Synthesis and Electrical Properties of the Pr_0.5+x−yBi_yLi_0.5−3xTiO₃ System

Abstract

The stoichiometry, polymorphism, and electrical behaviour of the solid solutions Pr 0.5+x−y Bi y Li 0.5−3x TiO 3 with perovskitelike structure have been studied. Data are given as a solid solution triangle, XRD patterns for two polymorphs T and O, the composition dependence of their parameters, and ionic conductivity plots. A region of perovskite-like solid solutions was obtained when the bismuth content in the general formula Pr 0.5+x−y Bi y Li 0.5−3x TiO 3 was y Յ 0.10 and the lithium IntroductionThere has been much recent interest in the development of novel ionic conductors as solid electrolytes in lithium batteries.[1Ϫ12] Fast ionic conductors with the general formula RE 0.5ϩx Li 0.5Ϫ3x TiO 3 , where RE ϭ La, Pr, Nd, and Sm have been reported, [7Ϫ12] for which the maximum conductivity was for the La series (1.1·10Ϫ3 S·cm Ϫ1 for x ϭ 0.07 at room temperature). [7] More recently the phase diagram, crystal chemistry, and ionic conductivity of the system La 0.5ϩxϪy Bi y Li 0.5Ϫ3x TiO 3 have been reported.[13] The compounds of this system are ionic conductors whose conductivity increases as the amount of lithium increases, up to x ϭ 0.075, but decreases when the amount of bismuth increases. The system with Bi needs less time in the thirst treatment at 1250°C than a similar system without bismuth. [13] We aimed to investigate the stoichiometry range, crystal chemistry, and electrical behaviour of materials of the general formula Pr 0.5ϩxϪy Bi y Li 0.5Ϫ3x TiO 3 and to establish the phase diagram at room temperature of the system Pr 0.67 TiO 3 /Pr 0.5 Li 0.5 TiO 3 /Bi 0.5 Li 0.5 TiO 3 . XRD patterns of perovskites with different Li and Bi contents have been analyzed and a study of the thermal treatment time with the [a] content was 0.033 Յ x Յ 0.133. The compounds are mixed conductors. With increasing amounts of lithium the ionic conductivity first increased, reached a maximum for x = 0.20, with a conductivity at 25°C of 6.639·10 −3 S·cm −1 , and then decreased.

Comparison of the electrical properties of the new conductor Pr0.5Bi0.05Li0.35TiO3 prepared by sol–gel and ceramic methods

“…The system RE 0.5+x-y Bi y Li 0.5-3x TiO 3 with RE: La [7] and Pr [8,9] has been reported. The materials were prepared using a ceramic method and showed perovskite-like structure and lithium conductivity.…”

Síntesis y caracterización del conductor iónico La0.43Ce0.1Li0.30TiO3.

“…Note that this structure is different to the tetragonal in reference (Fernández 2012, 59) as the low temperature sol-gel synthesis leads always to the tetragonal polymorph. This transformation ortorhombic-tetragonal is reversible and it is associated with the A-site cation ordering (Martínez 2003(Martínez , 2458. Table I The cell parameters calculated from the diffraction data are a = 3.8690 (4) Electric properties.…”

“…This fact is related to the decreasing of unit cell size due to the introduction of a smaller size cation. The reduction of cell parameters shrinks the bottleneck and raises the activation barrier for ionic movement (Martínez 2003(Martínez , 2458. As a rule, none of these substitutional related solids improve the maximum conductivity value previously reported.…”

“…The chemicals were weighed in proper quantities, mixed in an agate mortar with acetone, dried, and heated to 600-700 °C for 2 h to remove CO 2 . After ground up, the samples were pressed into pellets placed in folded platinum foil containers, covered with powder of the same composition and with another platinum foil as stopper to minimize the loss of lithium during thermal treatments (Martínez 2003(Martínez , 2458. hours, giving green products that were reground, repelleted and heated at 1200 ºC during 14 hours.…”

Preparation, Stability and Thermodynamic Properties of Nd‐ and Lu‐Doped BaCeO3 Proton‐Conducting Ceramics

“…[1][2][3][4][5][6][7][8][9][10] Rare-earthdoped barium cerates with high protonic conductivity have a wide range of technological applications in fuel cells, sensors, batteries, electro catalysis devices, etc. The investigation of proton conductivity in perovskite ceramics started more than 20 years ago.…”