Ferroelectric properties of Li‐doped BaTiO₃ ceramics

Abstract

We prepared 3 kinds of Li + -doped BaTiO 3 ceramics by the solid-state reaction method: (i) (Ba 1Àx Li x )TiO 3Àx/2 having A-site Li + , (ii) Ba(Ti 1Àx Li x )O 3À3x/2 having B-site Li + , and (iii) x/2 Li 2 CO 3 +BaTiO 3 mixed one, for which we investigated the stable site of Li. The density of all prepared ceramics is above 95%. The results show that the lattice structure, the grain size, and the electric properties of Li + -doped BaTiO 3 ceramics are dependent on Li + site. According to the increase in Li content, the cell volume of Ba 1Àx Li x TiO 3Àx/2 decreases, but that of BaTi 1Àx Li x O 3À3x/2increases. That of x/2Li 2 CO 3 +BaTiO 3 decreases by the small addition of Li, but increases by the large addition of Li. All Li + -doped ceramics show antiferroelectriclike double hysteresis loops. The shape of loops and the dielectric properties are also dependent on the Li site. We suggest that the role of oxygen vacancy accompanied by the Li-doping is important. By comparison with the results of 3 type ceramics, it is concluded that at x/2Li 2 CO 3 +BaTiO 3 ceramics, the Li + prefers to favorably substitute Ba 2+ at A site for the low concentration of Li but its location was changed to Ti 4+ site for the high concentration of Li.

Multifunctional barium titanate ceramics via chemical modification tuning phase structure

“…Two types of diffused behavior can be observed in the temperature dependence of dielectric constant ( ε r ‐ T ) curves, as shown in Figure 2E. For monovalent‐ion substitution such as Li + , Na + , K + , etc., 63‐66 the T C of BT is basically unchanged, while a suppressed dielectric constant at T C can be found. These ions mainly result in the shifting of T R‐O and T O‐T to low temperature and make ferroelectric R‐O and O‐T phase transitions diffusion (Type 1, Figure 2E1), 65,66 implying a certain degree of breaking in long‐range ferroelectric orders but the still remained ferroelectric phase.…”

“…Other schemes utilizing aliovalent cations substitution also exhibit the positive effect on piezoelectric improvement. For example, A‐site substitution by Li + or adding its compounds as the sintering aids can elevate the d 33 of BT to ~190‐340 pC/N even in a low sintering temperature 46,63,111,112 . The small ionic radii with high mobility of Li + can facilitate ceramic densification and improve its sinterability, which is responsible for the piezoelectric improvement.…”

“…Another situation is when the mixed peak drops below RT , a rapid decrease in ε r at RT will occur, such as A‐site Sr 2+ and some rare earth ions (eg, Sm 3+ ), B‐site Zr 4+ , Hf 4+ or Sn 4+ , and other substitutions with similar effect. The only distinction is the difference on their doping content, as displayed Figure 12A‐C 54,56,59,61,63,70,153,157,163,207‐209 . Dielectric capacitors based on BT‐based ceramics (eg, X7R, X8R, X9R) require high ε r with excellent temperature and frequency stabilities.…”

Synthesis of Bi0.5Li0.5TiO3 Nanoparticles by Sol-Gel Method for Photocatalytic Methylene Blue Degradation and Antibacterial Activity

“…Compared with other semiconductors, ABO 3 materials exhibit several advantages in photocatalysis due to their large scope to design, tunable band gap, and other photophysical properties attributed to the A and B cations [20]. BaTiO 3 , BiTiO 3 , and BiFeO 3 , known as a class of ferroelectric materials, were also considered in photocatalytic applications [21][22][23][24][25]. The use of BiFeO 3 /ZnFe 2 O 4 nanocomposites was reported for the photocatalytic degradation of organic dyes under visible light irradiation [26].…”

Excellent piezoelectric properties of PNN‐PHT ceramics sintered at low temperature with CuO addition

“…Till date, copper (II) oxide (CuO), ZnO, Bi 2 O 3 , LiF, Li 2 CO 3 , LiBiO 2 , CuF 2 , etc. have been reported for reducing the sintering temperature …”