Conventional synthesis of perovskite structured LaTixFe1-xO3: A comprehensive evaluation on phase formation, opto-magnetic, and dielectric properties

2021 ◽  
Vol 112 (9) ◽  
pp. 753-765
Author(s):  
Ramesh Kumar Raji ◽  
Tholkappiyan Ramachandran ◽  
M. Muralidharan ◽  
R. Suriakarthick ◽  
Muthu Dhilip ◽  
...  
Keyword(s):  
Single Phase ◽  
Optical Band Gap ◽  
Comprehensive Evaluation ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
Conventional Solid State Reaction ◽  
Raman Analysis ◽  
Excitonic Absorption ◽  
Magnetic And Dielectric Properties ◽  
Quantitative Chemical

Abstract Perovskite structured LaTixFe1-xO3 (x = 0, 0.05, 0.15, 0.25) lanthanum ferrites were synthesized by conventional solid-state reaction. The structural Rietveld refinement and Raman analysis were conducted and confirmed that single-phase orthorhombic phase with Pbnm symmetry formed. The positions of the ions and their bonds of these ferrites were investigated. The spherical shaped morphology of these ferrites was examined. The quantitative chemical composition and distribution of these ferrites were confirmed. The excitonic absorption edge was observed at 590 nm; ascribed to the electronic transition from O2p→Fe3d and optical band gap values increased from 1.85– 2.02 eV as Ti concentration increased. The dielectric and magnetic behavior of these ferrites was studied. It is suggested that synthesized LaTixFe1xO3 powders with different properties could be tailored for different requirements.

scholarly journals Conventional synthesis of perovskite structured LaTixFe1-xO3: A comprehensive evaluation on phase formation, opto-magnetic, and dielectrical properties

2020 ◽  
Author(s):  
Ramesh Kumar Raji ◽  
Vishista Kurapati ◽  
Tholkappiyan Ramachandran ◽  
M Muralidharan ◽  
R Suriakarthick ◽  
...  
Keyword(s):  
Comprehensive Evaluation ◽  
Lattice Structure ◽  
Orthorhombic Phase ◽  
Spectroscopic Studies ◽  
Chemical Compositions ◽  
Excitonic Absorption ◽  
Substitution Level ◽  
Tan Δ ◽  
Dielectrical Properties ◽  
Ti Substitution

Abstract In the current study, we report a comprehensive evaluation of the microstructures, optical, dielectric and magnetic traits of Ti-substituted perovskite structured lanthanum ferrite with chemical compositions LaTixFe1−xO3 (x = 0, 0.05, 0.15, 0.25). X-ray diffraction with Rietveld refinement and Raman analysis confirmed that both pure and Ti-substituted LaFeO3 maintained single-phase orthorhombic phase with Pbnm symmetry. Fourier transform infrared spectroscopy (FTIR) studies revealed the information about the positions of the ions and their bonds within the lattice structure of the LaFeO3. The spherical shaped morphology of all products was confirmed by SEM. The quantitative chemical composition and their distribution were confirmed by EDAX and mapping. The UV-Vis spectroscopic studies showed an excitonic absorption edge at 590 nm is ascribed to the electronic transition from O2p→Fe3d. Optical band gap (Eg) values were assessed by applying Tauc schemes, showed that Eg values are in a narrow range (1.85–2.02 eV). The dielectric properties such as, dielectric constant (ε’), dielectric loss (tan δ) was examined by varying with temperature and frequency. The magnetic results revealed weak ferromagnetic nature trait at 300 K. The variation in Ms (saturation magnetization), Hc (coercivity) and Mr (remanence) values were observed with increasing Ti substitution level.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

The Hexagonal ↔ Orthorhombic Structural Phase Transition in Claringbullite, Cu4FCl(OH)6

2021 ◽  
Author(s):  
Mark D. Welch ◽  
Jens Najorka ◽  
Michael S. Rumsey ◽  
John Spratt
Keyword(s):  
Phase Transition ◽  
Data Storage ◽  
Structural Phase Transition ◽  
Structural Changes ◽  
Structural Phase ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
New Mineral ◽  
Storage Devices ◽  
Definition Of

ABSTRACT Frustrated magnetic phases have been a perennial interest to theoreticians wishing to understand the energetics and behavior of quasi-chaotic systems at the quantum level. This behavior also has potentially wide applications to developing quantum data-storage devices. Several minerals are examples of such phases. Since the definition of herbertsmithite, Cu3ZnCl2(OH)6, as a new mineral in 2004 and the rapid realization of the significance of its structure as a frustrated antiferromagnetic phase with a triangular magnetic lattice, there has been intense study of its magnetic properties and those of synthetic compositional variants. In the past five years it has been recognized that the layered copper hydroxyhalides barlowite, Cu4BrF(OH)6, and claringbullite, Cu4FCl(OH)6, are also the parent structures of a family of kagome phases, as they also have triangular magnetic lattices. This paper concerns the structural behavior of claringbullite that is a precursor to the novel frustrated antiferromagnetic states that occur below 30 K in these minerals. The reversible hexagonal (P63/mmc) ↔ orthorhombic (Pnma or Cmcm) structural phase transition in barlowite at 200−270 K has been known for several years, but the details of the structural changes that occur through the transition have been largely unexplored, with the focus instead being on quantifying the low-temperature magnetic behavior of the orthorhombic phase. This paper reports the details of the structural phase transition in natural claringbullite at 100−293 K as studied by single-crystal X-ray diffraction. The transition temperature has been determined to lie between 270 and 293 K. The progressive disordering of Cu at the unusual trigonal prismatic Cu(OH)6 site on heating is quantified through the phase transition for the first time, and a methodology for refining this disorder is presented. Key changes in the behavior of Cu(OH)4Cl2 octahedra in claringbullite have been identified that suggest why the Pnma structure is likely stabilized over an alternative Cmcm structure. It is proposed that the presence of a non-centrosymmetric octahedron in the Pnma structure allows more effective structural relaxation during the phase transition than can be achieved by the Cmcm structure, which has only centrosymmetric octahedra.

Microwave and Electrical Properties of Zr-Doped SrTiO3 for Dielectric Resonator Antenna Application

2018 ◽  
Vol 280 ◽  
pp. 142-148 ◽  
Author(s):  
Norhizatol Fashren Muhamad ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
Faizal Jamlos ◽  
Nor Azura Malini Ahmad Hambali
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Dielectric Resonator ◽  
Ceramic Powder ◽  
Experimental Studies ◽  
Orthorhombic Phase ◽  
Solid State Reaction Method ◽  
Dielectric Resonator Antenna ◽  
Conventional Solid State Reaction

Present investigation provides experimental studies on cylindrical dielectric resonator antennas (CDRAs) fabricated from SrTi1-xZrxO3ceramic with different substitution of Zr in place of Ti for (0 ≤ x ≤1). Ceramic powder were prepared using conventional solid state reaction method. X-ray Diffraction exposes physical properties Zr-doped SrTiO3which exhibit phase transition from cubic, tetragonal to orthorhombic phase. The electrical properties such as dielectric constant (εr) and dielectric loss (tan δ) were studied in variation of temperatures and frequencies. At room temperature the dielectric constant decreased from 240 to 21 with increase of Zr content however the amazing result was obtained for multiband antenna by Zr content. The dielectric loss obtain shows very low loss value roughly below 0.07 for all samples. The variations of return loss, resonance frequency and bandwidth of CDRAs at their respective resonant frequencies are studied experimentally.

Significant reduction in the optical band-gap and defect assisted magnetic response in Fe-doped anatase TiO2 nanocrystals as dilute magnetic semiconductors

2019 ◽  
Vol 43 (15) ◽  
pp. 6048-6062 ◽  
Author(s):  
V. R. Akshay ◽  
B. Arun ◽  
Guruprasad Mandal ◽  
Anupama Chanda ◽  
M. Vasundhara
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Magnetic Behavior ◽  
Anatase Tio2 ◽  
Magnetic Response ◽  
Tio2 Nanocrystals

The nature of BMPs, whether overlapped or isolated, determines the magnetic behavior of Fe-doped TiO2.

PHASE STRUCTURE, PIEZOELECTRIC AND MULTIFERRIOC BEHAVIOR OF (K0.48Na0.52)NbO3-Co2O3 PIEZOELECTRIC CERAMICS

2011 ◽  
Vol 04 (03) ◽  
pp. 225-229 ◽  
Author(s):  
WENJUAN WU ◽  
DINGQUAN XIAO ◽  
JIAGANG WU ◽  
JING LI ◽  
JIANGUO ZHU
Keyword(s):  
Room Temperature ◽  
Sintering Temperature ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
Piezoelectric Ceramics ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Solid State Sintering ◽  
Sintering Method

( K 0.48 Na 0.52) NbO 3-x% Co 2 O 3 (x = 0, 0.03 and 0.05) (KNN-x% Co2O3 ) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. An orthorhombic phase was observed for all KNN-x% Co2O3 ceramics at room temperature, and two phase transitions were confirmed by the high temperature X-ray diffraction and the temperature dependence of the dielectric constant. The Co2O3 greatly improves the density and decreases the sintering temperature of KNN ceramics. The KNN-0.05 mol%Co2O3 ceramic exhibits good properties (d33 = 120 pC/N , k p = 0.41, Q m = 213 and T c = 407°C) and a good age stability. The multiferroic behavior was also observed at room temperature for the KNN-0.05 mol%Co2O3 ceramic, as confirmed by P–E loops and magnetic behavior.

scholarly journals Dielectric Properties of Rhombohedral PbNb2O6

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Kriti Ranjan Sahu ◽  
Udayan De
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
High Temperature ◽  
Single Phase ◽  
Rhombohedral Phase ◽  
Orthorhombic Phase ◽  
Dielectric Materials ◽  
Rietveld Analysis ◽  
Bulk Resistance ◽  
Relaxation Time Constant

Dielectric materials are needed in many electrical and electronic applications. So, basic characterizations need to be done for all dielectrics. PbNb2O6 (PN) is ferroelectric and piezoelectric only in its orthorhombic phase, with potential high temperature applications. So, its rhombohedral phase, frequently formed as an undesirable impurity in the preparation of orthorhombic PN, has been ignored with respect to possible dielectric characterizations. Here, essentially single phase rhombohedral PN has been prepared, checking structure from XRD Rietveld Analysis, and the real and imaginary parts of permittivity measured in an Impedance Spectrometer (IS) up to ~700∘C and over 20 Hz to 5.5 MHz range, for heating and some cooling runs. Variations, with temperature, of relaxation time constant (τ), AC and DC conductivity, bulk resistance, activation energy and capacitance have been explored from our IS data.

Preparation and Properties of Low-Temperature Sintered SrBi4Ti4O15/Ag Composites

2007 ◽  
Vol 280-283 ◽  
pp. 145-150 ◽  
Author(s):  
Ping Huang ◽  
Ting Xian Xu ◽  
Feng Hou ◽  
Qiang Zou
Keyword(s):  
Dielectric Constant ◽  
Single Phase ◽  
Sintering Temperature ◽  
Secondary Phase ◽  
Solid State Reaction Method ◽  
Dielectric Measurement ◽  
Layered Perovskite ◽  
Conventional Solid State Reaction ◽  
Ag Particles ◽  
The Matrix

Strontium bismuth titanate (SBTi) matrix composites containing Ag particles were synthesized by the conventional solid-state reaction method. The SBTi/Ag composites have been characterized by various techniques: x-ray diffraction, optical metallurgical microscope, scanning electron microscope and dielectric measurement. It is found that Ag doping significantly affect the physical properties of composites. By adding Ag particles to the SBTi matrix, the single-phase layered perovskite structure of the matrix is preserved and the sintering temperature of the system decrease from 1120°C of the single-phase SBTi to 950°C of the SBTi/Ag composites. With the increase of sintering temperature, the size of silver particles increase, but the SBTi grains have no significant growth. The SBTi/Ag composites show a significant change of the dielectric constant. By increasing Ag content, a gradual increase of the dielectric constant is observed and the dielectric loss of the SBTi/Ag composites remain unchanged when the temperature rangers from room temperature to 200°C, however, the Curie peak of dielectric constant is repressed, which has been interpreted based on the effective dielectric fields developed around conducting phases and the inhibition effect of nonferroelectric secondary phase to electro-strain.

MULTIFERROIC MATERIALS Bi1-xSmxFeO3: A STUDY OF RAMAN AND ABSORPTION SPECTROSCOPIES

2010 ◽  
Vol 19 (02) ◽  
pp. 247-254 ◽  
Author(s):  
NGUYEN VAN MINH ◽  
DAO VIET THANG
Keyword(s):  
Lattice Dynamics ◽  
Optical Band Gap ◽  
Solid State Reaction Method ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Lattice Constants ◽  
Raman Measurement

Multiferroic Bi 1-x Sm x FeO 3(x = 0.00, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. X-ray diffraction measurement was carried out to characterize the crystal structure and to detect the impurities existing in these ceramics. The substitution of rare earth Sm for Bi was found to decrease the impurity phase in BiFeO 3 ceramics. There is strong evidence that both lattice constants a and c of the unit cell become smaller as the Sm 3+ content is increased. The effect of introducing Sm 3+ is shown to decrease the optical band gap for doped sample Bi 1-x Sm x FeO 3. Additionally, the temperature-dependent Raman measurement performed for the lattice dynamics study of Bi 1-x Sm x FeO 3 samples reveals a strong band centered at around 1000–1300 cm-1 which is associated with the resonant enhancement of two-phonon Raman scattering in the multiferroic Bi 1-x Sm x FeO 3 samples. This two-phonon signal is shown to broaden with increasing x. The Raman spectra at low wavenumbers are suggested to be related with magnon in this system.

Preparation of a high active photocatalyst, K2La2Ti3O10, by polymerized complex method and its photocatalytic activity of water splitting

1998 ◽  
Vol 13 (4) ◽  
pp. 852-855 ◽  
Author(s):  
Shigeru Ikeda ◽  
Michikazu Hara ◽  
Junko N. Kondo ◽  
Kazunari Domen ◽  
Hiroyuki Takahashi ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Solid State ◽  
Single Phase ◽  
Layered Perovskite ◽  
Complex Method ◽  
Conventional Solid State Reaction ◽  
Perovskite Type Oxide ◽  
Gel Technique ◽  
Perovskite Type ◽  
Pc Method

A layered perovskite type oxide, K2La2Ti3O10, was prepared by a gel technique using the polymerized complex (PC) method. A single phase K2La2Ti3O10 was obtained by adding twice the potassium required for stoichiometry. The Ni–K2La2Ti3O10 catalyst prepared by the PC method exhibited a higher photocatalytic activity for decomposition of H2O into H2 and O2 than that prepared by a conventional solid state reaction.

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