The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family,... more The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family, (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 doped with Cu2+ (KNSBN:Cu), have been comparatively studied in a wide temperature range around the ferroelectric transition. Step-like anomalies in hypersonic velocity and damping confirm the first-order structural transition. These anomalies look like some perturbations on the high-temperature slopes of both a broad dip in
Development of lead-free BaTiO3/NiFe2O4/BaTiO3 (BTO/NFO/BTO) trilayer structure thin films is sig... more Development of lead-free BaTiO3/NiFe2O4/BaTiO3 (BTO/NFO/BTO) trilayer structure thin films is significant for the realization of eco-friendly and implantable microelectromechanical systems (MEMS)-based devices. In the present work, we report BTO/NFO/BTO trilayer structure as a representative ferroelectric/ferromagnetic/ferroelectric (FE/FM/FE) system deposited on Pt(111)/TiO2/SiO2/Si using Pulsed Laser Deposition (PLD) technique. We report the ferroelectric, magnetic, and ME properties of BTO/NFO/BTO trilayer nanoscale heterostructure having dimensions 140/80/140 nm, at room temperature. High room temperature dielectric constant ~2145 at 100 Hz with low dielectric loss ~0.05 at 1 MHz is observed. Further, the deposited (BTO/NFO/BTO) tri-layered thin films showed magnetoelectric, multiferroic behavior with remanent polarization of 8.63 μCcm−2 at about 0.25 MV/cm and a reasonably high saturation magnetization of ~16 emu/cm3 at ~10 kOe is witnessed at room temperature. Tri-layered film...
... N. Ortega, Ashok Kumar, RS Katiyar, JF Scott. Abstract. ... These loops become more and more ... more ... N. Ortega, Ashok Kumar, RS Katiyar, JF Scott. Abstract. ... These loops become more and more melon shaped with increase in temperature and applied field. The pseudoremanent polarization (artifact) decreases from without showing any proper saturation. ...
ABSTRACT We report the fabrication and characterization of highly oriented Pb(Zr0.53Ti0.47)0.60(F... more ABSTRACT We report the fabrication and characterization of highly oriented Pb(Zr0.53Ti0.47)0.60(Fe0.5Ta0.5)0.40O3 thin films. Dielectric spectra showed a maximum (Tm) around 350 K for 1 kHz that shifted to higher temperatures (by ∼ 30 K) with an increase in frequency up to 1 MHz. High dielectric dispersion below and above Tm, low dielectric loss (2%–5%), high dielectric constant ( ∼ 1380@1 kHz), ferroelectric polarization, and weak magnetic moment are observed. Real and imaginary dielectric data were fitted with a nonlinear Vogel–Fulcher equation, implying a relaxor nature. The ac conductivity shows frequency-dependent conductivity, low loss, and frequency-dependent kinks near Tm.
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY
This work is aimed at investigating three types of barium titanate materials (single crystal as a... more This work is aimed at investigating three types of barium titanate materials (single crystal as a bulk system, epitaxial film and BaTiO3/SrTiO3 (BT/ST) superlattice as the nanostructures), using in situ Raman spectroscopy in a wide range of temperatures (from 80 to 500 K) as an experimental tool. Special attention is paid to strain-sensitive A1(2TO) and E(1TO) soft mode components, which temperature evolution is carefully monitored in order to furnish information about phase transition sequences for each of these structures. It is established that, while the single crystal exhibits the typical T–O–R phase transformation of the bulk BT within a specified temperature range, the nanostructured epitaxial film and superlattice drastically deviate from that sequence.
Layered LiMnO2 has been proposed to be a potential alternate to LiCoO2 as a positive electrode ma... more Layered LiMnO2 has been proposed to be a potential alternate to LiCoO2 as a positive electrode material in rechargeable Li ion batteries. Thermodynamically, layered LiMnO2 is the least stable of all manganese oxides. However, since the report of synthesizing LiMnO2 in layered ...
The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family,... more The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family, (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 doped with Cu2+ (KNSBN:Cu), have been comparatively studied in a wide temperature range around the ferroelectric transition. Step-like anomalies in hypersonic velocity and damping confirm the first-order structural transition. These anomalies look like some perturbations on the high-temperature slopes of both a broad dip in
Development of lead-free BaTiO3/NiFe2O4/BaTiO3 (BTO/NFO/BTO) trilayer structure thin films is sig... more Development of lead-free BaTiO3/NiFe2O4/BaTiO3 (BTO/NFO/BTO) trilayer structure thin films is significant for the realization of eco-friendly and implantable microelectromechanical systems (MEMS)-based devices. In the present work, we report BTO/NFO/BTO trilayer structure as a representative ferroelectric/ferromagnetic/ferroelectric (FE/FM/FE) system deposited on Pt(111)/TiO2/SiO2/Si using Pulsed Laser Deposition (PLD) technique. We report the ferroelectric, magnetic, and ME properties of BTO/NFO/BTO trilayer nanoscale heterostructure having dimensions 140/80/140 nm, at room temperature. High room temperature dielectric constant ~2145 at 100 Hz with low dielectric loss ~0.05 at 1 MHz is observed. Further, the deposited (BTO/NFO/BTO) tri-layered thin films showed magnetoelectric, multiferroic behavior with remanent polarization of 8.63 μCcm−2 at about 0.25 MV/cm and a reasonably high saturation magnetization of ~16 emu/cm3 at ~10 kOe is witnessed at room temperature. Tri-layered film...
... N. Ortega, Ashok Kumar, RS Katiyar, JF Scott. Abstract. ... These loops become more and more ... more ... N. Ortega, Ashok Kumar, RS Katiyar, JF Scott. Abstract. ... These loops become more and more melon shaped with increase in temperature and applied field. The pseudoremanent polarization (artifact) decreases from without showing any proper saturation. ...
ABSTRACT We report the fabrication and characterization of highly oriented Pb(Zr0.53Ti0.47)0.60(F... more ABSTRACT We report the fabrication and characterization of highly oriented Pb(Zr0.53Ti0.47)0.60(Fe0.5Ta0.5)0.40O3 thin films. Dielectric spectra showed a maximum (Tm) around 350 K for 1 kHz that shifted to higher temperatures (by ∼ 30 K) with an increase in frequency up to 1 MHz. High dielectric dispersion below and above Tm, low dielectric loss (2%–5%), high dielectric constant ( ∼ 1380@1 kHz), ferroelectric polarization, and weak magnetic moment are observed. Real and imaginary dielectric data were fitted with a nonlinear Vogel–Fulcher equation, implying a relaxor nature. The ac conductivity shows frequency-dependent conductivity, low loss, and frequency-dependent kinks near Tm.
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY
This work is aimed at investigating three types of barium titanate materials (single crystal as a... more This work is aimed at investigating three types of barium titanate materials (single crystal as a bulk system, epitaxial film and BaTiO3/SrTiO3 (BT/ST) superlattice as the nanostructures), using in situ Raman spectroscopy in a wide range of temperatures (from 80 to 500 K) as an experimental tool. Special attention is paid to strain-sensitive A1(2TO) and E(1TO) soft mode components, which temperature evolution is carefully monitored in order to furnish information about phase transition sequences for each of these structures. It is established that, while the single crystal exhibits the typical T–O–R phase transformation of the bulk BT within a specified temperature range, the nanostructured epitaxial film and superlattice drastically deviate from that sequence.
Layered LiMnO2 has been proposed to be a potential alternate to LiCoO2 as a positive electrode ma... more Layered LiMnO2 has been proposed to be a potential alternate to LiCoO2 as a positive electrode material in rechargeable Li ion batteries. Thermodynamically, layered LiMnO2 is the least stable of all manganese oxides. However, since the report of synthesizing LiMnO2 in layered ...
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