Cleavage Surface Energy of {100} Magnesium Oxide

Abstract

The modification of the Gilman cleavage technique described recently by Westwood and Hitch has been used to determine the surface energy γ0 of {100} MgO at 298°K. The value 1150±80 ergs/cm2 is in good agreement with previous experimental estimates of γ0, but somewhat lower than theoretical estimates. Metallographic studies were made of the plastic relaxation that occurs in the vicinity of the crack tip when cleavage cracks are repropagated, and a correlation between the extent of plastic relaxation, crack length, and the measured cleavage surface energy was observed.

First-principles calculation of Mg/MgO interfacial free energies

“…Surface energies σ Mg(0001) and σ MgO(100) under full relaxation of surface unit cells were obtained from σ=(E slab -nE bulk )/2S where E slab is the total energy of an n-layer slab at the ground state from DFT calculations, and the value of E bulk can be taken as the slope that is extracted by the straight line fitted to all of the values of total energies of the n-layer slabs versus n. S is the surface area of the unit cell. The value of σ Mg(0001) agrees well with experiment [38] and reported DFT calculations (with GGA) [41,44] while σ MgO(100) is ~10% lower than previous results [41,50,51] The ground state interfacial energy, work of separation and the corresponding strain energy of the two models with a (√3×1)/(2×1) supercell containing an Mg(0001)/MgO(100) interface and consisting of 5 layers of each component are obtained (see Table 4 Table 5. The strain energy contribution from the Mg(0001) component is found to increase linearly with the increase in the number of its atomic layers and the strain energy contribution from MgO(100) component remains almost invariant.…”

Error estimates for density-functional theory predictions of surface energy and work function

“…As an example, DFT-predicted work functions of ZrC{100} [88] and Cu 3 Pt{111} [89] are transformed using the regression results from Table I, provided with an error bar and compared to experimental results. The same comparison is made for the surface energy of MgO {100}, although the experimental data in this case originate from cleavage experiments [24,90,91]. The transformed DFT results and the corresponding experimental data are presented in Table III.…”

Growth of Co ultrathin films on MgO(001)

“…The surface energy g MgO of the MgO (1 0 0) planes has been measured by cleavage technique at 298 K equal to 1.15 J/m 2 and found to be independent of temperature [25].…”