475 °C embrittlement refers to a phenomenon observed in certain types of ferritic stainless steels and other iron-based alloys, where prolonged exposure to temperatures around 475 °C (about 885 °F) leads to a reduction in ductility and toughness. This embrittlement is primarily attributed to the precipitation of an iron-rich phase known as "sigma phase" or the formation of non-uniform compositions in the microstructure, which can lead to the loss of the material's structural integrity.

Chemical bonding is the process by which atoms connect with each other to form molecules and compounds. It involves the interactions between the electrons of different atoms, allowing them to achieve greater stability. There are several types of chemical bonds, the most common being: 1. **Ionic Bonds**: Formed when one atom donates an electron to another, resulting in the formation of positively and negatively charged ions (cations and anions).

Correlated electrons refer to electrons in a material that exhibit strong interactions with each other, leading to collective behavior that cannot be adequately described by treating them as independent particles. In systems of interacting electrons, the motions and states of individual electrons become dependent on one another, resulting in complex phenomena that are not captured by the simple principles of non-interacting particle physics.

Electronic band structures describe the range of energies that electrons can have in a solid material and the corresponding ranges of energies that they cannot have, often referred to as "forbidden bands" or "band gaps." The band structure is a fundamental concept in solid-state physics and is crucial for understanding the electronic properties of materials, including conductors, semiconductors, and insulators.

Laboratory techniques in condensed matter physics involve various experimental methods used to study the properties and behaviors of condensed matter systems, which include solids and liquids. These techniques aim to investigate the microscopic and macroscopic characteristics of materials, often at the atomic or molecular level.

Semiconductor properties refer to the characteristics and behaviors of semiconductor materials, which are crucial in the fields of electronics and optoelectronics. Semiconductors have unique electrical properties that allow them to conduct electricity under certain conditions while acting as insulators under others. Here are some key properties of semiconductors: 1. **Band Gap**: Semiconductors have a band gap between the valence band (where electrons are bound) and the conduction band (where electrons can move freely).