiyo Yuden R&D Center 5607-2 Nakamuroda – Machi Gunma – Gun Gunma 370-3347, Japan
M. Couzi Groupe de Spectroscopie Moleculaire (GSM) Institut des Sciences Moleculaires (ISM) UMR 5255- CNRS, Universite Bordeaux1, cours de la Liberation, 33405 Talence, France
B. Elouadi Laboratoire d'Elaboration, Analyse Chimique et Ingenierie des Materiaux (LEACIM), Universite de La Rochelle, avenue Michel Crepeau, 17042 La Rochelle Cedex 01, France

DOI:

https://doi.org/10.18321/ectj407

Abstract

Fibre single crystals of K₃Sr₂RNb₁₀O₃₀ (R = La, Nd, Eu, Gd, Sm) have been successfully grown using the μ-pulling down method. Single crystal X-ray diffraction technique has confirmed that all isolated compounds crystallize with the tetragonal tungsten bronze structure. The elemental analyses of Nd- and Eucrystals using EDX has evidenced the presence of some inclusions corresponding to the composition KNb₃O₈. The presence of such compound in the matrix of the grown fibres could be interpreted as a revelation of the quaternary equilibrium involved during the crystal growth. Dielectric and Raman investigations within a wide temperature range [–150 °C; 400 °C], tend to confirm the existence of the same thermal anomalies. Although these anomalies are found at almost the same temperatures, the nature and the mechanisms of the so-revealed phase transitions are not yet totally evidenced.

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