Conventional and Microwave Hydrothermal Synthesis and Application of Functional Materials: A Review

Abstract

With the continuous development and progress of materials science, increasingly more attention has been paid to the new technology of powder synthesis and material preparation. The hydrothermal method is a promising liquid phase preparation technology that has developed rapidly during recent years. It is widely used in many fields, such as the piezoelectric, ferroelectric, ceramic powder, and oxide film fields. The hydrothermal method has resulted in many new methods during the long-term research process, such as adding other force fields to the hydrothermal condition reaction system. These force fields mainly include direct current, electric, magnetic (autoclaves composed of non-ferroelectric materials), and microwave fields. Among them, the microwave hydrothermal method, as an extension of the hydrothermal reaction, cleverly uses the microwave temperature to compensate for the lack of temperature in the hydrothermal method, allowing better practical application. This paper reviews the development of the hydrothermal and microwave hydrothermal methods, introduces their reaction mechanisms, and focuses on the practical application of the two methods.

Keywords: application; functional materials; hydrothermal method; microwave hydrothermal method.

Figure 1

Application field of hydrothermal methods.

Figure 2

Schematic of typical hydrothermal method equipment.

Figure 3

General steps for hydrothermal preparation.

Figure 4

Spectral wavelength-frequency diagram.

Figure 5

Schematic diagram of water molecular motion in a microwave field.