Lead-free PTCR ceramics based on ytterbium doped (1 − x)BaTiO3-xBi4Ti3O12

Abstract

Ytterbium (Yb)-doped (1 -x)BaTiO 3 -xBi 4-Ti 3 O 12 (abbreviated as BT-BIT, where x = 0, 0.005, 0.01, 0.015, 0.02 and 0.03) semiconducting ceramics were fabricated by the conventional mixed oxide method, all the samples were sintered in a pure N 2 atmosphere and annealed in air for several hours. The Curie temperature (Tc) firstly increased and then decreased with the increase of BIT, which corresponded to the trend of c/a value. In addition, the effect of Yb 3? on the PTCR was also investigated. It was found that the Curie temperature was shifted to a higher level and the dielectric constant decreased with the increase of Yb 3? .

Barium titanate-based thermistors: Past achievements, state of the art, and future perspectives

“…265 Recently, other lead-free compositions include those based on BIT(1-x)BaTiO 3 -xBi 4 Ti 3 O 12 , doped with Ytterbium have been prepared via a reduction-reoxidation route. 266 Takeda et al studied lead-free Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 (BT-BNT) systems based on the composition and with x ¼ 0.05. La-doped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 [of composition (Ba 1-x (Bi 0.5 Na 0.5 ) x ) 1-y La y TiO 3 with x ¼ 0.05 and y ¼ 0.002-0.005] samples sintered in air, 267 and undoped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 sintered under N 2 reducing conditions, resulted in an increase in the ferroelectric to paraelectric phase transition to approximately 160 C. The La-doped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 samples displayed a much larger PTCR intensity compared to the undoped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 reduced samples, the a values being comparable to the lead-substituted analogs (9-15%/ C).…”

“…La-doped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 [of composition (Ba 1-x (Bi 0.5 Na 0.5 ) x ) 1-y La y TiO 3 with x ¼ 0.05 and y ¼ 0.002-0.005] samples sintered in air, 267 and undoped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 sintered under N 2 reducing conditions, resulted in an increase in the ferroelectric to paraelectric phase transition to approximately 160 C. The La-doped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 samples displayed a much larger PTCR intensity compared to the undoped Ba 1-x (Bi 0.5 Na 0.5 ) x TiO 3 reduced samples, the a values being comparable to the lead-substituted analogs (9-15%/ C). [264][265][266][267][268][269] Applied Physics Reviews REVIEW scitation.org/journal/are…”

Improved Thermoelectric Properties of Hot‐Extruded Bi–Te–Se Bulk Materials with Cu Doping and Property Predictions via Machine Learning

“…Doping is well known as an effective way to enhance thermoelectric properties. The common dopants for Bi 2 Te 3 -based compounds mainly include metals, [13] halogens, [14] and rare earth elements, [15] of which safe and cost-effective element copper (Cu) has been widely employed as an efficient dopant. [16][17][18][19][20][21][22][23] Although remarkable improvements in thermoelectric performance were achieved, different doping levels of Cu significantly affected the microstructure and thermoelectric properties.…”