Investigation of diffuse phase transition in ferroelectric Pb2-xK1+xLixNb5O15 (0 <= x <= 1.5) ceramics

E. Choukri (1) , A. Neqali (1) , Z. Abkhar , A. Alimoussa (2) , L. Hajji , D. Mezzane (1) , A. Belboukhari , M. Amjoud (1) , Y. Gagou (3) , M. El Marssi (3) , I. Luk’yanchuk

1 LMCN - Laboratoire de Matière Condensée et Nanostructures
2 Laboratory of Condensed Matter and Nanostructures
3 LPMC - Laboratoire de Physique de la Matière Condensée - UR UPJV 2081

Substitution of Pb with Li and K in the Pb-2-KNb5O15 phases leads to a new composition with chemical composition Pb2-xK1+xLixNb5O15 which crystallizes with tetragonal tungsten bronze-type structure. Ferroelectric ceramics with different compositions were synthesized using solid-state reaction and complex dielectric permittivity measurements in these compounds were performed in a frequency and temperature range of 20 Hz-1 MHz and from 25 to 550 degrees C, respectively. Special attention was paid to the diffuse phase transition (DPT) that occurs close to the Curie temperature. The empirical equation proposed by Santos-Eiras for a phenomenological description of the temperature dependence of the dielectric permittivity (epsilon(r)') peak is used to calculate some characteristic parameters of DPT. From the results, it must be assumed that these compounds show a diffuse phase transition with non-relaxor behavior. A basic phase diagram showing the evolution of T-m function of composition x is deduced from this study.

Domaines: Matière Condensée [cond-mat]

E. Choukri, A. Neqali, Z. Abkhar, A. Alimoussa, L. Hajji, et al.. Investigation of diffuse phase transition in ferroelectric Pb2-xK1+xLixNb5O15 (0 <= x <= 1.5) ceramics. Applied physics. A, Materials science & processing, 2016, 122 (6), pp.570. ⟨10.1007/s00339-016-9616-7⟩. ⟨hal-03627589⟩