scholarly journals Structure, magnetic and magnetic transport properties of layered cobaltite Sr0.9Y0.1CoO2.63

2018 ◽  
Vol 62 (5) ◽  
pp. 555-562
Author(s):  
M. О. Troyanchuk ◽  
M. V. Bushinsky
Keyword(s):  
Monoclinic Phase ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Magnetic Transport ◽  
Diffraction Patterns ◽  
Increasing Temperature

The structure, magnetic and magnetotransport properties of perovskite Sr0.9Y0.1CoO2.63are studied. It is shown that the sample is structurally two-phase. The main phase has a tetragonal-distorted unit cell and is described by the spatial group I4/mmm. The broadening of the reflexes with indexes corresponding to a doubling of the parameter from the unit cell indicates that there is no strict translational symmetry along the с-axis. The presence of a broadened superstructural reflex observed at small angles on X-ray diffraction patterns at temperatures below 400 K is due to the monoclinic phase, whose content is much smaller than the tetragonal phase. Spontaneous magnetization appears during the formation of the monoclinic phase. The magnetic structure is predominantly an antiferromagnetic G-type structure with magnetic moments of 1.5µBin the layers of CoO6octahedra and 2µBin the anion-deficient CoO4+γlayers. The electrical conductivity of Sr0.9Y0.1CoO2.63has a semiconductor in character. The magnetoresistance reaches 57 % in a field of 14 T at a temperature of 5 K and decreases strongly with increasing temperature.

scholarly journals Магнитные свойства слоистого кобальтита Sr-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-CoO-=SUB=-3-delta-=/SUB=- (x = 0.1)

2018 ◽  
Vol 60 (10) ◽  
pp. 1957
Author(s):  
И.О. Троянчук ◽  
М.В. Бушинский ◽  
Р.А. Лановский ◽  
В.В. Сиколенко ◽  
К. Риттер
Keyword(s):  
Tetragonal Phase ◽  
Monoclinic Phase ◽  
Cell Parameter ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Unit Cell ◽  
Superstructure Reflection ◽  
Two Phase ◽  
Group I ◽  
Translation Symmetry

AbstractThe structure, the magnetic and magnetotransport properties of perovskite Sr_0.9Y_0.1CoO_2.63 have been studied. The sample is shown to have a two-phase structure. The main phase has a tetragonally distorted unit cell and is described by space group I 4/ mmm . The broadening of the reflections with indices corresponding to doubling unit cell parameter c indicates the absence of the rigorous translation symmetry along axis c . The existence of the broadened superstructure reflection observed in the diffraction pattern at small angles at temperature lower than 400 K is explained by the existence of the monoclinic phase whose content is significantly lower than that of the tetragonal phase, but is dominant in the Sr_0.8Y_0.2CoO_3–δ composition. The spontaneous magnetization appears as the monoclinic phase forms. The magnetic structure is mainly G-type antiferromagnetic with magnetic moments 1.5μ_B in the layers of CoO_6 octahedra and 2μ_B in the anion-deficit CoO_4 + γ layers. The conduction of the Sr_0.9Y_0.1CoO_2.63 composition has a semiconducting character. The magnetoresistance is 57% in a field of 14 T at a temperature of 5 K and strongly decreases with the temperature increase.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

Ferromagnetic properties and Nanocrystallization behavior of Amorphous (Fe0.99Mo0.01)78Si9B13 Ribbons

2001 ◽  
Vol 674 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
J. A. Toledo ◽  
S. Galindo ◽  
W. S. Sun
Keyword(s):  
Amorphous Phase ◽  
Magnetic Ordering ◽  
Metastable Phases ◽  
X Ray Diffraction ◽  
Ferromagnetic Properties ◽  
X Ray ◽  
Diffraction Patterns ◽  
Optimum Annealing Temperature ◽  
Increasing Temperature ◽  
Differential Scanning Calorimeters

ABSTRACTFerromagnetic properties and nanocrystallization process of soft ferromagnetic (Fe0.99Mo0.01)78Si9B13 ribbons are studied by transmission electron microscope (TEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetization measurements. The Curie and crystallization temperature are determined to be TC=665K and Tx = 750K, respectively. The Tx value is in well agreement with DSC measurement results. X-ray diffraction patterns had shown a good reconfirm of two metastable phases (Fe23B6, Fe3B) were formed under in-situ nanocrystallization process. Of which these metastable phases embedded in the amorphous matrix have a significant effect on magnetic ordering. The ultimate nanocrystalline phases of α-Fe (Mo, Si) and Fe2B at optimum annealing temperature had been observed respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of nanocrystalline ferromagnetism, suggesting the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents.

X-ray powder diffraction data for compound DyNiSn

1997 ◽  
Vol 12 (3) ◽  
pp. 134-135
Author(s):  
Liangqin Nong ◽  
Lingmin Zeng ◽  
Jianmin Hao
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns

The compound DyNiSn has been studied by X-ray powder diffraction. The X-ray diffraction patterns for this compound at room temperature are reported. DyNiSn is orthorhombic with lattice parameters a=7.1018(1) Å, b=7.6599(2) Å, c=4.4461(2) Å, space group Pna21 and 4 formula units of DyNiSn in unit cell. The Smith and Snyder Figure-of-Merit F30 for this powder pattern is 26.7(0.0178,63).

scholarly journals The crystal structures of two polyamides (‘nylons’)

1947 ◽  
Vol 189 (1016) ◽  
pp. 39-68 ◽  
Keyword(s):  
Crystal Structures ◽  
Unit Cell ◽  
Chain Molecule ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
C Fibre ◽  
Diffraction Patterns ◽  
Unit Cell Dimensions ◽  
Crystalline Forms

Detailed interpretations of the X -ray diffraction patterns of fibres and sheets of 66 and 6.10 polyamides (polyhexam ethylene adipamide and sebacamide respectively) are proposed. The crystal structures of the two substances are completely analogous. Fibres of these two polyam ides usually contain two different crystalline forms, α and β, which are different packings of geometrically similar molecules; most fibres consist chiefly of the α form. In the case of the 66 polymer, fibres have been obtained in which there is no detectable proportion of the β form. Unit cell dimensions and the indices of reflexions for the α form were determined by trial, using normal fibre photographs, and were checked by using doubly oriented sheets set at different angles to the X -ray beam. The unit cell of the a form is triclinic, with a — 4·9 A, b = 5·4 A, c (fibre axis) = 17·2A, α = 48 1/2º, β = 77º, γ = 63 1/2º for the 66 polymer; a = 4·95A, b = 5·4A, c (fibre axes) = 22·4A, α = 49º, β = 76 1/2º, γ = 63 1/2º for the 6.10 polymer. One chain molecule passes through the cell in both cases. Atomic coordinates in occrystals were determined by interpretation of the relative intensities of the reflexions. The chains are planar or very nearly so; the oxygen atoms appear to lie a little off the plane of the chain. The molecules are linked by hydrogen bonds between C = 0 and NH groups, to form sheets. A simple packing of these sheets of molecules gives the α arrangement.

X-ray powder diffraction analysis of the heteropoly-molybdate (MoO2)0.5PMo14O42

2003 ◽  
Vol 18 (3) ◽  
pp. 236-239 ◽  
Author(s):  
L. Marosi ◽  
J. Cifré ◽  
C. Otero Areán
Keyword(s):  
Catalytic Activity ◽  
Diffraction Analysis ◽  
Computer Modeling ◽  
Powder Diffraction ◽  
Rietveld Analysis ◽  
Nitrogen Atmosphere ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.

scholarly journals Correlations between structure, microstructure, density and dielectric properties of the lead-free ferroelectrics Bi0.5(Na,K)0.5TiO3

2015 ◽  
Vol 05 (04) ◽  
pp. 1550028 ◽  
Author(s):  
K. Anjali ◽  
T. G. Ajithkumar ◽  
P. A. Joy
Keyword(s):  
Monoclinic Phase ◽  
Structural Transition ◽  
Lead Free ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Close Relationship ◽  
Diffraction Patterns ◽  
Microstructure Density ◽  
Ferroelectric Oxides

Solid solutions of the lead-free ferroelectric oxides Bi[Formula: see text]Na[Formula: see text]TiO3 (BNT) and Bi[Formula: see text]K[Formula: see text]TiO3 (BKT), represented as ([Formula: see text])BNT–xBKT, are studied for very close compositions in the range [Formula: see text] to understand the correlation between the structure and the properties. Compositions are varied in steps of [Formula: see text] in the range [Formula: see text] and [Formula: see text] and [Formula: see text] in the range [Formula: see text], to precisely locate the structural transition as well as the morphotropic phase boundary (MPB) region and the compositional region of best performance. Rietveld refinement analysis of the powder X-ray diffraction patterns showed monoclinic phase up to x = 0.17 and a mixture of monoclinic and tetragonal phases for [Formula: see text]. Similarly, the density and the dielectric constant showed linear variation up to [Formula: see text] and a large increase above this composition, showing maximum values in the compositional range [Formula: see text], corresponding to the MPB region. Microstructural features also showed corresponding changes, indicating close relationship between the structure, microstructure and properties of the different compositions.

Magnetoresistance Effects for the Inhomogeneous Perovskite System of Ag Doped La0.833Na0.167MnO3

2011 ◽  
Vol 110-116 ◽  
pp. 553-558
Author(s):  
Jian Wu
Keyword(s):  
Perovskite Phase ◽  
Inhomogeneous System ◽  
X Ray Diffraction ◽  
Magnetoresistance Effect ◽  
Two Phase ◽  
X Ray ◽  
Magnetoresistance Ratio ◽  
Diffraction Patterns ◽  
System 1 ◽  
Relative Change

The transport properties of the inhomogeneous system (1/4) Ag2O-La0.833Na0.167MnO3(LNMO/Ag) have been systematically studied. X-ray diffraction patterns show that the LNMO/Ag sample is the two-phase composite and consists of a magnetic La0.833Na0.167MnO3(LNMO) perovskite phase and a nonmagnetic Ag metal phase. The resistivity of the sample decreases dramatically with Ag added into the pure perovskite LNMO manganites. For the LNMO/Ag sample, the Curie temperatureTCis 331 ± 2 K and slightly higher than that of the LNMO sample (323 ± 2 K). Due to the dope of Ag metal, the room temperature magnetoresistance effect is enhanced significantly (from 7% for the pure LNMO manganites to 23% for the LNMO/Ag sample under a relative lower field of 0.5 T and from 37.5% for the LNMO sample to 41 % for the LNMO/Ag sample under a high field of 6 T at the temperature of 330 K. In the low temperature regime, the magnetoresistance ratio of the LNMO/Ag sample is smaller than that of the LNMO sample, which is contrary to the magnetoresistance effect in high temperature. The effects are discussed qualitatively by use of a model which is based on the relative change among the intrinsic magnetoresistance effect and the extrinsic magnetoresistance effect.

EFFECT OF Ni ON THE ELECTRICAL AND MICROSTRUCTURAL PROPERTIES OF NANOCRYSTALLITES Fe2O3/TiO2 SYSTEM

2006 ◽  
Vol 13 (04) ◽  
pp. 479-484 ◽  
Author(s):  
MAGED S. SOBHY
Keyword(s):  
Electrical Resistivity ◽  
Spinel Ferrite ◽  
Average Crystalline Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Value ◽  
Semiconductor Behavior ◽  
Ion Substitution ◽  
Diffraction Patterns ◽  
Increasing Temperature

Nominal compositions of Ni x Ti 1-x Fe 2 O 5-δ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by a solid state reaction using stoichiometric amounts of Fe 2 O 3/ TiO 2 system and NiO as a dopant. The effects of small substitution of Ni ions on the electrical and structural properties were studied for the above system. The X-ray diffraction patterns revealed that the ferroelectric phase of iron titanate and the spinel ferrite phase of Ni -ferrite having a single phase at x = 0 and 1, respectively. The substitution of Ni ions increases the average value of lattice constant aav. Solid–solid interaction took place between the ternary oxides at 1200°C for 4 h yielding a new phase of NiTiO 3. The presence of the three phases was confirmed by X-ray diffraction technique. The resultant compositions have nanocrystallites with average crystalline size "D av " in the range 100–300 nm. The DC electrical resistivity ρ, Curie temperature TC and activation energies for electric conduction around TC region increase as Ni ion substitution increases. The ferrite samples have a semiconductor behavior where electrical resistivity ρ decreases on increasing temperature. The activation energy for electrical conduction was affected by both the ratio "ferroelectric/ferrite" and the position of the Curie temperatures in the compositions depending on the ( Ni , Ti ) to Fe ratio.

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