Crystal growth and dielectric characterization of crystals derived from the solid-solution Ba(1−x)NaxTi(1−x)NbxO3 (BTNN) |
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Authors: | Lakhdar Gacem Djamel Ouadjaout Mario Maglione Stanislas Pechev |
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Affiliation: | a ICMCB-CNRS, Université de Bordeaux, 87 av. Schweitzer, 33608 Pessac, France b Département de physique, Université Mohamed Khider de Biskra, Biskra 07000, Algeria c UDTS, 2 Bd. Frantz Fanon, BP. 140 Alger-7 Merveilles, 16200 Alger, Algeria |
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Abstract: | Single crystals of (1 − x)BaTiO3 + xNaNbO3 (BTNN) for x = 0.84 were obtained by high temperature solution growth using Na2B4O7 as solvent. The room temperature crystal structure of BTNN 16/84-phase was determined from X-ray single crystal diffraction data, in the tetragonal system with space group P4bm. The refinement from 246 independent reflections led to the following parameters: a = b = 5.5845(3) Å, c = 3.9453(2) Å, V = 123.041(11) Å3, Z = 2, with final cRwp = 0.150 and RB = 0.041. The structure of BTNN 16/84-phase can be described as a three-dimensional framework built up from (Nb-Ti)O6 octahedra with Na and Ba in the dodecahedral site of perovskite-like type. Some mm3-sized crystals have been selected and various dielectric measurements (ferroelectric, pyroelectric, and piezoelectric) have been performed. Transition from paraelectric to ferroelectric state at around 460 K has been observed to be in good agreement with ceramics of closer composition. Dielectric, piezoelectric and pyroelectric measurements on crystal confirm the ferroelectric behaviour of BTNN 16/84. |
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Keywords: | Oxides Crystal growth Crystal structure Dielectric properties Ferroelectricity Piezoelectricity Phase transition |
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