Phosphorus recovery from wastewater: Nitrogen K-edge micro-XANES spectroscopy unravels the effects of nitrification inhibitor on fertilizer phosphorus uptake of maize
Phosphorous containing fertilizers are essential to feed the growing population on earth. Because phosphorus (P) is a scarce resource in the European Union, recovering P from wastewater and sewage sludge has become extremely important. However, the availability of P to the plant is limited in such recycling P fertilizers. To overcome this problem, co-fertilization with nitrogen (N) in the form of ammonium and nitrification inhibitors, is a promising pathway. By applying the novel N K-edge micro-XRF and micro-XANES methods at the PHOENIX beamline on the soils, we could verify that a nitrification inhibitor indeed promotes ammonium fixation in fertilized soils, and hence causing a slow-release of temporarily fixed ammonium. This deceases local pH, making P better available to plants.
High entropy alloys (HEA), medium entropy alloys and multi-phase compositionally complex alloys (CCA) have gained much attention in the last 20 years because of their outstanding mechanical properties. Such baseless alloys provide different open questions on local chemical ordering, lattice distortions, orbital hybridization and/or charge transfer which define the very nature of alloys’ mechanical properties. By combining EXAFS measurements in the rarely served tender x-ray range (PHOENIX-SLS, Al K-edge) and at higher X-ray energies (BM08-ESRF, transition metal K-edges), local chemical ordering in a CCA, Al8Cr17Co17Cu8Fe17Ni33 was quantified showing preferred Al-Ni and Al-Cu pairs. In addition, slight structural distortions, much lower than the predicted ones of metallic radii, were found.
From magnetic order to quantum disorder in the Zn-barlowite series of S = 1/2 kagomé antiferromagnets
We report a comprehensive muon spectroscopy study of the Zn-barlowite series of S=1/2 kagomé antiferromagnets, ZnxCu4−x(OH)6FBr, for x = 0.00 to 0.99(1). By combining muon spin relaxation and rotation measurements with state-of-the-art density-functional theory muon-site calculations, we observe the formation of both μ–F and μ–OH complexes in Zn-barlowite. From these stopping sites, implanted muon spins reveal the suppression of long-range magnetic order into a possible quantum spin liquid state upon the increasing concentration of Zn-substitution.
In the past years, the strategies used to break the Cu(In,Ga)Se2 (CIGS) light to power conversion effi- ciency world record value were based on improvements of the absorber optoelectronic and crystalline properties, mainly using complex post-deposition treatments. To reach even higher efficiency values, fur- ther advances in the solar cell architecture are needed, in particular, with respect to the CIGS interfaces. In this study, we evaluate the structural, morphological and optoelectronic impact of an Al2O3 layer as a potential front passivation layer on the CIGS properties, as well as an Al2O3 tunneling layer between CIGS and CdS.
Sodium-ion batteries: a study of the structural and electrochemical properties of the layered cathode material NaxMnyO2
Being able to replace Lithium by the much more abundant sodium for new batteries would be an important asset for energy storage. For example, NaxMnyO2 cathodes would offer a high initial specific charge and a relatively high working potential. Despite long, intensive research of the electrochemical properties of these materials, the open key question remains unresolved: Where does the sodium goes to in the charging /discharging process. Unfortunately, the (de)sodiation mechanism in those materials was not completely understood, especially in terms of types of phases in which Na stays during cycling, which in turn impeded the optimization of its performance. Using the unique tender energy range of the PHOENIX beamline, we used Na K-edge X-ray absorption spectra measurements to gain a better understanding about the Na atomic positions in phases appearing during cycling. Thanks to this unique method, we established that observed high capacity in NaxMnyO2 is due to the high-voltage phase being an intergrowth structure between P2 and O2 type phases were Na ions stays both in tetrahedral and octahedral sites.
Lithium-ion batteries: following the redox reaction of oxygen and transition metals in the Li1.2Mn0.6Ni0.1Co0.1O2 electrode using X-ray absorption spectroscopy
The new generation of cathode materials from the Li-rich NMC (nickel-manganese-cobalt) group are under constant investigation due to their extremely high energy densities resulting from redox reactions involving both transition metals and lattice oxygen. Although a lot of research has been done so far, the exact mechanism of lithium (de)insertion in those materials, especially the reactions involving redox reactions of lattice oxygen is still elusive. Due to the particular battery design the observed reactions starts at the surface of the electrode that contacts the electrolyte and, as the reaction continues, goes deeper into the bulk structure. In order to follow the reactions taking place in the Li-rich NMC materials we aimed to exactly distinguish and characterize the phase transitions taking place on the surface and within the bulk of the Li1.2Mn0.6Ni0.1Co0.1O2 electrode. To do so we used comprehensive XAS measurements at the PHOENIX beamline, taking advantage of the unique options to perform in situ experiments in the soft energy range to study both the Oxygen K edge and the L edges of Ni, Co and Mn.
The structural changes of Na3.32Fe2.11Ca0.23(P2O7)2 during several charge discharge cycles is viewed by its powder pattern and selected cell parameter evolution.
A novel concept for extracting information from spectra where traditional post-processing procedures fail, dubbed ‘software-defined spectroscopy’, offers a fresh approach to high-resolution terahertz spectroscopy. The new method implements an ‘optical comb’ and combines it with a programmable modulator, all using components from the optical internet.
Dr. Manuel Guizar-Sicairos, beamline scientist at the cSAXS beamline, was elected as a Fellow Member of The Optical Society (OSA) for seminal contributions to methods and applications of coherent lensless imaging, ptychography, x-ray nanotomography, and new modalities of x-ray microscopy.
Root induced soil deformation influences Fe, S and P: rhizosphere chemistry investigated using synchrotron XRF and XANES
Taking up nutrients from the soil is key to plant growth. Understanding and potentially controlling this process is important when growing food but also when caring for natural habitats, which are the basis for life on Earth. Typically, nutrients are tightly chemically bound to the soil, and roots need to create a chemical environment to harvest nutrients. Here we use the special capabilities X-ray microscopy with tender X-rays to study the chemical changes of sulfur, phosphorus, and iron in the vicinity of plant roots (rhizosphere). We can show that Fe is slightly reduced, S is increasingly transformed into sulfate (SO42−) and phosphorus (P) is increasingly adsorbed to humic substances in this enrichment zone around the root.