Structure and properties of Bi2Ti2O7 pyrochlore type phase stabilized by lithium

JOURNAL OF ALLOYS AND COMPOUNDS

卷:732

Article

Lelievre, Jerome¹  Marchet, Pascal¹ 

[1] Univ Limoges, SPCTS UMR 7315, Ctr Europeen Ceram, 12 Rue Atlantis, F-87068 Limoges, France

关键词: Pyrochlore;    Solid state reaction;    Li2O-Bi2O3-TiO2 phase-diagram;    Neutron diffraction;    Dielectric response;    Ionic conduction;   

DOI  :  10.1016/j.jallcom.2017.10.128

来源: Elsevier

【 摘 要 】

A study of the Li2O-Bi2O3-TiO2 ternary system evidenced a Bi2Ti2O7 pyrochlore phase in a large range of composition, centered on (Li1/2Bi1/2) TiO3 (LBT). This composition led to a pyrochlore phase stable up to 1100 degrees C, while pure Bi2Ti2O7 phase has been reported as metastable, with decomposition temperature around 600 degrees C. According to previous studies, this pyrochlore phase was not obtained without lithium and here only a few percent of lithium was necessary for stabilization. The structural study, performed by neutron diffraction, evidenced a cubic Fd (3) over barm structure (a = 10.317 angstrom), similar to the one of pure Bi2Ti2O7 pyrochlore phase. The Li-ion is probably located on the Bi-site and is responsible for the stabilization of the pyrochlore structure. The electrical properties of the LBT composition were studied and appeared as very similar to the one of pure Bi2Ti2O7. Because of its large thermal stability range, this pyrochlore phase appears to be a promising material for dielectric or tunability applications. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free