**Abstract**

The synthesis of polycrystalline powder is a key step for materials sciences. In this chapter, we present the well-known methods of preparation of powders such as: solid-state reaction, sol–gel, hydrothermal, combustion, co-precipitation. Moreover, synthesis methods by arc furnace, by heating in a "high frequency" induction furnace and by high energy grinding are presented. The obtained powders could be defined by their purity, gain size, crystallinity, and morphology, which are influenced by the synthesis method. In addition, each method is dependent on some parameters like pH, concentration and temperature.

**Keywords:** solid-state, sol–gel, hydrothermal, combustion, coprecipitation, intermetallic

## **1. Introduction**

Optimizing the physico-chemical properties of materials is a challenge for many scientific researchers, and it could be altered using different synthesis methods. The synthesis of ceramics is influenced by many parameters; the choice of such a synthesis method is generally conditioned by the morphology as well as by the particle size and the specific surface of the samples, which it is desired to synthesis. Ceramics, when prepared by different routes, exhibit different properties, even with the same starting compositions. There are two ways of synthesizing ceramics:


Microstructure plays an important role in the properties of materials. In fact, for ceramic materials, the presence of porosities between the grains has a negative effect on the conductive properties. In addition, ceramic materials made of small grain size are thermally more stable mechanically than samples with larger grain size [1]. For example, barium hexaferrite (BaFe12O19) could be used either as a permanent magnet or as a recording medium depending on the morphology of the compound, which depends on the route of preparation [2].

A variety of metal oxides, both simple and complex, is prepared by conventional ceramic process. This involves the mixing of metal oxides, carbonates, and their

repeated heating and grinding. This method is used on both a laboratory and industrial scale. Nevertheless, the need for alternative routes to the synthesis of oxides has arisen due to intrinsic problems related to:


To have better control of stoichiometry, structure, and desired phase purity, mild chemical pathways are becoming increasingly important in preparing a variety of oxides, including nanocrystalline oxide materials [3].

This chapter is divided in two parts. The first one is dedicated to powders prepared by chemical methods while the second describes the methods of preparation of intermetallic compounds.
