SUPPLEMENTAL MATERIAL:
Probing Bismuth Ferrite Nanoparticles by Hard X-ray Photoemission: Anomalous Occurrence of Metallic Bismuth
Smita Chaturvedi,1 Indranil Sarkar,2 Mandar M. Shirolkar,3 Ranguwar Rajendra,1 Nirmalya Ballav1 and Sulabha Kulkarni1a)
1Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune-411008, India
2DESY Photon Science, Deutsches Elektronen-Synchrotron, 22607 Hamburg, Germany
3Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China,
Hefei, Anhui 230026, People’s Republic of China
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a) Sulabha Kulkarni. Electronic mail:
X RAY DIFFRACTION ANALYSIS
Table 1. Structural parameters obtained from Rietveld refinement of XRD data.
Lattice Parameters / Bond length (Å) / Bond angle (Å)BFO-1
a = 5.573 Å / Bi – O / 1st : 2.398
2nd : 2.071
Δ (1st – 2nd) = 0.327 / O– Bi – O / 68o
c = 13.849Å / Fe – O / 1st : 2.341
2nd : 1.878
Δ (1st – 2nd) = 0.463 / Fe– O– Fe / 155o
V = 372.50 Å3
BFO-2
a = 5.588 Å / Bi – O / 1st : 2.272
2nd : 2.115
Δ (1st – 2nd) = 0.157 / O– Bi – O / 73o
c = 13.861Å / Fe – O / 1st : 2.178
2nd : 1.945
Δ (1st – 2nd) = 0.233 / Fe–O – Fe / 154o
V=374.83 Å3
The Rietveld refinement of the data shows that the BFO samples are well crystallized in a single Rhombohedral phase (R3c) and no impurity phases were present the sample.1,2 The analysis shows that in BFO-1, the lattice parameters (a = 5.573 Å, c = 13.849 Å and V = 372.50Å3) are the contracted compared to bulk BiFeO3.2 While, the lattice parameters of BFO-2 (a = 5.588 Å and c = 13.861 Å) are nearly close to the lattice parameters reported for bulk BiFeO3.1, 2
ROOM TEMPERATURE RAMAN SPECTRA OF BFO-1 AND BFO-2
Sup. FIG. 1. Raman Spectra of samples BFO-1 and BFO-2 performed at room temperature using 532 nm excitation wavelength
SURVEY SCANS OF BFO-1 AND BFO-2
Sup. FIG. 2. Survey scans of samples BFO-1 and BFO-2 for excitation energy 7500 eV
HIGH ENERGY X-RAY PHOTOELECTRON SPECTROSCOPY (HXPES) SPECTRA of Fe 2p for SAMPLES BFO-1 (~ 75 nm) AND BFO-2 (~ 155 nm) NANOPARTICLES
Sup. FIG. 3. HXPES spectra of Fe 2p for samples BFO-1 (A) and BFO-2 (B).
Sup. Fig.3. Shows HXPES spectra of Fe 2p for the samples BFO-1 (A) and BFO-2 (B). For both the samples the pure Fe2p doublet consists of two wide peaks of Fe 2p3/2 (710.7 eV) and Fe 2p1/2 (724.2), which are mainly due to Fe-O bonds for Fe2+ in oxygen octahedra or other relaxed Fe phase.3,4,5 Spin orbit splitting energy of pure Fe 2p doublet is 13.5 eV, which is close to theoretical value (ΔFe 2p) of 13.6 eV for Fe2O3.4
HIGH ENERGY X-RAY PHOTOELECTRON SPECTROSCOPY (HXPES) SPECTRA of O 1s for SAMPLES BFO-1 (~ 75 nm) AND BFO-2 (~ 155 nm) NANOPARTICLES
Sup. FIG. 4. HXPES spectra of O 1s for samples BFO-1 (A) and BFO-2 (B).
Sup. Fig. 4 shows HXPES spectra of O 1s for the samples BFO-1 (A) and BFO-2 (B). Both the spectra show Broad O1s peak at 529.7 eV, which is consist of three subpeaks located at 528.8, 529.7 and 531 eV ( subpeaks more evident for sample BFO-2). These peaks are mainly ascribed to Fe2 – (O 1s)3 (529.6 eV), Fe – (O 1s) (529.8 eV)4 and 531 eV peak can be ascribed to relaxed O phase, associated with oxygen vacancies and surface species (H2O and CO2) likely to absorbed from the air during the sol-gel process.4
MAGNETIZATION MEASUREMENTS (M - H) OF BFO-1 AND BFO-2 NANOPARTICLES AT 5 K AND 300K
Sup. FIG. 5 (A). Magnetization for samples BFO-1 and BFO-2 measured at 5 K (a) and 300 K (b) and magnified view representing coercivity as well as shifting in the hysteresis loops at 5 K (c) and 300 K (d)
Sup. FIG. 5 (B). Magnified view of magnetization representing coercivity as well as shifting in the hysteresis loops at 5 K and 300 K for sample BFO-1 (a) and (b) and for sample BFO-2 (c) and (d)
REFERENCES (Supplemental Material)
1 S. Chaturvedi, M. M. Shirolkar, R. Rajendra, S. Singh, N. Ballav and S. K. Kulkarni, J. Appl. Phys. 115, 123906 (2014).
2 F. Kubel and H. Schmid, Acta Cryst. B46, 698-702, (1990).
3 B.S. Zhang, Z.C. Quon, T.J.Zhang, T. Gao and S.B. Mo, J.Appl. Phus.101,01407 (2007).
4 J.F. Moulder, W.F.Stickel, P.E. Sobol and K.D. Bomben, Handbook of X ray Photoelectron Spectroscopy, Perkin –Elmer Corporation, Minnesota (1992).
5 Y.Wang, Q.H. Jiang, H.C. He and C.W. Nan, App. Phys. Lett. 88, 142503 (2006).
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