Transmission Electron Microscopy of 2D Materials: Structure and Surface Properties

Abstract

Linköping 2016Cover: Multiple stacked Ti 3 C 2 T x MXene sheets imaged by low-voltage, monochromated, aberration-corrected transmission electron microscopy.During the course of research underlying this thesis, Linda Karlsson was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden.c Linda Karlsson, unless stated otherwise Printed by LiU-Tryck 2016 I rarely end up where I was intending to go, but often I end up somewhere I needed to be. -Douglas Adams The Long Dark Tea-Time of The Soul AbstractDuring recent years, new types of materials have been discovered with unique properties. One family of such materials are two-dimensional materials, which include graphene and MXene. These materials are stronger, more flexible, and have higher conductivity than other materials. As such they are highly interesting for new applications, e.g. specialized in vivo drug delivery systems, hydrogen storage, or as replacements of common materials in e.g. batteries, bulletproof clothing, and sensors. The list of potential applications is long for these new materials.As these materials are almost entirely made up of surfaces, their properties are strongly influenced by interaction between their surfaces, as well as with molecules or adatoms attached to the surfaces (surface groups). This interaction can change the materials and their properties, and it is therefore imperative to understand the underlying mechanisms. Surface groups on two-dimensional materials can be studied by Transmission Electron Microscopy (TEM), where high energy electrons are transmitted through a sample and the resulting image is recorded. However, the high energy needed to get enough resolution to observe single atoms damages the sample and limits the type of materials which can be analyzed. Lowering the electron energy decreases the damage, but the image resolution at such conditions is severely limited by inherent imperfections (aberrations) in the TEM. During the last years, new TEM models have been developed which employ a low acceleration voltage together with aberration correction, enabling imaging at the atomic scale without damaging the samples. These aberration-corrected TEMs are important tools in understanding the structure and chemistry of two-dimensional materials.In this thesis the two-dimensional materials graphene and Ti 3 C 2 T x MXene have been investigated by low-voltage, aberration-corrected (scanning) TEM. High temperature annealing of graphene covered by residues from the synthesis is studied, as well as the structure and surface groups on single and double Ti 3 C 2 T x MXene. These results are important contributions to the understanding of this class of materials and how their properties can be controlled. Populärvetenskaplig sammanfattningTvådimensionella material har unika egenskaper som beror på deras speciella struktur. De lämpar sig därmed väl för framtidens elektronik som kräver dels kontroll ner på atomnivå och dels atomärt tunna material. Jag har undersökt dessa egenskaper med Linköping...

Nanoparticles of Chitosan and Bougainvillea Leaf Extract: Characterization and Its Application to Control Bean common mosaic virus strain Blackeye Cowpea

“…Karakteristik nanopartikel menggunakan TEM, mampu menghasilkan pencitraan langsung dengan spektroskopi kristal. Pola difraksi elektron transmisi menentukan struktur kristalografi suatu material (Karlsson 2016). Karateristik NP yang terbentuk hanya diperoleh untuk Kit-NP, yaitu berukuran < 100 nm; sedangkan untuk EDB-NP dan KEDB-NP diperoleh ukuran partikel yang lebih besar, yaitu berturut-turut 163.68 dan 221.42 nm.…”