Study On The Electronic Structure Of Alkaline Earth Metal Electrides

Electride is an ionic compound in which interstitial electrons serve as anions.Anion electrons make the electrides have high mobility,low work function and other characteristics,and have broad application prospects in the fields of catalysis,metal ion batteries,OLEDs,etc.The thesis studies two kinds of alkaline earth metal electride.First,the electronic structure properties of the alkaline earth metal compound Ba₂Ni₃ are systematically analyzed through theoretical calculations.The research results show that Ba₂Ni₃ is an electride with a layered structure.There is an interstitial electronic state as an anion in the Ba₆ octahedral coordination center between the layers.This periodic electronic anion electron forms an anion electronic energy band near the Fermi surface.The chemical formula can be expressed as[Ba²⁺₂Ni^-₃]+·e^-.The charge analysis results prove that the nickel element in Ba₂Ni₃ is negative.In addition,the research results also show that Ba₂Ni₃ has a lower work function（2.4 eV）,which is close to the early discovered low work function electride C12A7:e-,so it has important applications prospect.At the same time,we also conducted a systematic study on the electronic structure,work function,mechanical properties,elasticity and optical properties of the alkaline earth metal electride Ca₃Pb.The research results show that Ca₃Pb with inverse perovskite structure has anion electrons in the Ca₆ octahedral coordination center,and periodic anion electrons form additional energy bands near the Fermi level.Its chemical formula can be expressed as [Ca²⁺₃Pb^4-]²⁺·2e^-.Ca₃Pb also has the characteristics of low work function of alkaline earth metals.Calculations of elastic properties show that Ca₃Pb has strong brittleness.According to the results of optical properties,the absorption spectrum of surface Ca₃Pb mainly comes from the continuous transition between Pb-6p and Ca-3d energy bands.In summary,the two alkaline earth metal electrides Ba₂Ni₃ and Ca₃Pb we studied all have the typical characteristics of electrides,and their anion electrons all come from the contribution of s electrons outside the alkaline earth metal nucleus.Both materials have lower work functions.These research results will further stimulate researchers to conduct in-depth research on electride materials.