A family of ferroelectric bismuth compounds

High performance Aurivillius type Na0.5Bi4.5Ti4O15 piezoelectric ceramics with neodymium and cerium modification

“…But tanδ increases with the further increasing amount of (Nd,Ce) modification due to the enlarged lattice distortion and the increased oxygen vacancies in the perovskite layer. The piezoelectric coefficient d 33 of NBT-0.2 is found to be 28 pC/N, the highest value among the NBT-based ceramics, which is also higher than those of other reported BLSF systems [1][2][3]13,24]. The enhancement of the piezoelectric activities can be attributed to induced lattice distortion, increased density and decreased dielectric loss tanδ.…”

“…Shimakawa et al [28,29] suggested that T C of the Aurivillius phase materials depends strongly on the crystal structure distortion. The decrease of T C is due to the lattice distortion [1][2][3]28,29], the electronic configuration [30], the decrease of electronegativity [31] (Nd 1.14, Ce 1.12, Bi 2.02) and the Bi amounts [1][2][3]31] in NBT piezoelectric ceramics by the A-site Nd 3+ and Ce 3+ co-substitution for Bi 3+ . With the increasing of (Nd,Ce) content, the dielectric peak values decrease and the dielectric maximal peak becomes broad, as shown in Fig.…”

“…Aurivillius first reported that the family of bismuth layer-structured ferroelectrics (BLSFs) shows interesting physical properties [1][2][3]. The BLSFs have a structure expressed by the general formula of (Bi 2 O 2 ) 2+ (A m1 B m O 3m+1 ) 2 , which consists of pseduo-perovskite (A m1 B m O 3m+1 ) 2 layers interleaved with bismuth oxide (Bi 2 O 2 ) 2+ layers along the c-axis.…”

“…In the general formula of Aurivillius family, A is a mono-, di-or trivalent ion (or their combination) such as Na + , Ba 2+ , Ca 2+ , Sr 2+ or Bi 3+ , B is a transition element suited to octahedral coordination such as Ti 4+ , Ta 5+ , Nb 5+ or W 6+ , and m is the number of BO 6 octahedral (m = 1-5) [4][5][6]. Compounds of this group such as Bi 2 [1][2][3][4]7]. NBT piezoelectric ceramic system chosen herein is due to its high Curie temperature and outstanding piezoelectric and electromechanical properties [8].…”

“…NBT piezoelectric ceramic system chosen herein is due to its high Curie temperature and outstanding piezoelectric and electromechanical properties [8]. At room temperature NBT is orthorhombic with a = 5.427 Å, b/a = 1.006 and c = 40.650 Å, and undergoes a ferro-to para-electric (orthorhombic A2 1 am to tetragonal  I4/mmm) phase transition at T C = 655 ℃ [1][2][3]7]. In addition, NBT is a classical ferroelectric with a sharp maximum of the dielectric permittivity close to T C .…”