Effect of the lanthanum concentration on the physical properties of the (Bi0.5Na0.5)0.92Ba0.08-3/2La TiO3 ceramic system

Raman spectroscopy study of the La‐modified (Bi0.5Na0.5)0.92Ba0.08TiO3 lead‐free ceramic system

“…These supplementary modes have been associated with a structural change with relation to the pure BNT (with rhombohedral symmetry R3 c ), being attributed to the coexistence of phases in BNT–BT‐based systems, such as (1– x )BLNT–( x )BCT, Er‐modified 0.93Bi 0.5 Na 0.5 TiO 3 –0.07BaTiO 3 , and other (1– x )BNT–( x )BT compositions . Recently, the structural properties reported for the BNLBT–0 ceramic system from X‐ray diffraction revealed the coexistence of both ferroelectric (P4 mm ) and AFE (P4 bm ) tetragonal phases . Additionally, a phases coexistence has also been reported for other lead‐free compounds, such as BNT‐related systems as well as other bulk solid solutions, for compositions close to the MPB region.…”

“…The structural results after Rietveld refinements revealed the major contribution of the P4 mm ferroelectric phase (94.8%) for the BNLBT–0 composition. Meanwhile, a decrease of the weight percent corresponding to the P4 bm AFE phase and an increase to the R3 c ferroelectric phase have been reported for the modified samples . The weight percent's values for each phase are listed in Table S1 for all compositions.…”

“…The weight percent's values for each phase are listed in Table S1 for all compositions. The dielectric analysis revealed three anomalies in the temperature dependence of the dielectric permittivity, which have been associated with different phase transitions . On the other hand, the temperature and frequency dependences of the hysteresis loops have suggested an important dependence of the stability of either ferroelectric or AFE phase on the temperature, frequency and the lanthanum concentration …”

“…Recent studies on structural, dielectric, and ferroelectric properties have been reported for pure and lanthanum‐modified (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08 TiO 3 ceramics . A mixture of both AFE (P4 bm ) and ferroelectric (P4 mm ) tetragonal phases has been reported for the pure sample, whereas for the doped ceramics, it has been revealed the coexistence of both AFE (tetragonal, P4b m ) and ferroelectric (rhombohedral, R3 c ) phases .…”

“…The confirmation of the phase's coexistence from the Raman spectroscopy results is very important from the fundamental point of view, because it allows to study the relationship between the microstructure and the macroscopic physical properties for the compositions near the MPB. Therefore, considering the previous X‐ray diffraction results as well as the dielectric and electrical properties reported for the (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08‐3 x /2 La x TiO 3 ceramics ( x = 0, 1, 2, and 3 at.%), the structural properties have been investigated in this work from Raman spectroscopy, at room temperature (25°C), in order to evaluate the evolution of the crystal structure. The influence of the lanthanum content on the vibration modes spectra has been analyzed in detail.…”