Band-gap narrowing and magnetic behavior of Ni-doped Ba(Ti0.875Ce0.125)O3 thin films. (14th October 2015)

• Record Type: Journal Article
• Authors: Zhou, Wenliang; Deng, Hongmei; Yu, Lu; Yang, Pingxiong; Chu, Junhao
• Is Part Of: Journal of physics. Volume 48:Number 45(2015)
• Publication Date: 2015-10-14
• Subjects: ferroelectrics -- thin films -- structure distortions -- band-gap narrowing -- magnetic property; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/45/455308
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Band-gap narrowing and magnetic effects have been observed in a Ni-doped Ba(Ti0.875 Ce0.125 )O3 (BTC) thin film. Structural characterizations and microstructural analysis show that the as-prepared Ba(Ti0.75 Ce0.125 Ni0.125 )O3− δ (BTCN) thin film exhibits a cubic perovskite structure with an average grain size of 25 nm. The Ce doping at the Ti-site results in an increasing perovskite volume to favour an O-vacancy-stabilized Ni 2+ substitution. Raman spectroscopy, however, shows the cubic symmetry of crystalline structures is locally lowered by the presence of dopants, significantly deviating from the ideal Pm 3 m space group. Moreover, BTCN presents a narrowed band-gap, much smaller than that of BaTiO3 and BTC, due to new states of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital in an electronic structure with the presence of Ni. Also, magnetic enhancement driven by co-doping has been confirmed in the films, which mainly stems from the exchange interaction of Ni 2+ ions via an electron trapped in a bridging oxygen vacancy. These findings may open an avenue to discover and design optimal perovskite compounds for solar-energy devices and information storage.