We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal each step is caused an impact on C atom next to dopant. Although atomic motion happens below our experimental time resolution, stochastic analysis 38 such jumps reveals probability for their occurrence good agreement with simulations. Conversions from three- fourfold coordinated dopant structures and subsequent...

Deviations from the perfect atomic arrangements in crystals play an important role affecting their properties. Similarly, diffusion of such deviations is behind many microstructural changes solids. However, observation point defect hindered both by difficulties related to direct imaging non-periodic structures and timescales involved process. Here, instead thermal diffusion, we stimulate follow migration a divacancy through graphene lattice using scanning transmission electron microscope...

The direct manipulation of individual atoms in materials using scanning probe microscopy has been a seminal achievement nanotechnology. Recent advances imaging resolution and sample stability have made transmission electron promising alternative for single-atom covalently bound materials. Pioneering experiments an atomically focused beam demonstrated the directed movement silicon over handful sites within graphene lattice. Here, we achieve much greater degree control, allowing us to...

One of the keys behind success modern semiconductor technology has been ion implantation silicon, which allows its electronic properties to be tailored. For similar purposes, heteroatoms have introduced into carbon nanomaterials both during growth and using post-growth methods. However, due nature samples, it challenging determine whether incorporated lattice as intended, with direct observations so far being limited N B dopants, incidental Si impurities. Furthermore, these materials is more...

In this work we demonstrate that a free-standing van der Waals heterostructure, usually regarded as flat object, can exhibit an intrinsic buckled atomic structure resulting from the interaction between two layers with small lattice mismatch. We studied freely suspended membrane of well aligned graphene on hexagonal boron nitride (hBN) monolayer by transmission electron microscopy (TEM) and scanning TEM (STEM). developed detection method in STEM is capable recording direction scattered beam...

The effect of electron irradiation on two-dimensional (2D) materials is an important topic, both for the correct interpretation microscopy experiments and possible applications in lithography. After importance including inelastic scattering damage theoretical models describing beam lack oxygen sensitivity under 2D <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>MoS</a:mi><a:mn>2</a:mn></a:msub></a:math> were recently shown, role temperature has remained unexplored a...

Graphene has many claims to fame: it is the thinnest possible membrane, unique electronic and excellent mechanical properties, provides perfect model structure for studying materials science at atomic level. However, practical studies applications ordered hexagon arrangement of carbon atoms in graphene not directly suitable. Here, we show that can be locally either removed or rearranged into a random pattern polygons using focused ion beam (FIB). The disordered regions confirmed with...

The {\AA}ngstr\"om-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This unambiguously resolve chemical structure materials, but not their isotopic composition. Here we differentiate between two isotopes same element by quantifying how likely energetic imaging electrons are to eject First, measure displacement probability in graphene grown either $^{12}$C or $^{13}$C describe process using a quantum mechanical model lattice...

Abstract Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further reduction DNDs would bring these nanoparticles to the molecular-size level open new prospects for research applications various fields, ranging from quantum physics biomedicine. Here we show controllable DND mean down 1.4 without significant particle loss additional disintegration core agglutinates by air annealing, leading significantly narrowed distribution...

Surface impurities and contamination often seriously degrade the properties of two-dimensional materials such as graphene. To remove contamination, thermal annealing is commonly used. We present a comparative analysis treatments in air vacuum, both ex situ "pre-situ", where an ultra-high vacuum treatment chamber directly connected to aberration-corrected scanning transmission electron microscope. While do it challenging obtain atomically clean surfaces after ambient transfer. However,...

Heterostructures composed of 2D materials are already opening many new possibilities in such fields technology as electronics and magnonics, but far more could be achieved if the number diversity were increased. So far, only a few dozen crystals have been extracted from that exhibit layered phase ambient conditions, omitting entirely large may exist at other temperatures pressures. This work demonstrates how structures can stabilized van der Waals (vdw) stacks under room temperature via...

Abstract Understanding electron irradiation effects is vital not only for reliable transmission microscopy characterization, but increasingly also the controlled manipulation of 2D materials. The displacement cross sections monolayer hexagonal boron nitride (hBN) are measured using aberration‐corrected scanning in near ultra‐high vacuum at primary beam energies between 50 and 90 keV. Damage rates below 80 keV up to three orders magnitude lower than previously edges under poorer residual...

Two-dimensional (2D) materials have considerably expanded the field of science in last decade. Even more recently, various 2D been assembled into vertical van der Waals heterostacks, and it has proposed to combine them with other low- dimensional structures create new hybridized properties. Here, we demonstrate first direct images a suspended 0D/2D heterostructure incorporating $C_{60}$ molecules between two graphene layers buckyball sandwich structure. We find clean ordered islands...

While an increasing number of two-dimensional (2D) materials, including graphene and silicene, have already been realized, others only predicted. An interesting example is the form silicon carbide (2D-SiC). Here, we present observation atomically thin hexagonally bonded nanosized grains SiC assembling temporarily in oxide pores during atomic resolution scanning transmission electron microscopy experiment. Even though these small do not fully represent bulk crystal, simulations indicate that...

Along with hydrogen, carbon, nitrogen and oxygen are the arguably most important elements for organic chemistry. Due to their rich variety of possible bonding configurations, they can form a staggering number compounds. Here, we present detailed analysis configurations in defective carbon (graphene) lattice. Using aberration-corrected scanning transmission electron microscopy single-atom energy loss spectroscopy, directly imaged atoms graphene oxide, as well implanted into graphene. The...

Structural engineering is the first step toward changing properties of materials. While this can be at relative ease done for bulk materials, example, using ion irradiation, similar 2D materials and other low-dimensional structures remains a challenge. The difficulties range from preparation clean uniform samples to sensitivity these overwhelming task sample-wide characterization subjected modifications atomic scale. Here, we overcome issues near ultrahigh vacuum system comprised an...

The deformation-induced nanostructure developed during high-pressure torsion of B2 long-range ordered FeAl is shown to be unstable upon heating. structural changes were analyzed using transmission electron microscopy, differential scanning calorimetry and microhardness measurements. Heating up 220 °C leads the recurrence chemical order that destroyed deformation. It transition long-range-ordered phase evolves in form small domains homogeneously distributed inside nanosized grains. At...

We demonstrate the growth of overlapping grain boundaries in continuous, polycrystalline hexagonal boron nitride (h-BN) monolayer films via scalable catalytic chemical vapor deposition. Unlike commonly reported atomically stitched boundaries, these do not consist defect lines within but are composed self-sealing bilayer regions limited width. characterize this h-BN boundary structure detail by complementary (scanning) transmission electron microscopy techniques and propose a mechanism linked...

The chemical and electrical properties of single-walled carbon nanotubes (SWCNTs) graphene can be modified by the presence covalently bound impurities. Although this achieved introducing additives during synthesis, it often hinders growth leads to limited crystallite size quality. Here, through simultaneous formation vacancies with low-energy argon plasma thermal activation adatom diffusion laser irradiation, silicon impurities are incorporated into lattice both materials. After an exposure...

Single atoms and few-atom nanoclusters are of high interest in catalysis plasmonics, but pathways for their fabrication placement remain scarce. We report here the self-assembly room-temperature-stable single indium (In) In clusters (2–6 atoms) that anchored to substitutional silicon (Si) impurity suspended monolayer graphene membranes. Using atomically resolved scanning transmission electron microscopy (STEM), we find symmetry structures is critically determined by three- or fourfold...