Raman vibrations and photovoltaic conversion in rare earth doped (Bi0.93RE0.07)FeO3 (RE=Dy, Gd, Eu, Sm) ceramics. Issue 1 (January 2016)

• Record Type: Journal Article
• Authors: Chang, Li-Yun; Tu, Chi-Shun; Chen, Pin-Yi; Chen, Cheng-Sao; Schmidt, V.H.; Wei, Hsiu-Hsuan; Huang, Ding-Jie; Chan, Ting-Shan
• Is Part Of: Ceramics international. Volume 42:Issue 1:Part A(2016)
• Page Start: 834
• Page End: 842
• Publication Date: 2016-01
• Subjects: Rare-earth doped BiFeO3 ceramics -- Raman vibration -- Structure -- Optical band gap -- Photovoltaic conversion; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2015.09.005
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: High-resolution Raman spectra, X-ray diffraction, oxygen vacancies, synchrotron X-ray absorption spectroscopy, magnetization, optical band gap, and photovoltaic (PV) conversion have been studied in BiFeO3 (BFO) and (Bi0.93 RE0.07 )FeO3 (RE=Dy, Gd, Eu and Sm) multiferroic ceramics (7%Dy–BFO, 7%Gd–BFO, 7%Eu–BFO, and 7%Sm–BFO). 7%Dy–BFO exhibits a weak ferromagnetic behavior instead of the linear antiferromagnetic responses found in the other compounds. Optical transmissions reveal band gaps of 2.20–2.21 eV, which are slightly smaller than 2.24 eV in pure BFO. The current vs. voltage ( I – V ) characteristic curves of indium tin oxide (ITO)/(Bi0.93 RE0.07 )FeO3 ceramics/Au heterostructures suggest a p – n -junction-like behavior. The maximal PV power-conversion efficiencies under illumination of λ =405 nm in ITO/7%Dy–BFO/Au, ITO/7%Gd–BFO/Au, ITO/7%Eu–BFO/Au, and ITO/7%Sm–BFO/Au respectively reach 0.22%, 0.35%, 0.27%, and 0.24%, which are much larger than 0.017% in ITO/BFO/Au. The PV open-circuit voltage and short-circuit current can be reasonably described by a junction model as a function of illumination intensity.