Dielectric properties of lead-free solid solution of Bi_0.487Na_0.487La_0.017TiO₃and BaTiO₃

Abstract

Bismuth sodium titanate (Bi 0.5 Na 0.5 TiO 3 ; BNT) is one of the most preferred materials for the preparation of lead-free ceramics; however its dielectric property is lower than that of lead-based materials. Thus, the substitution of A and B-site cations is considered to be one of the best solutions in order to improve both the dielectric and piezoelectric properties. In this study, lead-free ceramics from bismuth sodium lanthanum titanate (Bi 0.487 Na 0.487 La 0.017 TiO 3 ; BNLT) and barium titanate (BaTiO 3 ; BT) systems were prepared by a modified two-step mixed oxide method. BT powder was added to BNLT powder with the desired compositions of (1 À x)BNLT-xBT, where x ¼ 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10. It was found that the addition of BT in the BNLT improved the electrical properties of ceramics. Phase transition of rhombohedral to tetragonal structure was significantly dependent on the amount of BT added. It was also found that the change in crystal structure affected the ferroelectric property of the ceramics where the transition from ferroelectric to antiferroelectric started from the samples with x ! 0.06 mol% and higher. This may be useful in terms of using these materials in the desired applications.

Effect of KNbO3 on physical and electrical properties of lead-free BaTiO3 ceramic

“…The result indicates that the addition of KN causes a decrease in dielectric loss. This is because that niobium reduces the concentration of oxygen vacancies as shown in equation (6). When Nb 5+ ion diffused into BT ceramics, the defect…”

“…Much effort has been expended to improve the dielectric properties by way of substitution for the host cations perovskite lattice. Various BaTiO 3 -based solid solutions have been developed, such as Ba(ZrTi)O 3 [3][4][5], Ba(Bi 0.5 Na 0.5 )TiO 3 [6][7], (Ba,Sr)TiO 3 [8], Bi 0.5 Na 0.5 TiO 3 -KNbO 3 [9]. Potassium niobate, KNbO 3 is the ferroelectric material that shows the same phase symmetries and the same sequence of transition as BaTiO 3 .…”

The effect of BZT doping on phase formation, dielectric and ferroelectric properties of BNLT ceramics

“…BNLT exhibited relaxor ferroelectric behavior with the diffuse phase transition (DPT) [4,13]. The BNLT ceramic showed the dielectric anomalies at T p and T m of 195 and 345°C, respectively [6]. The BZT ceramic were found to exhibit relatively high piezoelectric constant (d 33 = 236 pC/N) as compared to other lead-free ferroelectric materials [36].…”

“…In perovskite materials, the normal and relaxor ferroelectric behaviors are exhibited in both lead-based and leadfree compounds [1][2][3][4][5][6][7]. Because their excellent piezo-/ferroelectric properties, they are promising for applications as electronic devices such as multilayer capacitors, piezoelectric sensors and actuators, and ferroelectric-based random access memories (FeRAMs) [8][9][10].…”

“…However, the toxicity of PbO, which is a potential threat to our health and environment, is the major drawback of Pb-based materials [11,12]. In order to avoid the use of PbO, many researchers have focused on finding alternative Pb-free piezoelectric materials [3][4][5][6]. The BNT-based material, which is one of Pb-free ferroelectrics, has been widely studied due to the electromechanical properties possible to be improved and using instead Pb-based ceramics [13][14][15].…”