Influence of transition metal doping (X = Co, Fe) on structural, optical properties of Ferroelectric Bi3.25La0.75X1Ti2O12

Abstract

Studies of the photoelectric properties of complex oxides have recently focused on materials with a narrow band gap because the wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To tune the band gap of complex oxides, this study examined the effects of cobalt and iron doping on lanthanum-modified Bi 4 Ti 3 O 12 -based oxides (BLT) synthesized using a solid reaction method. The structural, optical and electrical properties of the synthesized powers were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy. Doping with both atoms affected the tunability of the band gap dramatically without breaking symmetry. On the other hand, the transition region in the band gap from the iron-doped sample was much sharper than that from the cobalt-doped sample. Control of the band gap chemical doping can be applied to other complex oxides materials and provides a new tool for manipulating oxide optoelectronics.

Large enhancement of the photovoltaic effect in ferroelectric complex oxides through bandgap reduction

“…Based on our previous results, the doping concentrations of Co and Fe atoms in the doped BLT targets were chosen to maximize the bandgap reduction, and the doping ratios were Bi 3.25 La 0.75 Co 1 Ti 2 O 12 (BLCT) and Bi 3.25 La 0.75 Fe 0.25 Ti 2 O 12 (BLFCT)2223. The BLT, BLCT, and BLFCT powders were blended thoroughly at the stoichiometric ratio in a ball mill for 24 h, dried in an oven at a temperature of 100 °C, and calcined at 700 °C for 2.5 h in air.…”

Octahedral distortion and oxygen vacancies induced band-gap narrowing and enhanced visible light absorption of Co/Fe co-doped Bi3.25Nd0.75Ti3O12 ferroelectrics for photovoltaic applications

“…On other hand, the bandgap reducing by 0.4 eV in Zr doped Ti site of BiT [25], ∼0.9 eV with Co and ∼0. 73 eV with Fe doped Ti site in Bi 3.25 La 0.75 Ti 3 O 12 powders (but presenting secondary phase) [26] were reported. Han [26] reported that the second phase does not affect the bandgap, but might affect the ferroelectric response, which is a very important property for PVs applications.…”

Structural and optical properties of Fe doped bismuth titanate thin film deposited by RF sputtering

“…Lanthanum-modified bismuth titanate powders (BLT) calcined at 700 °C were previously reported to crystallize with an orthorhombic structure. 21,22) The results showed that the XRD patterns of the samples calcined under 700 °C showed the incomplete formation of an orthorhombic BLT structure in the mixture state. Also, Besland et al 23) suggested that the optimal annealing temperature to crystallize BLT films by RF magnetron sputtering was above 650 °C.…”