Synthesis, structural, magnetic and phase-transition studies of the ferromagnetic La2CoMnO6 double perovskite by symmetry-adapted modes

2015 ◽  
Vol 44 (31) ◽  
pp. 13867-13880 ◽  
Author(s):  
B. Orayech ◽  
I. Urcelay-Olabarria ◽  
G. A. López ◽  
O. Fabelo ◽  
A. Faik ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Rietveld Analysis ◽  
Neutron Diffraction Data ◽  
Reaction Method ◽  
X Ray ◽  
Space Groups ◽  
Transition Studies

A powdered La2CoMnO6 double perovskite was synthesized by the solid-state reaction method, and its crystal structure and phase-transitions were investigated by (Mode Crystallography) Rietveld analysis using X-ray and neutron diffraction data. Three indistinguishable ferromagnetic models with the space groups P21/n and P2′1/n′ are proposed.

Magnetic and Transport Properties of the Double Perovskite Sr2FeMnO6

2011 ◽  
Vol 393-395 ◽  
pp. 157-160 ◽  
Author(s):  
Lei Cui ◽  
Li Juan Yang
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Double Perovskite ◽  
Superlattice Reflection ◽  
Solid State Reaction Method ◽  
Paramagnetic Phase ◽  
Hysteresis Curve ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray

The double perovskite Sr2FeMnO6 has been synthesized by the solid-state reaction method. X-ray diffraction and subsequent Rietveld refinement confirm that Sr2FeMnO6 has the double-perovskite structure with a cubic cell (a=7.726 Å) and space group Fm3m (No. 225) . The appearance of the superlattice reflection (111) indicates that Fe and Mn atoms alternatively occupy the center of oxygen octahedron in an ordered way. Based on magnetization hysteresis curve and ESR measurements, a ferrimagnetic to paramagnetic phase transition for the double perovskite Sr2FeMnO6 was observed, and the Neel temperature was determined to be TN ~475K. In paramagnetic phase above TN, the value of gyromagnetic factor was determined to be very close to 2.

Thermal enhancement of 2H11/2→4I15/2 up-conversion luminescence of Er3+ doped K2Yb(PO4)(MoO4) phosphors

2021 ◽  
Author(s):  
Hongqiang Cui ◽  
Yongze Cao ◽  
Lei Zhang ◽  
Yuhang Zhang ◽  
Siying Ran ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Reaction Method ◽  
X Ray ◽  
Thermal Enhancement

Er3+ with different concentrations doped K2Yb(PO4)(MoO4) phosphors were prepared by a solid-state reaction method, and the layered orthorhombic crystal structure of the samples was confirmed by X-ray diffraction (XRD). Under...

scholarly journals Structural Study of Ferroelectric Phase Transition of Sn-doped SrTiO3

2014 ◽  
Vol 70 (a1) ◽  
pp. C61-C61 ◽  
Author(s):  
Hirofumi Kasatani ◽  
Shoichiro Suzuki ◽  
Akira Ando ◽  
Eisuke Magome ◽  
Chikako Moriyoshi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Local Structure ◽  
Ferroelectric Phase Transition ◽  
Nearest Neighbor ◽  
Ferroelectric Phase ◽  
Rietveld Analysis ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

Recently, ferroelectricity was discovered in Sn-doped SrTiO3 (abbreviated by SSTO), in which Sr-atom was substituted by a few percent Sn-atom[1]. The ferroelctricity of SSTO was confirmed by means of the appearance of the dielectric anomaly, that reached several thousands and the clear D-E hysteresis loop in low temperature phase. In order to clarify the mechanism of ferroelectric phase transition of SSTO from the viewpoint of the crystal structure, we investigated the average crystal structure and the local structure around the substitutional Sn-atom of SSTO10 (10% Sn concentration, ferroelectric phase transition temperature 180K) by means of synchrotron-radiation powder X-ray diffraction and transmission XAFS spectrum of Sn:K-edge, respectively. From the results of MEM/Rietveld analysis of powder X-ray diffraction data, it was obtained that crystal structure of paraelectric phase of SSTO10 was cubic perovskite structure with the disorder state of Sn-atom. In ferroelectric phase, the crystal system was tetragonal, which was similar in structure to tetragonal ferroelectric structure of BaTiO3, and Sn-atom was order state. XAFS study revealed that the valence of Sn-ion was +2 charge and the local structure of Sn-atom was seemed as being the self-insistent state of SnO crystal structure. However, strangely, the coordination number of the nearest neighbor atom, that is O-atom, was 2 instead of 4. This is a mystery result and we have been analyzing. We have considered that the ferroelectricity of SSTO is induced by the distortion around the subsitituional Sn-atom. At the meeting, we are planning to discuss the precise crystal structure and the mechanism of the ferroelectric phase transition of SSTO.

EFFECT OF SINTERING TEMPERATURE ON THE CRYSTAL STRUCTURE, MICROSTRUCTURE AND PHASE TRANSITION OF (Pb1-xSrx)TiO3 CERAMICS

2009 ◽  
Vol 02 (04) ◽  
pp. 193-197 ◽  
Author(s):  
RATTIPHORN SUMANG ◽  
THEERACHAI BONGKARN
Keyword(s):  
Phase Transition ◽  
Paraelectric Phase ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Dielectric Constants ◽  
Paraelectric Phase Transition ◽  
Reaction Method ◽  
X Ray ◽  
Grain Sizes

Polycrystalline ( Pb 1-x Sr x) TiO 3 (PST) (x = 0.25, 0.50) ceramics were synthesized by the solid-state reaction method. PST sintering temperatures ranged between 1050–1250°C. The samples were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The sintered pellets showed pure perovskite in all samples. The lattice parameter c increased, while the lattice parameter a decreased with increasing sintering temperatures. The tetragonality and average grain sizes increased when sintering temperatures were increased. The dielectric constants vs temperature curves of PST ceramics with x = 0.25 and x = 0.50 associated with the ferroelectric to paraelectric phase transition, showed a maximum peak at around 311 and 139°C, respectively. The dielectric constants of both compositions were related with their densities.

Investigate Oxygen Content in YBa2Cu3O7-δ Superconductors

2014 ◽  
Vol 979 ◽  
pp. 124-127 ◽  
Author(s):  
Thitipong Kruaehong
Keyword(s):  
Crystal Structure ◽  
Oxygen Content ◽  
Resistivity Measurement ◽  
Solid State Reaction Method ◽  
Superconducting Phase ◽  
X Ray Diffraction ◽  
Atomic Position ◽  
Reaction Method ◽  
X Ray ◽  
Structure Properties

The YBa2Cu3O7-δ(Y123) compounds were synthesized by solid state reaction method. The home-made four-probes apparatus was used for the resistivity measurement. The highest Tc is 91.95 K in sample C and sample A has lowest Tc onset at 89.85 K. The crystal structure properties and oxygen content were characterized by powder X-ray diffraction using CuKα radiation (λ=1.5406 Å). The Pmmm and Pnma space group corresponding on the superconducting phase and the non-superconducting phase. The atomic position of samples were consisted of various element atom. The longer time of oxygen-doping, the increase the critical temperature , superconducting phase and c lattice parameters.

Electrical and Dielectrical Propeties of Gas-Sensor Resistive Type Bi2Sn2O7

2014 ◽  
Vol 215 ◽  
pp. 503-506 ◽  
Author(s):  
Lubov V. Udod ◽  
Maxim N. Sitnikov ◽  
Sergei S. Aplesnin ◽  
Maxim S. Molokeev
Keyword(s):  
Phase Transition ◽  
Electrical Resistivity ◽  
Structural Phase ◽  
Dielectric Permeability ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
X Ray ◽  
Temperature Dependences ◽  
Resistive Type

Polycrystalline samples of Bi2Sn2O7 have been synthesized by conventional solid-state reaction method. According to the X-ray powder diffraction research, our sample co-existing of two polymorphs phases: cubic and rhombic, concurrently. The real dielectric permeability Re (ε) monotonic grows versus temperature and the imaginary dielectric permeability Im (ε) nonmonotonic is increased at the heating. There are maxima at Т=450 K on both temperature dependences Im (ε) and Re (ε) reveal. Anomalies in the temperature dependence of electrical resistivity at temperatures are found and to be correlated with the α→ β structural phase transition temperature.

scholarly journals Ferroelectric Transition in Sr- and W-Doped BaTiO3 Solid Solutions

2021 ◽  
Vol 11 (15) ◽  
pp. 6760
Author(s):  
Heeju Ahn ◽  
Eunjeong Lee ◽  
Yujin Cho ◽  
Dongyeon Bae ◽  
Hee Jung Park ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Curie Temperature ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lattice Constants ◽  
A Value ◽  
Curie Temperature Tc

We synthesized Sr- and W-doped BaTiO3 (BTO) polycrystals by using a solid-state reaction method. The X-ray diffraction results showed that Sr and W atoms occupied the Ba and Ti sites in tetragonal BTO, respectively, and there were changes in the lattice constants and the volumes in the Sr- and W-doped BTO. We found a change in the latent heat and the Curie temperature (TC) during the transition between the ferroelectric and paraelectric phases while increasing the contents of Sr and W in the Sr- and W-doped BTO. This can be explained by the fact that the doping of Sr and W atoms in BTO prevented a distinct transition between the ferroelectric tetragonal and paraelectric cubic structures by decreasing the c/a ratio to a value close to unity. This study shows a way toward a strategy for modulating a crystal structure by using proper dopants for future applications in ferroelectricity-based devices.

Magnetic structure of bornite, Cu5FeS4

1981 ◽  
Vol 59 (4) ◽  
pp. 535-539 ◽  
Author(s):  
M. F. Collins ◽  
G. Longworth ◽  
M. G. Townsend
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Magnetic Structure ◽  
Magnetic Phase ◽  
Magnetic Ordering ◽  
Neutron Powder Diffraction ◽  
Spin Rotation ◽  
Neutron Diffraction Data ◽  
X Ray ◽  
Antiferromagnetic Ordering

Neutron powder diffraction techniques have been used to investigate the magnetic structure of bornite, Cu5FeS4. Below the antiferromagnetic ordering temperature of 76 ± 2 K extra peaks appear in the diffraction pattern corresponding to magnetic ordering. The data are consistent with an antiferromagnetic alignment of iron atoms with moments of 4.4 ± 0.3 μB on the iron sites proposed by Koto and Morimoto on the basis of X-ray measurements of the crystal structure. Mössbauer and neutron diffraction data suggest that the second magnetic phase transition at 8 K arises from a spin rotation. Since the magnetic structure gives only superexchange paths between iron atoms through two or more anions, it is difficult to understand why the Néel temperature is so high without invoking small moments on copper atoms

scholarly journals Synchrotron X-ray diffraction study of double perovskites Sr2RNbO6 (R = Sm, Gd, Dy, Ho, Y, Tm, and Lu)

2018 ◽  
Vol 33 (4) ◽  
pp. 279-286
Author(s):  
W. Wong-Ng ◽  
J. A. Kaduk ◽  
S. H. Lapidus ◽  
L. Ribaud ◽  
S. P. Diwanji
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Powder Diffraction ◽  
Double Perovskite ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Analysis Technique ◽  
Diffraction Patterns

A series of double-perovskite oxides, Sr2RNbO6 (R = Sm, Gd, Dy, Ho, Y, Tm, and Lu) were prepared and their crystal structure and powder diffraction reference patterns were determined using the Rietveld analysis technique. The crystal structure of each of the Sr2RNbO6 phase is reported in this paper. The R = Gd, Ho, and Lu samples were studied using synchrotron radiation, while R = Sm, Dy, Y, and Tm samples were studied using laboratory X-ray diffraction. Members of Sr2RNbO6 are monoclinic with a space group of P21/n and are isostructural with each other. Following the trend of “lanthanide contraction”, from R = Sm to Lu, the lattice parameters “a” of these compounds decreases from 5.84672(10) to 5.78100(3) Å, b from 5.93192(13) to 5.80977(3) Å, c from 8.3142(2) to 8.18957(5) Å, and V decreases from 288.355(11) to 275.057(2) Å3. In this double-perovskite series, the R3+ and Nb5+ ions are structurally ordered. The average Nb–O bond length is nearly constant, while the average R–O bond length decreases with the decreasing ionic radius of R3+. Powder diffraction patterns for these compounds have been submitted to the Powder Diffraction File (PDF).

Synthesis and Structural Characterization of La0.8Sr0.2MO3 (M=Mn, Fe, Co and Cr) Solid Ionic Material for Catalyst Application

2016 ◽  
Vol 840 ◽  
pp. 48-51
Author(s):  
Muhammad Nor Azri Aziz ◽  
Johar Banjuraizah ◽  
Shing Fhan Khor ◽  
Zainal Arifin Ahmad
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Raw Materials ◽  
Solid State Reaction Method ◽  
Cold Isostatic Pressing ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Scanning Electron

La0.8Sr0.2MO3+δ, (M=Mn, Fe, Cr, Co) ceramics were prepared by using solid state reaction method. All raw materials were mixed and ground using mortar. Homogenized powders were calcined at 900°C for three hour followed by grounding and uniaxial pressed at 100MPa. Compacted pellets were further pressed using cold isostatic pressing machine at 2600kg/m.s and sintered at 1300°C with heating rate 5°C/min for 4 hour. Crystal structure and phase transformation of sintered samples were obtained using X-ray diffraction. Density and porosity are measured by using Archimedes principle. The morphology of sintered samples is observed using scanning electron microscopy, while elemental analysis using the EDX.

Sign in / Sign up

Export Citation Format

Share Document