With the continuous consumption of non-renewable energy and the increasingly serious environmental problems, the development and use of high-performance, environmentally friendly energy storage materials has become a research hotspot in the current technology and industry. Due to its advantages of high power density, fast charge and discharge speed, excellent stability and low manufacturing cost, dielectric energy storage capacitors have shown great application prospects in the fields of automotive electronics, communications, aviation, aerospace and cutting-edge technology.
In recent years, the team of Dong Xianlin of the Shanghai Institute of Ceramics of the Chinese Academy of Sciences has carried out research work on new lead-free dielectric materials for energy storage capacitors, and has achieved a series of research results. The team designed and synthesized a new type of high-performance BaTiO3-based relaxed ferroelectric (BaTiO3-Bi (Zn1 / 2Sn1 / 2) O3) energy storage dielectric material with barium titanate (BaTiO3) as the matrix. By introducing Bi (Zn1 / 2Sn1 / 2) O3 into the BaTiO3 matrix, the A-site and B-site ions are disordered, which destroys the long-range order of ferroelectricity and transforms the ferroelectric domains into polar nano-domains. The rapid response of polar nano-domains under an applied electric field significantly improves the energy storage density and energy storage efficiency of the material. This dielectric material not only has high energy storage density (2.41 J / cm3) and high energy storage efficiency (91.6%), but also its energy storage characteristics show excellent temperature (20 ~ 160 â„ƒ), frequency (1 ~ 1000Hz) And fatigue (105 cycles) stability, can meet the requirements of X8R capacitors. Related studies have clarified that the high stability of the energy storage characteristics comes from the "weak coupling relaxation behavior" of polar nano-domains. This work was published in the Journal of Materials Chemistry C (J. Mater. Chem. C, 2018, 6, 8528-8537) in the form of Hot Paper.
Miniaturization and light weight have always been important development trends for energy storage capacitors. To this end, the team focused on the sodium niobate (NaNbO3) system that has not been reported in the literature. The volume density of NaNbO3 is only 4.55g / cm3, compared with other lead-free dielectric material systems such as bismuth ferrite (8.37g / cm3), barium titanate (6.02g / cm3), sodium bismuth titanate (5.977g / cm3), etc. , It has obvious advantages in the lightweight of energy storage capacitors. However, the metastable ferroelectricity induced by the electric field and the low electrical strength caused by the volatilization of alkali sodium restrict the application of NaNbO3 in energy storage. The team has adopted paraelectric regulation and A-site vacancy strategies to enhance the energy storage characteristics of NaNbO3, and constructed two new types of NaNbO3-based energy storage dielectric ceramic materials: NaNbO3-SrTiO3 and Na1-3xBixNbO3. Both of these NaNbO3 based energy storage dielectric ceramic materials exhibit excellent energy storage characteristics, charge and discharge characteristics and stability, of which the comprehensive energy storage characteristics of Na1-3xBixNbO3 (energy storage density: 4.03J / cm3, energy storage efficiency: 85.4%, power density: 62.5 MW / cm3) is the best value reported in the literature. This work opens up new application directions for NaNbO3 materials, and also provides new methods and ideas for designing high-energy storage lead-free dielectric materials. Related research results were published in Journal of Materials Chemistry A (J. Mater. Chem. A, 2018, 6, 17896-17904) and ACS Sustainable Chemistry & Engineering (ACS Sustainable Chem. Eng. 2018, 6, 10, 12755-12765) on.
The first authors of the above series of research papers are PhD students Zhou Mingxing, and the co-corresponding authors of the paper are researchers Dong Xianlin and Liang Ruihong.
Energy storage and charge-discharge characteristics of a novel barium titanate-based relaxed ferroelectric
Comparison chart of bulk density of several typical lead-free dielectric material systems (left) and comparison chart of comprehensive energy storage characteristics of Na1-3xBixNbO3 and literature (right)
In the old days, if you were hanging dry wall you'd have to drive 6,000 drywall nails a day to attach 3,000 square feet of drywall.
That's the old way. Luckily, we now have specialized power tools to make working with drywall much, much easier.
A drywall screw gun is similar to a drill, but is designed just for driving screws into drywall (Source).
How do they work?
The screw gun utilizes clutches, which when pressure is applied to the bit, engages these clutches. Once pressure is released, so too do the clutches. Most guns allow users to set the depth at which they want the screw to sink into the drywall (Source).
When choosing a screw gun, users have two main choices: Corded and cordless. Many users swear by the corded drills because, although not as convenient, you don`t have to worry about running out of a charge halfway through a job. As with all screw guns, being able to quickly and easily alter the depth is important, so look for that feature as well (Source).
The DeWalt DCF620B is our favorite cordless model, while its corded compatriot, the DeWalt DW255 is our favorite corded- based on the user feedback we've analyzed.
Hand Tool Nailer,Concrete Eye Pins,Nail Gun Accessories,Self Tapping Screw Wood Fasteners
Yibin Heheng Technology Co.,Ltd , https://www.chinadirectfastening.com