scholarly journals Engineered Layer-Stacked Interfaces Inside Aurivillius-Type Layered Oxides Enables Superior Ferroelectric Property

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 710 ◽  
Author(s):  
Shujie Sun ◽  
Xiaofeng Yin
Keyword(s):  
Single Phase ◽  
Ferroelectric Properties ◽  
Solid State Reactions ◽  
Layered Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Phase Compound ◽  
Layer Sample ◽  
Lattice Distortions

Layer engineering with different layer numbers inside Aurivillius-type layered structure, similar to interface engineering in heterojunctions or superlattices, can give rise to excellent physical properties due to the correlated layer-stacked interfaces of two different layer phases with different strain states. In this work, using the solid-state reactions from Aurivillius-type Bi3TiNbO9 (2-layer) and Bi4Ti3O12 (3-layer) ferroelectric powder mixtures, single-phase compound of Bi7Ti4NbO21 with an intergrowth structure of 2-layer and 3-layer perovskite slabs sandwiched between the Bi-O layers was synthesized and the effects of this layer-engineered strategy on the structure, Raman-vibration and ferroelectric properties were systematically investigated. The mostly-ordered intergrowth phase was observed clearly by utilizing X-ray diffraction and advanced electron micro-techniques. Uniformly dispersions and collaborative vibrations of Ti and Nb ions in the layer-engineered Bi7Ti4NbO21 were demonstrated. Remarkably, dielectric and ferroelectric properties were also recorded and an enhanced ferroelectric response was found in the layer-engineered mixed-layer sample with high ferroelectric Curie temperature, compared with the homogeneous 2-layer and 3-layer samples. Analyses of the Raman spectra and atomic structures confirmed that the performance improvement of the layer-engineered sample is intrinsic to the correlated layer-stacked interfaces inside the Aurivillius-type layered oxides, arising from strain-induced lattice distortions at the interfaces.

scholarly journals Study of multiferroic properties of Bi2Fe2WO9 ceramic for device application

2016 ◽  
Vol 06 (03) ◽  
pp. 1650023 ◽  
Author(s):  
Jyoshna Rout ◽  
R. N. P. Choudhary
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Electrical Parameters ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
X Ray ◽  
Universal Power Law ◽  
Phase Compound ◽  
Comprehensive Study

The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200[Formula: see text]C and 450[Formula: see text]C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization ([Formula: see text]) of 0.052[Formula: see text]em[Formula: see text]/g at room temperature. The existence of magneto-electric (ME) coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity) of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher’s universal power law.

scholarly journals Ferroelectric Properties of Strontium Bismuth Titanate (SrBi4Ti4O15) Synthesized Using Solution Combustion Technique

Nano Hybrids ◽  
2013 ◽  
Vol 3 ◽  
pp. 67-79 ◽  
Author(s):  
Saransh Shrivastava ◽  
Oroosa Subohi ◽  
M.M. Malik
Keyword(s):  
Single Phase ◽  
Bismuth Titanate ◽  
Ferroelectric Properties ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Low Dielectric ◽  
Combustion Technique ◽  
Single Phase Formation ◽  
Ferroelectric Transition Temperature

The ferroelectric properties of layer-structured Strontium Bismuth Titanate (SBT) have been investigated in this study. SBT was prepared using solution combustion technique with glycine as a fuel. Single-phase formation of the layer-structured compound of SBT with orthorhombic structure was achieved after calcinations at 800 °C, and was confirmed by x-ray diffraction studies. Scanning electron micrograph shows that the grains exhibit a plate like morphology and possesses ne particle size. The as prepared sample exhibits ferroelectric properties with remnant polarization of 2Pr = 1.84 μC/cm2at coercive field 2Ec= 2.61 kV/cm and displays low dielectric loss. Its ferroelectric transition temperature (Tc) is found to be 450 °C.

Phase transition in Bi8Fe6Ti3O27 multiferroic ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (3) ◽  
Author(s):  
Sunanda Patri ◽  
Ram Choudhary
Keyword(s):  
Remanent Polarization ◽  
Single Phase ◽  
Microstructural Analysis ◽  
Elemental Content ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
X Ray ◽  
Phase Compound

AbstractThe polycrystalline Bi8Fe6Ti3O27 compound was prepared by a high-temperature solid-state reaction technique. Preliminary structural analysis by X-ray diffraction (XRD) confirms the formation of a single-phase compound in an orthorhombic crystal system at room temperature. The elemental content of the compound was analyzed by EDAX microanalysis. Microstructural analysis by scanning electron microscopy (SEM) shows that the compound has well defined grains, which are distributed uniformly throughout the surface of the pellet sample. Detailed studies of temperature-dependent dielectric response at various frequencies show dielectric anomalies at 380, 389 and 403°C for 10 kHz, 100 kHz, and 1 MHz respectively. The hysteresis loop observed by applying an electric field of 12 kV/cm on the poled sample with smaller remanent polarization supports the existence of ferroelectricity in this material. The value of d33 of the compound was found to be 19 pC/N.

STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba2Sr3SmTi3V7O30

2008 ◽  
Vol 22 (30) ◽  
pp. 2999-3005 ◽  
Author(s):  
P. S. SAHOO ◽  
S. K. PATRI ◽  
R. N. P. CHOUDHARY ◽  
A. PANIGRAHI
Keyword(s):  
Activation Energy ◽  
Single Phase ◽  
Tungsten Bronze ◽  
Polycrystalline Sample ◽  
Tangent Loss ◽  
X Ray Diffraction ◽  
Solid State Reaction Technique ◽  
X Ray ◽  
Phase Compound ◽  
Grain Distribution

The polycrystalline sample of Ba 2 Sr 3 SmTi 3 V 7 O 30, a member of the tungsten bronze structural family, was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis suggests the formation of a single-phase compound with orthorhombic structure. Detailed studies of the dielectric constant and tangent loss as a function of frequency (100 Hz to 1 MHz) and temperature (32°–500°C) show that this compound has a diffused-type of ferroelectric phase transition at 230°C. Study of the surface morphology by SEM showed uniform grain distribution on the surface of the sample with less porosity. The activation energy, calculated from the plot of temperature dependence of AC conductivity, of the compound was found to be 0.11 eV and 0.14 eV at 500 kHz and 1 MHz respectively. The nature of the variation of conductivity and value of activation energy suggest that the conduction process is of a mixed-type.

DIELECTRIC AND FERROELECTRIC PROPERTIES OF (Li, Ce)-DOPED Sr2Bi4Ti5O18 LEAD-FREE CERAMICS

2011 ◽  
Vol 01 (04) ◽  
pp. 439-445 ◽  
Author(s):  
QIAN CHEN ◽  
ZHIJUN XU ◽  
RUIQING CHU ◽  
YONG LIU
Keyword(s):  
Electrical Properties ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Lead Free ◽  
High Curie Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
Lead Free Ceramics ◽  
Ce Modification

The influence of (Li, Ce) doping on the electrical properties of bismuth layer Sr 2-x (Li, Ce) x/2 Bi4Ti5O18 [abbreviated to SBTi-(Li, Ce) X/2] ceramics was investigated. X-ray diffraction analysis showed that all the ceramic samples were single-phase compounds. The (Li, Ce) modification significantly decreased the dielectric loss of Sr2Bi4Ti5O18 ceramics and greatly improved the piezoelectric activity. At x/2 = 0.0125, the SBTi-(Li, Ce) x/2 ceramics exhibited the excellent properties with high remnant polarization (P r = 9.3 μC/cm2) and high Curie temperature (T c = 299°C). Meanwhile, the SBTi-(Li, Ce)0.0125 ceramics had the largest piezoelectric constant (d33 = 26 pC/N). The results showed that the SBTi-(Li, Ce) x/2 ceramic was a promising lead-free piezoelectric material.

EFFECTS OF La DOPING ON FERROELECTRIC PROPERTIES OF CaBi4Ti4O15 THIN FILMS

2007 ◽  
Vol 14 (02) ◽  
pp. 277-281
Author(s):  
YANXIA DING ◽  
GUANGDA HU ◽  
SUHUA FAN
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
La Doping ◽  
Gel Technique ◽  
A Site

La modified CBTi ( CLBTi ) thin films were prepared on Pt/Ti/SiO 2/ Si (100) substrates by a sol–gel technique. X-ray diffraction analysis showed that single phase of CLBTi thin films were obtained. Their crystallization and hysteresis behavior were strongly dependent on the La contents. An increase of 2Pr as well as a decrease of 2Ec with the increase of La concentration were observed. The leakage properties of CBTi thin films were found to be improved by the La doping. The results were discussed with respect to the effects of La 3+ substitution at perovskite A-site.

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.

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

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