Structure of La(Fe$_{0.88}$Si$_x$Al$_{0.12-x}$)$_{13}$ compounds in the paramagnetic state

X-ray diffraction patterns and nuclear gamma resonance spectra of La(Fe$_{0.88}$Si$_x$Al$_{0.12-x}$)$_{13}$ compounds in the paramagnetic state at room temperature have been investigated. It has been found that all samples have a cubic structure of the NaZn$_{13}$ type, in which Si and Al atoms disorderly substitute for iron in the crystallographic position 96$i$. An analysis of the Mössbauer spectra using the fitting with doublets with different quadrupole splittings has revealed that the distributions of the aluminum and silicon impurity atoms substituting for iron differ significantly. Aluminum is statistically distributed over nine positions of the 96$i$ type in the generalized coordination sphere of the Fe2 atom, whereas silicon predominantly substitutes for only six of the nine positions.