0000000000749509
AUTHOR
S Wacke
Effect of the milling conditions on the degree of amorphization of selenium by milling in a planetary ball mill
The effect of the milling parameters (rotation speed of the milling device and duration of milling) on the phase composition of the products of milling of fully crystalline selenium has been investigated. The milling was conducted using a planetary micromill and the phase composition of the milling products was determined by differential thermal analysis. It has been found that ball milling leads to the partial amorphization of the starting crystalline material. The content of amorphous phase in the milling products depends, in a rather complicated way, on the milling parameters. At the milling parameters adopted in the present study, the milling product was never fully amorphous. The compl…
Investigation of the effect of intensive ball milling in a planetary ball mill on the thermal decomposition of cadmium carbonate and basic zinc carbonate
The kinetics of thermal decomposition of cadmium carbonate CdCO3 and basic zinc carbonate ZnCO3?nZn(OH)2 and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energies of thermal decomposition have been determined for both the compounds. Investigations of the thermal decomposition of the products of ball milling of investigated compounds revealed a slight effect of milling conditions on the reaction temperature and heat consumed during the thermal decomposition of ZnCO3?nZn(OH)2. No effect of ball milling on the thermal decomposition of CdCO3 has been found.
Structural phase transition in [(C2H5)4N][(CH3)4N]ZnCl4
The hybrid crystal [(C2H5)4N][(CH3)4N]ZnCl4 was studied using several experimental methods. DSC studies revealed the first order phase transition to the high temperature phase at about 496 K. This phase transition was confirmed in dielectric studies. Optical observation revealed the domain structure appearance characteristic for that of the phase transition between tetragonal and orthorhombic phases. This phase transition shows a lowering of symmetry as in the case of bromide analogs. Additionally, the optical studies showed the appearance of a number of cracks in the sample and in some cases, the samples became milky after cooling from the high temperature to the room temperature phase.
Relations between the cohesive energy, atomic volume, bulk modulus and sound velocity in metals
By analysing the experimental data available in the literature, it has been found that the bulk modulus B of metals is proportional to the cohesive energy density Ec/V. For metals which start to melt having the close packed structure A1 or A3 the proportionality factor in the forementioned correlation is distinctly greater than that for metals melting from the A2 type structure. The existence of the correlation between the bulk modulus and the cohesive energy density leads to another, hitherto unrevealed correlation between the sound velocity, cohesive energy and the molar mass of metals: u2 ~ Ec/μ.
Investigation of the effect of intensive milling in a planetary ball mill on the thermal decomposition of basic nickel carbonate
The kinetics of thermal decomposition of basic nickel carbonate NiCO3Ni?(OH)2?nH2O and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energy of thermal decomposition have been determined. Investigations of the thermal decomposition of the products of ball milling of investigated compound revealed a distinct effect of milling on the reaction temperature and heat consumed during the thermal decomposition of investigated compound.