Aurivillius Bi5Ti3FeO15 (BTF) ceramics were synthesized using the conventional solid state reaction method by optimizing excess of Bi2O3 and sintering time. Their structures, magnetic, and optical properties were investigated in detail. The optimum process to sinter pure Aurivillius BTF ceramics was confirmed to be 3 wt. % excess Bi2O3 to compensate the Bi volatilization at 1050 °C for 240 min (BTF-240M). The microstructure and crystalline structure of the BTF ceramics had little dependence on the sintering time from the x-ray diffraction (XRD) and scanning electron microscopic data. Nevertheless, the magnetic and optical properties were closely related with the sintering time. The overall magnetic behavior of these BTF ceramics was superparamagnetic (SPM), whereas there were unambiguous clues for the existence of antiferromagnetic (AFM) interactions. However, whether the SPM behavior was intrinsic or arised from a tiny amount of spinel Fe3O4 impurity phase cannot be thoroughly ruled out in the XRD detection limit in the present stage. The AFM interactions were weakened upon extending the sintering time. The effective magnetic moment (μeff), however, demonstrated different dependency on the sintering time. It increased with the sintering time from 80 min to 240 min, and then dropped with further extending the sintering time. Compared with other BTF ceramics, the BTF-240M ceramic showed the highest values of the refractive index n and real part ε1, as well as the lowest ones of the extinction coefficient k and imagine part ε2 in whole photon energy range. Finally, a direct inter-band transition was confirmed for these BTF ceramics and optical energy band gaps were determined to be about 3.08, 3.18, and 3.39 eV for 80 min, 150 min, and 240 min sintered BTF ceramics, respectively, yet abnormal optical behavior was observed in BTF-360M ceramic.
A new equation related to the surface tension and concentration of solute in the surface region is derived and a three-step procedure is proposed to determine the molecular area of...
In this paper, we present the application of transmissive terahertz (THz) time-domain spectroscopy for determining molecular polarizability for three widely applied solvents: water, ethanol, and acetone. Molecular polarizabilities of those solvents are obtained from the refractive index by using the Lorentz–Lorenz equation. The measured THz molecular polarizabilities are comparable with theoretical values estimated with both the first principle calculation and the atomic polarizability additive model. The THz spectra are presented over frequencies ranging from 0.3 to 1.2 THz (
10
−
40
c
m
−
1
). The molecular polarizability at 1.0 THz is determined as
3.81
±
0.03
,
7.04
±
0.07
, and
7.9
±
0.2
Å3 for water, ethanol, and acetone, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.