Jeanne Ayache

Introduction to Materials

Natural materials such as organic matter, mineral matter, and living matter, along with artificial materials produced industrially, make up all of the materials found on the Earth. They all have a chemical composition and particular structure that give them specific properties or functions in relation to their surroundings or their formation conditions.

Artifacts in Transmission Electron Microscopy

An artifact is damage caused by a preparation technique and can easily be confused with the sample’s microstructure. Artifacts can be due to mechanical, chemical, ionic, or physical action. During TEM observation, especially in a TEM/STEM, other artifacts may be produced due to irradiation under the electron beam.

Grain boundaries in high temperature superconducting ceramics

The aim of this paper is to review the different types of grain boundaries found in YBa2Cu3O7− d superconducting ceramics, which have been investigated over the past decade. A variety of samples covering a wide range of current density J c values are examined, including classical bulk ceramics, melt-textured bulk ceramics, bulk and thin film bicrystals with specific orientations, thin films and single crystals. From electronic coupling, J c is expected and found to decrease with increasing grain boundary (GB) misorientation. From the magnetic behaviour, the critical current density J c(H) is expected to increase with the number of pinning centres. The properties of the various types of GBs are discussed. All the studies reviewed lead to the conclusion that grain boundaries in YBCO materials cannot be understood without specific information on their local composition, structure and electronic state. They confirm that research on bicrystals is crucial for high-temperature superconductor development.

Characteristics of HgS nanoparticles formed in hair by a chemical reaction

A chemical reaction, derived from an ancient recipe for hair dyeing, is used to precipitate nanoparticles of mercury sulphide in hair by the simple process of immersion in a water solution of Ca(OH)2 and HgO. After several days, HgS nanoparticles appear throughout the hair and are particularly numerous in the various interfaces. The formation of these nanoparticles has been studied by analytical and atomic resolution electron microscopy. High resolution quantitative analysis allowed the determination of two varieties of HgS precipitate crystal structures formed: a hexagonal cinnabar and a cubic metacinnabar structure. This very simple process of a chemical reaction in hair is a particularly inexpensive way to fabricate semiconductor sulphide nanoparticles with specific properties.

Mechanical Preparation Techniques

Crushing is used to very quickly produce a fine powder from a bulk material or fine particle using mechanical crushing.

Thinning Preparation Techniques

This technique is used to produce a thin slice (measuring 3 mm in diameter and between 50- and 100-μm thick) without strain hardening, by thinning until a perforation is made in the center. The resulting hole has electron-transparent thin edges.

Preliminary Preparation Techniques

This technique is used to make slices of bulk samples in order to reduce their dimensions and then prepare them using other preparation or finishing techniques (final thinning for transmission electron microscopy). In most cases, this means obtaining a slice with parallel faces of the right thickness (a foil or disk 1- to 0.1-mm thick).

Contrast Enhancement and Labeling Techniques

This technique is used to enhance contrast in a sample. It is particularly useful for highlighting very faint surface relief. The method consists of depositing heavy-metal (high Z) particles on or around a sample’s relief. The contrast of a sample is enhanced by shadowing resulting from a metallic deposit.

Methodology: General Introduction

This book is aimed at the entire scientific community (solid state physics, chemistry, earth sciences, and live sciences), to those who use transmission electron microscopy (TEM) to analyze structure in relation to the properties and specific functions of materials. This work is essentially dedicated to the recommended methodology for beginning the preparation of a sample for the TEM. In particular it stresses the approach to take in selecting the best technique by taking into account the material problem presented, the type of material, its structure, and its properties. It proposes the tools for the most appropriate preparation of samples for observing the true structure of the material.

Techniques: General Introduction

The second volume of the “Sample Preparation Handbook for Transmission Electron Microscopy” contains descriptions of 14 preliminary and/or complementary sample preparation techniques and 21 thin slice preparation techniques for the transmission electron microscope (TEM).