Altering magnetic and optical features of rare earth orthoferrite LuFeO3 ceramics via substitution of Ir into Fe sites

Rare earth intermetallic compound Sm2Fe17N3 exhibits notalble magnetic properties such as high Curie temperature and high coercivity which are very suitable for permanent magnets [1,2]. Although microscopic magnetic structure is one of the basic information for magnetic materials, there is no report about the magnetic structure of Sm2Fe17N3 for our knowledge. This is because samarium's neutron absorption cross section is huge enough to make researchers hesitate to have neutron diffraction experiments of Sm compounds. We have carried out powder neutron diffraction measurement of Sm2Fe17N3 with a straightforward solution to the problem by taking long measurement time. Synchrotron x-ray diffraction measurements with single crystal has also been done to obtain initial crystal structure parameters for magnetic structure analysis and we have succeeded to analyze the magnetic structure of Sm2Fe17N3 at room temperature. Among four Fe sites in the unit cell, while one Fe site which is the nearest neighbor of nitrogen shows smaller magnetic moment than normal iron, two Fe sites show enhancement in their magnetic moments. This phenomenon can be understood as 'cobaltization' of Fe by the adjacent nitrogen through hybridization.

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Mössbauer Spectroscopic Analysis of Nd2Fe14B/α-Fe Hard Magnetic Nanocomposites

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.170.154 ◽

2011 ◽

Vol 170 ◽

pp. 154-159

Author(s):

Bozidar Cekić ◽

Valentin Ivanovski ◽

Mirela Maria Codescu ◽

Ana Umićević ◽

Tanja Barudzija ◽

...

Keyword(s):

Rare Earth ◽

Melt Spinning ◽

Room Temperature ◽

Spectroscopic Analysis ◽

Magnetic Hyperfine Field ◽

Exchange Interactions ◽

Magnetic Nanocomposites ◽

Magnetic Intermetallics ◽

Paramagnetic Doublet ◽

Fe Sites

Among novel magnetic intermetallics based on rare earth-transition compounds, the Nd2Fe14B/α-Fe isotropic nanocomposites have been obtained by recrystallization from an amorphous phase, prepared by melt spinning. For variable 5 wt.% Fe and 10 wt.% Fe contents we recorded transmission 57Fe Mössbauer spectra at the room temperature, hardened of the α-Fe phase by exchange interactions. The spectra have been analyzed in terms of ten Zeeman sextets and one paramagnetic doublet related to the Nd1.1Fe4B4 phase. One sextet corresponds to the α-Fe phase, whereas others are attributed to six non-equivalent Fe sites in the Nd2Fe14B structure, namely 16k1, 16k2, 8j1, 8j2, 4c, and 4e. The three remaining sextets belong to the Fe3B structure with three inequivalent Fe sites FeI(8g), FeII(8g) and FeIII(8g). All relevant parameters for both nanocomposites: the magnetic hyperfine field, the isomer shift and the quadrupole splitting are determined for each of these sites.

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Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064761 ◽

1971 ◽

Vol 29 ◽

pp. 142-143

Author(s):

N. M. P. Low ◽

L. E. Brosselard

Keyword(s):

Electron Microscopy ◽

Rare Earth ◽

Elevated Temperatures ◽

Stoichiometric Composition ◽

Rare Earth Ions ◽

Crystalline Solid ◽

Precipitation Process ◽

Rare Earth Fluoride ◽

Earth Fluoride ◽

Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

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Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125294 ◽

1987 ◽

Vol 45 ◽

pp. 54-55

Author(s):

T. F. Kelly ◽

P. J. Lee ◽

E. E. Hellstrom ◽

D. C. Larbalestier

Keyword(s):

Rare Earth ◽

High Field ◽

Transport Current ◽

Total Thickness ◽

New Class ◽

Ceramic Superconductors ◽

Current Densities ◽

Group Ii ◽

Eds Microanalysis

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.

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Microstructural characterization of a cast RENi5-based alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151714 ◽

1993 ◽

Vol 51 ◽

pp. 1176-1177

Author(s):

G. M. Micha ◽

L. Zhang

Keyword(s):

Electron Microscopy ◽

Rare Earth ◽

Microstructural Characterization ◽

Binary Compound ◽

Nickel Metal ◽

Cast Material ◽

Nickel Metal Hydride ◽

Transmission Electron ◽

Cast Condition

RENi5 (RE: rare earth) based alloys have been extensively evaluated for use as an electrode material for nickel-metal hydride batteries. A variety of alloys have been developed from the prototype intermetallic compound LaNi5. The use of mischmetal as a source of rare earth combined with transition metal and Al substitutions for Ni has caused the evolution of the alloy from a binary compound to one containing eight or more elements. This study evaluated the microstructural features of a complex commercial RENi5 based alloy using scanning and transmission electron microscopy.The alloy was evaluated in the as-cast condition. Its chemistry in at. pct. determined by bulk techniques was 12.1 La, 3.2 Ce, 1.5 Pr, 4.9 Nd, 50.2 Ni, 10.4 Co, 5.3 Mn and 2.0 Al. The as-cast material was of low strength, very brittle and contained a multitude of internal cracks. TEM foils could only be prepared by first embedding pieces of the alloy in epoxy.

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