scholarly journals Surface Modification and Enhancement of Ferromagnetism in BiFeO3 Nanofilms Deposited on HOPG

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1990 ◽  
Author(s):  
Shikhgasan Ramazanov ◽  
Dinara Sobola ◽  
Farid Orudzhev ◽  
Alexandr Knápek ◽  
Josef Polčák ◽  
...  
Keyword(s):  
Active Sites ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Pyrolytic Graphite ◽  
Atomic Layer ◽  
Active Centers ◽  
Layer Deposition ◽  
Strong Hybridization ◽  
Two Phases

BiFeO3 (BFO) films on highly oriented pyrolytic graphite (HOPG) substrate were obtained by the atomic layer deposition (ALD) method. The oxidation of HOPG leads to the formation of bubble regions creating defective regions with active centers. Chemisorption occurs at these active sites in ALD. Additionally, carbon interacts with ozone and releases carbon oxides (CO, CO2). Further annealing during the in situ XPS process up to a temperature of 923 K showed a redox reaction and the formation of oxygen vacancies (Vo) in the BFO crystal lattice. Bubble delamination creates flakes of BiFeO3-x/rGO heterostructures. Magnetic measurements (M–H) showed ferromagnetism (FM) at room temperature Ms ~ 120 emu/cm3. The contribution to magnetization is influenced by the factor of charge redistribution on Vo causing the distortion of the lattice as well as by the superstructure formed at the boundary of two phases, which causes strong hybridization due to the superexchange interaction of the BFO film with the FM sublattice of the interface region. The development of a method for obtaining multiferroic structures with high FM values (at room temperature) is promising for magnetically controlled applications.

scholarly journals In situ tuning of electronic structure of catalysts using controllable hydrogen spillover for enhanced selectivity

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mi Xiong ◽  
Zhe Gao ◽  
Peng Zhao ◽  
Guofu Wang ◽  
Wenjun Yan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Active Sites ◽  
Pt Nanoparticles ◽  
Atomic Layer ◽  
Hydrogen Spillover ◽  
General Strategy ◽  
Layer Deposition ◽  
Styrene Derivatives ◽  
Enhanced Selectivity

Abstract In situ tuning of the electronic structure of active sites is a long-standing challenge. Herein, we propose a strategy by controlling the hydrogen spillover distance to in situ tune the electronic structure. The strategy is demonstrated to be feasible with the assistance of CoOx/Al2O3/Pt catalysts prepared by atomic layer deposition in which CoOx and Pt nanoparticles are separated by hollow Al2O3 nanotubes. The strength of hydrogen spillover from Pt to CoOx can be precisely tailored by varying the Al2O3 thickness. Using CoOx/Al2O3 catalyzed styrene epoxidation as an example, the CoOx/Al2O3/Pt with 7 nm Al2O3 layer exhibits greatly enhanced selectivity (from 74.3% to 94.8%) when H2 is added. The enhanced selectivity is attributed to the introduction of controllable hydrogen spillover, resulting in the reduction of CoOx during the reaction. Our method is also effective for the epoxidation of styrene derivatives. We anticipate this method is a general strategy for other reactions.

Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

2017 ◽  
Author(s):  
Younghee Lee ◽  
Daniela M. Piper ◽  
Andrew S. Cavanagh ◽  
Matthias J. Young ◽  
Se-Hee Lee ◽  
...  
Keyword(s):  
Lithium Ion ◽  
Atomic Layer ◽  
Mass Gain ◽  
Alloy Film ◽  
Ex Situ ◽  
X Ray ◽  
Layer Deposition ◽  
Ion Conducting ◽  
Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH<sub>3</sub>)<sub>3</sub> as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF<sub>3</sub> and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF<sub>3</sub>)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film was measured as σ = 7.5 × 10<sup>-6</sup> S/cm.</div>

scholarly journals HfS2 thin films deposited at room temperature by an emerging technique, solution atomic layer deposition

2021 ◽  
Author(s):  
Yuanyuan Cao ◽  
Sha Zhu ◽  
Julien Bachmann
Keyword(s):  
Thin Films ◽  
Atomic Layer Deposition ◽  
Room Temperature ◽  
Atomic Layer ◽  
Two Dimensional ◽  
Molecular Precursors ◽  
Layer Deposition

The two-dimensional material and semiconducting dichalcogenide hafnium disulfide is deposited at room temperature by atomic layer deposition from molecular precursors dissolved in hexane.

RECENT DEVELOPMENTS ON 3D INTEGRATION OF METALLIC SET ONTO CMOS PROCESS FOR MEMORY APPLICATION

2012 ◽  
Vol 11 (04) ◽  
pp. 1240024 ◽  
Author(s):  
N. JOUVET ◽  
M. A. BOUNOUAR ◽  
S. ECOFFEY ◽  
C. NAUENHEIM ◽  
A. BEAUMONT ◽  
...  
Keyword(s):  
Room Temperature ◽  
Memory Cell ◽  
Atomic Layer ◽  
Cmos Process ◽  
3D Integration ◽  
Simulation Tools ◽  
Layer Deposition ◽  
Recent Developments ◽  
Sram Memory ◽  
Electrical Characterizations

This work presents a nanodamascene process for a CMOS back-end-of-line fabrication of metallic single electron transistor(SET), together with the use of simulation tools for the development of a SET SRAM memory cell. We show room temperature electrical characterizations of SETs fabricated on CMOS with relaxed dimensions, and simulations of a SET SRAM memory cell. Using their physical characteristics achievable through the use of atomic layer deposition, it will be demonstrated that it has the potential to operate at temperature up to 398 K, and that power consumption is less than that of equivalent circuit in advanced CMOS technologies. In order to take advantage of both low power SETs and high CMOS drive efficiency, a hybrid 3D SET CMOS circuit is proposed.

ZnO Schottky Nanodiodes Processed From Plasma-Enhanced Atomic Layer Deposition at Near Room Temperature

2018 ◽  
Vol 65 (10) ◽  
pp. 4513-4519
Author(s):  
Mei Shen ◽  
Triratna P. Muneshwar ◽  
Kenneth C. Cadien ◽  
Ying Yin Tsui ◽  
Douglas W. Barlage
Keyword(s):  
Atomic Layer Deposition ◽  
Room Temperature ◽  
Atomic Layer ◽  
Layer Deposition
Sign in / Sign up

Export Citation Format

Share Document