Ferroelectricity in SrTiO3 Ceramics Induced by Pr Doping

2004 ◽  
Vol 848 ◽  
Author(s):  
A. Durán ◽  
E. Martínez ◽  
J. Mata ◽  
J. Heiras ◽  
X. Solans ◽  
...  
Keyword(s):  
Single Phase ◽  
Temperature Differential ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
Ferroelectric State ◽  
X Ray ◽  
The Difference ◽  
Diffraction Patterns ◽  
A Site ◽  
Srtio3 Ceramics

ABSTRACTFerroelectricity was induced in SrTiO3 by the Sr exchange for Pr ion in the A site of the perovskite ABO3-type structure. X-ray diffraction patterns show single phase crystalline structure in the SrxPr1-xTiO3 compound for x=0, 0.025, 0.050, 0.075 and 0.1 compositions. Rietveld refinement shows that the unit cell volume decreases with the increasing of Pr content as a consequence of the difference between Sr/Pr ionic radii. Furthermore, high-temperature differential thermoanalysis (DTA) displays a small anomaly at about 118 °C which is probably due to the Pr ion producing a distortion of the perovskite structure via an off-center site. This deformation in the lattice induces a measurable polar behavior of the solid solution. Dielectric permittivity (ε vs T) measurements display a well defined peak at about 238 °C. Furthermore, a well defined hysteresis loop at 30 °C with a remnant polarization that tends to decrease with increasing Pr concentration is observed. Both experimental results confirm the ferroelectric state induced by the Pr ion.

THE XRD STUDY OF THE EFFECT OF SLIGHT CHANGE IN STRUCTURE ON THE SUPERCONDUCTIVITY OF Y-Ba-Cu-O SYSTEM MATERIAL

1987 ◽  
Vol 01 (07n08) ◽  
pp. 289-293 ◽  
Author(s):  
WANG HUAQIN ◽  
ZHANG SHIYUAN ◽  
JIN TONGZHENG ◽  
HAN SHIYING ◽  
QIU DIRONG ◽  
...  
Keyword(s):  
Single Phase ◽  
Crystal Symmetry ◽  
Epr Spectra ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrd Study ◽  
The Difference ◽  
Diffraction Patterns ◽  
Flowing Oxygen

In this paper the differences in diffraction intensities from some crystal planes in the X-ray diffraction patterns of high Tc Y-Ba-Cu-O system superconductors prepared by different processing conditions and the difference among various structure cells in references are interpreted using computer fitting. The results suggest that there exists two structure cells in the single phase YBa2Cu3O7−x samples. Both structure cells have the same crystal symmetry and almost the same lattice parameters, a=3.821Å, b=3.892Å and c=11.676Å, but the different distortion degree of Cu2-O plane. According to EPR spectra measured on the same samples, it is considered that the improvement of superconductivity for the samples prepared by two-step annealing in flowing oxygen may be related to concentration of the structure cell with more serious distortion on the Cu2-O plane.

scholarly journals Ferromagnetic Order in the Intermetallic Alloys laNi5-xMgx

2012 ◽  
Vol 29 (1) ◽  
pp. 50
Author(s):  
D.N Ba ◽  
L.T Tai ◽  
N.T Trung ◽  
N.T Huy
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Chemical Doping ◽  
Intermetallic Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ferromagnetic Order ◽  
Diffraction Patterns

The influences of the substitution of Ni with Mg on crystallographic and magnetic properties of the intermetallic alloys LaNi5-xMgx (x ≤ 0.4) were investigated. The X-ray diffraction patterns showed that all samples were of single phase, and the lattice parameters, a and c, decreased slightly upon chemical doping. LaNi5 is well known as an exchange-enhanced Pauli paramagnet. Interestingly, in LaNi5-xMgx, the ferromagnetic order existed even with a small amount of dopants; the Curie temperature reached the value of room temperature for x = 0.2, and enhanced with increasing x.

Analysis of Selected Area Diffraction Patterns With Winjade

1998 ◽  
Vol 4 (S2) ◽  
pp. 342-343 ◽  
Author(s):  
S. D. Walck ◽  
P. Ruzakowski-Athey
Keyword(s):  
Single Phase ◽  
Xrd Analysis ◽  
Analysis Program ◽  
X Ray Diffraction ◽  
Program Module ◽  
Vast Number ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Patterns ◽  
Xrd Patterns

The analysis of Selected Area Diffraction (SAD) patterns that are collected from a single phase material having sufficient crystallites to provide continuous rings is relatively straightforward. However, when this condition is not met and there may be several phases present having rings of a spotty nature, the pattern is complex and can be quite difficult to analyze manually because of the vast number of discrete spots. WinJade from MDI is an X-ray diffraction (XRD) analysis program with an Electron Diffraction Program Module (EDPM) that can be used to aid in the analysis of SAD patterns. The EDPM produces Integrated Circular Density Plots (ICDP), which are one-dimensional intensity profiles plotted as a function of equivalent XRD 20 values or crystal d-spacings. These ICDP's can be overlayed with XRD patterns or with reference lines from the NIST and JCPDS crystalline databases for direct comparisons.

Degradation of phenol by using magnetic photocatalysts of titania

2013 ◽  
Vol 67 (7) ◽  
pp. 1434-1441 ◽  
Author(s):  
Chiung-Fen Chang ◽  
I.-Peng Tseng
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Single Phase ◽  
Health Impacts ◽  
X Ray Diffraction ◽  
Final Temperature ◽  
Soaking Time ◽  
X Ray ◽  
Green Materials ◽  
Diffraction Patterns

Magnetic TiO2 (MT) composites were prepared and applied to degrading phenol, which is one of the listed priority pollutants. The effects of heat treatment under preparation on the photocatalytic activity of MT composites have been investigated by varying the soaking time under a constant final temperature of 823 K. The total organic carbon and ring-remaining intermediates of o-DHB, p-DHB and 1,4-BQ in solution were detected during the photodegradation of phenol. All the resulting MT composites were the single-phase anatase and magnetite judged by X-ray diffraction patterns. The calcination of the as-prepared particles was proven to be extremely crucial to the photocatalytic activity. The best condition of heat treatment was found to be soaking time of 2 h at T = 823 K due to the good performance of photocatalytic activity, stable magnetic property, and reusability over three times. The results lead to the conclusion that recyclable MT composites prepared in this study, which belonged to the category of recyclable green materials, exhibit good photocatalytic activity to degrade phenol so as to possess applicable potential for the degradation of refractory organics in the aqueous solution. Furthermore, the environmental and health impacts were reduced as MT composites were applied in the treatment of water pollution.

Evidence for cooling-rate-dependent icosahedral short-range order in a Cu–Zr–Al metallic glass

2014 ◽  
Vol 47 (6) ◽  
pp. 1906-1911 ◽  
Author(s):  
Helmut Hermann ◽  
Uta Kühn ◽  
Horst Wendrock ◽  
Valentin Kokotin ◽  
Björn Schwarz
Keyword(s):  
Metallic Glass ◽  
Cooling Rate ◽  
Short Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rate Dependent ◽  
Icosahedral Clusters ◽  
Thermal Displacements ◽  
The Difference ◽  
Diffraction Patterns

Samples of Cu47.5Zr47.5Al5metallic glass were prepared at different cooling rate,R. The dependence of the X-ray diffraction patterns onRwas analysed by comparing them with corresponding patterns of computer-simulated models generated at different cooling rates as well. The observed changes in the experimental diffraction patterns are reproduced by the simulations, showing an increasing fraction of icosahedral clusters with decreasing cooling rate. The difference of the fractions of icosahedrally coordinated atoms in mould-cast and rapidly quenched Cu47.5Zr47.5Al5averages to 3 (1)%. Different frozen-in thermal displacements and different density are ruled out as a possible origin for the experimental observations.

Reduced-pressure MOCVD of highly crystalline BaTiO3 thin films

1992 ◽  
Vol 7 (3) ◽  
pp. 542-545 ◽  
Author(s):  
Peter C. Van Buskirk ◽  
Robin Gardiner ◽  
Peter S. Kirlin ◽  
Steven Nutt
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Total Pressure ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Reduced Pressure ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Diffraction Patterns ◽  
First Time

Epitaxial BaTi3 films have been grown on NdGaO3 [100] substrates by reduced pressure MOCVD for the first time. The substrate temperature was 1000 °C and the total pressure was 4 Torr. Electron and x-ray diffraction measurements indicate highly textured, single phase films on the NdGaO3 substrate which are predominantly [100], with [110] also present. TEM and selected area electron diffraction (SAED) indicate two specific orientational relationships between the [110] and the [001] diffraction patterns.

scholarly journals Структура и сегнетоэлектрические свойства гетероэпитаксиальных тонких пленок NaNbO-=SUB=-3-=/SUB=-, полученных методом RF-катодного распыления

2020 ◽  
Vol 46 (2) ◽  
pp. 15
Author(s):  
А.В. Павленко ◽  
Д.В. Стрюков ◽  
Н.В. Тер-Оганесян
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Single Phase ◽  
Oxygen Atmosphere ◽  
Cell Deformation ◽  
X Ray Diffraction ◽  
Cathode Sputtering ◽  
Ferroelectric State ◽  
X Ray ◽  
First Time

For the first time, thin films of NaNbO3 on a MgO(001) substrate, on which a SrRuO3 layer was previously deposited, were obtained by RF cathode sputtering in an oxygen atmosphere. According to x-ray diffraction analysis the films are single phase and single-crystalline. The lattice parameters in the tetragonal approximation for the NaNbO3 and SrRuO3 layers were: с(NaNbO3) = 0.3940(1) nm, a(NaNbO3) = 0.389(1) nm; с(SrRuO3) = 0.4004(1) nm, a(SrRuO3) = 0.392(3) nm. The unit cell deformation for NaNbO3 was ε33 = 0.007, ε11 = 0.002. Dielectric and piezoelectric measurements indicate that the films are in a ferroelectric state.

The stability and screw sense of the α -helix in poly- β -benzyl-L-aspartate

1960 ◽  
Vol 259 (1296) ◽  
pp. 110-128 ◽  
Keyword(s):  
Optical Rotatory Dispersion ◽  
Molecular Models ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
The Difference ◽  
Diffraction Patterns ◽  
The Stability ◽  
Α Helix ◽  
The Right

A number of polymers and copolymers containing β -benzyl-L-aspartate has been prepared and their optical rotatory dispersion in a variety of solvents has been measured. The results of these measurements together with studies of infra-red spectra, X-ray diffraction patterns, deuteration rates and molecular models lead to the following conclusions. (i) The α -helical form of poly- β -benzyl-L-aspartate is considerably less stable relative to the solvated randomly coiled form than that of poly- γ -benzyl-L-glutamate. (ii) The left-handed α -helix of poly- β -benzyl-L-aspartate is more stable than the right-handed one. (iii) The difference in stability between the two senses of α -helix is much less in the case of poly- β -benzyl-L-aspartate than in that of poly- γ -benzyl-L-glutamate or poly-L-alanine.

Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure

2013 ◽  
Vol 77 (1) ◽  
pp. 57-67 ◽  
Author(s):  
I. E. Grey ◽  
W. G. Mumme ◽  
C. M. MacRae
Keyword(s):  
Tungsten Bronze ◽  
Partial Ordering ◽  
X Ray Diffraction ◽  
Black Forest ◽  
X Ray ◽  
Pyrochlore Type ◽  
Diffraction Patterns ◽  
A Site ◽  
Clara Mine ◽  
The Ideal

AbstractLead-bearing phyllotungstite from the Clara mine in the central Black Forest, Germany has a formula (Cs0.41)Na0.14K0.05Pb2+2.01Ca0.26[W6+10.87Fe3+3.13O35.75(OH)6.25](O(H2O)3). X-ray diffraction patterns exhibit pseudohexagonal symmetry, but refinement of single-crystal synchrotron data has shown that the true symmetry is orthorhombic, Cmcm, with a = 7.298(1), b = 12.640(2), c = 19.582(4) Å, and that the pseudohexagonal character is due to submicrometre-scale cyclical twinning by rotation about the pseudohexagonal c axis. The structure can be described in terms of an ordered intergrowth, parallel to (001), of (111)py blocks with pyrochlore-type structures, which are ~6 Å in width, and two-layer wide regions with a hexagonal tungsten bronze (HTB) type structure. Caesium atoms occupy 18-coordinate cavities in the HTB regions, and H2O molecules occupy Φ sites in the A2B2O6Φ pyrochlore blocks. The lowering of symmetry from hexagonal to orthorhombic is due to partial ordering of W and Fe in the octahedral B sites and of Pb and vacancies in the A sites of the pyrochlore blocks. The ideal formula for the intergrowth structure (with no vacancies) is C 2A10[B14(O,OH)42]Φ4, where C is the cavity site in the HTB slabs. The mineral has only 21% occupancy of the C site and 25% occupancy of the A site, but full occupancy of the Φ site. There may be some mixing of Cs and H2O between the C and Φ sites.

New structure, reconstruction, and behaviour of the coordination polymer framework [CuZn(CN)4]– towards hydrated alkali metal ions

2015 ◽  
Vol 93 (8) ◽  
pp. 913-919 ◽  
Author(s):  
Junpei Yamada ◽  
Shin-ichi Nishikiori
Keyword(s):  
Coordination Polymer ◽  
Crystal Structure Analysis ◽  
Atmospheric Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Channel ◽  
Unknown Structure ◽  
The Difference ◽  
Diffraction Patterns ◽  
Polymer Framework

A new framework structure of the coordination polymer [CuZn(CN)4]– has been discovered in the newly synthesized [Na(H2O)n][CuZn(CN)4] (n = 12.7; 1). X-ray crystal structure analysis revealed a 3D framework comprised of tetrahedral Cu(I) and Zn(II) centres with bridging cyanide ligands containing both octagonal and square channel cavities; these channels contain hydrated Na+ ions as guests. In open air, complex 1 is extremely unstable and loses water molecules to form [Na(H2O)n][CuZn(CN)4] (n = 5.2–6.8; 2) within 30 min. Powder X-ray diffraction patterns showed that this change results in the conversion of the framework of complex 1 to the same framework observed in [K(H2O)n][CuZn(CN)4]. The [CuZn(CN)4]– framework of [K(H2O)n][CuZn(CN)4] has a tridymite structure with hexagonal channel cavities occupied by hydrated K+ ions. Like 1, 2 is also unstable under atmospheric conditions, yielding [Na(H2O)n][CuZn(CN)4] (n = 3), which has an unknown structure. While the framework of [K(H2O)n][CuZn(CN)4] is structurally flexible and robust, the framework of 2 is unstable and fragile. This contrast comes from the difference between the nature of the hydrated K+ and Na+ ions present in the frameworks.

Sign in / Sign up

Export Citation Format

Share Document