Hydrothermal synthesis of ABi2Ta2O9Aurivillius phase: A comparative study of A-site cation size on structure, dielectric, optical properties

In this study, the double-layered Aurivillius phases CaBi2Ta2O9 (CBT) and PbBi2Ta2O9 (PBT) were prepared through a hydrothermal route with NaOH as a mineralizer. XRD analysis confirmed that the CBT and PBT compounds were successfully formed and adopted an orthorhombic crystal structure with an [Formula: see text]21am symmetry. Le Bail refinements of XRD data indicated that the unit cell volume of CBT was smaller than PBT and is associated with the smaller ionic radius of Ca[Formula: see text] compared to Pb[Formula: see text]. The surface morphology of both samples, as determined using SEM, demonstrated plate-like grains with anisotropic grain growth. It was found that the different ionic radii of [Formula: see text]-site cations (Ca[Formula: see text] and Pb[Formula: see text] strongly affected the structural, optical and electrical properties of the Aurivillius phase. The occupation of smaller Ca[Formula: see text] cations induced a higher structural distortion, which resulted in higher bandgap ([Formula: see text] energy and ferroelectric transition temperature ([Formula: see text] of CBT, compared to those of PBT.

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Struktur dan Sifat Dielektrik Senyawa Aurivillius CaBi3LaTi4O15 yang Disintesis dengan Teknik Hidrotermal

Jurnal Riset Kimia ◽

10.25077/jrk.v11i1.343 ◽

2020 ◽

Vol 11 (1) ◽

pp. 9-15

Author(s):

Zulhadjri Zulhadjri ◽

Firmanul Qadri Amir ◽

Marsal Mahmud ◽

Upita Septiani ◽

Syukri Arief

Keyword(s):

Crystal Structure ◽

Single Phase ◽

X Ray Diffraction ◽

Aurivillius Phase ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Hydrothermal Technique ◽

X Ray ◽

Structure Morphology ◽

Ferroelectric Transition Temperature

Synthesis of four-layer Aurivillius CaBi3LaTi4O15 has been successfully carried out by hydrothermal technique using NaOH 4 M as mineralizer. The reaction was carried out at 220 °C for 72 h. Crystal structure, morphology, and dielectric properties were analyzed in this study. X-ray diffraction confirmed that the single-phase product was successfully obtained. The refinement result shows the product has orthorhombic crystal structure with space group A21am. The morphology analyzed using SEM shows plate-like grains are observed, which is characteristic of Aurivillius phase. Dielectric curves show peaks at 585 °C which indicate ferroelectric transition temperature.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.547.41 ◽

2013 ◽

Vol 547 ◽

pp. 41-48 ◽

Cited By ~ 2

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.

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FT-IR Spectroscopic and XRD Studies on Tris-Thiourea Strontium Chloride Single Crystals

Material Science Research India ◽

10.13005/msri/080129 ◽

2011 ◽

Vol 8 (1) ◽

pp. 201-204

Author(s):

H. O. Jethva ◽

R. R. Hajiyani

Keyword(s):

Single Crystals ◽

Xrd Analysis ◽

Wave Number ◽

Strontium Chloride ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Number Range ◽

Aqueous Solvent ◽

Powder Xrd Analysis ◽

Ft Ir

There are various nonlinear optical materials having crystalline nature and find various applications in science and technology. Tris-thiourea strontium chloride was synthesized and single crystals were grown by the slow solvent evaporation technique using aqueous solvent. The grown crystals were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). The FT-IR spectra of these crystals were recorded in the wave number range 400-4000 cm-1 which reveals the presence of various functional groups. The powder XRD analysis suggested orthorhombic crystal structure.

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A structural study of the Aurivillius phases by X-ray powder diffraction

Powder Diffraction ◽

10.1154/1.1810158 ◽

2005 ◽

Vol 20 (1) ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

V. G. Vlasenko ◽

A. T. Shuvaev ◽

D. S. Drannikov

Keyword(s):

Powder Diffraction ◽

Rietveld Method ◽

Orthorhombic Crystal ◽

Aurivillius Phases ◽

Orthorhombic Crystal Structure ◽

Space Group ◽

X Ray ◽

Cell Parameters ◽

Lattice Constants ◽

Bismuth Oxides

New layered bismuth oxides Bi2(BiCaNa)m−1NbmO3m+3(m=2-4) with the Aurivillius type phase were successfully synthesized. The structures of the compounds have been studied by X-ray powder diffraction and refined by the Rietveld method. Bi2.25Ca0.5Na0.25Nb2O9(m=2) has an orthorhombic crystal structure with lattice constants a=5.4478(1) Å;b=5.4770(2) Å;c=24.883(8) Å, space group A21am (No. 36). Bi2CaNaNb3O12 and Bi2.25Ca0.5Na1.25Nb3O12(m=3) are orthorhombic with Fmmm(No. 69) space group and the unit-cell parameters a=5.4473(7) Å, b=5.4770(3) Å, c=32.722(6) Å and a=5.4574(7) Å, b=5.4884 (3) Å, c=32.711(6) Å, respectively. The structure of Bi2CaNa2Nb4O15(m=4) was found to be orthorhombic with parameters a=5.4584(8) Å, b=5.4833(3) Å, c=40.534(1) Å and was refined in the space group A21am (No. 36).

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A-Site Cational Size Disorder Effects in La0.55Ca0.45MnO3

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.351 ◽

2007 ◽

Vol 336-338 ◽

pp. 351-355

Author(s):

K.F. Wang ◽

X.P. Liu ◽

Q.C. Li ◽

Y. Wang ◽

L.F. Wang ◽

...

Keyword(s):

Ground State ◽

Curie Point ◽

Atomic Fraction ◽

Ionic Radii ◽

Disorder Effects ◽

Radial Distortion ◽

Site Disorder ◽

Glass Insulator ◽

A Site ◽

Cation Size

The effects of A-site cation size disorder in ABO3 type ferromagnetic metallic La0.55Ca0.45MnO3 system have been studied by substituting La3+ and Ca2+ by other ions, while keeping the valency of Mn ions and the A-site cation mean radius <rA> constant in the substituted compounds with different A-site ionic radii variance σ2 = Σi (xiri 2 − <rA>2), where xi and ri are the atomic fraction and ionic radii of i-type ions at A-site, respectively. It is revealed that the A-site disorder induces the decreasing of the magnetization and the increasing of the resistivity. The ferromagnetic Curie point TC decreases with the increasing of the A-site ionic radii variance, too. Moreover, the ground state of the system transits from ferromagnetic metal to glass insulator upon increasing variance of the A-site ionic radii from 0.0003 for La0.55Ca0.45MnO3 to 0.009 for Gd0.55Sr0.45MnO3. It is argued that the suppression of the ferromagnetism is ascribed to the enhanced radial distortion of the MnO6 octahedra due to the increasing A-site disorder.

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Crystal Structure–microwave Dielectric Property Relations in R2BaZnO5 (R= Sm, Eu, Gd, Dy, Ho, Er, and Tm) Ceramics

Journal of Materials Research ◽

10.1557/jmr.2002.0267 ◽

2002 ◽

Vol 17 (7) ◽

pp. 1803-1807 ◽

Cited By ~ 3

Author(s):

Akinori Kan ◽

Hirotaka Ogawa

Keyword(s):

Crystal Structure ◽

Dielectric Properties ◽

Microwave Dielectric Properties ◽

Dielectric Constants ◽

Orthorhombic Crystal ◽

Ionic Radii ◽

Orthorhombic Crystal Structure ◽

Property Relations ◽

Microwave Dielectric ◽

Bond Valence Sum

R2BaZnO5 (R = Sm, Eu, Gd, Dy, Ho, Er, and Tm) were synthesized, and the effects of the differences in ionic radii of R ions on the microwave dielectric properties and crystal structure have been investigated by using x-ray powder diffraction. It was shown that the R2BaZnO5compounds have an orthorhombic crystal structure with Pnma (No. 62) and the lattice parameters of the samples increase linearly with the increase in the ionic radii of the R ions. The dielectric constants (εr) of R2BaZnO5sintered at the optimum temperatures vary linearly from 16.1 to 19.3, suggesting that these variations in εr are the result of the differences in the ionic polarizabilities of R ions. Moreover, it is suggested that the variations in the valences of R ions determined by using bond valence sum may exert an influence on quality factor (Qf ), because the values of valences of R ions in R(1)O7 polyhedra and Qf exhibit similar tendencies with changes in the ionic radii of R ions. In the R2O3–BaO–ZnO system, Dy2BaZnO5showed the appropriate microwave dielectric properties: εr = 17.1, Qf = 29669 GHz, and τf = −1.5 ppm/°C.

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FT-IR Spectroscopic and XRD Studies on Tetra-thiourea Strontium Chloride Single Crystals

Material Science Research India ◽

10.13005/msri/090124 ◽

2012 ◽

Vol 9 (1) ◽

pp. 165-167

Author(s):

H. O. Jethva ◽

R. R. Hajiyani2

Keyword(s):

Single Crystals ◽

Xrd Analysis ◽

Wave Number ◽

Strontium Chloride ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Number Range ◽

Aqueous Solvent ◽

Powder Xrd Analysis ◽

Ft Ir

There are various nonlinear optical materials having crystalline nature and find various applications in science and technology. Tetra-thiourea strontium chloride was synthesized and single crystals were grown by the slow solvent evaporation technique using aqueous solvent. The grown crystals were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), and Xray diffraction analysis (XRD). The FT-IR spectra of these crystals were recorded in the wave number range 400-4000cm-1 which reveals the presence of various functional groups. The powder XRD analysis suggested orthorhombic crystal structure.

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Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076263 ◽

1983 ◽

Vol 41 ◽

pp. 518-519

Author(s):

George G. Cocks ◽

Louis Leibovitz ◽

DoSuk D. Lee

Keyword(s):

Crystal Structure ◽

Crassostrea Virginica ◽

Crystal Orientation ◽

Developmental Changes ◽

Gastrula Stage ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Stages Of Growth ◽

Early Stages ◽

Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

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A New Phase of the Na+ Ion Conductor Na3PS4

10.26434/chemrxiv.8003717.v1 ◽

2019 ◽

Author(s):

Theodosios Famprikis ◽

James Dawson ◽

François Fauth ◽

Emmanuelle Suard ◽

Benoit Fleutot ◽

...

Keyword(s):

Solid Electrolytes ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Ion Conductor ◽

Solid State Batteries ◽

Density Analysis ◽

Two Phases ◽

Dynamics Simulations

<div> Solid electrolytes are crucial for next‑generation solid‑state batteries and Na3PS4 is one of the most promising Na+ conductors for such applications. At present, two phases of Na3PS4 have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na3PS4 based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na+ superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on ab initio molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes. </div>

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Crystal Engineering of Bi2WO6 to Polar Aurivillius-Phase Oxyhalides

10.26434/chemrxiv.9741701.v1 ◽

2019 ◽

Author(s):

Kazuki Morita ◽

Ji-Sang Park ◽

Sunghyun Kim ◽

Kenji Yasuoka ◽

Aron Walsh

Keyword(s):

Photocatalytic Activity ◽

Crystal Engineering ◽

First Principles ◽

Parent Compound ◽

Aurivillius Phase ◽

Aurivillius Phases ◽

Charge Neutrality ◽

Bismuth Oxides ◽

Structure Surface ◽

Electric Dipoles

The Aurivillius phases of complex bismuth oxides have attracted considerable attention due to their lattice polarization (ferroelectricity) and photocatalytic activity. We report a first-principles exploration of Bi2WO6 and the replacement of W6+ by pentavalent (Nb5+, Ta5+) and tetravalent (Ti4+, Sn4+) ions, with charge neutrality maintained by the formation of a mixed-anion oxyhalide sublattice. We find that Bi2SnO4F2 is thermodynamically unstable, in contrast to Bi2TaO5F, Bi2NbO5F and Bi2TiO4F2. The electric dipoles introduced by chemical substitutions in the parent compound are found to suppress the spontaneous polarization from 61.55 μC/cm2 to below 15.50 μC/cm2. Analysis of the trends in electronic structure, surface structure, and ionization potentials are reported. This family of materials can be further extended with control of layer thicknesses and choice of compensating halide species.

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