Manganese tetroxide (Mn₃O₄), also known as Trimanganese tetraoxide, is a black or brown tetragonal crystal. It is a spinel-like compound in which divalent and trivalent manganese ions are distributed in two different lattice positions. The relative density of manganese tetroxide is 4.856 and the melting point is about 1564°C. It is insoluble in water but can be soluble in hydrochloric acid and sulfuric acid. At temperatures below 1443K, it exhibits a twisted tetragonal spinel structure, and above this temperature it is a cubic spinel structure.

Uses of manganese tetroxide:

1. Electronic Materials: Manganese tetroxide is used in the production of soft magnetic materials, which are used in electronic devices to make inductors, transformers, and other magnetic components. It is also used in the production of semiconductor electronic materials.

2. Battery Material: It is an important raw material for the manufacture of lithium-ion batteries, especially in the production of lithium manganese oxide batteries and lithium iron manganese phosphate battery materials. These batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems.

3. Ceramics and glass manufacturing: Manganese tetroxide is used as a raw material for ceramics and glass, especially in the production of specific types of glass, it can be used as an additive to change the properties of glass.

4. Catalyst: In some chemical reactions, manganese tetroxide can be used as a catalyst to promote the reaction rate.

5. Pigments and dyes: It is also used as an ingredient in certain pigments and is used to color products.

6. Thermistor: Manganese tetroxide is used in the manufacture of thermistors, the resistance value of this resistor changes with temperature, and is used for temperature control and measurement.

7. Other Applications: including as a weight gainer in oil drilling muds, and as an additive in certain metal smelting processes, etc.