Mechanochemistry of Hexagonal Boron Nitride: 1. Destruction and Amorphization During Mechanical Treatment

The regularities of the mechanical activation of hexagonal boron nitride are analyzed using the X-ray diffraction, IR spectroscopy, transmission electron microscopy, dynamic light scattering, and adsorption methods. At the initial state of mechanical activation, the main process is material destruction. At this stage, the specific surface area increases to 400 m2/g and crystallographically oriented nanosized needles are formed. At the same time, boron nitride crystal structure is disordered with an increase in interplanar distance d(002). The disordering is assumed to be due to a shift along planes (001). At a specific dose of supplied mechanical energy above 6–8 kJ/g, the disordering processes dominate and the material is amorphized. At this stage, the specific surface area of samples decreases

Destruction, Amorphization and Reactivity of Nano-BN Under Ball Milling

The processes of mechanical activation of a hexagonal boron nitride (h-BN) and its reactivity upon interaction with hydrogen and water were investigated using X-ray, TEM, Microdiffraction, Dynamic Light Scattering, FTIR-spectroscopy, adsorption (BET). Initial h-BN samples were monocrystalline plates 70–80 nm thick. Mechanical treatment of h-BN is accompanied by plate splitting and formation of crystallographically oriented “rods.” The rod thickness gradually diminishes to less than 5 nm. Specific surface area of the rods (400 m2/g), is found to be equal to the outer geometrical surface of rods. As nanocrystallites form “c” parameter of h-BN increases. When nanocrystallites are less than several nanometers in size, mechanical treatment results in BN amorphization; in this case specific surface of the system begins to decrease. Splitting of BN plates in the atmosphere of hydrogen is accompanied by the material hydrogenation and formation of BH and NH bonds. The amount of adsorbed hydrogen corresponds to monolayer filling. The amorphous part of activated BN interacts with water even at room temperature

Mechanochemistry of Hexagonal Boron Nitride: 1. Destruction and Amorphization During Mechanical Treatment

The regularities of the mechanical activation of hexagonal boron nitride are analyzed using the X-ray diffraction, IR spectroscopy, transmission electron microscopy, dynamic light scattering, and adsorption methods. At the initial state of mechanical activation, the main process is material destruction. At this stage, the specific surface area increases to 400 m2/g and crystallographically oriented nanosized needles are formed. At the same time, boron nitride crystal structure is disordered with an increase in interplanar distance d(002). The disordering is assumed to be due to a shift along planes (001). At a specific dose of supplied mechanical energy above 6–8 kJ/g, the disordering processes dominate and the material is amorphized. At this stage, the specific surface area of samples decreases

Destruction, Amorphization and Reactivity of Nano-BN Under Ball Milling

The processes of mechanical activation of a hexagonal boron nitride (h-BN) and its reactivity upon interaction with hydrogen and water were investigated using X-ray, TEM, Microdiffraction, Dynamic Light Scattering, FTIR-spectroscopy, adsorption (BET). Initial h-BN samples were monocrystalline plates 70–80 nm thick. Mechanical treatment of h-BN is accompanied by plate splitting and formation of crystallographically oriented “rods.” The rod thickness gradually diminishes to less than 5 nm. Specific surface area of the rods (400 m2/g), is found to be equal to the outer geometrical surface of rods. As nanocrystallites form “c” parameter of h-BN increases. When nanocrystallites are less than several nanometers in size, mechanical treatment results in BN amorphization; in this case specific surface of the system begins to decrease. Splitting of BN plates in the atmosphere of hydrogen is accompanied by the material hydrogenation and formation of BH and NH bonds. The amount of adsorbed hydrogen corresponds to monolayer filling. The amorphous part of activated BN interacts with water even at room temperature