Emerging switchable ultraviolet photoluminescence in dehydrated Zn/Al layered double hydroxide nanoplatelets

Layered double hydroxides show intriguing physical and chemical properties arising by their intrinsic self-assembled stacking of molecular-thick 2D nanosheets, enhanced active surface area, hosting of guest species by intercalation and anion exchanging capabilities. Here, we report on the unprecedented emerging intense ultraviolet photoluminescence in Zn/Al layered double hydroxide high-aspect-ratio nanoplatelets, which we discovered to be fully activated by drying under vacuum condition and thermal desorption as well. Photoluminescence and its quenching were reproducibly switched by a dehydration–hydration process. Photoluminescence properties were comprehensively evaluated, such as temperature dependence of photoluminescence features and lifetime measurements. The role of 2D morphology and arrangement of hydroxide layers was demonstrated by evaluating the photoluminescence before and after exfoliation of a bulk phase synthetized by a coprecipitation method.

Stability enhancement of organic photovoltaic devices utilizing partially reduced graphene oxide as the hole transport layer: nanoscale insight into structural/interfacial properties and aging effects

A powerful insight into the structural and interfacial properties of post-fabricated bulk heterojunction (BHJ) organic photovoltaic (OPV) devices, utilizing partially reduced graphene oxide as the hole transport layer, is reported.

Spatially-resolved in-situ structural study of organic electronic devices with nanoscale resolution: the plasmonic photovoltaic case study

A novel high spatial resolution synchrotron X-ray diffraction stratigraphy technique has been applied in-situ to an integrated plasmonic nanoparticle-based organic photovoltaic device. This original approach allows for the disclosure of structure-property relations linking large scale organic devices to length scales of local nano/hetero structures and interfaces between the different components.

Ferromagnetic Mn-doped Si0.3Ge0.7 nanodots self-assembled on Si(100)

Densely packed epitaxial Mn-doped Si(0.3)Ge(0.7) nanodots self-assembled on Si(100) have been obtained. Their structural properties were studied using reflection high-energy electron diffraction, energy dispersive x-ray diffraction, atomic force microscopy, extended x-ray absorption fine structure measurements and high-resolution transmission electron microscopy. Mn(5)Ge(1)Si(2) crystallites embedded in Si(0.3)Ge(0.7) were found. They exhibit a ferromagnetic behaviour with a Curie temperature of about 225 K.

Crystallization process of carbonate substituted hydroxyapatite nanoparticles in toothpastes upon physiological conditions: an in situ time-resolved X-ray diffraction study

The crystallization process in recently developed toothpastes, containing nanoparticles of carbonate substituted hydroxyapatite (nano-CHA), was investigated. For this purpose, the non-conventional Energy Dispersive X-Ray Diffraction technique, that demonstrated to be a powerful tool to follow in situ phase transformations, was applied, for the first time, to products of pharmaceutical-cosmetic interest. Two types of toothpastes, containing 15 and 20 wt% of nano-CHA, respectively, have been studied. It was observed that, after mixing the toothpastes with water and saliva in order to reproduce in vivo conditions, a crystallization of nano-CHA takes place. Such process occurs in a characteristic time of (22 +/- 1) min for the toothpaste containing 15 wt% of nano-CHA and of (3.9 +/- 0.5) min for the one containing 20% of nano-CHA. For both toothpastes, a 10% increase in grain dimensions was observed over an average characteristic time of (55 +/- 5) min.

Energy-dispersive X-ray diffraction on thin films and its application to superconducting samples

Energy-dispersive X-ray diffraction is applied to investigate double-layer PBCO/YBCO thin films deposited by laser ablation. The merits of this technique for the structural study of films are discussed. It is shown that the rocking curves of the Bragg reflections of a film along thecdirection can be simultaneously collected, allowing the accurate evaluation of its angular spread. A systematic displacement of the rocking curves of the film with respect to those of the substrate was found, revealing a slight divergence of the growth direction from the normal to the substrate surface.