Effects of Organic Material on Magnetoresistance in Electron-doped Double Perovskite

Abstract The Curie temperature of electron-doped Sr2FeMoO6 can be optimized significantly due to the band-filling effect, but accompanying an almost absent low-field magnetoresistance (LFMR), which is unfavorable to applications in the magnetoresistive devices operated at room-temperature. Our previous works confirmed that, a remarkable enhanced LFMR was observed in Sr2FeMoO6 by modifying the grain boundary with insulating organic small molecules (glycerin, CH2OHCHOHCH2OH). However, in this work, modifying the grain boundary strength of the La0.5Sr1.5FeMoO6 with the insulating organic macromolecules (oleic acid, CH3(CH2)7CH=CH(CH2)7COOH) or small molecules (glycerin), both of them have negligible functions on the magnetoresistance behavior in La0.5Sr1.5FeMoO6. Contrary to the glycerin-modified Sr2FeMoO6, Sr2FeMoO6/oleic acid composites don’t exhibit an obviously increased magnetoresistance property. Based on the above experimental results and the related works, it is proposed that, maintaining high spin polarization of the carriers at the Fermi level and improving the tunneling process across the grain boundary by using the suitable organic materials are decisive factors for optimizing the magnetoresistance behavior in the similar electron-doped double perovskites.

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Room-Temperature Low-Field Colossal Magnetoresistance in Double-Perovskite Manganite

Physical Review Letters ◽

10.1103/physrevlett.123.126602 ◽

2019 ◽

Vol 123 (12) ◽

Cited By ~ 9

Author(s):

S. Yamada ◽

N. Abe ◽

H. Sagayama ◽

K. Ogawa ◽

T. Yamagami ◽

...

Keyword(s):

Colossal Magnetoresistance ◽

Room Temperature ◽

Double Perovskite ◽

Perovskite Manganite ◽

Low Field

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Bulrush-Like Double Perovskite: Synthesis, Tunneling Magnetoresistance, and Magnetocaloric Effects

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18308 ◽

2008 ◽

Vol 8 (6) ◽

pp. 2793-2810 ◽

Cited By ~ 5

Author(s):

W. Zhong ◽

N. J. Tang ◽

C. T. Au ◽

Y. W. Du

Keyword(s):

Room Temperature ◽

Recent Observation ◽

Chemical Properties ◽

Double Perovskite ◽

Tunneling Magnetoresistance ◽

Double Perovskites ◽

New Approach ◽

Half Metallic ◽

Physical And Chemical ◽

And Chemical Properties

The recent observation of room temperature tunneling magnetoresistance (TMR) in half-metallic A2FeMoO6 (A = Ca, Sr, Ba) double perovskites, and their importance to the emerging field of spintronics has led to considerable effort being dedicated to detailed investigations of the physical and chemical properties of these materials. This article will present an review of our recent investigations covering the synthesis, structures, magnetic and transport properties of "bulrush-like" A2FeMoO6 (A = Sr, Ba). Utilizing the high shape anisotropy as well as the reactivity of A2FeMoO6 to water and a sonochemical technique, we managed to manipulate the properties of grain boundary barriers, and thus put forward a new approach for the enhancement of room temperature TMR. The magnetocaloric effects of A2FeMoO6 double perovskites will also be discussed.

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SYNTHESIS, STRUCTURAL AND MAGNETIC PROPERTIES OF DOUBLE PEROVSKITES Sr2CrWO6

International Journal of Modern Physics B ◽

10.1142/s0217979205028992 ◽

2005 ◽

Vol 19 (01n03) ◽

pp. 537-540 ◽

Cited By ~ 2

Author(s):

T. S. CHAN ◽

R. S. LIU ◽

C. Y. HUANG

Keyword(s):

Crystal Structure ◽

Valence State ◽

Room Temperature ◽

Standard Sample ◽

Double Perovskite ◽

Lattice Parameter ◽

Double Perovskites ◽

X Ray ◽

Structural And Magnetic Properties ◽

X Ray Absorption

The double perovskite ( Sr 2 CrWO 6) has been prepared in polycrystalline state by solid state reaction. At room temperature, the crystal structure is cubic (space group: Fm3m) with lattice parameter of 7.8200(2) (Å). Both ρ( H =0) and ρ( H =5 T ) show a semiconductor-like behavior over the whole temperature range up to 5 K. The highest MR(magnetoresistance) value of 55% ( H =5 T ) was observed at 25 K. The valence state of Cr was determined by the X-ray absorption spectroscopy at Cr -L edge. The results, compared to the standard sample, show that the valence state of Cr is 3+.

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Grain-boundary room-temperature low-field magnetoresistance in Sr2FeMoO6 films

Journal of Applied Physics ◽

10.1063/1.372833 ◽

2000 ◽

Vol 87 (9) ◽

pp. 6761-6763 ◽

Cited By ~ 47

Author(s):

H. Q. Yin ◽

J.-S. Zhou ◽

R. Dass ◽

J.-P. Zhou ◽

J. T. McDevitt ◽

...

Keyword(s):

Grain Boundary ◽

Room Temperature ◽

Low Field

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Competing Effects of Band Filling and Steric Factors on Magnetic and Transport Properties of Double Perovskite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.490-495.325 ◽

2012 ◽

Vol 490-495 ◽

pp. 325-328

Author(s):

Qin Zhang ◽

Heng Chang Qian ◽

Juan Pei ◽

Suo Jia Yuan

Keyword(s):

Room Temperature ◽

Steric Effect ◽

Parent Compound ◽

Double Perovskite ◽

Electron Doping ◽

X Ray ◽

Lattice Constants ◽

Band Filling ◽

Steric Factors ◽

Semiconducting Behavior

Ordered double perovskite oxides (Sr2-3xLa2xBax)FeMoO6 (0≤x≤0.3) have been investigated in this work. X-ray powder diffraction reveals that the crystal structure of the compounds changes from a tetragonal I4/m lattice to a cubic Fm m lattice around x=0.2. Due to the electron doping, the lattice constants increase with x. Owing to the competing contribution of electron doping and steric effect, Curie temperature of the compounds is almost unchanged. The resistivity of the parent compound shows a semiconducting behavior below room temperature, but those of the doped samples exhibit a metal-semiconductor transition. A correlation between the resistivity and metal-semiconducting transition temperature (TM-S) is observed. The resistivity and TM-S of the compounds decrease with x for x  0.2 and increase for x≥0.2.

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Dependence of Intergranular Fracture on Boundary Topography and Cohesion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071193 ◽

1973 ◽

Vol 31 ◽

pp. 150-151

Author(s):

J. E. Doherty ◽

A. F. Giamei ◽

B. H. Kear ◽

C. W. Steinke

Keyword(s):

Grain Boundary ◽

Room Temperature ◽

Nickel Base Superalloy ◽

Boundary Shear ◽

Room Temperature Ductility ◽

Solid Solution Matrix ◽

Nickel Base ◽

Solution Matrix ◽

Different Levels ◽

Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106466 ◽

1988 ◽

Vol 46 ◽

pp. 880-881

Author(s):

Bradley L. Thiel ◽

Chan Han R. P. ◽

Kurosky L. C. Hutter ◽

I. A. Aksay ◽

Mehmet Sarikaya

Keyword(s):

Grain Boundary ◽

Cuprous Oxide ◽

Room Temperature ◽

Boundary Phase ◽

Spectroscopic Techniques ◽

Transition Width ◽

Practical Applications ◽

Thin Foils ◽

Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

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Reusability Study of Sulfated Zirconia Functionalized SBA-15 Catalyst for Biolubricant Oil Production from Oleic Acid

Journal of Engineering and Scientific Research ◽

10.23960/jesr.v1i1.10 ◽

2019 ◽

Vol 1 (1) ◽

pp. 46

Author(s):

F R Rangganita ◽

L Hermida ◽

A Angraeni ◽

D Khoirunnisa

Keyword(s):

Oleic Acid ◽

Sulfated Zirconia ◽

Room Temperature ◽

Oil Production ◽

Catalyst Reusability

Sulfated zirconia functionalized SBA-15 catalsyt (SZr-SBA-15) was prepared byreacting SBA-15 with Zirkoniumoxychloride and urea at 90oC to form ZrO2-SBA-15. Then, ZrO2-SBA-15 was reacted with H2SO4 at room temperature to produceSZr-SBA-15 catalsyt.. The catalyst was characterized in terms of adsorptiondesorption nitrogen analysis, SEM-EDX and FTIR. Based on SEM-EDX andadsorption-desorption nitrogen analysis results, it was found that Zr had beenincorporated in SBA-15. By using the SZr-SBA-15 catalyst, esterification reactionof oleic acid with TMP to produce biolubricant oil of Trimethylolpropanetrioleatachieved 85% oleic acid conversion and selectivity of 63,7%. Reusability study ofSZr-SBA-15 catalyst was carried out for 3 rounds of reaction. It was found that thecatalyst could be used up to 3 rounds without significant decrease in activityKeywords: biolubricant oil, catalyst reusability, sba-15, sulfated zirconia.

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