Barium titanate is a typical perovskite-type crystal with high dielectric constant, low dielectric loss, large resistivity, high withstand voltage, and excellent insulation properties. It is widely used in multilayer ceramic capacitors. (MLCC), thermistor (PTCR), electro-optical device and dynamic random access memory (FRAM), etc., are the basic raw materials of electronic functional ceramic devices, so they have been called the backbone of the electronic ceramic industry by scholars and manufacturers.
1. Barium titanate for multilayer ceramic capacitors (MLCC)
Multilayer ceramic capacitors, also known as monolithic capacitors, are the most widely used chip electronic components in the world today. They have large capacitance, small dimensions, and good sealing characteristics. MLCC as a basic electronic component has been widely used in mobile communication, home appliances, automotive electronics, aviation and military industries.
Multilayer Ceramic Capacitors (MLCC)
Mass production of MLCCs made from barium titanate has begun in the 1950s. MLCC uses electronic ceramic material as the dielectric. The prepared ceramic paste is prepared by screen printing or casting to produce a thick ceramic dielectric film. Then, internal electrodes are printed on the thick dielectric film, and the thick ceramic film is printed. Alternately staggered and hot isostatically pressed to form a plurality of thick film capacitors in parallel, and then sintered to coat the external electrode paste to obtain a multilayer ceramic capacitor.
In recent years, with the development of miniaturization of electronic devices, the thickness of dielectric layers of MLCCs has been continuously reduced and the number of dielectric layers has been continuously increased. MLCCs containing more than 500 layers and each layer thickness of 2 μm have been developed. The rapid development of MLCC will inevitably lead to higher market requirements for its raw materials. Among them, barium titanate powder is one of the basic raw materials for preparing MLCC, and its market share is about 60% -70%. Body improvement is particularly important. In order to prepare thinner and better dielectric layers, the preparation method of high-purity nano-scale monodispersed barium titanate powder has become a focus of attention at home and abroad.
2. Barium titanate for positive temperature coefficient thermistor (PTCR)
Thermistor devices with positive temperature coefficients are widely used in almost all engineering fields. The PTC thermistor is usually made of barium titanate ceramic material. It has ferroelectric semiconductor barium titanate. When the temperature reaches the Curie point Tc, it changes from a tetragonal phase to a cubic phase. Orders of magnitude (103-107 times), PTCR is based on this feature. One of the important applications of PTCR made of semiconductor barium titanate ceramics is as the detection and controller of temperature or temperature-related parameters.
3.Barium titanate is used in other special ceramics
Piezoelectric properties refer to the properties of the polarization state of the crystal with the applied stress, including positive piezoelectric effect and reverse piezoelectric effect. Based on the good piezoelectric properties of barium titanate, it is mainly used in sound sensors, ultrasonic motors, medical imaging, electronic igniters, buzzers, etc.
Piezoelectric effect of barium titanate
Ferroelectricity refers to the property that a crystal can undergo spontaneous polarization, and the direction of spontaneous polarization changes with the direction of the applied electric field. Based on the good ferroelectric properties of barium titanate, it can be used in ferroelectric random access memory (FRAM), ferroelectric field effect transistor (FFET), ferroelectric dynamic random access memory (FDRAM) and other aspects.