Factors influencing the martensitic transformation in Ni50Mn35Sn15: an EXAFS study

Bhobe, P. A.; Priolkar, K. R.; Sarode, P. R.

doi:10.1088/0953-8984/20/01/015219

Cited by 54 publications

(47 citation statements)

References 22 publications

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“…The outcome of such investigation presents new evidence for the crucial hybridization component that influences and leads to structural transitions in Ni-Mn based SMA. The inferences drawn from this work have been found to be robust and validated through experiments like photoemission spectroscopy by others 9,10 , and in other SMA like Ni-Mn-In and Ni-MnSn series by us [11][12][13] ; here we present the case study of Ni-Mn-Ga series alone.…”

Section: Ni-mn-ga Shape Memory Alloyssupporting

confidence: 73%

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Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Bhobe

2017

Current Science

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Over the last few decades, there has been growing interest for developing technologies aimed at providing cleaner and more sustainable energy sources. Great efforts are directed towards synthesis of newer functional materials and tailoring the existing ones with an aim to optimize their usability. As materials are being developed with various complexities in their physical properties and forms like single crystals, thin-films, nanostructure and composites, measurement of their basic physical properties is also getting equally challenging. This review deals with a brief summary of our efforts in developing the basic understanding of some functional materials, using experimental tools that are best known to us, viz. measurement of Seebeck coefficient and X-ray absorption fine structure spectroscopy (XAFS). In particular, we discuss the results of our investigation of magnetic shape memory alloy Ni 2 MnGa and multiferroic CdCr 2 Se 4 . Keywords: Magnetic shape memory alloys, XAFS, thermopower measurements, spin-phonon coupling, magnetic semiconductors. IntroductionTHE present age research in materials science is largely focussed around providing alternative technologies aimed at cleaner and more sustainable energy sources. Hence the mention of thermoelectric power in the perspective of contemporary research generally implies new schemes for materials synthesis and device fabrication with enhanced performance. This article, however, focusses on thermopower and XAFS measurements as an investigative tool, used for understanding material properties, not limited to thermoelectrics. What is thermoelectric power?In most simple terms, thermoelectric power or thermoelectricity is all about generating electrical power from heat, using a solid-state device without combustion or moving parts. It is an effect that involves interplay between electrical and thermal properties of a material with electrons acting as the active fluid. The two primary physical phenomena that are at play in thermoelectrics are the Seebeck effect and the Peltier effect.Discovered in 1821 by T. J. Seebeck and hence named after him, this effect describes how a temperature gradient (T) across a conductor leads to electric charge flow, causing a measureable potential gradient (V) across it. Thus, V = ST, where S is the Seebeck coefficient. The opposite effect, i.e. generation of temperature gradient upon passage of electric current (I) through a conductor was discovered by J. Peltier. The expression for heat absorbed/emitted being, Q = I, where  is the Peltier coefficient. It was not until 1855, when W. Thomson (Lord Kelvin), using thermodynamics laws, showed that the Seebeck and Peltier effects are basically inter-linked. He also pointed out the need for the third effect to be considered, which is reversible heating or cooling when there is both a flow of electric current and a temperature gradient.Thus was the birth of a concept -a type of heat engine that could be used either as a device for generating electricity from heat or, alternatively, as a h...

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Section: Ni-mn-ga Shape Memory Alloyssupporting

confidence: 73%

“…Keeping this in view, XAFS spectra were fitted using appropriate structural models. The fitting process was described earlier 8,11 . The magnitude and real component of FT of XAFS spectra in R-space and real component of FT in the back transformed k-space for Mn K-edge data obtained for the parent composition of Ni 2 MnGa is shown in Figure 9.…”

Section: Resultsmentioning

confidence: 99%

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Bhobe

2017

Current Science

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“…The role of e/a in relation to martensitic transformation temperature in Ni-Mn-Ga alloys has been discussed at length by Entel et al [4]. Keeping in view the dependence of T M on e/a it is interesting to compare the two systems: Ni [14].…”

Section: Introductionmentioning

confidence: 99%

Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study

Bhobe¹,

Priolkar²,

Sarode³

2008

J. Phys. D: Appl. Phys.

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Abstract. Heusler alloys that undergo martensitic transformation in ferromagnetic state are of increasing scientific and technological interest. These alloys show large magnetic field induced strains upon martensitic phase change thus making it a potential candidate for magneto-mechanical actuation. The crystal structure of martensite is an important factor that affects both the magnetic anisotropy and mechanical properties of such materials. Moreover, the local chemical arrangement of constituent atoms is vital in determining the overall physical properties. Ni 50 Mn 35 In 15 is one such ferromagnetic shape memory alloy that displays exotic properties like large magnetoresistance at moderate field values. In this work, we present the extended xray absorption fine-structure measurements (EXAFS) on the bulk Ni 50 Mn 35 In 15 which reveal the local structural change that occurs upon phase transformation. The change in the bond lengths between different atomic species helps in understanding the type of hybridization which is an important factor in driving such Ni-Mn based systems towards martensitic transformation.

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“…As a result, the Co and Mn co-doping produces a competition between AFM and FM, which is similar to the state in the Co and Fe co-doped Ni 2 MnGa alloys [12]. Extended X-ray Absorption Fine Structure (EXAFS) results show that the distance of Mn atoms decreases across MT from austenite to martensite [16]. The decrease of the Mn-Mn distance between 4(a) and 4(b) sites (4(a) and 4(b) sites are the Mn and Ga sites in the stoichiometric compound, respectively) may introduce AFM exchange, forming partial AFM in the FM matrix, i.e., coexistence of FM and AFM in martensite in the present alloy.…”

Section: Resultsmentioning

confidence: 70%

Exchange Bias and Inverse Magnetocaloric Effect in Co and Mn Co-Doped Ni2MnGa Shape Memory Alloy

Wang

Liu

2013

Metals

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Exchange bias effect observed in the Ni 1.68 Co 0.32 Mn 1.20 Ga 0.80 alloy confirms the coexistence of antiferromagnetic and ferromagnetic phases in the martensite phase. A large inverse magnetocaloric effect has been observed within the martensitic transformation temperature range, which is originated from modified magnetic order through magnetic-field-induced phase transformation from partially antiferromagnetic martensite to ferromagnetic austenite. The magnetic entropy change is 16.2 J kg . These properties indicate Co and Mn co-doped Ni 2 MnGa alloy is a multifunctional material potentially suitable for magnetic refrigeration and spintronics applications.

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Factors influencing the martensitic transformation in Ni₅₀Mn₃₅Sn₁₅: an EXAFS study

Cited by 54 publications

References 22 publications

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study

Exchange Bias and Inverse Magnetocaloric Effect in Co and Mn Co-Doped Ni2MnGa Shape Memory Alloy

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Factors influencing the martensitic transformation in Ni50Mn35Sn15: an EXAFS study

Cited by 54 publications

References 22 publications

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

Local atomic arrangement and martensitic transformation in Ni50Mn35In15: an EXAFS study

Exchange Bias and Inverse Magnetocaloric Effect in Co and Mn Co-Doped Ni2MnGa Shape Memory Alloy

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Factors influencing the martensitic transformation in Ni₅₀Mn₃₅Sn₁₅: an EXAFS study

Local atomic arrangement and martensitic transformation in Ni₅₀Mn₃₅In₁₅: an EXAFS study