Raman and THz spectra of CH₃NH₃PbX₃ interpreted with a catalogue of computed vibrations and their influence on heat and electrical transport.

Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 10⁴ cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.

This study explores the use of green pigments and mixtures in manuscript illumination, drawing upon experimental evidence derived from a non-invasive spectroscopic survey of green pigments used in 31 bound manuscripts and 23 manuscript cuttings or single folios in the collections of the Fitzwilliam Museum in Cambridge, UK. Analytical investigations were carried out on green-coloured areas by visible and near-infrared fibre optic reflectance spectroscopy (FORS), at times supplemented by X-ray fluorescence (XRF). FORS spectra can easily be acquired in great numbers and without subjecting the manuscripts to any physical strain, making this technique especially suitable for analytical surveys of valuable and fragile objects. Despite some drawbacks, its use in combination with XRF often provides a relatively complete characterisation of pigments and mixtures, particularly when FORS analysis is extended into the shortwave-infrared range (to 2500 nm). The experimental results are examined in light of the recipes for green pigments found in medieval technical treatises. The outcome is a contextualized study with a focus on French illumination between the 13th and the 16th century, but allowing for comparisons with contemporary materials of different geographic origin.

Phase‐change alloys are the functional materials at the heart of an emerging digital‐storage technology. The GeTe‐Sb₂Te₃ pseudo‐binary systems, in particular the composition Ge₂Sb₂Te₅ (GST), are one of a handful of materials which meet the unique requirements of a stable amorphous phase, rapid amorphous‐to‐crystalline phase transition, and significant contrasts in optical and electrical properties between material states. The properties of GST can be optimized by doping with p‐block elements, of which Bi has interesting effects on the crystallization kinetics and electrical properties. A comprehensive simulational study of Bi‐doped GST is carried out, looking at trends in behavior and properties as a function of dopant concentration. The results reveal how Bi integrates into the host matrix, and provide insight into its enhancement of the crystallization speed. A straightforward explanation is proposed for the reversal of the charge‐carrier sign beyond a critical doping threshold. The effect of Bi on the optical properties of GST is also investigated. The microscopic insight from this study may assist in the future selection of dopants to optimize the phase‐change properties of GST, and also of other PCMs, and the general methods employed in this work should be applicable to the study of related materials, for example, doped chalcogenide glasses.