A monoclinic to tetragonal crossover in (Na0.5Bi0.5TiO3)(1−x)(BaZrO3)xceramic: a lead-free ferroelectric material

2016 ◽  
Vol 49 (3) ◽  
pp. 866-872 ◽  
Author(s):  
Rachna Selvamani ◽  
Gurvinderjit Singh ◽  
V. S. Tiwari
Keyword(s):  
Phase Boundary ◽  
Single Phase ◽  
Structural Phase ◽  
Superlattice Reflection ◽  
Solid State Reaction Method ◽  
Rietveld Analysis ◽  
Ferroelectric Material ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Ionic Radii

A single-phase solid solution of Na0.5Bi0.5TiO3(NBT) and BaZrO3(BZ),i.e.(NBT)(1−x)(BaZrO3)x(x= 0.00, 0.01, 0.03, 0.05 and 0.07), was synthesized using the solid-state reaction method. It is found that the temperature for single-phase formation increases with increasing BZ content. A detailed structural investigation was carried out as a function of composition using Rietveld analysis of powder X-ray diffraction data. The structural refinement reveals a crossover from monoclinic (Cc) to tetragonal (P4mm) symmetry in the composition range 0.03 <x< 0.05. The intensity of superlattice reflection due toa−a−c−tilting of oxygen octahedra in theCcphase was found to decrease with increasing BZ content. The unit-cell volume was also found to increase with BZ content, which was attributed to the higher ionic radii of Ba2+and Zr4+in comparison to Bi3+(Na+) and Ti4+. The structural phase boundary observed in (NBT)(1−x)(BaZrO3)xis concurrent with the observation of morphotropic phase boundary like behaviour.

Powder X-ray diffraction and Rietveld analysis of La1−xCaxMnO3(0

2006 ◽  
Vol 21 (1) ◽  
pp. 40-44 ◽  
Author(s):  
P. R. Sagdeo ◽  
Shahid Anwar ◽  
N. P. Lalla
Keyword(s):  
Phase Transformation ◽  
Calcium Concentration ◽  
Single Phase ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
Magnetic Phases ◽  
X Ray

Single-phase samples of La1−xCaxMnO3compounds have been synthesized by solid-state reaction. Detailed Rietveld analysis of powder X-ray diffraction data showed that La1−xCaxMnO3undergoes a structural phase transformation fromR-3ctoPnmaatX=0.05–0.075. There is a linear variation of lattice parameters as a function of calcium concentration. The slope of this linear variation changes atX=0.6. A correlation between observed Mn-O bond lengths, corresponding to different compositions, and possible magnetic phases is discussed.

scholarly journals Influence of Li2CO3 addition on electrical and magnetic properties of Ni0.6Mg0.4Fe2O4

2020 ◽  
Vol 10 (03) ◽  
pp. 2050003
Author(s):  
M. R. Hassan ◽  
M. T. Islam ◽  
M. N. I. Khan
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Frequency Regime ◽  
Xrd Patterns

In this research, influence of adding Li2CO3 (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of [Formula: see text][Formula: see text]Fe2O4 (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300∘C for 6[Formula: see text]h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li2CO3 reduces the hysteresis loss. DC resistivity increases with Li2CO3 contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li2CO3 additions.

Structural, Dielectric and Electrical Studies of Ba4CaRTi3Nb7O30 (R = Eu, Dy) Ferroelectric System

2013 ◽  
Vol 547 ◽  
pp. 41-48 ◽  
Author(s):  
Prasun Ganguly ◽  
A.M. Biradar ◽  
A.K. Jha
Keyword(s):  
Single Phase ◽  
Microstructural Analysis ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Paraelectric Phase Transition ◽  
Orthorhombic Crystal Structure

The polycrystalline samples of Ba4CaRTi3Nb7O30 (R = Eu, Dy), members of tungsten-bronze family, were prepared by high-temperature solid state reaction method and studied for their dielectric and electrical properties. X-ray diffraction (XRD) analysis reveals the formation of single-phase compounds having orthorhombic crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compounds have well defined grains, which are distributed uniformly throughout the sample. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor kind of ferroelectric-paraelectric phase transition of diffuse nature. Ferroelectric, piezoelectric and pyroelectric studies of the compounds have been discussed in this paper. The temperature dependence of dc conductivity of the compounds have been investigated. The conductivity study over a wide temperature range suggests that the compounds have negative temperature coefficient of resistance (NTCR) behaviour.

PREPARATION OF SOME NANO SIZE COLOSSAL MAGNETO RESISTANCE MATERIALS BY THE SOL-GEL ROUTE

2003 ◽  
Vol 17 (01) ◽  
pp. 19-24 ◽  
Author(s):  
K. PADMAVATHI ◽  
V. RAJAKUMARI ◽  
M. VITHAL ◽  
V. PRASD ◽  
S. V. SUBRAMANYAM ◽  
...  
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Temperature Range ◽  
Ionic Size ◽  
Colossal Magneto Resistance ◽  
Magneto Resistance ◽  
Nano Size

A series of colossal magneto resistance materials having compositional formula Re 0.67 Sr 0.33 MnO 3 (Re = Nd, Gd, … etc.) were prepared by the sol-gel method, using Ethylene glycol as a gelating reagent. The materials were characterized by the powder X-ray diffraction technique and are found to be single phase with orthorhombic structure. The particle size of all the materials were calculated using the well known Shearer formula and are found to be in the range of 20–45 nm. In order to determine the transition temperature (T c ), the DC electrical resistivity measurements were also carried out over a temperature range 80–300 K using the four probe method and it has been observed that the T c values are found to increase with increasing ionic size. Finally the magneto resistance measurements were also undertaken in the temperature range 80–300 K and it has been found that the MR values of these materials are better when compared with those prepared by the solid state reaction method.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

scholarly journals Structure and electric properties of cerium substituted SrBi1.8Ce0.2Nb2O9 and SrBi1.8Ce0.2Ta2O9 ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Mohamed Afqir ◽  
Amina Tachafine ◽  
Didier Fasquelle ◽  
Mohamed Elaatmani ◽  
Jean-Claude Carru ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lcr Meter ◽  
Curie Temperature Tc

SrBi1.8Ce0.2Nb2O9 (SBCN) and SrBi1.8Ce0.2Ta2O9 (SBCT) powders were prepared via solid-state reaction method. X-ray diffraction analysis reveals that the SBCN and SBCT powders have the single phase orthorhom-bic Aurivillius structure at room temperature. The contribution of Raman scattering and FTIR spectroscopy of these samples were relatively smooth and resemble each other. The calcined powders were uniaxially pressed and sintered at 1250?C for 8 h to obtaine dense ceramics. Dielectric constant, loss tangent and AC conductivity of the sintered Ce-doped SrBi2Nb2O9 and SrBi2Ta2O9 ceramics were measured by LCR meter. The Ce-doped SBN (SBCN) ceramics have a higher Curie temperature (TC) and dielectric constant at TC (380?C and ?? ~3510) compared to the Ce-doped SBT (SBCT) ceramics (330?C and ?? ~115) when measured at 100Hz. However, the Ce-doped SBT (SBCT) ceramics have lower conductivity and dielectric loss.

scholarly journals Effects of (Mg1/3Sb2/3)4+ Substitution on the Structure and Microwave Dielectric Properties of Ce2Zr3x(Mg1/3Sb2/3)3-3x(MoO4)9 Ceramics

2020 ◽  
Author(s):  
Zhou Xu ◽  
Sun Jiajia ◽  
Zhang Ningkang ◽  
Sun Huazhang ◽  
Tao Wenhong ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Microwave Dielectric Properties ◽  
Far Infrared ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Refinement Method ◽  
Traditional Solid State Method

Abstract Ce2[Zr1-x(Mg1/3Sb2/3)x]3(MoO4)9 (0.02≤x≤0.10) ceramics were prepared well through the traditional solid-state method. A single phase, belonging to the space group of R-3c, was detected by using X-ray diffraction at sintering temperatures ranging from 700 to 850 °C. The crystallization micro-structural of specimens was examined by applying Scanning electron microscopy. The structural refinement of these samples was investigated in detail by performing the Rietveld refinement method. The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy. The correlations between the chemical bonds parameters and microwave dielectric properties were calculated and analyzed by P-V-L theory. Ce2[Zr0.94(Mg1/3Sb2/3)0.06]3(MoO4)9 ceramics with excellent dielectric properties: εr = 10.37, Q×f = 71748 GHz and τf = −13.6 ppm/°C sintered at 725 °C for 6 hours.

scholarly journals Dielectric and Raman studies of Ba0.06(Na1/2Bi1/2)0.94TiO3–NaNbO3 ceramics

2016 ◽  
Vol 34 (2) ◽  
pp. 437-445 ◽  
Author(s):  
Sumit K. Roy ◽  
S. Chaudhuri ◽  
R.K. Kotnala ◽  
D.K. Singh ◽  
B.P. Singh ◽  
...  
Keyword(s):  
Single Phase ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Orthorhombic Symmetry ◽  
Dielectric Studies ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
New Phase ◽  
Diffusivity Parameter

AbstractIn this work the X-ray diffraction, scanning electron microscopy, Raman and dielectric studies of lead free perovskite (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 (0 ⩽ x ⩽ 1.0) ceramics, prepared using a standard solid state reaction method, were investigated. X-ray diffraction studies of all the ceramics suggested the formation of single phase with crystal structure transforming from rhombohedral-tetragonal to orthorhombic symmetry with the increase in NaNbO3 content. Raman spectra also confirmed the formation of solid solution without any new phase. Dielectric studies showed that the phase transition is of diffusive character and diffusivity parameter decreases with increasing NaNbO3 content. The compositional fluctuation was considered to be the main cause of diffusivity.

THE MICRO-REGION COMPOSITIONAL VARIATION OF Y1Ba2Cu3O9−x SINGLE PHASE SUPERCONDUCTOR

1987 ◽  
Vol 01 (02) ◽  
pp. 231-236 ◽  
Author(s):  
Zhenhong Mai ◽  
Liquan Chen ◽  
Xi Chu ◽  
Daoyang Dai ◽  
Yongming Ni ◽  
...  
Keyword(s):  
Single Phase ◽  
Structural Phase ◽  
Compositional Variation ◽  
Interfacial Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Distribution ◽  
New Superconductor ◽  
Phase Superconductor ◽  
The Ideal

We have investigated the microstructure and compositional distribution of the Y 1 Ba 2 Cu 3 O 9−x single phase superconductor with scanning electron microscopy, energy dispersion x-ray spectrometry and x-ray diffraction. It has been found that the micro-region compositions are far front the ideal values, especially the yttrium content is quite higher than the suspected amount in the interfacial region. between crystalline grains. We propose that there might be another structural phase co-existed with the Y 1 Ba 2 Cu 3 O 9−x compound and it can not be distinguished from the main phase with diffraction methods. This phase would influence the properties, in particular the critical current density jc of the new superconductor.

Studies on Internal Friction and Curie Temperature of NiMgCuZn Spinel Ferrites for Micro-Inductor Applications

2015 ◽  
Vol 241 ◽  
pp. 202-225
Author(s):  
N. Varalaxmi ◽  
K.V. Sivakumar ◽  
Hardev Singh Virk
Keyword(s):  
Internal Friction ◽  
Curie Temperature ◽  
Single Phase ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
Piezoelectric Resonator ◽  
X Ray ◽  
Compositional Changes ◽  
Single Stress

Three series of NiMgCuZn ferrites were prepared by conventional double sintering ceramic process. The formation of single phase in these ferrites was confirmed by X-ray diffraction. A brief review of the important investigations carried out on the internal friction behaviour of NiMgCuZnFe2O4, in the temperature range 40oC to 360oC, has been reported. In the present investigation, the composite piezoelectric resonator method has been used. The effect of compositional changes of ferrites on Curie temperature and internal friction are reported. Results and discussions on the temperature variation of internal friction of the three series of NiMgCuZnFe2O4samples are discussed. In all the series studied, only single stress induced relaxation peaks are observed. These studies were carried out to develop a ferrite composition for their use as core materials for microinductor applications. The results are explained in the light of structural phase transitions.

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