Somnath C. Roy

Bio: Somnath C. Roy is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Materials science & Thin film. The author has an hindex of 30, co-authored 143 publications receiving 3992 citations. Previous affiliations of Somnath C. Roy include Instituto Superior Técnico & Indian Institute of Technology Kharagpur.

Effect of starting microstructure on austenite grain sizes developed after reheating of HSLA steel

Abstract: Austenite grain structure has been studied over a wide range of soaking temperatures (950–1250°C) in a high strength low alloy steel containing Nb, Ti and V for different starting conditions, namely as cast, hot rolled and thermomechanical controlled rolled. Mixed (or bimodal) austenite grain structures were developed as a result of abnormal grain growth at different soaking temperatures in as cast slab (∼1200°C) and in rolled plates (∼1000°C), which has hardly been reported earlier. Higher fraction of finer precipitates, such as NbC and VC (<200 nm in size), were present in the rolled plate as compared to as cast slab, where the precipitates were coarser and complex in nature. Rapid dissolution of fine VC precipitates was primarily responsible for the observed abnormal grain growth in rolled plates at lower soaking temperature (∼1000°C). Coarse precipitates of complex nature, such as (Nb,Ti,V)(C,N) and (Nb,Ti)(C,N), remained stable up to ∼1150°C and restricted the formation of abnormal grain grow...

Designing TiO2 nanostructures through hydrothermal growth: influence of process parameters and substrate position

Abstract: Synthesis conditions and processing parameters profoundly affect the growth and morphology of nanostructures. In particular, when nanostructures are fabricated through a chemical technique such as hydrothermal, the process parameters such as reaction time, temperature, precursor concentration, and substrate orientation play a crucial role in determining the structure-property relationships. In this work, we report the hydrothermal growth of Titanium dioxide (TiO2) nanostructures as a function of these parameters and show that specific morphologies can be obtained by a variation of these parameters. A systematic study is carried out to understand the influence of reaction time (from 0.5 h to 3.0 h), reaction temperature (180 °C–200 °C), titanium precursor concentration (0.25 ml and 0.50 ml in 20 ml solution of HCl and deionized water) and substrate orientation (horizontal and tilted at an angle), and we show that significant variation in morphology- from nanowires to nanorods and then dandelions can be achieved. In particular, we demonstrate that high surface area multidirectional growth of nanorods leading to flower-like nanostructures or dandelions resulting from precipitation during the hydrothermal process. This is in contrast with previous reports on similar structures, where the role of precipitations was not analyzed. The work shows a possibility to control such growth by manipulating substrate position inside the autoclave during the hydrothermal process and will be useful for surface-dependent applications.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Nano‐photocatalytic Materials: Possibilities and Challenges

Abstract: Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

Photocatalytic reduction of CO2 on TiO2 and other semiconductors.

Abstract: Rising atmospheric levels of carbon dioxide and the depletion of fossil fuel reserves raise serious concerns about the ensuing effects on the global climate and future energy supply. Utilizing the abundant solar energy to convert CO2 into fuels such as methane or methanol could address both problems simultaneously as well as provide a convenient means of energy storage. In this Review, current approaches for the heterogeneous photocatalytic reduction of CO2 on TiO2 and other metal oxide, oxynitride, sulfide, and phosphide semiconductors are presented. Research in this field is focused primarily on the development of novel nanostructured photocatalytic materials and on the investigation of the mechanism of the process, from light absorption through charge separation and transport to CO2 reduction pathways. The measures used to quantify the efficiency of the process are also discussed in detail.

An overview of current status of carbon dioxide capture and storage technologies

Abstract: Global warming and climate change concerns have triggered global efforts to reduce the concentration of atmospheric carbon dioxide (CO2). Carbon dioxide capture and storage (CCS) is considered a crucial strategy for meeting CO2 emission reduction targets. In this paper, various aspects of CCS are reviewed and discussed including the state of the art technologies for CO2 capture, separation, transport, storage, leakage, monitoring, and life cycle analysis. The selection of specific CO2 capture technology heavily depends on the type of CO2 generating plant and fuel used. Among those CO2 separation processes, absorption is the most mature and commonly adopted due to its higher efficiency and lower cost. Pipeline is considered to be the most viable solution for large volume of CO2 transport. Among those geological formations for CO2 storage, enhanced oil recovery is mature and has been practiced for many years but its economical viability for anthropogenic sources needs to be demonstrated. There are growing interests in CO2 storage in saline aquifers due to their enormous potential storage capacity and several projects are in the pipeline for demonstration of its viability. There are multiple hurdles to CCS deployment including the absence of a clear business case for CCS investment and the absence of robust economic incentives to support the additional high capital and operating costs of the whole CCS process.