Preface

Chapter 8 **High-Porosity Metal Foams: Potentials, Applications, and**

Chapter 10 **Role of Interparticle Space in Hollow Spheres of Silica-Based Solid Acids on Their Acidic Properties and Activity for Hydrolytic Dehydrogenation of Ammonia Borane 221** Tetsuo Umegaki, Toyama Naoki and Yoshiyuki Kojima

Chapter 9 **Porosity Evolution during Chemo-Mechanical**

Ahmed Niameh Mehdy Alhusseny, Adel Gharib Nasser and Nabeel

**Formulations 181**

**Compaction 201** Anders Nermoen

M J Al-zurf

**VI** Contents

Given their practical importance in improving the general or specific properties, the porosity in materials has been extensively investigated and prepared in the recent decades with vari‐ ous techniques. The preparation techniques can be mechanical, chemical, or electrical, such as electrical discharge machining (EDM) and electrochemical anodization process. Several sci‐ entists have been oriented toward the production of well-spaced and well-organized nano‐ metric and micrometric pores, which constitute a technological revolution useful for a wide variety of applications. Nowadays, numerous studies have been focused on the effect of po‐ rosity by exploring the effect of pore size, shape, and density with the goal to enhance some surface or volume properties, such as heat capacity, thermal conductivity, gap energy, optical absorption, optical emissivity, and mechanical hardness. Several techniques are used in the characterizations of the porous materials, such as scanning electron microscopy (SEM); atom‐ ic force microscopy (AFM); transmission electron microscopy (TEM); X-ray diffraction (XRD) for the imagining and structural characterization; and the photoluminescence (PL), ultravio‐ let-visible (UV-VIS), and infrared (IR) spectroscopy for the optical characterization.

The purpose of this book is to present various techniques for the production of pores on the surface and the volume of different materials; to investigate the influence of some parame‐ ters, such as the anodizing current, the annealing temperature, the heating time, the chemi‐ cal composition and concentration, and the nature of some additive and deposited thin layers on the total properties; and to give more ways to use them in different fields.

> **Taher Hcine Ghrib** College of Science of Dammam Imam Abdulrahman Bin Faisal University Dammam, Saudi Arabia

**Section 1**

**Porous Materials**

**Section 1**

**Porous Materials**

**Chapter 1**

**Provisional chapter**

**Porous Silicon**

**Porous Silicon**

Farshid Karbassian

**Abstract**

**1. Introduction**

**2. Properties of porous silicon**

Farshid Karbassian

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

DOI: 10.5772/intechopen.72910

Porous silicon is a sponge-like structure of monocrystalline silicon which although accidentally discovered, soon became one of the most well-researched silicon structures. Its properties and applications have been the main subject of several books and more than a dozen review articles. However, a survey of porous silicon fabrication methods has not been published even though more than 20 different routes have been developed to synthesize this material. This chapter briefly discusses the properties of porous silicon,

Porous silicon, solid silicon with voids therein, is one of the most important porous materials with a wide range of applications from batteries and fuel cells to drug delivery and diagnostics [1–3]. Although optoelectronics, especially light emission, has been porous silicon's primary area of interest for the last 25 years, the material has recently found its way to cosmetics, consumer care, nutrition, and food industry. The preparation of porous silicon is rather simple and inexpensive. It can be performed by several methods depending on the desired structure and properties. It shows highly tunable structural, mechanical, optical, electrical, thermal, emissive, and physiochemical properties. Some of its properties like luminescence and medical biodegradability are direct consequences of nanoscale porosification and are not observed in bulk silicon.

describes its fabrication methods, and introduces its applications.

**Keywords:** porous silicon, fabrication, synthesis, preparation method, etching

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Porous silicon structures, like other porous materials, are classified by their dominant pore dimensions. Structures with pore dimensions below 2 nm and above 50 nm are called microporous

http://dx.doi.org/10.5772/intechopen.72910
