Spin Polarization and Phase Transformation-Aided Efficient Overall Water Splitting Using NiMnGaCu Ferromagnetic Shape Memory Heusler Alloy.

We demonstrate experimentally that the combination of half-metallic property and shape memory features of the NiMnGaCu (NMGC) alloy can synergistically catalyze both the oxygen and hydrogen evolution reactions, leading to excellent water splitting. NMGC, a copper-doped nickel-based ferromagnetic shape memory alloy, undergoes first-order martensite to austenite phase transition with temperature variations. The martensite phase of NMGC demonstrates remarkable efficiency for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).

Comprehensive characterization of the structure of Zr-based metallic glasses.

Structure of metallic glasses fascinates as the generic amorphous structural template for ubiquitous systems. Its specification necessitates determination of the complete hierarchical structure, starting from short-range-order (SRO) → medium-range-order (MRO) → bulk structure and free volume (FV) distribution. This link has largely remained elusive since previous investigations adopted one-technique-at-a-time approach, focusing on limited aspects of any one domain.

Nucleation-Growth Versus Spinodal Decomposition in Fe-Cr Alloys: An Experimental Verification by Atom Probe Tomography and Small Angle Neutron Scattering.

Identifying the operative mode of phase separation [spinodal decomposition (SD) or nucleation-growth (NG)] remains an extremely important area of research. The present work examines this critically in the Fe-Cr system using atom probe tomography (APT) and small angle neutron scattering (SANS), and establishes the framework to distinguish the two different modes of α' phase separation in thermally aged Fe-35 at% Cr and Fe-20 at% Cr alloys. Independent APT analysis determines the mode of phase separation on the basis of (i) the presence/absence of periodic chemical fluctuation through radial distribution function analysis and (ii) interphase interface characteristics (diffuse/sharp).

A Combinatorial Approach to Reliable Quantitative Analysis of Small Nano-Sized Precipitates: A Case Study with ' Precipitates in Fe-20 at% Cr Alloy.

The quantitative characterization of small nano-sized precipitates poses genuine challenges and is often deficient in accuracy due to the inherent limitations inevitably associated with the individual experimental techniques. A convenient solution is to utilize multiple complementary techniques. The present work demonstrates an effective way to reliably quantify nano-sized precipitates using a combination of complementary techniques of atom probe tomography (APT), small angle neutron scattering (SANS), and transmission electron microscopy (TEM).

Confinement driven anomalous freezing in nano porous spray dried microspheres.

One-step evaporative jamming of colloidal silica particles in contact-free spray droplets resulted in well-defined powder micro-granules with interstitial nanopores. This paper reports the anomalous freezing behaviour of confined water in the microspheres synthesized using spray drying. It has been revealed that the freezing point of water in these microspheres gets significantly lowered (∼-45 °C) owing to the confinement effect.

Magnetic ordering of the martensite phase in Ni-Co-Mn-Sn-based ferromagnetic shape memory alloys.

The magnetic state of low temperature martensite phase in Co-substituted Ni-Mn-Sn-based ferromagnetic shape memory alloys (FSMAs) has been investigated, in view of numerous conflicting reports of occurrences of spin glass (SG), superparamagnetism (SPM) or long range anti-ferromagnetic (AF) ordering. Combination of DC magnetization, AC susceptibility and small angle neutron scattering (SANS) studies provide clear evidence for AF order in the martensitic phase of NiCoMnSn alloy and rule out SPM and SG orders. Identical studies on another alloy of close composition, NiCoMnSn, point to the presence of SG order in the martensitic phase and the absence of SPM behavior, contrary to earlier reports.

Revisiting Temporal Evolution of Cu-Rich Precipitates in Fe-Cu Alloy: Correlative Small Angle Neutron Scattering and Atom-Probe Tomography Studies.

Binary Fe-Cu alloys are effective prototypes for investigating radiation-induced formation and growth of nanometric Cu-rich precipitates (CRPs) in nuclear reactor pressure vessels. In this report, the temporal evolution of CRPs during thermal aging of Fe-Cu binary alloys has been investigated by using complementary techniques such as atom probe tomography (APT) and small-angle neutron scattering (SANS). We report a detailed quantitative evolution of a rarely observed morphological transformation of Cu precipitates from spherical to ellipsoid with a significant change (approximately two times) in aspect ratio, an effect known to be associated with the 9R-3R structural transition of the precipitates.