Microhardness and dielectric properties of nanocrystalline magnesium phosphate

Nanocrystalline materials have attracted much attention due to their potential use as catalysts, sensors, ceramics and biomaterials. Materials with nanometer size have unusual electronic, magnetic, optical, and structural properties. Nanocrystalline magnesium phosphate (Mg2P2O7) of different grain sizes was prepared by changing the concentration of the reactants. The microhardness studies were carried out for different indentation loads for all the samples compacted under different pressures and their variations are plotted. Initially the hardness shows an increase with the load and then becomes practically independent of load. When the compacting pressure is gradually increased, the hardness also is seen to increase. The microhardness is further improved as the grain size of the sample is reduced. The dielectric properties of the prepared samples were analysed as a function of frequency and temperature. It is found that the dielectric constant (epsilon') and dielectric loss (tan delta) of all the samples decrease sharply as the frequency is increased and attains a constant low value at higher frequencies. The ac conductivity (sigma ac) has a low value at smaller frequencies, which increases as the frequency is increased. There is an upward shift in all these values as the temperature is raised and also when the grain size of the samples is reduced.