International Journal of Research in Engineering and Innovation Vol-1, Issue-6 (2017), 57-59 __________________________________________________________________________________________________________________________________ International Journal of Research in Engineering and Innovation (IJREI) journal home page: http://www.ijrei.com ISSN (Online): 2456-6934 _______________________________________________________________________________________ Corresponding author: Abdelali laaraj Email Id: abdelali.laaraj@gmail.com 57 Elaboration and characterization of the tetragonal tungsten bronze ferroelectric Sr 2(1-x) Na (1+x) Gd x Nb 5 O 15 Abdelali laaraj 1 , Youssef Guaaybess 1 , El moussafir El miloudi 1 , Loubna Zerhouni 1 , Bouazza Tbib 2 , Rahma Adhiri 1 and Mohammed Moussetad 1 1 University of Hassan 2st, Faculty of sciences Ben M’sik, Laboratory of engineering and materials, Casablanca, Morocco 2 University of Hassan 1st, Faculty of Khouribga, Laboratory of Nanosciences and Modeling, Khouribga, Morocco ____________________________________________________________________________________________________________________ Abstract The nanopowders ferroelectric Sr2(1-x)Na(1+x)GdxNb5O15 was synthesized by solid-state method, were prepared by the precursor calcination at 1200 o C during 24 hours in oxygen atmosphere and by a high-temperature solid-state reaction technique. The structural characterization of Sr2(1-x)Na(1+x)GdxNb5O15 nanopowders was carried out by the X-ray diffraction. The profile of adjusting of the set of diffraction lines and refinement of the structural parameters were performed by the Rietveld method, using the FULLPROF program. The results reveal an orthorhombic phase, with space group Pmmm for 0 ≤ x ≤ 0.8 and a tetragonal phase, with space group P4mm, for 0.9 ≤ x ≤ 1. © 2017 ijrei.com. All rights reserved Keywords: Solid-state, X-ray diffraction, Space group, Ferroelectric _______________________________________________________________________________________ 1. Introduction Niobates with a tetragonal tungsten bronze (TTB)-type structure are of great scientific, technical, and industrial interest as materials for laser modulation, frequency multiplicity, and the generation of second harmonics for applications in pyroelectric detectors and piezoelectric transducers [1]. The tetragonal tungsten bronze-type structure (TTB) can be considered as a derivative of the classical perovskite one. It can be described by the chemical formula (A1)2(A2)4C4Nb10O30. A1, A2, and C denote different sites in the crystal structure. The A1 cavities have a cuboctahedral coordination of oxygen atoms, the A2 cavities a Penta capped pentagonal prismatic, and the C cavities a tricapped trigonal prismatic one. The size of these cavities decreases in the order A2 > A1 > C. In this work, we report the growth and structural characterization of the new family of ferroelectric compounds of TTB type Sr2(1-x)Na(1+x)GdxNb5O15 (SNGN) as a function of x (0 ≤ x ≤ 1). The aim of this work is the study of symmetry changes as a function of gadolinium (Gd 3+ ) concentration in SNGN compounds. 2. Sample preparation Sodium strontium niobate, Sr2(1-x)Na(1+x)GdxNb5O15 , was synthesized by solid-state method. Crystalline Nano powders were obtained by the precursor calcination at 1200 o C during 10 hours in oxygen atmosphere. The powder obtained from this calcination was characterized by X-ray diffraction (XRD). The diffraction pattern was refined in according to the Rietveld method. The refinement was performed using the program Full prof. The reason for having interest in the TTB family, it has been found that their physical properties can be modified by different ionic substitution at above mentioned sites [2]. The ferroelectric niobate materials with TTB structure are quite attractive materials due to their remarkable electro-optic, pyroelectric, piezoelectric, nonlinear optical properties [3].