I07-Surface & interface diffraction
|
Dario
Mastrippolito
,
Ashkan
Shahmanesh
,
Mariarosa
Cavallo
,
Erwan
Bossavit
,
Iman
Laqchaa El Abed
,
Corentin
Dabard
,
Shalini
Singh
,
Mathieu
Silly
,
Francesco
Capitani
,
Nemanja
Peric
,
Louis
Biadala
,
Andrea
Zitolo
,
Jose
Avila
,
Francesco
Carla
,
Cesare
Tresca
,
Emmanuel
Lhuillier
,
Benoit
Mahler
,
Debora
Pierucci
Diamond Proposal Number(s):
[38497]
Abstract: Controlling the crystal phase of two-dimensional transition metal dichalcogenides (TMDs) is essential for tailoring their electronic and optical properties. Among the polymorphs of WS2, the metastable 1T′ phase exhibits semimetallic or narrow-bandgap character and hosts quantum functionalities distinct from the semiconducting 1H phase. Here, we investigate the temperature-induced 1T′/1H phase transition in colloidally synthesized monolayer WS2 nanosheets functionalized with organic ligands. The reducing conditions of the synthesis stabilize the 1T′ phase via electron doping. Through in situ analyses of both the structural and electronic properties, we monitor the phase evolution during annealing and find that the 1T′ phase remains stable up to 300 °C, accompanied by a relative lattice contraction. Between 300 and 350 °C, a mixed 1T′/1H regime appears, where the 1H content can be finely tuned by controlling the annealing time. Above 350 °C, a rapid and complete transformation to the 1H phase occurs. We demonstrate that the decomposition of the reducing ligand serves as the primary trigger of the structural transition, revealing a strong interplay among doping, surface chemistry, and lattice structure. Notably, nanosheets with smaller lateral dimensions exhibit slower phase transition kinetics, suggesting that finite size could influence the structural rearrangement underlying the phase transformation.
|
Oct 2025
|
|
I07-Surface & interface diffraction
|
Alexandra L.
Martin
,
Philip N.
Jemmett
,
Thomas
Howitt
,
Mary H.
Wood
,
Liam R.
Cox
,
Timothy R.
Dafforn
,
Mario
Campana
,
Rebecca J. L.
Welbourn
,
Maximilian W. A.
Skoda
,
Luke A.
Clifton
,
Hadeel
Hussain
,
Jonathan L.
Rawle
,
Francesco
Carla
,
Christopher L.
Nicklin
,
Thomas
Arnold
,
Sarah L.
Horswell
Diamond Proposal Number(s):
[22078, 21088]
Open Access
Abstract: The reasons for the wide diversity of lipids found in natural cell membranes are still not fully understood but could potentially be exploited in treating disease and infection. This study aims to establish whether charge alone or specific chemical structure of an anionic lipid headgroup determines the structure and properties of model bacterial cell membranes. We compare different compositions of a zwitterionic lipid di-myristoyl phosphatidylethanolamine (DMPE) and two anionic lipids, di-myristoyl phosphatidylglycerol (DMPG) and tetra-myristoyl cardiolipin (TMCL). TMCL has a distinct condensing effect, increasing packing and decreasing the pressures of the phase transitions. Although relatively well solvated itself, TMCL does not substantially alter the solvation of mixed monolayers or bilayers. DMPE:TMCL mixtures have very similar electrochemical behaviour to mixtures of DMPE with di-myristoyl phosphatidylserine (DMPS) but DMPE:DMPG bilayers have greater surface charges. A ternary mixture representing an Escherichia coli membrane has similar electrochemical response to but is more tightly packed than DMPE:DMPG. These results establish the importance of the anionic lipid in modelling different types of cell membranes: DMPG will be required in model bacterial membranes and should not be replaced with DMPS. Even very small amounts of CL will have a measurable effect on structure, so its inclusion is important. Our results also highlight the importance of diverse techniques in understanding membrane behaviour: reflectivity measurements of monolayers over a range of surface pressure provide excellent insight into the electrochemical responses of lipid bilayers, while surface diffraction and infrared spectroscopy are much more sensitive to differences in packing between lipids.
|
Aug 2025
|
|
I04-Macromolecular Crystallography
I07-Surface & interface diffraction
I18-Microfocus Spectroscopy
I19-Small Molecule Single Crystal Diffraction
Optics
|
Open Access
Abstract: A study on the thermal load of cryogenically cooled silicon in synchrotron double-crystal monochromators is presented, based on experimental data from four different beamlines at Diamond Light Source. Different amounts of power are deposited on the first monochromator crystal by varying the storage ring current. The resulting crystal deformation causes a decline in the diffraction efficiency when power and power density are above threshold values. The results are compatible with an analytical model of thermo-mechanical deformation. Acceptable monochromator heat load values are determined with this model, to ensure optimal function of the monochromator. This model, previously tested against finite element analyses, is now validated against measured data and it will be used as a tool for initial analysis of monochromator performance on upgraded photon sources.
|
Jul 2025
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[32019]
Open Access
Abstract: Lead chalcogenide colloidal quantum dots are one of the most promising materials to revolutionize the field of short-wavelength infrared optoelectronics due to their bandgap tunability and strong absorption. By self-assembling these quantum dots into ordered superlattices, mobilities approaching those of the bulk counterparts can be achieved while still retaining their original optical properties. The recent literature focused mostly on PbSe-based superlattices, but PbS quantum dots have several advantages, including higher stability. In this work, we demonstrate highly ordered 3D superlattices of PbS quantum dots with tunable thickness up to 200 nm and high coherent ordering, both in-plane and along the thickness. We show that we can successfully exchange the ligands throughout the film without compromising the ordering. The superlattices as the active material of an ion gel-gated field-effect transistor achieve electron mobilities up to 220 cm2 V–1 s–1. To further improve the device performance, we performed a postdeposition passivation with PbI2, which noticeably reduced the subthreshold swing making it reach the Boltzmann limit. We believe this is an important proof of concept showing that it is possible to overcome the problem of high trap densities in quantum dot superlattices enabling their application in optoelectronic devices.
|
Jul 2024
|
|
|
|
Roberto
Felici
,
Tommaso
Baroni
,
Francesco
Carla
,
Nicola
Cioffi
,
Francesco
Di Benedetto
,
Claudio
Fontanesi
,
Andrea
Giaccherini
,
Walter
Giurlani
,
Mathieu
Gonidec
,
Alessandro
Lavacchi
,
Enrico
Berretti
,
Patrick
Marcantelli
,
Giordano
Montegrossi
,
Marco
Bonechi
,
Rosaria Anna
Picca
,
Lorenzo
Poggini
,
Francesca
Russo
,
Maria Chiara
Sportelli
,
Luisa
Torsi
,
Massimo
Innocenti
Abstract: Our society largely relies on inorganic semiconductor devices which are, so far, fabricated using expensive and complex processes requiring ultra-high vacuum equipment. Here we report on the possibility of growing a p-n junction taking advantage of electrochemical processes based on the use of aqueous solutions. The growth of the junction has been carried out using the Electrochemical Atomic Layer Deposition (E-ALD) technique, which allowed to sequentially deposit two different semiconductors, CdS and Cu2S, on an Ag(111) substrate, in a single procedure. The growth process was monitored in situ by Surface X-Ray Diffraction (SXRD) and resulted in the fabrication of a thin double-layer structure with a high degree of crystallographic order and a well-defined interface. The high-performance electrical characteristics of the device were analysed ex-situ and show the characteristic feature of a diode.
|
May 2024
|
|
|
|
Open Access
Abstract: Low activity and a short lifetime are the main weaknesses of photocatalysts. The photoactivity of copper oxide, which is known as one of the most promising materials for H2 evolution and CO2 reduction, can be improved by coupling with other semiconductors. This effect is based on a mutual charge transfer. The photocathode developed in this work, based on a CuO–ZnO composite with mutual self-doping, exhibits attractive photoelectrochemical properties, in particular a high density of generated photocurrent lasting for 24 h. Under visible light irradiation, the composite produces water-splitting, while in the presence of carbon dioxide it is able to perform CO2 reduction to methanol with good selectivity coupled to water oxidation. The high activity of the CuO-based cathode is due to the presence of zinc oxide, which is progressively leached, causing a slow decrease of the photoactivity of the material.
|
Mar 2024
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[30356]
Open Access
Abstract: In this study, we present a systematic investigation of the controlled fabrication of Au–Pd barcode nanowires within nanoporous anodic aluminum oxide (NP-AAO) templates. By using a combination of in situ X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), and transmission electron microscopy (TEM), we elucidate the influence of template preparation methods on the resulting nanowire properties. The template treatment, involving either pore widening or barrier layer thinning, significantly impacts nanowire growth. Through the analysis of the XRD data, we observe sequential deposition of Au and Pd segments with lattice parameter variations and strain effects. Particularly, the lattice parameters of Au and Pd segments display intricate temporal dependencies, influenced by interfacial effects and strain caused by growth under confinement. FIB-SEM imaging reveals uniform and reproducible nanowire lengths in the template treated with pore widening. Furthermore, TEM analysis confirms the presence of distinct Au and Pd segments, while scanning TEM–energy-dispersive X-ray spectroscopy revealed minor evidence of interdiffusion between the first and the second electrodeposited segments. Our findings emphasize the potential of the electrodeposition process within nanoporous templates for producing barcode nanowires with precise segmental properties. The combination of in situ XRD and electron microscopy offers valuable insights into the growth dynamics and structural characteristics of the fabricated Au–Pd barcode nanowires. This controlled fabrication strategy opens doors to tailoring nanowire properties for diverse applications, particularly in catalysis.
|
Feb 2024
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[32333, 32300]
Open Access
Abstract: X-ray scattering is used to characterise the initial stages of the growth of CdS on Au(1 1 1) surfaces via electrochemical atomic layer deposition (E-ALD). This work characterises E-ALD films using a unique in-situ setup, allowing for X-ray reflectivity and diffraction data to be obtained to characterise the growth process of the CdS film. Structural information, as well as information concerning growth rates, roughness and strain as a function of the stage in the growth process, are obtained to provide a unique perspective of the early stages of deposition for this methodology. The results show the self-limiting, linear growth rate of CdS films that are wurtzite in structure, are highly epitaxial with the underlying Au substrate, and exhibit little to no chemical impurities during the deposition procedure.
|
Dec 2023
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[25808]
Abstract: Among the functional materials suitable for the realization of solar cells and light emission diodes (LEDs), perovskites, especially fully inorganic perovskites, are considered among the most promising. CsPbBr3 is the most studied due to its favorable band gap value and stability under mild atmospheric conditions: moisture and UV visible radiation exposure. Using this material, highly efficient thin film solar cells have been produced at the lab scale, and researchers aim to scale the process up to the industrial level. Here, ultrathin films of CsPbBr3 were obtained by magnetron sputtering, and the texture and morphology of the deposited films were evaluated as a function of their thickness and the substrate's nature. The obtained films are composed of highly textured structures of submicrometric crystals homogeneously distributed all over the surface. Finally, the texture decreases as the deposit thickness increases.
|
Oct 2023
|
|
I07-Surface & interface diffraction
|
Cem
Ornek
,
Fan
Zhang
,
Alfred
Larsson
,
Mubashir
Mansoor
,
Gary S.
Harlow
,
Robin
Kroll
,
Francesco
Carla
,
Hadeel
Hussain
,
Dirk L.
Engelberg
,
Bora
Derin
,
Jinshan
Pan
Diamond Proposal Number(s):
[23388]
Open Access
Abstract: The passive film stability on stainless steel can be affected by hydrogen absorption and lead to microstructure embrittlement. This work shows that the absorption of hydrogen results in surface degradation due to oxide reduction and ionic defect generation within the passive film, which decomposes and eventually vanishes. The passive film provides a barrier to entering hydrogen, but when hydrogen is formed, atomic hydrogen infuses into the lattices of the austenite and ferrite phases, causing strain evolution, as shown by synchrotron x-ray diffraction data. The vacancy concentration and hence the strains increase with increasing electrochemical cathodic polarization. Under cathodic polarization, the surface oxides are thermodynamically unstable, but the complete reduction is kinetically restrained. As a result, surface oxides remain present under excessive cathodic polarization, contesting the classical assumption that oxides are easily removed. Density-functional theory calculations have shown that the degradation of the passive film is a reduction sequence of iron and chromium oxide, which causes thinning and change of the semiconductor properties of the passive film from n-type to p-type. As a result, the surface loses its passivity after long cathodic polarization and becomes only a weak barrier to hydrogen absorption and hence hydrogen embrittlement.
|
Aug 2023
|
|
