La³⁺ Substitution for BaBi₂Nb₂O₉ Ceramics

Abstract

A BaBi 2 Nb 2 O 9 (BBN) powder was synthesized by the double-calcination method at 800 C, which considerably suppressed the formation of the stable intermediate Ba 5 Nb 4 O 15 phase. Sintering of the stoichiometric BBN powder at 950 C for 4 h resulted in the production of densified BBN ceramics with a relative density of 90%. The La 3þ substitution was conducted for Ba-deficient BBN powders with nominal compositions of x ¼ 0:03 and 0.10 in Ba 1Àx Bi 2 Nb 2 O 9À , which were pre-formed by the double-calcination method prior to sintering. The result of the phase identification with XRD, microstructural observation and elemental analysis with SEM and TEM, and dielectric permittivity-temperature relationship that were obtained for the La 3þ -doped BBN ceramics suggested that the La 3þ cations could be predominantly substituted for the Ba 2þ -sites in the tetragonal BBN structure.

Low-temperature fabrication of BaBi2Nb2O9 ceramics by reaction controlled sintering

“…In this process, referred to as a reaction controlled process, pre-reacting Bi 2 O 3 and Ta 2 O 5 to form BiTaO 4 prior to the reaction with BaCO 3 led to the production of a BBT powder with a reduced particle size. The present authors applied this process using BiNbO 4 as a precursor to the fabrication of BBN ceramics and obtained the bulk sample with the relative density of 90% by sintering at 950°C for 4 h [10]. This result indicates that modified processes based on the reaction controlled process are a promising approach to further lowering of the sintering temperature of BBN ceramics.…”

Polarization and piezoelectric properties of high-quality (Bi,Na)TiO₃ crystals grown by high-oxygen-pressure flux method

“…Since the use of Pb(Zr,Ti)O 3 in electronic materials would be restricted in the near future due to the toxicity of lead, the development of lead-free ferroelectric and piezoelectric materials with sufficient properties has been strongly demanded from the environmental and economical points of view. Recently, lead-free perovskite ferroelectrics of BaTiO 3 (BT)-based materials [1][2][3] , (Bi, K, Na)TiO 3 [4][5][6][7] , (K, Na)NbO 3 (KNN) [8][9][10] and layered ferroelectrics of SrBi 2 Ta 2 O 9 [11][12][13][14] , Bi 4 Ti 3 O 12 (BiT) [15][16][17][18] , CaBi 4 Ti 4 O 15 [19][20][21][22] and their derivatives [23][24][25] have attracted a great deal of attention as alternative materials of Pb(Zr,Ti)O 3 . KNN [8][9][10] has been recognized as a promising lead-free material, because of its high Curie temperature (T C ) of 420 o C and superior piezoelectric properties.…”