Editorial

From this year onwards, readers will see an alteration in the format of Emerging Materials Research (beginning with Volume 4, Issue 1). The Editorial Board, in consultation with the Publisher, has chosen to transition from the traditional print process to a ‘continuous publication’ model. Authors will receive their final volume and page numbering as soon as their manuscript is ready to be published in its final typeset form. Readers will continue to have access to Ahead of Print digital publications.

Scientific research is now primarily found and read online. The digital version is rapidly becoming the version of record, being most widely read and containing additional information such as supplementary data that is available only online. We have chosen to reflect the change in working methods of researchers today by publishing articles in their final position in the journal as soon as they are ready, making citation more accurate. This will eliminate the delays that are imposed by printed journals while maintaining the rigorous peer reviewing standards. Materials research is constantly evolving and the journal’s new format will enable Emerging Materials Research to maintain its mission to stimulate new ideas, identify critical problems, provide promising solutions and assess future trends. Thus, Emerging Materials Research will continue to review papers and accept them in a traditional manner. Once the paper is accepted, it will roll into papers ahead of print.

One can reasonably argue that science is the future of humanity. Due to its inherent interdisciplinary nature, materials science and engineering has laid the foundation for all other sciences and engineering to advance. Through these combined efforts, the world is becoming a better place.

In this context, materials for energy conversion have continued to be at the forefront of research. Recently, in a paper entitled ‘Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films’, Professor Nathan S. Lewis and his team at Caltech, CA, USA, have developed electrically conductive films that could potentially lead to safe artificial photosynthesis with higher efficiencies¹  and will have improved ability to produce hydrogen and oxygen from sunlight. In a recent paper entitled ‘Preparation of nanocrystalline silicon from SiCl₄ at 200°C in molten salt for high-performance anodes for lithium ion batteries’,²  Professor Yitai Qian and collaborators of the University of Science and Technology of China, Anhui Sheng, China, show that ‘as anode for rechargeable lithium ion batteries, the as-prepared silicon delivers the reversible capacity of 3083 mAh g⁻¹ at 1.2 A g⁻¹ after 50 cycles, and 1180 mAh g⁻¹ at 3 A g⁻¹ over 500 cycles’.

The US Defense Advanced Research Project Agency’s (DARPA’s) Research Program, MATRIX (Materials for Transduction),³  aims at narrowing the gap between material and device performance by focusing on ‘The Material is the Device’. In a recent paper entitled ‘Flexible black phosphorus ambipolar transistors, circuits and AM demodulator’,⁴  Weinan Zhu and collaborators at the University of Texas at Austin, TX, USA, and the University of the Basque Country, Vizcaya, Spain, report their studies on the first flexible black phosphorous field-effect transistors with charge carrier mobilities that are superior to previous studies on transistors made from layered semiconductors such as MoS₂ and WSe₂.

Magnetic field assisted cooling is of enormous interest to material scientists and engineers. This is due to its ability to reduce the energy consumption and avoid the use of ozone-depleting refrigerants.⁵  In their studies on ‘Gd₅(Si,Ge)₄ thin film displaying large magnetocaloric and strain effects due to magnetostructural transition’, Ravi Hadimani of Iowa State University, IA, USA, Joao Silva of IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Porto, Portugal, and collaborators⁶  report improved properties and performance of Gd₅(Si,Ge)₄ thin films compared to the bulk.

The research study on the ‘Multifunctional heterostructures integrated on Si (100)’⁷  is a collaborative effort between Srinivasa Rao Singamaneni, J. T. Prater and J. Narayan of the Army Research Office, Research Triangle Park, NC, USA and North Carolina State University, Raleigh, NC, USA. The paper presents a study of complex oxide films and heterostructures integrated on silicon. These materials exhibit a wide range of functional properties, including colossal magneto-resistance, magnetocaloric effects, coupled magnetic and polarization (multiferroic) behavior, and some interesting physical phenomena including spin, charge and orbital ordering. However, putting this functionality to work remains a challenge. To date, most of the work reported in the literature has dealt with heterostructures deposited on closely lattice-matched insulating substrates such as DyScO₃, NdGaO₃, MgO and SrTiO₃. However, these substrates are incompatible with existing complementary metal oxide semiconductor (CMOS)-based technology, where Si (100) substrates dominate. This review covers the major advances in the integration of multifunctional (oxide and non-oxide) materials onto Si (100) substrates reported in the recent past by this group using pulsed laser deposition in conjunction with a novel layer growth approach called domain matching epitaxy (DME). This paper focuses on the growth of several important oxide systems including BiFeO₃, La_0.7Sr_0.3MnO₃, BaTiO₃ and non-oxide films including permalloy/MgO and Ni/MgO. The authors show that one can achieve thin film epitaxy over an extended misfit scale by using the paradigm of DME. This will be critical for the future integration of multifunctional heterostructures onto CMOS-based chips in order to create smart structures for the next-generation solid-state devices. In addition, this paper explores the use of laser processing to introduce defect populations that induce magnetism in nonmagnetic oxides, such as SrTiO₃ and BaTiO₃, as an alternative to incorporating more traditional magnetic layers into the structure.

In the paper by Yuebin Lin, Lei Liu and Yuwei Dong of the Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian, People’s Republic of China, entitled ‘Formation of α-Al₂O₃ on 316L stainless steel’,⁸  the authors discuss the results of their research on thin films of alpha-phase aluminum oxide deposited on 316L stainless steel substrates by RF magnetron sputtering in two steps. First, the Al/α-Al₂O₃ films are deposited at different concentrations of α-Al₂O₃ (10, 50, and 100%) in a vacuum chamber at a temperature of 400°C. Next, the samples are heat-treated at various temperatures for a period of 2 hours. The phase, microstructure, thickness and three-dimensional topography by X-ray diffraction, field emission scanning electron microscopy, ADE phase-shift, field emission transmission electron microscopy and high-resolution transmission electron microscopy are investigated. The authors find that using the 100% α-Al₂O₃ yields oxidized coatings with 61.4% α-Al₂O₃ at 800°C, but these films are very thin. In order to minimize the effect of thermal expansion mismatch between the substrate and the deposited coatings and increase the thickness of the coatings, they prepare Al₂O₃/Al/Al₂O₃ multilayers. These coatings are compact and have smooth, crack-free surfaces. The oxidized coatings have good bonding strength with the substrate and are very dense. After oxidation at 800°C, the coatings mainly consist of α-Al₂O₃ and θ-Al₂O₃ phases, indicating that the addition of seeds reduced the transformation temperature.

‘Non–precious metal catalysts with TBAH as carbon source for ORR’ by Uma Thanganathan of the Research Core for Interdisciplinary Sciences, Okayama University, Okayama, Japan, and V. Narayana Kalevaru of the Leibniz Institute for Catalysis at the University of Rostock, Rostock, Germany, reports a study on the development of inexpensive non-precious metal catalysts with high performance oxygen reduction reaction and durability.⁹  Here, facile nitrogen and carbon extracted TiO₂-based cathode catalysts have been prepared through sol–gel method for oxygen reduction in fuel cells. Iron is incorporated into the parent ‘Ti’ host lattice to improve the conductivity of the catalysts.

‘Effect of material on damping characteristics of impact mass during hard turning’ is a collaborative effort by P. Sam Paul, A. S. Varadarajan and G. Lawrance of the Department of Mechanical Engineering, Karunya University, Tamil Nadu, India, and Nehru college of Engineering and Research Centre, Kerala, India. Machining is a complex process in which many variables can affect the desired results. Among them, tool vibration is the most critical phenomenon that affects the life of the cutting tool, quality of the components machined and functional behavior of the machined tools. This tool vibration can be controlled by increasing the rigidity of the cutting tool through damper. In this study, suppression of tool vibration during the turning process has been performed by providing an impact mass to turning tool holder. An impact mass made of brass, copper, aluminum and mild steel were used. The size and shape of the impact mass was designed and the material that provides effective damping was determined using computational analysis. Cutting experiments were conducted to study the influence of the impact mass on the tool vibration during turning of hardened AISI4340 steel using a hard metal insert with a sculptured rake face. From the computational and experimental results, it was observed that the use of impact mass on tool shank reduces the tool vibration effectively.