Electron Diffraction Techniques Research Articles

Synthesis of fullerite(100) through epitaxy on a complex intermetallic surface

We report the first epitaxial growth of bulk-like C60(100) plane stabilized by a size-matching effect on the surface of a complex intermetallic compound. As characterized by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) techniques, the adsorption of C60 on Au-Si-Ho(100) surface is disordered at room temperature but ordered when the substrate is held at elevated temperature (669 K). In the submonolayer regime, different superstructures are observed depending on the fullerenes coverage. Upon completion of the first monolayer of C60, the thin film of c(1x1) superstructure is structurally equivalent to a (100) surface plane of the face-centered cubic structure of C60 bulk crystal. This structure is unusual for C60 monolayers on metal surfaces and appears to be favored by an almost perfect match between the most preferred C60 intermolecular distance and the distances separating specific adsorption sites of the large unit cell compound. The adsorption site selection is dictated by a local symmetry matching between the pentagonal fullerene facets and pseudo-five-fold symmetric atomic arrangements on the substrate. After the completion of the first monolayer, further deposition of C60 at 387 K results in the growth of a (100) oriented thicker epitaxial fullerite crystal.

Self-Heterodyne Diffractive Imaging of Ultrafast Electron Dynamics Monitored by Single-Electron Pulses.

The direct imaging of time-evolving molecular charge densities on atomistic scale and at femtosecond resolution has long been an elusive task. In this theoretical study, we propose a self-heterodyne electron diffraction technique based on single electron pulses. The electron is split into two beams, one passes through the sample and its interference with the second beam produces a heterodyne diffraction signal that images the charge density. Application to probing the ultrafast electronic dynamics in Mg-phthalocyanine demonstrates its potential for imaging chemical dynamics.

Studying Ru Dissolution in Pt, Ru, and Pd Core-Shell Nanostructures As a Function of Stress Test Coupled with CO Stripping Analyses

Hydrogen gas contaminated with CO, when used as a reactant on the fuel cell anode, has a detrimental impact on its performance. A low CO contamination of 5 ppm can decrease the fuel cell power density to less than half the value obtained with pure H2.1 To combat CO poisoning of the anode, PtRu/C is currently used on the fuel cell anode instead of the nominally more active Pt/C catalyst. The PtRu/C catalyst reduces CO poisoning by oxidizing this adsorbate within the potential range of hydrogen oxidation. The addition of a third metal such as Pd, Sn, or Co to this bimetallic alloy has demonstrated further improvements to the CO tolerance of the catalyst. The wide application of these alloys is, however, restricted due to the instability of non-noble metal, Ru, at high potentials experienced during fuel cell startup, shutdown, and fuel starvation conditions.2 Dissolution of Ru leads to structural modifications to the nanocatalyst and, thus, directly impacts the CO tolerance of the catalyst because of its structure-property relationship. The dissolution of Ru not only decreases the CO tolerance of the anode, but also reduces the oxygen reduction activity of the cathode due to Ru migration, causing an overall decline in fuel cell performance.3 These structural changes result in a complex heterogeneous particle surface with varying amounts of Pt atoms on each catalytic site, as observed at the atomic level using TEM imaging techniques. The use of TEM does, however, require a visual inspection of the sample. Thus, obtaining results based on TEM analysis alone is not only time-consuming but can also be subjective.4 Studying the structural changes of an ensemble of nanoparticles using a series of electrochemical techniques can help to better understand the degradation mechanism(s) of a catalyst. In this work, modifications to the structure of an ensemble of nanocatalysts because of Ru dissolution during stress tests were evaluated by conducting CO stripping analyses after a well-defined period of testing.Nanoparticles of Pd@PtRu, PtRu@Pd, and PdRu@Pt (core@shell) structures along with a PtRuPd alloy were prepared using a water-in-oil microemulsion synthesis method and examined for their structural stability. These nanoparticles were each adsorbed onto separate carbon supports. The successful formation of an alloy or core-shell structure was assessed by electron diffraction and X-ray spectroscopy techniques. The process of alloying metals and creating core-shell structures can alter the electronic structure of a material, which was studied using X-ray photoelectron spectroscopy. Given the applicability of these catalysts to the anode of the fuel cell, hydrogen oxidation activity was investigated using rotating disk electrode studies, while CO tolerance was assessed using CO stripping analysis. Their structural durability was tested by cycling the applied potential between 0.6 to 0.95 V (vs RHE) for 5000 complete cycles while immersing the electrocatalyst in 0.5 M H2SO4. Changes in the position and shape of the CO oxidation peak were analysed after 200, 500, 1000, 3000 and 5000 cycles to gain insights into the structural modifications occurring to each catalyst throughout these stress tests. The results provide insights into the structural changes and the processes of these modifications that take place during these tests. These studies also suggest an optimum structural configuration of Pt, Ru, and Pd metals among the tested alloys and nanostructures to provide a relatively high degree of structural stability while maintaining tolerance to CO poisoning. This type of comparative analysis can also be utilized in guiding the optimization of additional nanocatalysts for other electrocatalytic reactions. References H.-F. Oetjen, V. M. Schmidt, U. Stimming and F. Trila, J. Electrochem. Soc., 143, 3838 (1996).E. Antolini, J. Solid State Electrochem., 15, 455–472 (2011).L. Gancs, B. N. Hult, N. Hakim and S. Mukerjee, Electrochem. Solid-State Lett., 10, B150 (2007).A. Hrnjic et al., Electrochim. Acta, 388, 138513 (2021).

Hybrid NiCo2O4-BiOCOOH heterostructure nanocomposite impregnated porous polymer monolith as high-performance visible light photocatalyst for the decontamination of antimicrobial pollutants

We report a first-of-its-kind preparation of a NiCo2O4-BiOCOOH heterostructure as visible light-responsive nanocomposites (NCs) for the fast decontamination of moxifloxacin drug molecules, with longer persistence and non-biodegradability nature that could promote gene-resistance bacteria in aqueous medium. Further, a reusable/recoverable photocatalyst is fabricated through the uniform decoration of NiCo2O4(15 %)-BiOCOOH(85 %), i.e., NB-15 NCs across a tailor-made poly(EGDMA) monolith (PEM) that serves as the host template for the photoactive NCs. The electron microscopy, optical spectroscopy, diffraction, and surface analysis techniques confirm the photocatalyst's superior structural morphology, surface topography, and porosity features that assist in high-performance photocatalysis. The inorganic-organic hybrid photocatalyst exhibits a narrow energy bandgap that promotes ample generation of reactive oxygen species upon visible light irradiation, as confirmed by the electrochemical and spectroscopic analysis. The BET/BJH plot for the photocatalyst reveals a large surface area of 345 m2/g, with voluminous pore distributions (2–80 nm), indicating the coexistence of mesopores-infused macroporous framework that offers better contact/equilibration of the pollutant molecules with the abundantly dispersed photoactive sites. The optimized parameters reveal ≥99.2 % drug dissipation in ≤0.33 h and drug mineralization in ≤2.0 h, using a mere 50 mg of photocatalyst irradiated with a 150 W/cm2 tungsten lamp. The synthesized photocatalyst has a simple/cost-saving procedure that can transform into scalable, cheaper, and eco-friendly products for the real-time monitoring of toxic pollutants. Besides, the photocatalyst exhibits excellent stability and reusability characteristics for efficiently decontaminating organic pollutants, thus highlighting an innovative approach for fabricating high-performance photocatalysts.

Quasi-1D Moiré superlattices in self-twisted two-allotropic antimonene heterostructures.

Two-dimensional heterostructures, characterized by a twist angle between individual sublayers, offer unique and tunable properties distinct from standalone layers. These structures typically introduce a realm of exotic quantum phenomena due to the appearance of new, long range periodicities associated with Moiré superlattices. Using molecular beam epitaxy, we demonstrate the growth of bi-allotropic 2D-Sb heterostructures on a W(110) substrate composed of twisted α (α-Sb) and β (β-Sb) phases of antimonene. Due to the relatively weak interaction between sublayers, the twist angle is intrinsically determined for each heterostructure, revealing its inherent self-twisted nature. The different atomic lattice symmetries of both allotropes lead to the formation of distinctive quasi-1D Moiré superlattices, while the random nature of the twist angle allows for a wide modulation of the Moiré potential landscape. The observed Moiré patterns on β-Sb/α-Sb heterostructures were compared with a simple model, revealing satisfactory agreement with the experiments and strongly validating the formation of self-twisted β-Sb/α-Sb heterostructures. The samples were characterized in situ using low energy electron microscopy and diffraction techniques providing a real-time tracking of the growth process and insight into the atomic structure of the synthesized nanostructures.

3D Nanocrystallography and the Imperfect Molecular Lattice.

Crystallographic analysis relies on the scattering of quanta from arrays of atoms that populate a repeating lattice. While large crystals built of lattices that appear ideal are sought after by crystallographers, imperfections are the norm for molecular crystals. Additionally, advanced X-ray and electron diffraction techniques, used for crystallography, have opened the possibility of interrogating micro- and nanoscale crystals, with edges only millions or even thousands of molecules long. These crystals exist in a size regime that approximates the lower bounds for traditional models of crystal nonuniformity and imperfection. Accordingly, data generated by diffraction from both X-rays and electrons show increased complexity and are more challenging to conventionally model. New approaches in serial crystallography and spatially resolved electron diffraction mapping are changing this paradigm by better accounting for variability within and between crystals. The intersection of these methods presents an opportunity for a more comprehensive understanding of the structure and properties of nanocrystalline materials.

Green synthesis structural, morphological and sonocatalytic properties of CuO nanoparticles assisted by Camellia sinensis (Tea) extract

In this green synthesis approach for copper oxide (CuO) nanoparticles (NPs), the reducing agent obtained from Camellia sinensis (Tea) extract was used. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV-Vis) spectroscopy, field emission scanning electron microscope (FESEM) with energy-dispersive X-ray (EDX), high resolution transmission electron microscope (HRTEM) and Selected Area Electron Diffraction (SAED) techniques were used for as-prepared sample characterization. From XRD result, the crystallite size estimated by Scherrer method was found to be 35 nm. Morphological results reveals that the CuO NPs possesses small particle size with the range of 40–45 nm, led to high surface area, which enhances the absorption of more number of dye molecules, which results in high degradation efficiency. Present work reveals that degradation of malachite green (MG) dye in aqueous solutions under sonocatalytic treatment. CuO NPs exhibit excellent degradation efficiency against MG dye (95 % removal in 70 min). Moreover, the rate constant for the degradation efficiency was investigated with pseudo- first and second order kinetics. Moreover, CuO NPs possesses potential antibacterial activity against human pathogens such as Gram-positive (Staphylococcus pyogenes) and Gram-negative (Pseudomonas aeruginosa).

The photodissociation dynamics and ultrafast electron diffraction image of cyclobutanone from the surface hopping dynamics simulation

The comprehension of nonadiabatic dynamics in polyatomic systems relies heavily on the simultaneous advancements in theoretical and experimental domains. The gas-phase ultrafast electron diffraction (UED) technique has attracted significant attention as a unique tool for monitoring photochemical and photophysical processes at the all-atomic level with high temporal and spatial resolutions. In this work, we simulate the UED spectra of cyclobutanone using the trajectory surface hopping method at the extended multi-state complete active space second order perturbation theory (XMS-CASPT2) level and thereby predict the results of the upcoming UED experiments in the Stanford Linear Accelerator Laboratory. The simulated results demonstrate that a few pathways, including the C2 and C3 dissociation channels, as well as the ring opening channel, play important roles in the nonadiabatic reactions of cyclobutanone. We demonstrate that the simulated UED signal can be directly interpreted in terms of atomic motions, which provides a unique way of monitoring the evolution of the molecular structure in real time. Our work not only provides numerical data that help to determine the accuracy of the well-known surface hopping dynamics at the high XMS-CASPT2 electronic-structure level but also facilitates the understanding of the microscopic mechanisms of the photoinduced reactions in cyclobutanone.

Mechanochemically Robust LiCoO2 with Ultrahigh Capacity and Prolonged Cyclability.

Pushing intercalation-type cathode materials to their theoretical capacity often suffers from fragile Li-deficient frameworks and severe lattice strain, leading to mechanical failure issues within the crystal structure and fast capacity fading. This is particularly pronounced in layered oxide cathodes because the intrinsic nature of their structures is susceptible to structural degradation with excessive Li extraction, which remains unsolved yet despite attempts involving elemental doping and surface coating strategies. Herein, a mechanochemical strengthening strategy is developed through a gradient disordering structure to address these challenges and push the LiCoO2 (LCO) layered cathode approaching the capacity limit (256mAhg-1, up to 93% of Li utilization). This innovative approach also demonstrates exceptional cyclability and rate capability, as validated in practical Ah-level pouch full cells, surpassing the current performance benchmarks. Comprehensive characterizations with multiscale X-ray, electron diffraction, and imaging techniques unveil that the gradient disordering structure notably diminishes the anisotropic lattice strain and exhibits high fatigue resistance, even under extreme delithiation states and harsh operating voltages. Consequently, this designed LCO cathode impedes the growth and propagation of particle cracks, and mitigates irreversible phase transitions. This work sheds light on promising directions toward next-generation high-energy-density battery materials through structural chemistry design.

Design, development, and performance of a versatile graphene epitaxy system for the growth of epitaxial graphene on SiC.

A versatile graphene epitaxy (GrapE) furnace has been designed and fabricated for the growth of epitaxial graphene (EG) on silicon carbide (SiC) in diverse growth environments ranging from high vacuum to atmospheric argon pressure. Radio-frequency induction enables heating capabilities up to 2000 °C, with controlled heating ramp rates achievable up to 200 °C/s. The details of critical design aspects and temperature characteristics of the GrapE system are discussed. The GrapE system, being automated, has enabled the growth of high-quality EG monolayers and turbostratic EG on SiC using diverse methodologies, such as confinement-controlled sublimation (CCS), open configuration, polymer-assisted CCS, and rapid thermal annealing. This showcases the versatility of the GrapE system in EG growth. Comprehensive characterizations involving atomic force microscopy, Raman spectroscopy, and low-energy electron diffraction techniques were employed to validate the quality of the produced EG.

Bifunctional Mn‐Fe Oxide Catalysts for Zn‐Air Battery Air Electrodes Fabricated Through Atomic Layer Deposition

Zinc‐air batteries (ZABs) are one of many energy storage technologies that can help integrate renewable energy into the power grid. A key developmental goal for ZABs is replacing the precious metal catalysts at the air electrode with more abundant and inexpensive materials. In this work, a MnFexOy bifunctional catalyst is directly deposited on a ZAB air electrode using atomic layer deposition (ALD). With ALD, the atomic composition of the air electrode coating can be tuned based on catalytic activity. Characterization through electron microscopy, photoelectron spectroscopy and diffraction techniques indicate that the novel ALD film deposits as a nanocrystalline (Mn,Fe)3O4 cubic spinel. The mixed oxide catalyst outperforms its individual binary MnOx or FeOx constituents, operating at 50.7% bifunctional efficiency at 20 mA cm‐2. Moreover, the long term stability of the ALD catalyst is showcased by 600 h (1565 cycles) of ZAB cycling at 10 mA cm‐2. The efficiency retention of the bifunctional transition metal oxide catalyst is superior to a precious metal benchmark of Pt‐Ru‐C, with 84.7% efficiency retention after more than 1500 cycles versus only 66.2% retention for the precious metal catalyst. The ALD technique enables deep penetration of catalyst material into the air electrode structure, improving the cycling behaviour.

Fabrication, characterization, spectroscopic, and magnetic properties of polyaniline/magnetite (PANi/Fe3O4) nanocomposites

In this research, pure polyaniline (PANi), pure magnetite (Fe3O4), and then PANi/ Fe3O4 nanocomposites were prepared and characterized. FT-IR spectra of the prepared samples indicate successful polymerization of PANi onto Fe3O4. PANi/Fe3O4 nanocomposites exhibit broad absorption bands at specific wavenumbers, indicating the presence of various functional groups. The observed blue shift in certain peaks suggests the interaction between nitrogen atoms and oxygen atoms on the magnetite surface through hydrogen bonding. The intensity and wavenumber of the Fe3O4 band decrease, indicating weakened Fe–O bonds. These findings demonstrate a strong interaction and combination between PANi and Fe3O4 in the nanocomposites. Fe3O4 nanoparticles exhibit a regular spherical shape with an average diameter of 16 nm. However, they also show non-uniform size distribution due to aggregation into larger secondary particles, likely driven by attractive forces. PANi/Fe3O4 core-shell nanocomposites demonstrate clear morphological changes, with Fe3O4 nanoparticles well spread and wrapped by the PANi shell. The electron diffraction technique confirms the crystalline structure of Fe3O4 nanoparticles, showing diffraction rings consistent with magnetite. The results confirm the potential of incorporating magnetic Fe3O4 nanoparticles to impart magnetic functionality in the resulting PANi-based nanocomposite materials. Magnetic saturation measurements displayed an enhancement in magnetization with increasing Fe3O4 nanoparticles. The change in magnetic behavior for doped samples provides a means of tuning the magnetization strength of the composites to meet the application requirement such as data storage and magnetic sensors.

Investigation of the structural stability of polycrystalline cBN under near-industrial grinding process conditions

Cubic boron nitride (cBN) is an important material in the cutting and metal processing industries due to its exceptional hardness and high thermal stability, which allows it to withstand temperatures up to 1400 °C without decomposing. These properties make cBN and, with that, polycrystalline cBN (PcBN) ideal materials for high-speed machining and other applications, resulting in increased efficiency and reduced costs in production processes. Despite its established importance, the possibility of phase transformations into hexagonal boron nitride phases or partial amorphization during industrial PcBN grinding processes remains unclear and, due to the deteriorated mechanical characteristics, raised recently some concerns about possible losses of cBN's hardness, wear resistance, and abrasive properties. In order to address this issue and for identifying such potential structural changes, a commercial PcBN grade was exposed to near-industrial grinding process conditions and then characterized in detail by conventional (scanning) transmission electron microscopy (S)TEM and (scanning) electron diffraction techniques. To understand the influence of the PcBN machining on the material, the grinding process also needs to be assessed via the identification of chip formation mechanisms, which is as well addressed in this work. The main outcome of this study, combining a material analysis and a manufacturing technology point of view, is that there is so far no evidence of any structural instabilities of PcBN under usual processing conditions.

Lattice dynamics in the FeSi-based family of superconductors

The lattice dynamics of the superconducting materials LaFeSiH and LaFeSiO1-δ as well as their intermetallic precursor LaFeSi are investigated by polarized Raman spectroscopy and first-principles calculations, together with X-ray and advanced electron diffraction techniques for their structural analysis. We find that the Fe-dominated Raman-active modes reflect the chemical peculiarities of these silicides compared to their pnictide counterparts, with enhanced structural couplings between the FeSi layer and the spacer that can be related to the ionic vs. covalent character of the latter. In addition, we find signatures of enhanced electron-phonon coupling for some of the Raman-active modes. Beyond that, our study reveals intriguing Fe-based Raman features as well as structural subtleties in LaFeSiH suggesting that this superconductor may formally be non-centrosymmetric.

Nanotubes from Lanthanide-Based Misfit-Layered Compounds: Understanding the Growth, Thermodynamic, and Kinetic Stability Limits.

Gaining insights into the kinetics and the thermodynamic limits of nanostructures in high-temperature reactions is crucial for controlling their unique morphology, phase, and structure. Nanotubes from lanthanide-based misfit-layered compounds (MLCs) have been known for more than a decade and were successfully produced mostly via a chemical vapor transport protocol. The MLC nanotubes show diverse structural arrangements and lattice disorders, which could have a salient impact on their properties. Though their structure and charge transfer properties are reasonably well understood, a lack of information on their thermodynamic and kinetic stability limits their scalable synthesis and their applicability in modern technologies. In this study, the growth, thermodynamic stability, and decomposition kinetics of lanthanide-based misfit nanotubes of two model compounds, i.e., (LaS)1.14TaS2 and (SmS)1.19TaS2 are elucidated in detail. The nanotubes were carefully analyzed via atomic resolution electron microscopy imaging and synchrotron-based X-ray and electron diffraction techniques, and the information on their morphology, phase, and structures was deduced. The key insights gained would help to establish the parameters to explore their physio-chemical properties further. Furthermore, this study sheds light on the complex issue of the high-temperature stability of nanotubes and nanostructures in general.

Silver Nanoparticles Produced In Vitro by Berberis vulgaris Fruit and Their Antioxidant, Antimicrobial and Ex Ovo Irritation Potential Study

Green synthesis was successfully used for silver nanoparticles (Ag NPs) preparation using Berberis vulgaris aqueous extracts. The ultraviolet and visible (UV–Vis) spectroscopy, photon cross-correlation spectroscopy (PCCS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) techniques were used for characterization of the Ag NPs and confirmed the presence of Ag(0) in nanoparticles. The bimodal morphology was discovered, namely, the larger particles had elongated shape and size around 200 nm, while the smaller ones were spherical with a size of up to ten microns. All the nanoparticles (NPs) showed antioxidant activity against radical DPPH and ferric-reducing antioxidant power. The Ag NPs possess antibacterial effects against Escherichia coli and Staphylococcus aureus comparable to silver nitrate solution. In addition, also irritation potential of the produced Ag NPs has been investigated ex Ovo and no irritation of vessels and their surroundings was found, which shows the harmless character of the products.

Modular Design of Highly Stable Semiconducting Porous Coordination Polymer for Efficient Electrosynthesis of Ammonia.

Developing highly stable porous coordination polymers (PCPs) with integrated electrical conductivity is crucial for advancing our understanding of electrocatalytic mechanisms and the structure-activity relationship of electrocatalysts. However, achieving this goal remains a formidable challenge because of the electrochemical instability observed in most PCPs. Herein, we develop a "modular design" strategy to construct electrochemically stable semiconducting PCP, namely, Fe-pyNDI, which incorporates a chain-type Fe-pyrazole metal cluster and π-stacking column with effective synergistic effects. The three-dimensional electron diffraction (3D ED) technique resolves the precise structure. Both theoretical and experimental investigation confirms that the π-stacking column in Fe-pyNDI can provide an efficient electron transport path and enhance the structural stability of the material. As a result, Fe-pyNDI can serve as an efficient model electrocatalyst for nitrate reduction reaction (NO3RR) to ammonia with a superior ammonia yield of 339.2 μmol h-1 cm-2 (14677 μg h-1 mgcat. -1) and a faradaic efficiency of 87 % at neutral electrolyte, which is comparable to state-of-the-art electrocatalysts. The in-situ X-ray absorption spectroscopy (XAS) reveals that during the reaction, the structure of Fe-pyNDI can be kept, while part of the Fe3+ in Fe-pyNDI was reduced in situ to Fe2+, which serves as the potential active species for NO3RR.

Modular Design of Highly Stable Semiconducting Porous Coordination Polymer for Efficient Electrosynthesis of Ammonia

AbstractDeveloping highly stable porous coordination polymers (PCPs) with integrated electrical conductivity is crucial for advancing our understanding of electrocatalytic mechanisms and the structure–activity relationship of electrocatalysts. However, achieving this goal remains a formidable challenge because of the electrochemical instability observed in most PCPs. Herein, we develop a “modular design” strategy to construct electrochemically stable semiconducting PCP, namely, Fe‐pyNDI, which incorporates a chain‐type Fe‐pyrazole metal cluster and π‐stacking column with effective synergistic effects. The three‐dimensional electron diffraction (3D ED) technique resolves the precise structure. Both theoretical and experimental investigation confirms that the π‐stacking column in Fe‐pyNDI can provide an efficient electron transport path and enhance the structural stability of the material. As a result, Fe‐pyNDI can serve as an efficient model electrocatalyst for nitrate reduction reaction (NO3RR) to ammonia with a superior ammonia yield of 339.2 μmol h−1 cm−2 (14677 μg h−1 mgcat.−1) and a faradaic efficiency of 87 % at neutral electrolyte, which is comparable to state‐of‐the‐art electrocatalysts. The in‐situ X‐ray absorption spectroscopy (XAS) reveals that during the reaction, the structure of Fe‐pyNDI can be kept, while part of the Fe3+ in Fe‐pyNDI was reduced in situ to Fe2+, which serves as the potential active species for NO3RR.

Colloidal Synthesis of (PbBr2)2(AMTP)2PbBr4 a Periodic Perovskite "Heterostructured" Nanocrystal.

Heterostructures in nanoparticles challenge our common understanding of interfaces due to quantum confinement and size effects, giving rise to synergistic properties. An alternating heterostructure in which multiple and reoccurring interfaces appear in a single nanocrystal is hypothesized to accentuate such properties. We present a colloidal synthesis for perovskite layered heterostructure nanoparticles with a (PbBr2)2(AMTP)2PbBr4 composition. By varying the synthetic parameters, such as synthesis temperature, solvent, and selection of precursors, we control particle size, shape, and product priority. The structures are validated by X-ray and electron diffraction techniques. The heterostructure nanoparticles' main optical feature is a broad emission peak, showing the same range of wavelengths compared to the bulk sample.

Revisiting the Crystallography of {225}γ Martensite: How EBSD Can Help to Solve Long-Standing Controversy

Explaining the crystallography of iron alloys martensite with a {225}γ habit plane remains a challenging task within the phenomenological theory of martensite crystallography. The purpose of this study is to re-examine the martensite formed in a Fe-8Cr-1.1C alloy using EBSD, which has a better angular resolution than the conventional transmission electron diffraction techniques previously used. The results show that the single morphological plates, which hold a near {225}γ habit plane, are bivariant composites made up of two twin-related variants. It is shown that a {113}γ plane is systematically parallel to one of the three common 112α planes between the two twin-related crystals. This observation suggests that the lattice invariant strain of transformation occurs through a dislocation glide on the {113}γ ⟨110⟩γ system, rather than through twinning as is commonly accepted. Based on this assumption, the predictions of Bowles and Mackenzie’s original theory are in good agreement with the crystallographic features of {225}γ martensite. Unexpectedly, it is the high shear solution of the theory that gives the most accurate experimental predictions.