In this work, a synthesis method based on the Joule-Heating effect has been used to produce high density of alpha-Fe2O3 nanowires within only tens of seconds. Comprehensive morphological, structural and compositional characterization carried out by combined electron microscopy and spectroscopy techniques confirms that the alpha-Fe2O3 nanowires possess high crystalline quality and exhibit a characteristic ordered superstructure. The properties of the as-grown nanostructures and the mechanisms underlying their rapid growth (30-60 s) are discussed in comparison to conventional thermal oxidation processes which typically require extended treatments of several hours. Enhanced diffusion and electromigration effects are considered as key factors in the accelerated nanowire growth. The fast, environmental-friendly and cost-effective nature of the Joule-Heating synthesis, together with its potential scalability, reveal significant advantages over conventional thermal oxidation.

UV-C photodetectors are poised to play an increasingly important role in future photonic technologies, driven by the rapid emergence of UV-C light sources and new wide bandgap semiconductors. These advances are enabling new levels of spectral selectivity, radiation hardness, sensitivity, and device integration, while opening opportunities across a broad range of applications. This roadmap provides a comprehensive overview of the current landscape of UV-C photodetection, spanning established and emerging material platforms (Ga2O3, AlGaN, BN, diamond, MgZnO, 2-dimensional materials, metal halide perovskites, micro-electromechanical systems), and their applications in metrology, astronomy, communications, environmental monitoring, fire detection, missile warning, gas sensing, and medical diagnostics. By identifying opportunities, bottlenecks, and future directions, this roadmap aims to support both newcomers and established researchers, with the aim of accelerating the translation of UV-C photodetectors into impactful technologies.

The achievement of lithium ion batteries (LiBs) with improved electrochemical performance requires advances in the synthesis of cathode materials with controlled composition and properties. In particular, NMC core-shell materials formed by a Ni-rich core and a Mn-rich shell are recently gaining interest as they allow the achievement of increased energy density and high discharge capacity values. In order to overcome some of the limitations of these NMC compounds and broaden their applicability, controlled synthesis and detailed analysis of their properties are required. In this work, NMC in the form of core and core-shell microparticles have been synthesized by an oxalate-assisted co-precipitation synthesis method which allows control of the final composition. The morphology, crystalline structure and composition of the particles have been investigated as a function of the synthesis parameters and the presence of the Mn-rich shell, by means of diverse microscopy and spectroscopy techniques. Additionally, in situ SEM and XPS measurements allow analysis of the NMC particles in variable operation environments. Aspects such as the cationic mixing in the NMC compound or the formation of a rock-salt phase as the annealing temperature increases are discussed. Finally, preliminary electrochemical tests have been performed using NMC particles as cathodes in LiBs.

Nanostructured materials play a key role in modern technologies adding new functionalities and improving the performance of current and future applications. Due to their nature resulting in diffused heterogeneous structures (chemical and electronic composition typically organized in phases or building blocks) characterizing these materials needs state of the art technologies which combine nanometer spatial resolution, environmental reliability, and operando capabilities. Scanning photoelectron spectromicroscopy (SPEM) is one of the characterization tools that combine high spectral resolution X-ray photoelectron spectroscopy with submicron spatial resolution. In particular, the SPEM equipment hosted at the ESCA microscopy beamline at Elettra is capable of in situ and operando analysis regardless of sample morphology. The review presents three different case studies illustrating the capabilities of SPEM in the investigation of catalytic materials in different conditions and processes.

Silicon is a very promising material for lithium-ion batteries (LIBs) due to its high theoretical capacity (3579 mAh/g). However, the volumetric expansion (300%) of silicon during lithiation led to pulverization of the electrode and rapid capacity fading. Self-healing (SH) materials are thought of as a solution for the degradation of active materials, enabling higher capacity retention. Here, we synthesized and integrated an autonomous self-healing poly-(aniline-co-3-aminophenylboronic acid)/PVA composite (SHC) as a binder in a Si anode electrode for LIBs. The synthesized SHC was investigated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis, and elongation and conductivity tests. Si anodes were prepared with SHC and a PVP cobinder. In addition, Si anodes were prepared separately with PVDF and the CMC-SBR binder as control electrodes. The electrodes were electrochemically characterized by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge tests. The conductive SHC binder was successfully integrated into the Si anode, and a capacity of over 1700 mAh/g was obtained after 100 cycles at C/10, and 650 mAh/g was obtained after 200 cycles at C/2.

Ionic liquid (IL)-based electrolytes have garnered significant interest for enhancing lithium-ion battery (LIB) safety due to their non-flammability, thermal stability, high conductivity, and broad electrochemical stability. We propose novel pyrrolinium-based ionic liquids to enhance lithium-ion mobility and address safety concerns in LIBs. This study investigated LiTFSI in [Pyr13] [FSI] ionic liquid for Li-ion batteries. The cyclic stability and rate performance of single-layer full cells with commercial graphite anode and NMC532 cathode were examined for the electrolyte required per cell and compared to those using a carbonate electrolyte (LP30). Electrolytes containing LiTFSI/[Pyr13] [FSI] exhibited satisfactory rate performance and stable cycling for 100 cycles. The reversible capacity was maintained at over 22 mAh for a cycle period of 100 cycles with an electrolyte loading of 161.8 µL/cm2. These electrolytes exhibited the highest oxidation stability, surpassing 5.3 V compared to that of the Li+/Li reference electrode. Long cycle life of up to 1000 cycles was conducted, showing 80% capacity retention. Post-mortem analysis using scanning electron microscopy (SEM) and micro-Raman spectroscopy allowed observation of LiTFSI/ [Pyr13] [FSI] effects on cathode and anode active particle stability, and reduced formation of secondary reactions between the IL and battery electrodes.

The luminescence properties of semiconductors are key to the development of photonics. In recent years, the targeted semiconductor materials have shifted from narrow-bandgap to wide- and ultra-wide-bandgap ones, which means spanning the domains of operation for devices beyond those possible with conventional semiconductors in the fields of high-power devices and deep-ultraviolet photodetectors. Furthermore, materials nanostructures with one or more dimensions at the nanoscale drive additional novelties in their optical properties, boosting innovative features. The next step in advanced materials necessarily goes through the quantum - photonic link, in which electromagnetic waves and electronic quantum states display all possible degrees of freedom. To achieve effective advances in this field, both innovative research in materials science and the development of suitable strategies to assess the quantum signatures in the material systems under study are required. This work reviews the fascinating light emission and confinement in wide and ultra-wide bandgap semiconducting oxides of technological interest in nanostructured form, focusing on their luminescence and the key role they can play in future quantum photonic technologies, such as single photon sources and quantum sensing. Finally, an outlook on future avenues in research is outlined.

Modern electronics face several challenges during operation, such as interference of disruptive electromagnetic signals and high temperatures within a limited space. Both electromagnetic interference (EMI) and thermal management could be tackled simultaneously by employing smart efficient materials with high thermal and electrical conductivity. A dual-curing epoxy system, a new subset of adaptable materials, could potentially solve those challenges, with the proper selection of the reinforcement. Moreover, its manufacturing and synthesis process, which involves a sequential curing stage, constitute an attractive, selective, and fast methodology. The thiol-epoxy chemistry allows the synthesis of an epoxy system with high shape-memory capabilities while retaining optimal mechanical properties. Herein, dual-curing epoxy systems reinforced with graphene nanoplatelets (GNPs) are manufactured. The influence of the GNPs content is evaluated, which greatly increases upon loading while retaining a high shape-memory fixation and recovery rates (near 99%). A maximum EMI shielding efficiency of 24 dB is achieved for the higher GNPs content, which is endowed by the high electrical conductivity of the system. Moreover, a modelization of the near-field and far-field EMI shielding is reported, which agrees with experimental observation. This report shows the potential and multifunctional nature of dual-curing epoxy composites for EMI shielding and shape-memory-related application.

The high stability and intrinsic p-type nature of nickel oxide (NiO) make it an interesting material for modern oxide-based technology microdevices. Nowadays, the industry demands more sustainable, highly efficient, and low-energy-consumption synthesis routes as an alternative to conventional methods that commonly involve high temperatures for long times or complex chemical routes. In this work, a fast, low-cost, and energy-saving synthesis based on the Joule heating (JH) process has been employed for the fabrication of micro- and nanocrystalline NiO. The as-grown NiO samples have been investigated as a function of the growth parameters, and special attention has been paid to the differences and similarities between microcrystals grown by JH or vapor-solid (VS) thermal treatments. In particular, Raman spectroscopy reveals that the JH process results in a very reproducible and controllable NiO microcrystalline structure as compared to VS regardless of the fast oxidation process. Cross-sectional analysis of the NiO grown by JH confirms the presence of inner/outer regions with variable microstructure, composition, and physical properties as a function of the different oxidation conditions promoted during the JH process. The mechanisms underlying the JH process have been discussed and compared with those related to the VS method.

Lanthanide-doped ZrO2 ceramics are promising materials for optics due to their high refractive index and tunable luminescent properties. In this study, we investigated the impact of Yb3+ and Er3+ dopant concentrations on the emission behavior of lanthanide-doped 3D ZrO2 microarchitectures fabricated using two-photon lithography. Thermal treatments have been carried out at 600 degrees C and 750 degrees C to promote the stabilization of the ZrO2 tetragonal phase (t-ZrO2) and at 1000 degrees C to induce phase transition in ZrO2 to the monoclinic (m-ZrO2) phase in the 3D microarchitectures. Scanning transmission electron microscopy confirmed the crystallinity changes across the thermal treatments. Photoluminescence (PL) and cathodoluminescence (CL) measurements confirm emission bands of Yb3+ and Er3+ single dopants and Yb3+:Er3+ co-dopants. Variations in Yb3+ content reveal that the PL emission of Er3+ increases (e.g., 4S3/2 -> 4I15/2), which is attributed to the interplay between the dopant concentrations, defect structures and the ZrO2 host. The results highlight the importance of ZrO2microarchitectures' crystallinity and co-doping relationship, which enable the promotion of Er3+ emissions. We expect our research will find applications in 3D optical systems.

AbstractTwo‐photon lithography (TPL) is a powerful technique for creating 3D microarchitectures. Applied to high‐refractive‐index materials like ZrO2, it promises advanced optics. This is the case of ZrO2 host matrixes in combination with luminescent dopants. However, due to the nonideal crystallinity attained to the TPL pre‐ceramic replica from a custom‐made photoresin, the emission of lanthanide (Ln) dopants in ZrO2 microarchitectures can be suboptimal. However, crystallinity exacerbated by annealing can promote Ln‐emission, thereby enabling the integration of ceramic micro‐optic into a low‐temperature process. This work presents a photoresin containing a metal‐organic monomer tailored for TPL, enabling the fabrication of Ln‐doped tetragonal ZrO2 (t‐ZrO2) microarchitectures. The emission properties of Ln‐doped microarchitectures with trivalent Ln ions (Ln3+), i.e., Yb3+ (2.5 mol%), Er3+ (0.35 mol%), and Tm3+ (0.35 mol%) are studied. The results demonstrate that Ln emission is absent when annealing the microarchitectures at 600 °C. Annealing at 750 °C activates Ln3+ emissions, including 2F5/2–2F7/2 (infrared), 4S3/2–4I15/2 (green), and 3H4–3F6 (near‐infrared) transitions corresponding to Yb, Er, and Tm species. Transmission electron microscopy (TEM) confirms that t‐ZrO2 crystallinity becomes more prominent at 750 °C, demonstrating the promotion of Ln emissions upon thermal treatment and underscoring the role of crystalline in TPL micro‐optical ceramics.

Micro- and nano-structures of ZnO were synthesized by the vapor–solid method at 600, 700, and 800 °C in atmospheres of Ar and air, at atmospheric pressure. The structural characterization XRD shows that the nano-structures synthesized in air atmosphere at 600 °C, while diffraction peaks were found due to Zn because the presence of metallic Zn remains on the surface of the pellet. SEM images show that the morphologies range from nano-wires to micro-tubes. When cathodoluminescence is measured in micro-tubes, there is a shift of the near-band edge of the ZnO toward red; this is due to structural defects in the ZnO network. This result is corroborated with panchromatic CL measurements, which exhibit a difference in brightness between the micro-tubes. Furthermore, EDS measurements show an atomic quantity ratio of Zn:O that differs from the stoichiometric composition in the micro-tubes. The photocatalytic activity of three types of structures—nano-wires, micro-tubes, and micro-rods under UV irradiation using methylene blue as a model pollutant—were evaluated. The best response was obtained for nanowires, not only because they have a larger surface area but also because of the present defects.

Tailoring the properties of microfabricated ceramics through doping can unlock new avenues for the additive manufacturing (AM) of advanced 3D architectures. The first step to achieving optical functionality is to control material morphology, crystallinity, and defects associated with the composition of the produced AM architecture and dopants. For this purpose, AM of zinc‐doped zirconia (ZrO2:Zn) 3D microarchitectures is proposed using two‐photon lithography and tailor‐made resin. It is found that Zn doping modulates ZrO2:Zn architecture crystallinity and optical properties. The modification of optical properties through Zn doping is confirmed by micro‐photoluminescence, where higher energy photon emission is observed due to the promotion of oxygen vacancies and surface defects. It is also shown that Zn 2.5% and 5 wt% stabilizes the monoclinic ZrO2at a lower temperature than in the case of undoped ZrO2. Furthermore, there is evidence that Zn tends to form ZnO wurtzite, which is later sublimated. The findings provide a promising route to understand the role of defects ZrO2:Zn optically upon annealing.

We report the influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr through superexchange involving Mn–O–Mn, Fe–O–Fe, and Cr–N–Cr atomic configurations. Density Functional Theory (DFT) calculations demonstrated that these configurations originate within V_Ga-O_N complex defects by incorporating Mn2+, Fe2+, and Cr3+ ions into gallium vacancies ( V_Ga ) sites promoted by the presence of oxygen as a substitutional impurity ( O_N ). These co-doped GaN microstructures were synthesized using the thermal evaporation method. Cathodoluminescence (CL) and photoluminescence (PL) measurements confirmed the presence of V_Ga-O_N complex defects in all GaN-grown samples. X-ray photoelectron spectroscopy (XPS) measurements confirmed the successful incorporation of Mn2+, Fe2+, and Cr3+ ions in GaN samples. SQUID measurements demonstrated room-temperature ferromagnetism with respective saturation magnetization (Ms) and coercive field (Hc) values of ± 1.5 × 10−5 emu and 4 mT for GaN:O,Mn, ± 4.4 × 10−5 emu and 2.6 mT for GaN:O,Fe, and ± 1.7 × 10−5 emu and 2.6 mT for GaN:O,Cr.

In this work, core and core–shell microparticles formed by Ni-Mn-Co oxides with controlled composition were fabricated by an oxalate-assisted co-precipitation route, and their properties were analysed by diverse microscopy and spectroscopy techniques. The microparticles exhibit dimensions within the 2–6 μm range and mainly consist of NiO and NiMn2O4, the latter being promoted as the temperature of the treatment increases, especially in the shell region of the microparticles. Aspects such as the shell dimensions, the vibrational modes of the spinel compounds primarily observed in the shell region, the oxidation states of the cations at the surface of the microparticles, and the achievement of a Ni-rich 811 core and a Mn-rich 631 shell were thoroughly evaluated and discussed in this work.

PEDOT:PSS(poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate))-based composites often exhibit remarkable characteristics regarding high electrical conductivity and great processability, being a suitable candidate for thermoelectric (TE) applications. To increase its performance, PEDOT:PSS is commonly blended with scarce and toxic inorganic compounds based on Se, Te or Bi. In this work we propose the use of one p-type metal oxide semiconductor (MOs): tin(II) oxide (SnO), motivated by its abundance and low toxicity. Hybrid PEDOT:PSS/SnO composites were obtained by firstly blending Ethylene glycol (EG) with PEDOT:PSS and then by adding p-type SnO, previously synthesized by a chemical route. The mixture was deposited via spin-coating onto glass substrates. The Power Factor (PF) of the composites increased by a factor of 300 with the combined EG/SnO composition.

The additive manufacturing (AM) of yttria-stabilized zirconia (YSZ) microarchitectures with sub-micrometer precision via two-photon lithography (TPL), utilizing custom photoresin containing zirconium and yttrium monomers is investigated. YSZ 3D microarchitectures can be formed at low temperatures (600 °C). The low-temperature phase stabilization of ZrO2 doped with Y2O3 demonstrates that doping ZrO2 with ≈ 10 mol% Y2O3 stabilizes the c-ZrO2 phase. The approach does not utilize YSZ particles as additives. Instead, the crystallization of the YSZ phase is initiated after printing, i.e., during thermal processing in the air at 600 °C – 1200 °C for one and two hours. The YSZ microarchitectures are characterized in detail. This includes understanding the role of defect chemistry, which has been overlooked in TPL-enabled micro-ceramics. Upon UV excitation, defect-related yellowish-green emission is observed from YSZ microarchitectures associated with intrinsic and extrinsic centers, correlated with the charge compensation due to Y3+ doping. The mechanical properties of the microarchitectures are assessed with manufactured micropillars. Micropillar compression yields the intrinsic mechanical strength of YSZ. The highest strength is observed for micropillars annealed at 600 °C, and this characteristic decreased with an increase in the annealing temperature. The deformation behavior gradually changes from ductile to brittle-like, correlating with the Hall–Petch strengthening mechanism.

Nickel manganite (NiMn2O4) samples synthesized by a vapor-solid method at temperatures in the range of 1000-1400 degree celsius are studied in this work. The stability and properties of this ternary compound together with the presence of NiO in the form of p-n heterostructures have been analyzed by means of diverse electron microscopy and spectroscopy techniques. The formation of the ternary compound with improved crystallinity is promoted as the temperature of the synthesis is increased. Moreover, the samples synthesized at higher temperatures exhibit the growth of microcrystals with micro- and nanoislands on top of their lateral surfaces, leading to patterned surfaces with variable Ni and Mn composition. The combination of Raman spectroscopy, including wavenumber-filtered images, and electron backscattered diffraction confirms that most of these micro- and nanoislands consist of NiMn2O4 grown on top of NiO surfaces. X-Ray photoelectron spectroscopy and microscopy at synchrotron facilities confirm the presence of nickel manganite nanoislands covering the surface of NiO surfaces. Aspects such as the growth mechanisms, nickel manganite vibrational modes, and inversion factor of NiMn2O4 have been discussed in this work.

In this chapter, we introduce the basic concepts of sustainability and the need for sustainable nanomaterials to meet the requirements of the energy sector, taking into account the avoidance of critical elements and highlighting the current challenges and recent progress achieved in this area.

Tin(II) oxide (SnO), as one of the very few p-type semiconducting oxides is becoming a promising key material in different fields of research. However, the oxidation towards the most stable SnO2 commonly hinders its synthesis and applicability. In that sense, insights in the achievement of SnO with controlled dimensions, morphology and doping, as well as in the study of its optoelectronic properties and stability, are required in order to exploit and widen its applicability. In this work, we report on the synthesis of lithium-doped tin(II) oxide (SnO) nanostructures by a hydrolysis process. Li-doped SnO presents similar morphology as undoped SnO, nonetheless Li doping induces changes in the photoluminescence and electrical properties. Theoretical calculations have been also carried out, complementary to the experimental results. Moreover, the stability of this material under temperature and UV and VIS-laser irradiation is also studied, aiming to determine the ranges within this material could be exploited.