scholarly journals Martensitic Transformation, Thermal Analysis and Magnetocaloric Properties of Ni-Mn-Sn-Pd Alloys

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1582
Author(s):  
Asma Wederni ◽  
Mihail Ipatov ◽  
Eloi Pineda ◽  
Lluisa Escoda ◽  
Julian-Maria González ◽  
...  
Keyword(s):  
Structural Transition ◽  
Magnetic Measurements ◽  
Heusler Alloys ◽  
Martensitic Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Enthalpy Changes ◽  
Magnetocaloric Properties ◽  
Pd Doping ◽  
Peak Value

Martensitic transition and magnetic response of Ni50−x Pdx,y Mn36 Sn14−y (x = 0, 1, 2 and y = 0, 1) Heusler alloys were analysed. The crystalline structure of each composition was solved by X-ray diffraction pattern fitting. For x = 1 and 2, the L21 austenite structure is formed and, for y = 1, the crystallographic phase is a modulated martensitic structure. From differential scanning calorimetry scans, we determine characteristic transformation temperatures and the entropy/enthalpy changes. The temperatures of the structural transformation increase with the addition of Pd to replace Ni or Sn, whereas the austenitic Curie temperature remains almost unvarying. In addition, the magneto-structural transition, investigated by magnetic measurements, is adjusted by suitable Pd doping in the alloys. The peak value of the magnetic entropy changes reached 4.5 J/(kg K) for Ni50Mn36Sn13Pd1 (external field: 50 kOe).

scholarly journals Neutron diffraction and ab initio studies on the fully compensated ferrimagnetic characteristics of Mn2V1-xCoxGa Heusler alloys

2021 ◽  
Author(s):  
Midhunlal P V ◽  
Venkatesh Chandragiri ◽  
J Arout Chelvane ◽  
P D Babu ◽  
Harish Kumar Narayanan
Keyword(s):  
Neutron Diffraction ◽  
Ab Initio ◽  
Structural Transition ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atom Pairs ◽  
Co Concentration

Abstract Neutron diffraction and ab initio studies were carried out on Mn2V1-xCoxGa (x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys which exhibits high TC fully compensated ferrimagnetic characteristics for x = 0.5. A combined analysis of neutron diffraction and ab initio calculations revealed the crystal structure and magnetic configuration which could not be determined from the X-ray diffraction and magnetic measurements. As reported earlier, Rietveld refinement of neutron diffraction data confirmed L21 structure for Mn2VGa and Xa structure for Mn2CoGa. The alloys with x = 0.25 and 0.5 possess L21 structure with Mn(C)-Co disorder. As the Co concentration reaches 0.75, a structural transition has been observed from disordered L21 to disordered X a. Detailed ab initio studies also confirmed this structural transition. The reason for the magnetic moment compensation in Mn2(V1-xCox)Ga was identified to be different from that of the earlier reported fully compensated ferrimagnet (MnCo)VGa. With the help of neutron diffraction and ab initio studies, it is identified that the disordered L21 structure with antiparallel coupling between the ferromagnetically aligned magnetic moments of (Mn(A)-Mn(C)) and (V-Co) atom pairs enables the compensation in Mn2V1-xCoxGa.

Structure, Magnetic Properties and Hyperfine Parameters of Nd-Substituted Ni-Fe-Ga Heusler Alloys

MRS Advances ◽  
2017 ◽  
Vol 2 (25) ◽  
pp. 1341-1346
Author(s):  
Monica Sorescu ◽  
Felicia Tolea ◽  
Mihaela Valeanu ◽  
Mihaela Sofronie
Keyword(s):  
Melt Spinning ◽  
Magnetic Measurements ◽  
Heusler Alloys ◽  
Hyperfine Magnetic Field ◽  
Rapid Quenching ◽  
Linear Least Squares ◽  
X Ray Diffraction ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Field Distributions

ABSTRACTSamples of Ni57-xNdxFe18Ga25 with x=2 and 4 were prepared in ribbon form by rapid quenching via melt spinning route. The samples were analyzed by X-ray diffraction (XRD), magnetic measurements and Mössbauer spectroscopy, both in the as-quenched form and after thermal annealing at 900 oC for 2 min and 400 °C for 2 hours. For x=2 the Nd atoms are completely dissolved in the Ni-Fe-Ga matrix, while for x=4 the additional occurrence of the secondary 2:17 phase could be resolved. These findings were supported by the analysis of hyperfine magnetic field distributions obtained from the non-linear least-squares fitting of the Mössbauer spectra.

Study of the Liquid Crystalline Phases in Some Compounds of 4-Trans-(4-Alkyl)Cyclo-Hexylphenyl-Alkylcarboxylate

1983 ◽  
Vol 38 (12) ◽  
pp. 1362-1364 ◽  
Author(s):  
I. H. Ibrahim ◽  
W. Haase
Keyword(s):  
Differential Scanning Calorimetry ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Intermolecular Distance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Enthalpy Changes ◽  
Liquid Crystalline Phases ◽  
Nematic Phases

Abstract Three mesogenic compounds of the general formula have been investigated by differential scanning calorimetry. thermal optical microscopy and X-ray diffraction methods/Enthalpy changes of The different phase transitions for these compounds have been determined. H33 exhibits smectic B and nematic phases, whereas H34 and H75 exhibit only smectic B phases. The thickness of the smectic layers and the average intermolecular distance have been evaluated, as well as the corresponding molecular parameters in the nematic phase.

scholarly journals Martensitic Transformation and Crystalline Structure of Ni50Mn50−xSnx Melt-Spun Heusler Alloys

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 853
Author(s):  
Rim Ameur ◽  
Mahmoud Chemingui ◽  
Tarek Bachaga ◽  
Lluisa Escoda ◽  
Mohamed Khitouni ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Room Temperature ◽  
Solidification Rate ◽  
Heusler Alloys ◽  
X Ray Diffraction ◽  
Key Factors ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Characteristic Temperatures ◽  
Melt Spun

The structure and thermal behavior are key factors that influence the functional response of Ni–Mn–Sn alloys. The present study reports the production as well as the structure and thermal analysis of melt-spun (solidification rate: 40 ms−1) Ni50 Mn50−xSnx (x = 10, 11, 12 and 13 at.%) alloys. X-ray diffraction measurements were performed at room temperature. The austenite state has an L21 structure, whereas the structure of the martensite is 7M or 10M (depending on the Sn/Mn percentage). Furthermore, the structural martensitic transformation was detected by differential scanning calorimetry (DSC). As expected, upon increasing the Sn content, the characteristic temperatures also increase. The same tendency is detected in the thermodynamic parameters (entropy and enthalpy). The e/a control allows the development production of alloys with a transformation close to room temperature.

Characterization of Martensitic Transformation in Ferromagnetic Shape Memory Alloys Co-Ni-Ga Melt-Spun Ribbons

2005 ◽  
Vol 475-479 ◽  
pp. 2033-2036 ◽  
Author(s):  
F.B. Meng ◽  
Yang Xian Li ◽  
H.Y. Liu ◽  
J.P. Qu ◽  
M. Zhang ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Structural Transition ◽  
Magnetic Measurements ◽  
The Body ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

The martensitic transformation in Co50Ni20Ga30 ribbon has been characterized in detail by means of X-ray diffraction and magnetic measurements. The sample showed a structural transition from the body-centered cubic with indexed lattice parameters of a=5.743 Å to martensite with a tetragonal structure with lattice parameters of a=b=5.422 Å and c=6.401 Å. (c/a>1). By comparing the results of the diffraction intensity and the magnetic susceptibility measurements, we found that the proceeding of the martensitic transformation can be divided into several different steps during cooling from 283 K to 213 K. During heating from 673 K to 833 K, the peak width became very wide and the intensity became very low. It reveals an order-disorder transformation.

Structure Evolution of La(OH)3 /Fe Composite during Ball Milling

2020 ◽  
Vol 65 ◽  
pp. 123-134
Author(s):  
Samira Lalaoua ◽  
Bouguerra Bouzabata ◽  
Safia Alleg ◽  
Abedelmalik Djekoun ◽  
David Shmool
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Magnetic Measurements ◽  
Amorphous Structure ◽  
Structure Evolution ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Composite Powders ◽  
X Ray

Fe-10wt% La (OH)3 composite powders have been fabricated by ball milling, under argon atmosphere for milling periods of 0, 5 and 10 h, respectively. Changes in structural, morphological, thermal and magnetic properties of the powders during mechanical alloying and during subsequent annealing have been examined by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). XRD results: showed the formation of new phases (Fe and LaFeO3 perovskite) created through the ball milling. The results showed that the crystalline size of ball milled powders decreased with increasing the milling time. In fact, after 10 h of ball milling, La (OH)3 changes from nanostructure in amorphous structure. The magnetic measurements display a distinct saturation magnetization and coercivity.

In-Situ Characterisation of Precipitation in AI-Cu thin films

1999 ◽  
Vol 562 ◽  
Author(s):  
J. P. Lokker ◽  
A. J. Bottger ◽  
G. C. A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Differential Scanning Calorimetry ◽  
Bulk Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Enthalpy Changes ◽  
Thin Foils ◽  
Lower Temperature

ABSTRACTThe precipitate formation occurring in Al-Cu thin foils with copper concentrations of either 1.15 at.% or 0.3 at.%, has been studied. In-situ X-ray diffraction analysis and differential scanning calorimetry are applied to determine the phases formed and the enthalpy changes in the same samples. Both X-ray diffraction and differential scanning calorimetry indicate that the precipitation behaviour of thin films (about 500 nm thickness) differs significantly from that of bulk material. In the films studied the precipitation of Al2Cu occurs at a much lower temperature than expected on the basis of the (bulk) phase diagram. Moreover, no intermediate phases are observed prior to Al2Cu precipitation. Also the amount of Cu in solid solution (0.20 at%Cu) observed by electron-probe micro-analysis after slowly cooling from 500°C to room temperature, exceeds the solubility of bulk Al-Cu.

scholarly journals Effect of Process Control Agents on the FeSiB Powder Amorphisation by Wet Mechanical Alloying

2015 ◽  
Vol 13 ◽  
pp. 37-41
Author(s):  
Bogdan Viorel Neamţu ◽  
Traian Florin Marinca ◽  
Horea Florin Chicinaş ◽  
Ionel Chicinaş ◽  
Olivier Isnard
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Chemical Composition ◽  
Process Control ◽  
Mechanical Alloying ◽  
Magnetic Measurements ◽  
Amorphous Powder ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Result of research concerning the influence of milling conditions on the amorphisation of the Fe75Si20B5 (at.%) alloy is presented. Amorphous powder of Fe75Si20B5 (at.%) was prepared by dry and wet mechanical alloying (MA) route starting from a mixture of Fe, Si and B elemental powders. The mixture was wet/dry milled up to 50 hours. Benzene, oleic acid and ethanol were used as process control agents (PCA) in order to investigate the influence of their chemical composition on the powder amorphisation. The evolution of the powder crystalline structure, thermal stability and magnetic properties were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG) as well as magnetic measurements versus temperature and field. It is proved that the chemical composition of the PCA (especially the carbon content) plays an important role in the amorphisation process induced by wet MA.

scholarly journals Structure, Microstructure, and Magnetic Properties of Melt Spun Ni50Mn50−xInx Ribbons

2021 ◽  
Vol 7 (5) ◽  
pp. 63
Author(s):  
Karima Dadda ◽  
Safia Alleg ◽  
Joan Saurina ◽  
Lluïsa Escoda ◽  
Joan-Josep Suñol
Keyword(s):  
Magnetic Properties ◽  
Thermal Hysteresis ◽  
Equilibrium Temperature ◽  
Indium Content ◽  
Martensitic Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Patterns ◽  
Microstructure And Magnetic Properties

Structural, microstructural, and magnetic properties of Heusler Ni50Mn50−xInx (x = 5 and 10) ribbons have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and vibrating sample magnetometry (VSM). The as quenched Ni50Mn45In5 ribbons exhibit a mixture of monoclinic 14M (a = 4.329(3) Å, b = 5.530(3) Å, and c = 28.916(3) Å), and tetragonal L10 (a = b = 3.533(3) Å, and c = 7.522(3) Å) martensite structures, while Ni50Mn40In10 ribbons display a single monoclinic 14M phase (a = 4.262(3) Å, b = 5.692(3) Å, and c = 29.276(3) Å). After three heating/cooling cycles, in the temperature range of 303–873 K, the Rietveld refinement of the XRD patterns revealed the presence of a single 14M martensite for Ni50Mn45In5 ribbons, and a mixture of cubic L21 (31%) and 14M (69%) phases for Ni50Mn40In10 ribbons. The characteristic temperatures of the martensitic transition (Astart, Afinish, Mstart, and Mfinish), the thermal hysteresis temperature width, and the equilibrium temperature decreased with increasing indium content and heating cycles. The samples show a paramagnetic like behavior in the as quenched state, and a ferromagnetic like behavior after the third heating/cooling cycle.

scholarly journals On the Ferroelectric to Paraelectric Structural Transition of BaTiO3 Micro-/Nanoparticles and Their Epoxy Nanocomposites

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2686
Author(s):  
Georgia C. Manika ◽  
Konstantinos S. Andrikopoulos ◽  
Georgios C. Psarras
Keyword(s):  
Structural Transition ◽  
Ferroelectric Properties ◽  
Laser Raman Spectroscopy ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Raman ◽  
Broadband Dielectric Spectroscopy ◽  
Ceramic Components ◽  
Direct Results

BaTiO3 is one of the most widely used ceramic components in capacitor formulation due to its exceptional ferroelectric properties. The structural transition from the ferroelectric tetragonal to the paraelectric cubic phase has been studied in both nano- and micro-BaTiO3 particles. Several experimental techniques were employed for characterization purposes (X-ray diffraction-XRD, laser Raman spectroscopy-LRS, differential scanning calorimetry-DSC and broadband dielectric spectroscopy-BDS). All gave evidence for the structural transition from the polar tetragonal to the non-polar cubic phase in both nano- and micro-BaTiO3 particles. Variation of Full Width at Half Maximum (FWHM) with temperature in XRD peaks was employed for the determination of the critical Curie temperature (Tc). In micro-BaTiO3 particles (Tc) lies close to 120 °C, while in nanoparticles the transition is complicated due to the influence of particles’ size. Below (Tc) both phases co-exist in nanoparticles. (Tc) was also determined via the temperature dependence of FWHM and found to be 115 °C. DSC, LRS and BDS provided direct results, indicating the transition in both nano- and micro-BaTiO3 particles. Finally, the 15 parts per hundred resin per weight (phr) BaTiO3/epoxy nanocomposite revealed also the transition through the peak formation at approximately 130 °C in the variation of FWHM with temperature. The present work introduces, for the first time, a qualitative tool for the determination and study of the ferroelectric to paraelectric structural transition in both nano- and micro-ferroelectric particles and in their nanocomposites. Moreover, its novelty lies on the effect of crystals’ size upon the ferroelectric to the paraelectric phase transition and its influence on physical properties of BaTiO3.

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