scholarly journals The crystal structure of the heusler alloys

1934 ◽  
Vol 144 (852) ◽  
pp. 340-359 ◽  
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Heusler Alloys ◽  
The Other ◽  
X Rays ◽  
Ferromagnetic Alloys ◽  
Suitable Heat Treatment ◽  
Copper Manganese ◽  
Ferro Magnetic

Beginning in the year 1898 Heusler discovered as a series of ferromagnetic alloys, the most important containing copper, manganese, and aluminium. They are characterized by remarkable magnetic properties, because although composed only of paramagnetic or diamagnetic elements, they become ferro-magnetic after suitable heat treatment. Various explanations of this property have been advanced, but it was usually considered to be due to the formation of a series of solid solutions of the type (CuMn) 3 Al, in which the proportions of copper and manganese may be varied within fairly wide limits. The Heusler alloys have been repeatedly investigated by means of X-rays. Young, using molybdenum radiation examined alloys of two different compositions. He found that one was face-centred cubic, while the other was a mixture of face-centred and body-centred cubic structures. The mixed alloy was the more magnetic.

scholarly journals Synchrotron Nano-Diffraction Study of Thermally Treated Asbestos Tremolite from Val d’Ala, Turin (Italy)

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 311 ◽  
Author(s):  
Carlotta Giacobbe ◽  
Jonathan Wright ◽  
Dario Di Giuseppe ◽  
Alessandro Zoboli ◽  
Mauro Zapparoli ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Risk Management ◽  
Structure Analysis ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Adverse Health Effects ◽  
Nano Crystalline ◽  
Original Fibre

Nowadays, due to the adverse health effects associated with exposure to asbestos, its removal and thermal inertization has become one of the most promising ways for reducing waste risk management. Despite all the advances in structure analysis of fibers and characterization, some problems still remain that are very hard to solve. One challenge is the structure analysis of natural micro- and nano-crystalline samples, which do not form crystals large enough for single-crystal X-ray diffraction (SC-XRD), and their analysis is often hampered by reflection overlap and the coexistence of multiple fibres linked together. In this paper, we have used nano-focused synchrotron X-rays to refine the crystal structure of a micrometric tremolite fibres from Val d’Ala, Turin (Italy) after various heat treatment. The structure of the original fibre and after heating to 800 °C show minor differences, while the fibre that was heated at 1000 °C is recrystallized into pyroxene phases and cristobalite.

Magnetic and Structural Properties of Ferrimagnetic Bioceramics

2005 ◽  
Vol 473-474 ◽  
pp. 117-122 ◽  
Author(s):  
A.C. Kis ◽  
Th. Leventouri ◽  
J.R. Thompson
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Calcium Phosphate ◽  
Powder Diffraction ◽  
Magnetic Measurements ◽  
Treatment Temperature ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Phase Development

Structure and magnetic properties of ferrimagnetic bioceramics in the system {0.45(CaO, P2O5) ySiO2 xFe2O3 0.03Na2O}, x=0.05, 0.10, 0.15, 0.20, were studied by x-ray powder diffraction and magnetic measurements. Magnetite and calcium phosphate, crystallizing in the hexagonal and monoclinic crystal systems, are the major phases in the compounds. Phase development, crystal structure, and magnetic properties of the composites are determined by the specific starting composition of oxides and the heat-treatment temperature.

scholarly journals Electronic and Magnetic Properties of Li1.5Mn0.5As Alloys in the Cu2Sb Structure

2013 ◽  
Vol 702 ◽  
pp. 231-235 ◽  
Author(s):  
C.Y. Fong ◽  
Liam Damewood ◽  
L.H. Yang ◽  
C. Felser
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Ab Initio ◽  
Lattice Constant ◽  
Magnetic Moments ◽  
The Other ◽  
Half Metallicity ◽  
Ionic Model ◽  
Half Metals ◽  
Ferromagnetic Metals

We investigated two formula-units of Li1.5Mn0.5As alloys, such as Li3MnAs2, in the Cu2Sb crystal structure using an ab-initio algorithm. By interchanging Mn with each Li located at different positions of the Li4As2unit cell, four separate alloys are formed. At the optimized lattice constant, two of these alloys are predicted to be ferromagnetic metals and the other two are half metals. The possibility of half metallicity in the first two is also explored. Both the modified Slater-Pauling-Kübler rule and the ionic model can characterize the magnetic moments of the half metals.

scholarly journals Effect of Crystal Structure on Transport and Magnetic Properties of Bulk Ni$_{2}$MnSn Heusler Alloys

2016 ◽  
Vol 38 (4) ◽  
pp. 491-508
Author(s):  
Yu. V. Kudryavtsev ◽  
◽  
V. M. Nadutov ◽  
N. V. Uvarov ◽  
V. N. Uvarov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Heusler Alloys

scholarly journals On the interpretation of X-ray, single crystal, rotation photographs

1926 ◽  
Vol 113 (763) ◽  
pp. 117-160 ◽  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Powder Method ◽  
Convenient Form ◽  
Other Hand ◽  
Rotation Method ◽  
Laue Method

In the development of the study of crystals by X-rays the methods used divide themselves naturally into four types : the Bragg Ionisation Spectrometer method, the Laue method, the Powder method of Debye and Scherrer, and the Rotating Crystal method of Rinne, Schiebold and Polyani. The techniques of the first three of these methods are fully explained in such books as ‘ X-Rays and Crystal Structure,’ by W. H. and W. L. Bragg, ‘ The Structure of Crystals,’ by Wyckoff, and ‘ Krystalle und Rontgenstrahlen,’ by Ewald, as well as in original papers. On the other hand, the rotation method is only slightly touched on in these works, the literature is scattered in a great number of papers, and the technique has not so far been described at any length in a convenient form. Particularly in English, references to it are scanty. In this paper the author has tried to give a concise account of the method, together with various types of charts and tables as it is used in the Davy Faraday Laboratory. The methods described differ in certain respects from those used on the Continent,* but they have been found to be rapid and sufficiently accurate.

scholarly journals The reflection of X-rays by crystals. (II.)

1913 ◽  
Vol 89 (610) ◽  
pp. 246-248 ◽  
Keyword(s):  
Crystal Structure ◽  
Rock Salt ◽  
Royal Society ◽  
Wave Length ◽  
The Other ◽  
X Rays ◽  
Elementary Volume ◽  
Four Corners ◽  
Homogeneous Beam

This note is a supplement to a paper on the reflection of X-rays by crystals which has been recently communicated to the Royal Society. It is there shown that the wave-length of a homogeneous beam of X-rays can be found accurately in terms of the spacing of the elements of a crystal. There has been some doubt as to the actual arrangement of the atoms in the crystal and in consequence it was not possible in the paper quoted to draw any final conclusions as to wave-length values. From the work now described by W. L. Bragg it appears that the reflection phenomena lead to a more definite knowledge of crystal structure, and we may now complete various quantitative determinations. The elementary volume in rock-salt is a cube with 1 atom of sodium at each of four corners and 1 atom of chlorine at each of the other four. In other words the number of elementary volumes in any space of measurable dimensions is equal to the number of atoms in that space.

CHARACTERIZATION OF THE SINTERED Nd15Fe77B8 ALLOY

2011 ◽  
Vol 25 (06) ◽  
pp. 877-884
Author(s):  
L. HADJADJ
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Optical Microscope ◽  
The Other ◽  
Average Value ◽  
Nd15fe77b8 Alloy

In this work the purpose is, in addition to the determination of microhardness, to get some information about the effect of heat treatment on the microstructure of the magnetic Nd 15 Fe 77 B 8 alloy. For this study we have used an optical microscope and an electronic microprobe. The results show that the structure of the Nd 2 Fe 14 B phase, which confers good mechanical and magnetic properties on the alloy, is well tetragonal, as mentioned in several works. The morphology, the concentration and the quantity of this phase depend on the temperature of annealing. The microhardness of the phase has an average value between those of the other involved phases.

Crystal Structures of Modulated Martensitic Phases of FSM Heusler Alloys

2011 ◽  
Vol 684 ◽  
pp. 105-116 ◽  
Author(s):  
Lara Righi ◽  
Franca Albertini ◽  
Simone Fabbrici ◽  
Antonio Paoluzi
Keyword(s):  
Magnetic Field ◽  
Crystal Structure ◽  
Heusler Alloys ◽  
The Other ◽  
Basic Unit ◽  
Powder Diffraction Data ◽  
Unit Cells ◽  
Structural Modulation ◽  
Superspace Formalism ◽  
Ferromagnetic Shape Memory

Multifunctional ferromagnetic shape memory Heusler alloys are frequently characterized by structural modulation in martensitic phases. In particular, modulated martensitic phases, showing the higher magnetic field induced strain (MFIS) performance, are the most promising candidates for technological applications. Depending on the composition, as well as pressure and temperature conditions, this periodic structural distortion, consisting of shuffling of atomic layers along defined crystallographic directions, accompanies the martensitic transformation. Over the years, different Ni-Mn-Ga modulated martensitic structures have been observed and classified depending upon the periodicity of corresponding ideal nM superstructure (where n indicates the number of basic unit cells constituting the superlattices). On the other hand, it has been demonstrated that in most cases such structural modulation is incommensurate and the crystal structure has been fully determined by applying superspace formalism. The results, obtained by structure refinements on powder diffraction data, suggest a unified crystallographic description of the modulated martensitic structures, here presented, where every different “nM” periodicity can be straightforwardly represented.

Improvement of magnetic properties of nanostructured Ni79Fe16Mo5 alloyed powders by a suitable heat treatment

2013 ◽  
Vol 24 (3) ◽  
pp. 653-658 ◽  
Author(s):  
L. Karimi ◽  
H. Shokrollahi ◽  
Z. Karimi ◽  
M. Mohammadi
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Suitable Heat Treatment

III. Report on Martensitic Cast Irons

1941 ◽  
Vol 146 (1) ◽  
pp. 78-80
Author(s):  
J. G. Pearce
Keyword(s):  
Heat Treatment ◽  
The Other ◽  
Martensitic Structure ◽  
Cast Irons ◽  
Engineering Applications ◽  
Suitable Heat Treatment ◽  
Resistance To Wear

The resistance to wear, erosion, and abrasion which is characteristic of martensitic cast irons has brought about their employment in a number of engineering applications. Martensitic cast irons may be produced by heat treatment of an ordinary engineering pearlitic iron; or they may be specially produced and so treated that either of two varieties can be obtained. In one such variety the eutectic filling surrounding the primary grains is allowed to solidify white (cementitic), and in the other it is allowed to solidify grey (graphitic). There are thus two main classes of the martensitic cast irons which are specially made as such; they may be respectively described as “white” and “grey” in character, the former being the harder of the two. The “grey” variety can be made martensitic in the condition as cast, or alternatively a martensitic structure can be produced in it by suitable heat treatment.

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