Synthesis and thermal behavior of nanoceramic material based on Bi13Fe5Ti6O39

The process of formation by the chemical coprecipitation method of nanoceramic material based on layered perovskite-like complex oxide Bi13Fe5Ti6O39 with the structure of the Aurivillius phase has been described. The temperatures of the onset of formation, the onset of decomposition, and activation of sintering, as well as the coefficient of linear thermal extension of the material, have been determined. Technological parameters for the synthesis of the material with a high yield of the target product and the ability to vary the crystallite size in the range of 70‒85 nm have been determined.

Structural evolution and synthesis mechanism of ytterbium disilicate powders prepared by cocurrent chemical coprecipitation method

Ytterbium disilicate powders were synthesized by cocurrent chemical coprecipitation method. The influence of Si/Yb molar ratio and calcination temperature on compositions and structures of Yb2Si2O7 products were investigated. The formation mechanism and thermal behavior of precursor as well as the phase evolution of Yb2Si2O7 were also discussed in depth. Results show that pure β-Yb2Si2O7 powders with nanoscale size can be obtained from the precursor with Si/Yb molar ratio of 1.1 after being calcinated at temperatures above 1200 ℃. The Yb2Si2O7 precursor is an amorphous polymer cross-linked with -[Si-O-Yb]- chain segments which are formed though Yb atoms embedding in the -[Si-O-Si]- network. After a continuous dihydroxylation and structural ordering, the amorphous precursor transformed to α-Yb2Si2O7 crystals by atomic rearrangement. Elevated calcination temperature can induce to the coordination structures and environment evolutions of structural units and then converted to stable (Si2O7) groups and (YbO6) polyhedrons, which results in the formation of β-Yb2Si2O7.

Combustion-Free Synthesis of Lithium Manganese Oxide Composites with CNTs/GNPs by Chemical Coprecipitation for Energy Storage Devices

Nano Spinel Lithium Manganese Oxide (LiMn2O4) was distributed properly on carbon nanotubes ( CNTs) and graphene nanoplatelets (GNPs) using chemical coprecipitation method. The original particle size was less than 40 nm, and the average size of the crystallite was 20 nm without the application of any capping agents. Characteristic spectra of spinel structure and a peak of CNTs & GNPs obtained using X-ray powder diffraction (XRD). CNTs and GNPs in energy storage systems improve the rate capabilities and cyclic efficiency of cathode materials. The suggested technique, chemical coprecipitation, provides new avenues for the production of nano-sized lithium transition metal oxide composites with CNTs and GNPs in an inexpensive and simple way. Higher density energy storage systems raise significant safety issues, and for safety, they are restricted to 30 percent to 50 percent of their ability. The proposed composite would enable the energy storage systems to be used even at high temperatures and higher discharge rates above 60 percent of their ability. Besides, the parasitic reaction between the electrode surface and the electrolyte will decrease, which will increase the battery's projected life span. As an all-solid-state device, the new composite batteries would make the system non-flammable, immune from side reactions, and resistant to capacity erosion.