Piezoelectric properties and dielectric behavior of Bi1/2Na1/2[Ti1−x (Sb1/2Nb1/2) x ]O3 lead-free piezoelectric ceramics

Abstract

New lead-free piezoelectric ceramics of ABO 3 perovskite type, Bi 1/2 Na 1/2 [Ti 1−x (Sb 1/2 Nb 1/2 ) x ]O 3 , were synthesized by conventional solid state reaction. The effect of the replacement of complex ions of (Sb 1/2 Nb 1/2 ) 4+ in the B cationic site on structural and electrical properties was investigated. The XRD analysis showed that all samples exhibited a single phase of perovskite structure. Piezoelectric and dielectric measurement revealed that the substitution of (Sb 1/2 Nb 1/2 ) 4+ ions lead to an increase in piezoelectric constant(d 33 ), electromechanical coupling factor(k t ), relative dielectric constant(ɛ r ),and loss tangent (tanδ), while excess of (Nb 1/2 Sb 1/2 ) 4+ ions results in a decrease in d 33 , k t , ɛ r , but an increase in tanδ. Temperature dependence of dielectric constant ɛ r measurement indicated these compounds were relaxor ferroelectric. At low frequency and high temperature, dielectric constant increased sharply attributed to the superparaelectric clusters after (Sb 1/2 Nb 1/2 ) 4+ ions substitution.

Piezoelectric and ferroelectric properties of (Bi0.94−xLaxNa0.94)0.5Ba0.06TiO3lead-free ceramics

“…From figures 6(a)-(c), the ceramics with x = 0, 0.02 and 0.04 exhibit two dielectric anomalies at T d and T m , respectively. T d is the depolarization temperature which corresponds to the transition from a ferroelectric state to the so-called 'anti-ferroelectric' state [5][6][7][8][9][10][11][12][13][14][15][16][17], while T m is the maximum temperature at which ε r reaches a maximum value and corresponds to a transition from an 'anti-ferroelectric state' to a paraelectric state. However, as shown in figures 6(d)-(f ), for the ceramics with a high La 3+ level (x = 0.06, 0.08 and 0.10), only the high dielectric anomaly at T m can be observed, while the phase transition at T d disappears.…”

“…However, a pure BNT ceramic is difficult to fully pole due to a high coercive field (E c = 7.3 kV mm −1 ) and thus exhibits much weaker piezoelectric properties (d 33 = 58 pC N −1 ) [2] compared with pure Pb(Zr 0.52 Ti 0.48 )O 3 ceramics (d 33 = 223 pC N −1 ) [3]. To improve the electrical properties of BNT, a number of BNT-based solid solutions, such as BNT-Bi 0.5 K 0.5 TiO 3 -KNbO 3 [4], BNT-Bi 0.5 K 0.5 TiO 3 [5][6][7], (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 Zr y Ti 1−y O 3 [8], BNT-NaNbO 3 [9], BNT-KNbO 3 [10], Bi 0.5 Na 0.5 Ti 1−x (Sb 0.5 Nb 0.5 ) x O 3 [11], BNT-(Ba,Sr,Ca)TiO 3 [12], Bi 0.5 (Na 1−x−y K x Li y ) 0.5 TiO 3 [13],…”