Biography:

One of their most recent publications is Study of segregation coefficient of cationic impurities in ammonium oxalate monohydrate crystals during growth from aqueous solutions. Which was published in journal Journal of Crystal Growth.

More information about K Sangwal research including statistics on their citations can be found on their Copernicus Academic profile page.

K Sangwal's Articles: (3)

Study of segregation coefficient of cationic impurities in ammonium oxalate monohydrate crystals during growth from aqueous solutions

AbstractThe segregation coefficient keff of Cu(II), Fe(III) and Cr(III) ions in ammonium oxalate monohydrate single crystals during growth from aqueous solutions at a constant temperature was investigated as a function of solution supersaturation σ and impurity concentration ci. It was observed that: (1) irrespective of the impurity concentration, there is a threshold supersaturation of about 0.03 above which Cr(III) is captured in the crystals but there is no threshold supersaturation in the case of Cu(II) and Fe(III) ions, (2) above the threshold supersaturation, keff increases with increasing σ and decreasing ci, and (3) at a given σeff and ci,keff decreases in the sequence: keff[Cu(II)] ⪢keff[Fe(III)] >keff[Cr(III)]. The dependence of effective segregation coefficient keff on supersaturation and impurity concentration is in agreement with the predictions of the model involving surface coverage due to impurity adsorption and dependence of accumulation and depletion of solvated host molecules at kinks of steps on the F faces of crystals on supersaturation [J. Crystal Growth 212 (2000) 522]. Analysis of the effective segregation coefficient keff of different impurities suggests that the dehydration energies of cations mainly determine the capability of capture of impurity species by the growing crystal.

In situ study of the recovery of nanoindentation deformation of the (100) face of MgO crystals by atomic force microscopy

AbstractResults are described and discussed of an in situ atomic force microscopy study on the evolution of the surface morphology around indentations made on the (100) cleavage face of MgO crystals by square pyramidal silicon tips for loads up to 10 μN. It was found that: (1) nanoindentation does not introduce plastic deformation on the surface; (2) an indented surface always tends to heal with time but the time t of healing increases with penetration depth d (i.e., with applied load); (3) for indentations with d

Relationship between indentation size effect and material properties in the microhardness measurement of some cobalt-based alloys

AbstractThe load dependence of the Vickers microhardness of some cobalt-based alloys subjected to heat treatment at different temperatures for various durations, investigated using Hanemann’s method and a PMT-3 hardness tester, has been discussed. The experimental results show that: (1) the indentation size effect is best revealed by the proportional specimen resistance model of Li and Bradt, and (2) the plot of the ratio of indentation load P to indentation diagonal d against d for a sample exhibits two different slopes b with a transition in the slopes occurring at an indentation diagonal d lying between 9 and 20 μm. Analysis of the results revealed that: (1) the origin of indentation size effect is associated with the processes of relaxation of indentation stresses, (2) the load-dependent quantity a and load-independent quantity b for cobalt-based alloys are intimately connected with the grain size and defect structure of the alloys, and the grain-size dependence of their microhardness qualitatively agrees with the modified Hall–Petch relation, (3) in the range of high indentation loads the microhardness of cobalt-based alloys, as determined by using the proportional specimen resistance model, is practically independent of the applied load, and (4) the origin of a critical indentation diagonal dc*≈15 μm, when a change in the slope of the plot of a against b occurs, is associated with the value of indentation diagonal d when frictional resistance begins to contribute to the values of a.

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