High-resolution synchrotron x-ray powder diffraction study of the incommensurate modulation in the martensite phase of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Ni</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mtext>MnGa</mml:mtext></mml:math>: Evidence for nearly 7M modulation and phason broadening

Singh, Sanjay; Petřı́ček, V.; Rajput, Parasmani; Hill, A.H.; Suard, Emmanuelle; Barman, Sudipta Roy; Pandey, Dhananjai

doi:10.1103/physrevb.90.014109

Cited by 46 publications

(64 citation statements)

References 47 publications

(124 reference statements)

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“…We present here a brief overview of our recent work [30,31] on the Le-Bail and Rietveld refinements of the premartensite and martensite phases of Ni2MnGa using high 6 resolution synchrotron x-ray powder diffraction (SXRPD) patterns. Our results clearly rule out the commensurate structural modulation models [13,28] for both the premartensite and martensite phases of Ni2MnGa and confirm their incommensurate nature.…”

Section: Introductionmentioning

confidence: 99%

Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview

Singh¹,

Barman

Pandey

2014

Zeitschrift Für Kristallographie - Crystalline Materials

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This article presents a brief overview of our recent work on the nature of long period modulation in the premartensite and martensite phases of Ni2MnGa ferromagnetic shape memory alloy using high resolution synchrotron x-ray powder diffraction patterns. The commensurate structure model using the Pnnm space group is unable to account for the peak positions of the satellite reflections that appear due to modulations correctly. LeBail and Rietveld refinements using the (3+1)-D super space group Immm(00)s00 show that the peak positions of all the reflections, including the satellites, can be explained satisfactorily using incommensurate modulations for both the premartensite and martensite phases. The incommensurate modulation vectors are found to be q= 0.33761(5)c * = (1/3+δ1)c* and 0.43160(3)c * = (3/7+δ2)c*, where δ1 and δ2 are the degrees of incommensuration for the premartensite and martensite phases, respectively. The periodicity of the closest rational approximant of the premartensite and martensite phases are confirmed to be 3M and 7M, respectively, in agreement with single crystal diffraction results.

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Section: Introductionmentioning

confidence: 99%

Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview

Singh¹,

Barman

Pandey

2014

Zeitschrift Für Kristallographie - Crystalline Materials

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“…[28][29][30] The compositions were determined using energy dispersive analysis of x-rays, which gave the actual composition as Ni 1.99 Mn 1.01 Ga 1.00 and Ni 1.9 Mn 1.15 Ga 0.95 for X ¼ 0 (Ni 2 MnGa) and 0.15 (Ni 1.85 Mn 1.15 Ga), respectively. High pressure resistivity measurements were performed by four probe resistivity technique.…”

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confidence: 99%

Investigations on the electronic transport and piezoresistivity properties of Ni2−XMn1+XGa (X = 0 and 0.15) Heusler alloys under hydrostatic pressure

Devarajan

Singh

Muthu

et al. 2014

Applied Physics Letters

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The resisitivity of Ni2−XMn1+XGa (X = 0 and 0.15) magnetic shape memory alloys has been investigated as a function of temperature (4–300 K) and hydrostatic pressure up to 30 kilobars. The resistivity is suppressed (X = 0) and enhanced (X = 0.15) with increasing pressure. A change in piezoresistivity with respect to pressure and temperature is observed. The negative and positive piezoresistivity increases with pressure for both the alloys. The residual resistivity and electron-electron scattering factor as a function of pressure reveal that for Ni2MnGa the electron-electron scattering is predominant, while the X = 0.15 specimen is dominated by the electron-magnon scattering. The value of electron-electron scattering factor is positive for both the samples, and it is decreasing (negative trend) for Ni2MnGa and increasing (positive trend) for X = 0.15 with pressure. The martensite transition temperature is found to be increased with the application of external pressure for both samples.

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“…[25,26] For some compositions, the martensitic transformation is also associated with a periodic shift of specific lattices planes that can give rise to commensurate and incommensurate structure modulations. [11,[21][22][23]27] These displacive modulations can be viewed as a way for the lattice to maintain the proper geometrical bond requirements and can be compared with the characteristic oxygen tilting patterns in perovskite materials. [28,29] Many efforts of the research community were dedicated to the understanding of the various lattice distortions in perovskite materials [30] and how the interplay between them leads to functional properties like multiferroicity.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction and symmetry analysis of the martensitic transformation in Co-doped Ni2MnGa

et al. 2020

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Martensitic transformations are strain driven displacive transitions governing the mechanical and physical properties in intermetallic materials. This is the case in Ni 2 MnGa, where the martensite transition is at the heart of the striking magnetic shape memory and magneto-caloric properties.Interestingly, the martensitic transformation is preceded by a pre-martensite phase, and the role of this precursor and its influence on the martensitic transition and properties is still a matter of debate. In this work, we report on the influence of Co doping (Ni 50−x Co x Mn 25 Ga 25 with x = 3 and 5) on the martensitic transformation path in stoichiometric Ni 2 MnGa by neutron diffraction.The use of the superspace formalism to describe the crystal structure of the modulated martensitic phases, joined with a group theoretical analysis allows unfolding the different distortions featuring the structural transitions. Finally, a general Landau thermodynamic potential of the martensitic transformation, based on the symmetry analysis is outlined. The combined use of phenomenological and crystallographic studies highlights the close relationship between the lattice distortions at the core of the Ni 2 MnGa physical properties and, more in general, on the properties of the martensitic transformations in the Ni-Mn based Heusler systems.

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High-resolution synchrotron x-ray powder diffraction study of the incommensurate modulation in the martensite phase ofNi2MnGa: Evidence for nearly 7M modulation and phason broadening

Cited by 46 publications

References 47 publications

Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview

Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview

Investigations on the electronic transport and piezoresistivity properties of Ni2−XMn1+XGa (X = 0 and 0.15) Heusler alloys under hydrostatic pressure

Neutron diffraction and symmetry analysis of the martensitic transformation in Co-doped Ni2MnGa

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High-resolution synchrotron x-ray powder diffraction study of the incommensurate modulation in the martensite phase ofNi2MnGa: Evidence for nearly 7M modulation and phason broadening

Cited by 46 publications

References 47 publications

Incommensurate modulations in stoichiometric Ni2MnGa ferromagnetic shape memory alloy: an overview

Incommensurate modulations in stoichiometric Ni2MnGa ferromagnetic shape memory alloy: an overview

Investigations on the electronic transport and piezoresistivity properties of Ni2−XMn1+XGa (X = 0 and 0.15) Heusler alloys under hydrostatic pressure

Neutron diffraction and symmetry analysis of the martensitic transformation in Co-doped Ni2MnGa

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Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview

Incommensurate modulations in stoichiometric Ni₂MnGa ferromagnetic shape memory alloy: an overview