ABSTRACT
In this work, we proposed an efficient heterostructure photocatalyst by integrating the ferroelectric BaTiO3 (BTO) layer with the semiconductor MoO3 layer, availing the ferroelectric polarization of BaTiO3 and high generation of photoinduced charge carriers in the MoO3 layer. The effect of MoO3 layer thickness (tMoO3) on the photocatalytic efficiency of the BTO/MoO3 heterostructures is found to be optimum at tMoO3 = 67 nm as tMoO3 varies from 40 to 800 nm. The BTO/MoO3 heterostructure with tMoO3 = 67 nm exhibits a high efficiency of 86% for the degradation of rhodamine B (RhB) under the exposure of UV-visible light for 60 min. The photocatalysis rate kinetics analysis reveals that the rate constant in the heterostructure is 1.7 times of pure BTO and 3.2 times of pure MoO3 films. The enhanced photocatalytic activity in the heterostructures is attributed to the electric field-driven carrier separation due to the ferroelectric polarization and the heterojunction band bending. The charge coupling effect between BaTiO3 and MoO3 is evident from the current-voltage characteristics. The maximum lattice strain in the heterostructure with tMoO3 = 67 nm as evident from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis further confirms the charge transfer between the layers. The degradation as well as decolorization efficiency of the BTO/MoO3 heterostructure is higher than that of pure BTO and MoO3 films. Radical trapping experiments reveal that electrons are the major contributors to the photocatalytic activity of the BTO/MoO3 heterostructure. The reusability test shows only a reduction of 5% in the efficiency of the heterostructure after five photocatalysis cycles. The heterostructure can also efficiently decompose the other dyes such as rose bengal and methyl violet. Thus, our findings prove that an efficient and reusable photocatalyst can be designed through the integration of the ferroelectrics with the semiconductor layers.
ABSTRACT
In the present work, we study the hysteretic behavior in the electric-field-dependent capacitance and the current characteristics of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT)/ZnO bilayers deposited on 0.7 wt % Nb-doped (001)-SrTiO3 (Nb:STO) substrates in a metal-ferroelectric-semiconductor (MFS) configuration. The X-ray diffraction measurements show that the BCZT and ZnO layers are highly oriented along the c-axis and have a single perovskite and wurtzite phases, respectively, whereas high-resolution transmission electron microscopy revealed very sharp Nb:STO/BCZT/ZnO interfaces. The capacitance-electric field ( C- E) characteristics of the bilayers exhibit a memory window of 47 kV/cm and a capacitance decrease of 22%, at a negative bias. The later result is explained by the formation of a depletion region in the ZnO layer. Moreover, an unusual resistive switching (RS) behavior is observed in the BCZT films, where the RS ratio can be 500 times enhanced in the BCZT/ZnO bilayers. The RS enhancement can be understood by the barrier potential profile modulation at the depletion region, in the BCZT/ZnO junction, via ferroelectric polarization switching of the BCZT layer. This work builds a bridge between the hysteretic behavior observed either in the C- E and current-electric field characteristics on a MFS structure.
ABSTRACT
An enhanced resistive switching (RS) effect is observed in Pt/BaTiO3(BTO)/ITO ferroelectric structures when a thin HfO2:Al2O3 (HAO) dielectric layer is inserted between Pt and BTO. The P-E hysteresis loops reveal the ferroelectric nature of both Pt/BTO/ITO and Pt/HAO/BTO/ITO structures. The relation between the RS and the polarization reversal is investigated at various temperatures in the Pt/HAO/BTO/ITO structure. It is found that the polarization reversal induces a barrier variation in the Pt/HAO/BTO interface and causes enhanced RS, which is suppressed at Curie temperature (Tc = 140 °C). Furthermore, the Pt/HAO/BTO/ITO structures show promising endurance characteristics, with a RS ratio >103 after 109 switching cycles, that make them potential candidates for resistive switching memory devices. By combining ferroelectric and dielectric layers this work provides an efficient way for developing highly efficient ferroelectric-based RS memory devices.
Subject(s)
Parasitology/history , Philately , Brazil , History, 19th Century , History, 20th Century , Schistosomiasis/historyABSTRACT
Thematic or topical philately deals with stamp collection based on a particular topic or theme. This article deals with a thematic depiction of the history of anesthesia from ancient to modern times using stamps, postal stationery and cancellations.
