Combined effect of chemical pressure and valence electron concentration through the electron-deficient Li substitution on the RE4LiGe4 (RE=La, Ce, Pr, and Sm) system

Experimental and theoretical investigations for site preference and anisotropic size change of RE11Ge4In6−xMx (RE=La, Ce; M=Li, Ge; x=1, 1.96)

“…After the annealing process, a furnace was tuned-off allowing the reactants were cooled down to room temperature naturally. Two reactions produced each title compound mixed with some La 4 LiGe 4 , La 2 InGe 2 and Ce 4 LiGe 4 [11,32], respectively, according to powder X-ray diffraction patterns. Both compounds became visibly moisture-and air-sensitive after one day.…”

“…There have been several examples, where the observed site preference of components was successfully explained by the QVAL value. They include the Gd 5-x Y x Ge 4 (0 ≤ x ≤ 5) system [25], the EuZn x In 4-x (x = 1.1~1.2) system [12], BaLi 1.09(1) In 0.91 Ge 2 [45], and the RE 4 LiGe 4 (RE = La, Ce, Pr and Sm) system [11]. Therefore, we attempted to evaluate the QVAL value for each atomic site in the parental compound Ho 11 Ge 10 [13] in order to estimate which Ge-site would be the most susceptible for the In substitution.…”

“…Atomic coordinates and equivalent isotropic displacement parameters (U eq a ) from single-crystal structure refinements for La 11 Ge 4 In 5.00(1) Li 1.00 and Ce 11 (7) 3.4115 (8) RE2 -a M 3.1787 (7) 3.1916 (7) RE3 -a M 3.6214 (7) 3.5182 (8) RE4 -a M 3.5345 (6) 3.4937 (6) …”

“…This type of compounds consists of the more electropositive components, such as alkali metals, alkaline-earth metals or rare-earth metals, combined with the more electronegative components found near the Zintl border-line in the Periodic Table. In particular, the more electronegative components can form the anionic structural framework that often conform to a simple electron counting rule, such as the Zintl-Klemm formalism [7][8][9], whereas the electropositive components donate valence electrons to the anionic framework and simply act like cations. Since such polar intermetallic compounds contain both cationic and anionic elements, these can be good platforms for elemental tuning to obtain particular chemical or physical properties [9][10][11][12].…”

Ce11Ge3.73(2)In6.27: Solid-state synthesis, crystal structure and site-preference

“…More specifically, we firstly performed a series of calculations for several structural models having different anionic arrangements in the 3-D framework to evaluate the total electronic energy of each model. After then, we attempted to provide rationales for the energetically most favorable structural model with a particular atomic site-preference by using the QVAL value criterion [11,17,18].…”