Growth and characterization of Ba2LnFeNb4O15 (Ln = Pr, Nd, Sm, Eu) relaxor single crystals

Marjorie Albino (1) , Philippe Veber (2, 3, 1) , Stanislav Pechev (1) , Christine Labrugère (1) , Matias Velázquez (1) , Mario Maglione (1) , Michaël Josse (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 CNRS - Centre National de la Recherche Scientifique
3 UVT - Universitatea de Vest din Timișoara [România] = West University of Timișoara [Romania] = Université Ouest de Timișoara [Roumanie]

Ba2LnFeNb4O15 (Ln = Pr, Nd, Sm, and Eu) single crystals were grown from high-temperature solution under controlled atmosphere. Chemical, structural, and dielectric characterizations were performed on four crystals with tetragonal tungsten bronze (TTB) structure. The main difference between the four crystals' compositions is the proportion of rare-earth, as well as vacancies, located in the square site. All crystals displayed an incommensurately modulated structure at room temperature in the paraelectric state. The corresponding basic structures were refined using the P4/mbm space group (R = 0.0274; 0.0416; 0.0328; 0.0357 for Ln = Pr, Nd, Sm, and Eu, respectively). Examination of the structural parameters confirmed the central role played by square-shaped channels in the crystal chemistry of these materials. All crystals display a relaxor behavior with Tm (1 MHz) ranging from 110 to 270 K. The chemical, structural, and physical properties of the crystals are discussed and compared, for the latter, with those of corresponding ceramics.

Domaines: Matériaux

Marjorie Albino, Philippe Veber, Stanislav Pechev, Christine Labrugère, Matias Velázquez, et al.. Growth and characterization of Ba2LnFeNb4O15 (Ln = Pr, Nd, Sm, Eu) relaxor single crystals. Crystal Growth & Design, 2014, 14 (2), pp.500-512. ⟨10.1021/cg401181j⟩. ⟨hal-00956567⟩