Investigation of structural and optical spectroscopy of 5 % Pr doped (Bi0.5Na0.5) TiO3 ferroelectric ceramics: site depended study

Abstract

In this paper we report the structural and optical characterisation of 5 % Pr doped (Bi 0.5 3? Na 0.5 ? ) A Ti B O 3 (BNT) in A and B site of a distorted perovskite structure. The samples of pure and doped BNT were synthesized successfully by conventional solid state sintering method. The samples were sintered at 1100°C for 3 h. The sintered samples are subjected to structural and optical spectroscopy analysis such as Raman, Fourier Transform Infra red (FTIR) and Photoluminescence (PL). The XRD analysis show Pr doping of 5 % causes change in the lattice parameter and a significant change in the structure. In conjunction to XRD, Raman result shows a local structure distortion, in the region of 200-600 cm -1 , which confirms the formation of cluster type phase on Pr doping in both A and B site. Also, the degree of distortion in the structure is significantly high in the case of B site doping. This is confirmed in both XRD and Raman spectra. The UV-Vis spectra shows that Pr doping causes a red shift in the BNT band gap energy due to local distortion in A and B site doping. The PL emission observed at the excitation of 360 nm shows an intense red band on A site Pr doping, were the emission intensity decreases on B site doping. The observed results are discussed and reported.Electronic supplementary material The online version of this article (

Structural, Ferroelectric, Pyroelectric, and Dielectric Study of Bi0.5Na0.5TiO3 Ceramics synthesized with Precursors Obtained by Sol-Gel Method doped with Lanthanum

“…This result was achieved thanks to the encapsulation stage during the sintering process, without the need to add excess Na to compensate for its volatilization, when encapsulation is not included. The crystalline phase identified according to the crystallographic file (ICDD-PDF # 36-0340) for pure BNT corresponds to the R3c Rhombohedral structure [9,28,29].…”

“…D. Shannon [30] reports the next ionic radius for Na + (rNa=1.39Å, CN=12), La 3+ (rLa=1.36Å, CN=12) and for Bi 3+ only gives ionic radii for coordination 8, Bi 3+ (rBi=1.17 CN=8). In coordination XII Blessington et al [29] report a value of 1.36 Å for Bi, Liu et al and F. Yang et al [31.32] report a value of 1.38 and 1.39 Å respectively. As can be seen, the ionic radius are very close and taking in consideration the oxidation state of La 3+ then the probability to the La 3+ occupy Bi 3+ sites in the lattice is higher than occupy sites of Na, where a disbalance charge 2+ is expected.…”

“…The Raman spectra at room temperature using an excitation line of argon ion laser at 488.0 nm for the set of sintered samples are showed in Fig. 5-a stretching and breathing vibrations of the octahedral TiO6 [29]. Finally, the band LO3 in the highest frequency Raman modes located at 770 and 830 cm -1 which can be correlated to oxygen vacancies.…”

“…The Raman active phonon modes expected for a rhombohedral R3c phase with A-site disorder (e.g. Bi/Na sites into BNT system) are 13, 4A1+9E, actives also in IR [29,[38][39][40][41][42][43]. On the other hand, the cubic paraelectric phase (Pm3m) has four optical modes 3F1u+1F2u where only 3 modes with F1u symmetry are IR active and F2u is a silent mode, in principle those modes are not Raman actives modes [38,39], nevertheless, the distortions in the lattice, impurities and vacancies can give place to Raman bands in the cubic phase.…”

Fabrication, dielectric and electrical characteristics of 0.94 (BI0.5Na0.5)TiO3-0.06 BaTiO3 ceramics

“…The bands in the region of 500-850 cm -1 are generally used to find out the stretching vibration of Ti-O bond of the octahedral site in perovskite structure [20]. The bands at 634 and 857 cm -1 are assigned to the intrinsic vibrational mode of BNT [21]. The H-O-H bending mode appears at 1708 cm -1 .…”