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Based on the correlation between Raman shift and bond parameters, and further combined with experimental values of the Raman shift composition effect, the relationship between the composition and bond parameters of the 2D-M1−xM′xX2 and 2D-MX′2xX2(1−x) alloy materials was established. Numerical reproduction of the measurements clarified that the host atom phonons involved interaction with all of its z neighbors, whereas the doping atom phonon only involved interaction with a dimer. The doping of large atoms resulted in an elongation of the bond length, an increase in the equivalent coordination number, and enhancement of the binding energy. The doping of small atoms led to a contraction of the bond length, a decrease in the equivalent coordination number, and a weakening of binding energy. By quantifying the relationship between composition and bond parameters from Raman shifts, a deep understanding of two-dimensional alloy properties can be achieved. [ABSTRACT FROM AUTHOR]

It has long been puzzling regarding the trends and physical origins of the size-effect on the elasticity of ZnO nanostructures. An extension of the atomic “coordination-radius” correlation premise of Pauling and Goldschmidt to energy domain has enabled us to clarify that the elastic modulus is intrinsically proportional to the sum of bond energy per unit volume and that the size-induced elastic stiffening arises from (i) the broken-bond-induced local strain and skin-depth energy pinning and (ii) the tunable fraction of bonds between the undercoordinated atoms, and therefore, the elastic modulus of ZnO nanostructures should increase with the inverse of feature size. [ABSTRACT FROM AUTHOR]