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Recently superconducting transition temperature of Tc~45K have been reported in rare-earth-doped Ca1-xRexFe2As2(Re=La,Ce,Nd,and Pr)[1] compounds,which is the highest Tc among 122-type iron-based superconductors.It is still unclear,however,about the nature of the superconducting state in this system since full volume fraction screening has never been observed in these samples.[2] The effects of doping of lanthanides to iron based compound may be attributed to at least two aspects,the structural distortion and the electronic doping.It is argued which effect is dominant to influence electronic distribution and inducing superconducting transition.We have studied the La-doped Ca1-xLaxFe2As2(x=0.2,0.3)superconductors using M(o)ssbauer spectroscopy and first principles calculations.It is found that the temperature dependences of the line width and the spectra area exhibit anomalies above the superconducting transition point and can be ascribed to the appearance of spin-phonon coupling.The coupling persists below the superconducting transition temperature even for the over-doped sample which suggests that it may play some role in inducing superconductivity of these materials.The distribution of the eQVzz,as shown in Fig.1,provides evidence of heterogeneous distribution of the La atoms.According to the theoretical calculations of the band structures and EFG of the Ca1-xLaxFe2As2(x=0.125,0.25,0.5)model systems,the Vzz experienced by iron nucleus changes from positive to negative with increasing doping level,which is ascribed to the change of the spatial distribution of Fe-3d electrons induced by the distortion of the FeAs tetrahedron.By analyzing Vzz within the spin-orbital model,we have determined the tetragonal splitting of the t2g orbitals to be 17(2)and 19(3)meV for x = 0.2 and 0.3,respectively.According to the temperature dependence of QSD,it is clear that the La-rich phase and the La-short phase separate spatially and it is the La-rich phase that undergoes superconducting transition with decreasing temperature.These results may help us in understanding the nature of the exotic superconductivity found in these materials.