Stability and properties of the friendly environmental Zintl phases: Ca3Si4 and Ca14Si19. (15th February 2017)

• Record Type: Journal Article
• Authors: Moll, Adrien; Viennois, Romain; Hermet, Patrick; Haidoux, Abel; Bantignies, Jean-Louis; Beaudhuin, Mickaël
• Is Part Of: Acta materialia. Volume 125(2017)
• Page Start: 490
• Page End: 497
• Publication Date: 2017-02-15
• Subjects: Semiconductors -- Stability -- Raman spectroscopy -- Ab initio calculation -- Phase diagram; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2016.12.023
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: We report the synthesis, stability, lattice dynamics and electronic properties of two Zintl phases, Ca3 Si4 and Ca14 Si19, made of abundant and non-toxic elements in order to evaluate their potential applications. A simple two-step synthesis approach has permitted (i) to reach good purity of these two silicide phases and (ii) to reinvestigate their coexistence domain which permits to lift the uncertainty of the phase diagram within the 50–70 at. % Si region. Our first-principles calculations are able to well describe for the first time both the experimental vibrational properties studied by Raman spectroscopy and the energy bandgap determined by diffuse reflectance experiments. The two compounds are narrow-gap intrinsic semiconductors with indirect energy bandgaps about 0.56 eV and smaller than 0.1 eV for Ca3 Si4 and Ca14 Si19, respectively. Their Seebeck coefficient has been measured to 42 μV/K (Ca3 Si4 ) and −183 μV/K (Ca14 Si19 ) at room temperature which suggests their p - and n -type semiconducting behavior, respectively. Graphical abstract: Image 1