Petrography and geochemistry of the Mesozoic sedimentary rocks of the Kutch Basin in western India reveal the predominance of felsic source rocks. Single-grain chemistry of the detrital heavy minerals in these sediments refines the existing provenance interpretations by incorporating additional data related to source lithology. The study presents information on type, composition, and metamorphic grade of the source rocks for the Mesozoics of the Kutch Basin, which comprises Jhurio, Jhumara, Jhuran, and Bhuj formations. Chemistry of rutile, garnet, and tourmaline supports multiple sources of sediments. The ratio between Cr and Nb in rutile suggests the dominance of sediment input from metapelites. The relationship between (Fe + Mn)-Mg-Ca in garnets and CaFe total-Mg in tourmalines indicates the dominance of Ca-poor felsic metamorphic source along with intermediate-acidic plutonic rocks. The multivariate discrimination of the detrital garnets reveals the dominance of granulite and amphibolite facies source rocks. Rutile compositions indicate subordinate inputs from mafic sources across the investigated sedimentary succession. The single-grain analysis of heavy minerals, therefore, infers a wide variation in source rock types.

By developing a high rate-capable O3-structured Na(Li0.05Ni0.3Si0.05Ti0.45Cu0.1Mg0.05)O2-based cathode material for Na-ion batteries, wherein partial substitution of more electronegative Si4+ for Ti4+ in transition metal layer has weakened-cum-lengthened the Na-O bond,...

Tin (Sn)-based anodes for sodium (Na)-ion batteries possess higher Na-storage capacity and better safety aspects compared to hard carbon -based anodes but suffer from poor cyclic stability due to volume expansion/contraction and concomitant loss in mechanical integrity during sodiation/ desodiation. To address this, the usage of nanoscaled electrodeactive particles and nanoscaled-carbon-based buffers has been explored, but with compromises with the tap density, accrued irreversible surface reactions, overall capacity (for "inactive" carbon), and adoption of non-scalable/complex preparation routes. Against this backdrop, anode-active "layered" bismuth (Bi) has been incorporated with Sn via a facile-cum-scalable mechanicalmilling approach, leading to individual electrode-active particles being composed of well-dispersed Sn and Bi phases. The optimized carbon-free Sn−Bi compositions, benefiting from the combined effects of "buffering" action and faster Na transport of Bi, to go with the greater Na-storage capacity and lower operating potential of Sn, exhibit excellent cyclic stability (viz., ∼83−92% capacity retention after 200 cycles at 1C) and rate capability (viz., no capacity drop from C/5 to 2C, with only ∼25% drop at 5C), despite having fairly coarse particles (∼5−10 μm). As proven by operando synchrotron X-ray diffraction and stress measurements, the sequential sodiation/desodiation of the components and, concomitantly, stress build-ups at different potentials provide "buffering" action even for such "active−active" Sn−Bi compositions. Furthermore, the overall stress development upon sodiation of Bi has been found to be significantly lower than that of Sn (by a factor of ∼3.8), which renders Bi promising as a "buffer" material, in general. Dissemination of such complex interplay between electrode-active components during electrochemical cycling also paves the way for the development of high-performance, safe, and scalable "alloyingreaction"-based anode materials for Na-ion batteries and beyond, sans the need for ultrafine/nanoscaled electrode particles or "inactive" nanoscaled-carbon-based "buffer" materials.

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