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Single crystalline titled phase is synthesized by conventional high-temperature solid-state synthesis. Crystal structure of Ni 3 GaSb is re-investigated by single-crystal X-ray diffraction and energy dispersive X-ray analysis. The compound crystallizes in P6 3 /mmc space group, the structure can be described as an intermediate of NiSb and Ni 2 In structures, similar to Ni 3 GaAs. Electronic structure of the compound is investigated by firstprinciples electronic structure calculations on the ordered model of Ni 3 GaSb. Stability and bond analysis was done by COHP calculations. Hetero-atomic NiÀ Sb and NiÀ Ga interactions play a major role towards to stability of the compound, these interactions are also responsible to modify the electronic structure of the titled compound. It was tested for catalytic activity and selectivity for acetylene hydrogenation reaction. Ni 3 GaSb was found to be a selective catalyst with 95.53 % C 2 H 2 conversion giving 60 % selectivity towards C 2 H 4 at 550°C.

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Complete substitution of Li atoms for Ag atoms in AgGaSe2 and AgInSe2 was achieved, resulting in the solid solutions Li x Ag1–x GaSe2 and Li x Ag1–x InSe2. The detailed crystal structures were determined by single-crystal X-ray diffraction and solid-state 7Li nuclear magnetic resonance spectroscopy, which confirm that Li atoms occupy unique sites and disorder only with Ag atoms. The tetragonal CuFeS2-type structure (space group I4̅2d) was retained within the entirety of the Ga-containing solid solution Li x Ag1–x GaSe2, which is noteworthy because the end-member LiGaSe2 normally adopts the orthorhombic β-NaFeO2-type structure (space group Pna21). These structures are closely related, being superstructures of the cubic sphalerite and hexagonal wurtzite prototypes adopted by diamond-like semiconductors. For the In-containing solid solution Li x Ag1–x InSe2, the structure transforms from the tetragonal to orthorhombic forms as the Li content increases past x = 0.50. The optical band gaps increase gradually with higher Li content, from 1.8 to 3.4 eV in Li x Ag1–x GaSe2 and from 1.2 to 2.5 eV in Li x Ag1–x InSe2, enabling control to desired values, while the second harmonic generation responses become stronger or are similar to those of benchmark infrared nonlinear optical materials such as AgGaS2. All members of these solid solutions remain congruently melting at accessible temperatures between 800 and 900 °C. Electronic structure calculations support the linear trends seen in the optical band gaps and confirm the mostly ionic character present in Li–Se bonds, in contrast to the more covalent character in Ga–Se or In–Se bonds.

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