Development on the synthesis, fabrication and characterization of La-based perovskite nanostructures for reversible solid oxide cells
Reversible solid oxide cell (RSOC) technology as a solid-state and high efficient electrochemical energy conversion device is one of the most promising electricity storage/generation options and has been projected as a key component of the future electric grid to increase efficiency and allows large-scale penetration of intermittent renewable resources. It is constructed of a membrane electrode assembly comprising a laminated fuel electrode, solid electrolyte and oxygen electrode. Due to high temperature operation and having highly exothermic and endothermic reactions during fuel and electrolysis cell modes, respectively, one significant challenge of designing RSOC system is its thermal management. In this regard, several strategies including carefully controlling the RSOC stack temperature and pressure have been proposed. The feasibility of such stack operating conditions requires research and cell materials development for long-term durability.
The developments of perovskite materials with a flexible crystal structure (ABO3) have received many attentions as their structures can be tailored by doping and/or co-doping of the A- and B-site cations and obtain various properties accordingly. Despite many studies have concentrated on conduction properties and performance of newly developed perovskite materials, their associated mechanical properties studies is limited in the literature. Therefore in this work, La-based perovskite nanostructures has been proposed to investigate their structural, electrical and room and high temperature mechanical properties in order to improve their chemical stability and mechanical durability during fabrication and operation conditions by cations doping and co-doping strategies. The final phase of this investigation is focused on electrochemical performance analyses of the single cell assembly by fabrication of planar fuel electrode supported single cells.
1.Synthesis of nanostructure perovskite powders and their powder characteristics
2. Physical characterizations of prepared perovskite nanostructures
3. Mechanical characterizations of prepared perovskite nanostructures
4. Fabrication of a single cells and performance analyses by electrochemical measurements
Fabrication of Ferrite/Carbon hybrid nanomaterial for electrochemical energy storage applications
Carbon materials and carbon based composite hybrid materials are highly studied for the electrochemical energy storage applications. Our interest is on supercapacitors due to its high power density, fast charge-discharge rate, high capacitance, and superlong cycle life. Supercapacitors are the potential device which can complete the charge/discharge process in few seconds and it could able to produce high power density is in the order of 10 kW/kg. . Two types of supercapacitors are available based on the charge storage mechanism namely electrical double layer capacitors (EDLCs) and pseudo-capacitors. The electrode is made by using metal oxides, conducting polymers and carbon materials. Making hybrid nanostructures of carbon materials for supercapacitors with magnetic nanoparticle are in much interest due to the magnetic nature. In energy storage, the performance is subject to the properties of anode and cathode materials. Several advancements have been made to improve the efficiency of the batteries by applying new chemistry into it. RuO2, MnO2, NiO, Co3O4, V2O5 and other transition metal oxides are widely used as an electrode material. Currently, hybrid material such combination of different metal oxide and other carbon based materials are studied for the improvement in the performance. Our interest is to show the utilization of hybrid nanomaterial of ferrite with carbon layered structure for the better performance in electrochemical energy storage.
Materials can exhibit diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic behavior according to their magnetic nature. Magnetic materials can be classified as hard and soft magnetic materials based on the coercivity exhibited by them. Chemical methods have advantages to prepare magnetic materials due to controllable size, morphology and composition which are essential in the area of data storage, and biomedicine. However, the synthesis of non-agglomerated particles with uniform size and shape is a challenging task. In addition, the surface modification is simplest way to control the size and shape of magnetic nanostructures with required and improved biocompatible and physicochemical properties. Most of the reports have focused on the surface modification of super-paramagnetic iron oxide nanoparticles of single size for catalytic and sensor applications. However there are potential uses of magnetic nanoparticles in magnetic field related applications requires specific magnetic nanoparticles with higher saturation magnetization.
This project mainly focuses on the surface modification of the ferrite magnetic nanoparticles (MNPs) by carbon coating and the optimized hybrid nanomaterials are utilized to fabricate the supercapacitors.
- Synthesis of ferrite magnetic nanoparticles using chemical oxidation method.
- Formation of carbon layer on the ferrite magnetic nanoparticle.
- Investigation of structural properties of the prepared hybrid nanostructures.
- The magnetic properties of the hybrid structures will be analyzed using vibrating sample magnetometer.
- Raman and FTIR spectroscopic techniques will be used to characterize the local structure of the prepared materials and to get insight into the influence of influence of carbon on the ferrite nanostructures.
- Thermo-gravimetric (TG) analysis will be used to quantify the fraction of carbon on the hybrid nanostructures.
- The optimized carbon coated ferrite magnetic nanoparticles will be further subject to the analyses of their electrochemical properties.
Novel Multiferroic BiFe1-xTxO3/CoFe2O4/RTO3 (R=rare earth; T = Mn, Ni and Cr) Nanocomposites and Thin Films: Structural, Vibrational, Magneto-electric Properties for spintronic applications
Spin-based random access memory (spin-RAM) is a type of non-volatile information storage, which can be distinguished from permanent (secondary) or mass information storage such as tapes, had disk, CD, and DVD. While spin-RAM has a great advantage over other RAMs, it has some drawbacks of storage capacity and energy consumption. In order to overcome such drawbacks, development of spin-RAM with multiferroic heterostructures is important because no electric current is needed to write information but the application of an electric field can write and store information in the magnetic layer via magneto-electric effect. However, the energy efficient writing mechanism is still under debate. So far, there are different physical origins of magneto-electric effect in ferromagnetic/ferroelectric multiferroic heterostructures, e.g., magneto-electric coupling, interface chemical bonding coupling, and charging modulation coupling. Among them, magneto-electric coupling, where interaction between the magnetization and the strain transfer from a ferroelectric play a vital role, has been one of the most promising mechanisms to switch the magnetization in a controlled manner. Therefore, a detailed study of magneto-electric effects in multiferroic heterostructures can open a new avenue towards developing novel magnetic information storage technology that will be integrated in future spin-RAM devices. In this work, we focus on highly magnetism and ferroelectric materials which show fascinating study of enhance the magneto electric effect. Since the magnetic phase transition is associated with the cell volume and crystal symmetry, strain transfer at the BiFe1-xTxO3/CoFe2O4/RTO3 can manipulate the magnetic phases as well as magnetization orientation by electric field through magneto-electric effect. The purpose of this study is to present a clear demonstration of electric-field control of the magnetic properties of CoFe2O4, RTO3 based oxide such as magnetic phases and magnetization orientation. Electric-field control of spin wave excitation in this material is also the target of this study because it provides a clue to the mechanism of the electric-field induced magnetic phase transition as well as its potential for the use in magnonic information device applications.
- Synthesis and characterization of novel multiferroics BFO, CFO and RTO3 (R = rare earth, T = transition metal) nanocomposites, growth of thin films and heterostructures of these multiferroics.
- Field Emission Scanning Electron Microscope (FESEM) would investigate the morphology and thickness of the thin films and average surface roughness and inormation about domain orientation of BFO/CFO/RTO3 thin films using Atomic Force Microscopy (AFM) and Kelvin Probe Force Microscopy (KPFM), respectively.
- Nuclear Magnetic Resonance (NMR) studies will provide better insights into the magnetic structure, surface-interface phenomena, low energy spin excitations and electron spin correlations of the stated multiferroics.
- Raman spectroscopy studies will provide insights into the structural transition of the proposed materials.
- Ferroelectric properties would be investigated by recording polarization vs. electric field (P–E) loops using Sawyer–Tower circuit at different temperature to determine the remnant polarization (Pr) and electric coactivity (Ec).
- Measurement of magnetization as a function of electric field applied in plane and out-of-plane in VSM/SQUID magnetometer. Changes in magnetization as a function of applied field, anisotropy, order parameter from magnetization vs. temperature will be carried out using VSM/SQUID.