scholarly journals Role of Potassium Substitution in the Magnetic Properties and Magnetocaloric Effect in La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20)

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 407 ◽  
Author(s):  
Dhawud Sabilur Razaq ◽  
Budhy Kurniawan ◽  
Dicky Rezky Munazat ◽  
Kazumitsu Watanabe ◽  
Hidekazu Tanaka
Keyword(s):  
Bond Length ◽  
Bond Angle ◽  
Sol Gel ◽  
Double Exchange ◽  
Entropy Change ◽  
Average Bond Length ◽  
Rhombohedral Structure ◽  
Sem Images ◽  
Average Grain Size ◽  
Average Bond

The magnetic and magnetocaloric effects of potassium-substituted La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20) manganite were explored. The samples in polycrystalline form were synthesized by the sol–gel method, with a final sintering temperature of 1100 °C. Powder X-ray diffraction (XRD) patterns refined by Rietveld refinement show that all samples crystallized in rhombohedral structure with R-3c space group. The unit cell volume of the samples decreases with increasing potassium concentration. In addition, small changes in average bond length and bond angle are also observed in the samples. Scanning electron microscope (SEM) images reveal that the largest average grain size was observed for x = 0.10. Field-cooled (FC) magnetization measurements show that the Curie temperature ( T C ) of the samples increases from 320 K for x = 0 to 360 K for x = 0.2. The largest magnetocaloric (MCE) effect, which is represented by maximum magnetic entropy change (− Δ S M , M A X ), reaches its greatest value for the x = 0.10 sample. The monotonous increase in T C suggests that TC is mainly governed by the ferromagnetic coupling between Mn ions induced by the changes on average bond length and bond angle. The obtained − Δ S M , M A X value suggests that MCE property is more sensitive to Zener theory of double exchange, which is strongly related to the Mn3+/Mn4+ ratio of the samples.

Structure and Morphology Properties of Nanosized La0.75K0.05Ba0.05Sr0.15MnO3 Manganite

2020 ◽  
Vol 860 ◽  
pp. 106-111
Author(s):  
Dhawud Sabilur Razaq ◽  
Budhy Kurniawan ◽  
Ikhwan Nur Rahman ◽  
Dicky Rezky Munazat
Keyword(s):  
Bond Length ◽  
Crystallite Size ◽  
Sintering Temperature ◽  
Bond Angle ◽  
Sol Gel ◽  
Rhombohedral Structure ◽  
Phase Purity ◽  
X Ray ◽  
Structure And Morphology ◽  
Scanning Electron

Nanosized La0.75K0.05Ba0.05Sr0.15MnO3 manganite have been synthesized using sol-gel method. Afterwards, the samples were sintered at eight different temperature ranging from 650 to 1000 °C. Phase purity, crystal structure and the morphology of the sample have been examined using X-Ray Diffractometer (XRD) and Scanning Electron Microscope. It has been found that different higher sintering temperature greatly affect the phase purity and crystallite size of the sample. Regardless of the sintering temperature, all the samples crystallized in rhombohedral structure with R-3c space group. The crystallite size of the samples is found to increase from 41.59 nm up to 73.42 nm as the sintering temperature increases. Further analysis from XRD result shows that sintering temperature also affect the average Mn-O bond length and Mn-O-Mn bond angle of the sample. The average Mn-O bond length is found to increase while the average Mn-O-Mn bond angle tends to decrease as sintering temperature increases. SEM measurement shows that various grain size ranging from ~100 nm up to ~ 350 nm exists in all the sample regardless the sintering temperature.

scholarly journals 1,2,3,4,5,6,7,8,13,13,14,14-Dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-1,4:5,8-dimethanotriphenylene at 90 K

2012 ◽  
Vol 68 (8) ◽  
pp. o2538-o2538
Author(s):  
Brandon W. Jenkins ◽  
Frank R. Fronczek ◽  
Steven F. Watkins
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Title Compound ◽  
Room Temperature ◽  
Bond Angle ◽  
Average Bond Length ◽  
Volume Contraction ◽  
Compound C ◽  
Independent Unit ◽  
Average Bond

The previously reported room-temperature crystal structure [Jaud Baldy, Negrel, Poite & Chanon (1993).Z. Kristallogr.204, 289–291] of the title compound, C20H8Cl12, is monoclinic withZ′ = 1, whereas the 90 K structure reported herein is triclinic withZ′ = 2 and shows a 2% volume contraction. The crystallographically independent unit chosen consists of both enantiomers (Λ and Δ) of this propeller-like molecule. Both enantiomers display quasi-twofold symmetry, with average bond-length/bond-angle deviations of 0.0018 (4) Å and 0.41 (2)° for Λ, and 0.0026 (4) Å and 0.50 (2)° for Δ.

INFLUENCE OF GRAIN SIZE ON MAGNETOCALORIC EFFECT IN THE NANOCRYSTALLINELa0.8Te0.2MnO3

2011 ◽  
Vol 10 (04n05) ◽  
pp. 597-600
Author(s):  
RABINDRA NATH MAHATO ◽  
K. SETHUPATHI ◽  
V. SANKARANARAYANAN
Keyword(s):  
Grain Size ◽  
Landau Theory ◽  
Sol Gel ◽  
Entropy Change ◽  
Ferromagnetic Transition ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Paramagnetic Region ◽  
Rhombohedral Crystal Structure ◽  
Crystallite Sizes

The nanocrystalline La0.8Te0.2MnO3samples are prepared by sol-gel method and show rhombohedral crystal structure with R3c space group at room temperature. The calculated crystallite sizes are ~55 nm, 40 nm and 25 nm for calcined at 700°C, 800°C and 900°C temperatures. The SEM images show the grain size increases as the calcination temperature increases and the values are in good agreement with that obtained from X-ray diffraction analysis. The samples undergo paramagnetic to ferromagnetic transition and follow Curie–Weiss law in the paramagnetic region. The maximum entropy change are ~3.2 J kg-1K-1, 3 J kg-1K-1and 2 J kg-1K-1for a field change of 20 kOe for 55 nm, 40 nm and 25 nm samples respectively. In the framework of Landau theory of phase transition, the experimentally observed magnetic entropy change and theoretical predicted model fits well for all the nanoparticles.

Comparative Studies of Multiferroic BiFeO3 Powders Prepared by Hydrothermal Method versus Sol-Gel Process

2014 ◽  
Vol 670-671 ◽  
pp. 113-116 ◽  
Author(s):  
Xiao Yan Zhang ◽  
Xi Wei Qi ◽  
Zhi Yuan Yang ◽  
Rui Xia Zhong
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Hydrothermal Method ◽  
Sol Gel ◽  
Distribution Analysis ◽  
Sem Images ◽  
Multiferroic Bifeo ◽  
Average Grain Size ◽  
Sol Gel Process

Multiferroic BiFeO3 powders were synthesized by two methods: sol-gel process and hydrothermal method. The synthesized powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and particle size distribution analysis. The results obtained by XRD, which is consistent with 86-1518 JCPDS card, show that powders prepared by hydrothermal method are composed of the single phase with the trigonal structure (perovskite-type). It can be found by particle size distribution analysis that the particle size of the samples prepared by sol-gel process is finer and more uniform than that of the samples synthesized by the hydrothermal method. The SEM images of samples depicts that the synthesized BiFeO3 powders are united and the average grain size of hydrothermal processed samples is significantly large as compared to the sol-gel derived sample.

A contribution to the structure of coals from x-ray diffraction studies

1960 ◽  
Vol 252 (1019) ◽  
pp. 557-602 ◽  
Keyword(s):  
Bond Length ◽  
Structural Model ◽  
Structural Parameters ◽  
Amorphous Material ◽  
Average Bond Length ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Differences ◽  
Average Bond

Detailed X-ray diffraction studies have been carried out on a series of vitrains, anthracites, lignites, durains, fusains and certain coal extracts, of varying rank. The results are interpreted in terms of a basic structural model in which the carbon atoms are arranged in small aromatic layers linked to each other by aliphatic or alicyclic material or by five-membered rings to form large buckled sheets. Data have been obtained on the layer size distributions, the average layer diameters, the average bond length, the proportion of amorphous material and on the nature of the packing. The significance of the various structural parameters deduced from X-ray data is discussed critically. All the results are considered together in an attempt to develop as detailed a structural model as possible. The nature of the coalification process and the structural differences between various macerals are discussed and the results are compared with those deduced from other studies.

The average bond length in Pd clusters Pdn, n=4–309: A density-functional case study on the scaling of cluster properties

2001 ◽  
Vol 115 (5) ◽  
pp. 2082-2087 ◽  
Author(s):  
Sven Krüger ◽  
Stefan Vent ◽  
Folke Nörtemann ◽  
Markus Staufer ◽  
Notker Rösch
Keyword(s):  
Bond Length ◽  
Density Functional ◽  
Average Bond Length ◽  
Cluster Properties ◽  
Pd Clusters ◽  
Average Bond

Die Kristallstruktur von Bis-[methylammonium]-hexafluorosilikat, (MeNH3)2SiF6 / The Crystal Structure of Bis-[methylammonium]-hexafluorosilicate, (MeNH3)2SiF6

2002 ◽  
Vol 57 (9) ◽  
pp. 1003-1007 ◽  
Author(s):  
Jens Graulich ◽  
Dietrich Babel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Bond Length ◽  
Structure Determination ◽  
Average Bond Length ◽  
Space Group ◽  
X Ray ◽  
Average Bond

The results of a single crystal X-ray structure determination of monoclinic (MeNH3)2SiF6 are reported: a = 962.3(5), b = 964.4(1), c = 966.4(5) pm, " = 100.03(3)°; V = 883.2(7) Å3, Z = 4, space group C2/c; wR2 = 0.0999 based on F02 of 1291 independent reflections (including H refinement without restrictions). The structure is related to that of (NH4)2SiF6, but contains the dumb-bells of the cations well oriented along the greater cell diagonals and fixed by one nearly linear and two bi-furcated hydrogen bonds (N...F: 281 and 293 - 305 pm, resp.). The [SiF6]2- octahedron is nearly undistorted with average bond length Si-F: 167.7 pm (169.9 pm corrected for thermal motion)

Structural and Morphological La0.85-xBaxNa0.15MnO3 (x = 0, 0.05, 0.10 and 0.15) Perovskite Manganite

2020 ◽  
Vol 860 ◽  
pp. 95-100
Author(s):  
Ikhwan Nur Rahman ◽  
Budhy Kurniawan ◽  
Dhawud Sabilur Razaq ◽  
Arief Sudarmaji ◽  
Dicky Rezky Munazat
Keyword(s):  
Structural Parameters ◽  
Sol Gel ◽  
Double Exchange ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
Perovskite Manganite ◽  
Sem Images ◽  
Double Exchange Interaction ◽  
Unit Cells ◽  
Ba Substitution

Bulk polycrystalline samples La0.85-xBaxNa0.15MnO3 (x = 0, 0.05, 0.10 and 0.15) manganites were synthesized by the sol-gel route. The effect of Barium (Ba) existence on the structural and morphological was investigated by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The structural parameters were obtained using Rietveld refinement of the XRD pattern. It was revealed the structures of compounds have rhombohedral with R-3c space group without any impurities phase. Furthermore, several changes are found to exist due to Ba substitution such as the lattice parameter, unit cells volume, average crystallite size, average Mn-O bond length (<Mn – O>) and average Mn-O-Mn bond angle (<Mn – O – Mn>). The changes in <Mn – O> and <Mn – O – Mn> due to Ba substitution, affects the double exchange interaction of the samples. SEM images reveal the existence of Ba also affects the morphology of the studied samples, which consisted of polygonal grains with homogeneous chemical composition.

Lithium and sodium diffusion in solid electrolyte materials of AM2(PO4)3(A = Li, Na, M = Ti, Sn and Zr)

2014 ◽  
Vol 28 (26) ◽  
pp. 1450176 ◽  
Author(s):  
J. J. Shi ◽  
G. Q. Yin ◽  
L. M. Jing ◽  
J. Guan ◽  
M. P. Wu ◽  
...  
Keyword(s):  
Bond Length ◽  
Density Functional ◽  
Diffusion Barriers ◽  
Average Bond Length ◽  
Elastic Band ◽  
Functional Theory ◽  
Good Potential ◽  
Na Ions ◽  
Sodium Diffusion ◽  
Average Bond

Electrolytes with a high ionic conductivity are the prerequisite for the success of solid state rechargeable ion batteries. In this paper, density functional theory (DFT) calculations are applied in combination with a climbing-image nudged elastic band (CI-NEB) method to obtain the diffusion barriers of the lithium (Li) and sodium (Na) in stoichiometric AM 2( PO 4)3 (A = Li, Na, M = Ti, Sn and Zr) compounds. In the AM 2( PO 4)3, Li and Na ions occupy the interstitial sites, M1, which is coordinated by a trigonal antiprism of oxygen, and M2, which has a distorted eight-fold coordination. Results show that the diffusion barriers are closely related with the average bond length of A–O bond when the atom A occupies the M2 site in the AM 2( PO 4)3 compounds, and the diffusion barriers decrease with increasing the average bond length. Among the various types of the AM 2( PO 4)3 compounds, the AM 2( PO 4)3 has a good potential for solid electrolytes due to its low diffusion barriers for the Li and Na.

Effect of Different Synthesis Methods on Structural, Morphological and Magnetic Properties of La0.7Ba0.25Nd0.05MnO3

2020 ◽  
Vol 860 ◽  
pp. 89-94
Author(s):  
Dicky Rezky Munazat ◽  
Budhy Kurniawan ◽  
Dhawud Sabilur Razaq ◽  
Ikhwan Nur Rahman ◽  
Arief Sudarmaji ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Double Exchange ◽  
Average Crystallite Size ◽  
Rhombohedral Structure ◽  
Hysteresis Curve ◽  
Synthesis Methods ◽  
Double Exchange Interaction

La0.7Ba0.25Nd0.05MnO3 (LBNMO) compounds were synthesized using two different methods, namely are solid-state reaction (SS) and sol-gel (SG). All samples were heat-treated at 1200 °C for 12 hours. The investigation on structural, morphological, and magnetic properties was carried out by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Vibrating Samples Magnetometer (VSM) at room temperature. From the Rietveld refinement, both samples have formed a rhombohedral structure with an R-3c (167) space group. The average crystallite size was calculated using the Scherrer formula and Williamson-Hall (W-H) method for comparison. It was shown that the crystallite size of the sample produced by the SG method has larger than the SS method. This result is fairly consistent with the result obtained from SEM analysis, which shows that the average grain for the SG sample is larger than of the grain of the SS samples. From the magnetic hysteresis curve, the magnetization saturation value for the SG was higher and sharper than that of the SS sample. These confirm the occurrence of the double exchange interaction in the samples, which is mainly associated with the reduction of bandwidth and grain size.

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