Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Reentrant-spin-glass state in Ni 2 Mn 1.36 Sn 0.64 shape-memory alloy

Abstract: The ground-state properties of the ferromagnetic shape-memory alloy of nominal composition ${\text{Ni}}_{2}{\text{Mn}}_{1.36}{\text{Sn}}_{0.64}$ have been studied by dc magnetization and ac susceptibility measurements. Like few other Ni-Mn based alloys, this sample exhibits exchange bias phenomenon. The observed exchange pinning was found to originate right from the temperature where a steplike anomaly is present in the zero-field-cooled magnetization data. The ac susceptibility study indicates the onset of spin-glass freezing near this steplike anomaly with clear frequency shift. The sample can be identified as a reentrant spin glass with both ferromagnetic and glassy phases coexisting together at low temperature at least in the field-cooled state. The result provides us with a comprehensive view to identify the magnetic character of various Ni-Mn-based shape-memory alloys with competing magnetic interactions.

Phase-Stable CsPbI3 Nanocrystals: The Reaction Temperature Matters

Abstract: High temperature colloidal synthesis for obtaining thermal, colloidal and phase-stable CsPbI3 nanocrystals with near-unity quantum yield is reported. While standard perovskite synthesis reactions were carried out at 160 °C (below 200 °C), increase of another ≈100 °C enabled the alkylammonium ions to passivate the surface firmly and prevented the nanocrystals from phase transformation. This did not require any inert atmosphere storage, use of heteroatoms, specially designed ligands, or the ice cooling protocol. Either at high temperature in reaction flask or in the crude mixture or purified dispersed solution; these nanocrystals were observed stable and retained the original emission. Different spectroscopic analyses were carried out and details of the surface binding of alkyl ammonium ligands in place of surface Cs in the crystal lattice were investigated. As CsPbI3 is one of the most demanding optical materials, bringing stability by proper surface functionalization without use of secondary additives would indeed help in wide spreading of their applications.

White Light from Mn2+-Doped CdS Nanocrystals: A New Approach

Abstract: We report the generation of white light from a simple transition-metal-doped semiconducting nanocrystal, namely, Mn2+-doped CdS, for the first time by suitably tuning the relative surface-state emissions of the nanocrystal host and the dopant emission. White light emitted by these nanocrystals remains unchanged both in solution form as well as in the solid state and can be excited by a wide range of UV lights without disturbing the chromaticity; this desirable property arises from the intrinsic separation of the absorption energy and the emission energies due to a large stokes shift, thereby avoiding the vexing problem of self-absorption altogether.

Self-assembled TiO2 nanoparticles: mesoporosity, optical and catalytic properties

Abstract: Herein, we explore the idea of self-assembly of nearly monodisperse nanoparticles as uniform building blocks to design highly crystalline mesoporous TiO2 nanoparticles, through evaporation-induced self-assembly (EISA) and hydrothermal methods by using non-ionic Pluronic F127 and anionic surfactant SDS, respectively as structure directing agents. The small- and wide-angle powder X-ray diffraction and transmission electron microscopy (TEM) are used to characterize the mesophases. N2 adsorption–desorption studies and high-resolution TEM results further reveal that mesopores are formed by the arrangement of the nanoparticles of size ca. 4.0–5.0 nm for SDS-templated and 8.0–9.0 nm for F127-templated TiO2 nanoparticles with broad interparticle pore size distribution. Optical properties of these nanomaterials are studied by UV-visible diffuse-reflectance spectroscopy, photoluminescence (PL) and time-resolved fluorescence (TCSPC). These nanostructured titania exhibited excellent catalytic activity in the photodegradation of ecologically abundant dyes Methylene blue and Rose Bengal under UV-visible light irradiation.