Effect of Co substitution on the structural, dielectric and optical properties of KBiFe₂O₅

Abstract

Cobalt (Co)-modified brownmillerite KBiFe₂O₅ (KBFO; [KBiFe_2(1-x)Co_2xO₅ (x = 0, 0.05)]) polycrystalline is synthesized following the solid-state reaction route. Rietveld refinement of X-ray diffraction data confirmed the phase purity of KBFO and KBiFe_1.9Co_0.1O₅ (KBFCO). The optical bandgap energy (E _g) of KBFO decreased from 1.59 to 1.51 eV because of Co substitution. The decrease in bandgap can be attributed to the tilting of the Fe-O tetrahedral structure of KBFCO. The observed room-temperature Raman peaks of KBFCO shifted by 3 cm^-1 toward a lower wavenumber than that of KBFO. The shift in Raman active modes can be attributed to the change in the bond angles and bond lengths of the Fe-O tetrahedral structure and modification in response to oxygen deficiency in KBFO because of Co doping. Compared with that of KBFO, the frequency-dependent dielectric constant and dielectric loss of KBFCO decrease at room temperature, which is a consequence of the reduction in oxygen migration and modification in response to vibrational modes present in the sample.

Keywords

brownmillerite / rietveld refinement / Raman spectroscopy / bandgap

References

[1] Fiebig M, Lottermoser T, Meier D, Trassin M. The evolution of multiferroics. Nat. Rev. Mater., 2016, 1, 16046.

[2] Mettout B, Tolédano P, Sombra ASB, Furtado Filho AFG, do Nascimento JPC, Santos da Silva MA, Gisse P, Vasseur H. Magnetoelectric, photovoltaic, and magnetophotovoltaic effects in KBiFe₂O₅. Phys. Rev. B, 2016, 93(19): 195123.

[3] Zhang GH, Wu H, Li GB, Huang QZ, Yang CY, Huang FQ, Liao FH, Lin JH. New high Tc multiferroics KBiFe₂O₅ with narrow band gap and promising photovoltaic effect. Sci. Rep., 2013, 3, 1265.

[4] Jalaja MA, Dutta S. Switchable photovoltaic properties of multiferroic KBiFe₂O₅. Mater. Res. Bull., 2017, 88, 9.

[5] Vavilapalli DS, Srikanti K, Mannam R, Tiwari B, K MK, Rao MSR, Singh S. Photoactive brownmillerite multiferroic KBiFe₂O₅ and its potential application in sunlight-driven photocatalysis. ACS Omega, 2018, 3(12): 16643.

[6] Jalaja MA, Dutta S. Ferroelectrics and multiferroics for next generation photovoltaics. Adv. Mater. Lett., 2015, 6(7): 568.

[7] Li J, Zhang GH, Fan LK, Huang GQ, Gao ZP, Zeng T. Enhanced visible-light-driven photocatalytic activity of multiferroic KBiFe₂O₅ by adjusting pH value. J. Inorg. Mater., 2018, 33(7): 805.

[8] Vavilapalli DS, Melvin AA, Kavita S, Yadav AK, Jha SN, Bhattacharyya D, Sarma SC, Peter SC, Ramachandra Rao MS, Singh S. Multifunctional brownmillerite KBiFe₂O₅: Structural, magneto-dielectric, optical, photoelectrochemical studies and enhanced photocatalytic activity over perovskite BiFeO₃. Sol. Energy Mater. Sol. Cells, 2019, 200, 109940.

[9] Xu QY, Zai HF, Wu D, Qiu T, Xu MX. The magnetic properties of Bi(Fe_0.95Co_0.05)O₃ ceramics. Appl. Phys. Lett., 2009, 95(11): 112510.

[10] Chiang YS, Tu CS, Chen PY, Chen CS, Anthoniappen J, Ting Y, Chan TS, Schmidt VH. Magnetic and phonon transitions in B-site Co doped BiFeO₃ ceramics. Ceram. Int., 2016, 42(11): 13104.

[11] Khan U, Adeela N, Javed K, Riaz S, Ali H, Iqbal M, Han XF, Naseem S. Influence of cobalt doping on structural and magnetic properties of BiFeO₃ nanoparticles. J. Nanopart. Res., 2015, 17, 429.

[12] Rietveld HM. A profile refinement method for nuclear and magnetic structures. J. Appl. Crystallogr., 1969, 2(2): 65.

[13] Zhang M, Wang ZH, Lin SY, Wang Y, Pan YH. Investigation on a new multiferroic compound KBiFe2O5: Structural. optical, 2017, electricalandmagneticpropertiesJ.AlloysCompd.699, 561.

[14] Zhai XZ, Deng HM, Zhou WL, Yang PX, Chu JH, Zheng Z. Structural, optical and magnetic tunability in KBiFe₂O₅ multiferroics. RSC Adv., 2015, 5(100): 82351.

[15] Rhaman MM, Matin MA, Hossain MN, Mozahid FA, Hakim MA, Islam MF. Bandgap engineering of cobaltdoped bismuth ferrite nanoparticles for photovoltaic applications. Bull. Mater. Sci., 2019, 42, 190.

[16] Wood DL, Tauc J. Weak absorption tails in amorphous semiconductors. Phys. Rev. B, 1972, 5(8): 3144.

[17] Zhai XZ, Deng HM, Zhou WL, Yang PX, Chu JH, Zheng Z. Optical and magnetic properties of KBiFe₂O₅ thin films fabricated by chemical solution deposition. Mater. Lett., 2015, 161, 423.

[18] Rai R, Molli M. Effect of La doping on structural, magnetic, and optical properties of KBiFe₂O₅. J. Mater. Sci.: Mater. Electron., 2019, 30(4): 4318.

[19] Sarkar A, Khan GG. The formation and detection techniques of oxygen vacancies in titanium oxide-based nanostructures. Nanoscale, 2019, 11(8): 3414.

[20] Zhang GH, Liu FL, Gu TT, Zhao YS, Li NN, Yang WG, Feng SH. Ferroelectrics: enhanced ferroelectric and visible-light photoelectric properties in multiferroic KBiFe₂O₅ via pressure-induced phase transition (Adv. Electron. Mater. 3/2017). Adv. Electron. Mater., 2017, 3, 3.

[21] Mao WW, Wang XF, Han YM, Li XA, Li YT, Wang YF, Ma YW, Feng XM, Yang T, Yang JP, Huang W. Effect of Ln (Ln = La, Pr) and Co co-doped on the magnetic and ferroelectric properties of BiFeO₃ nanoparticles. J. Alloys Compd., 2014, 584, 520.

[22] Singh A, Chatterjee R, Mishra SK, Krishna PSR, Chaplot SL. Origin of large dielectric constant in La modified BiFeO₃-PbTiO₃ multiferroic. J. Appl. Phys., 2012, 111(1): 014113.

[23] Liu JJ, Duan CG, Yin WG, Mei WN, Smith RW, Hardy JR. Large dielectric constant and Maxwell-Wagner relaxation in Bi_2/3Cu₃Ti₄O₁₂. Phys. Rev. B, 2004, 70(14): 144106.

[24] Hoque MM, Dutta A, Kumar S, Sinha TP. Dielectric relaxation and conductivity of Ba(Mg_1/3Ta_2/3)o₃ and Ba(Zn_1/3 Ta_2/3)o₃. J. Mater. Sci. Technol., 2014, 30(4): 311.

[25] Si AL, Kiani M, Rizwan S. Structural, magnetic and dielectric properties of Sm³⁺ and Mn²⁺ co-doped BiFeO₃ nanoparticles. J. Powder Metall. Min., 2017, 6(1): 1.