Insights into the composition exploration of novel hydrogen storage alloys: evaluation of the Mg–Ni–Nd–H phase diagram. Issue 8 (1st February 2017)

• Record Type: Journal Article
• Authors: Li, Qian; Luo, Qun; Gu, Qin-Fen
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 8(2017)
• Page Start: 3848
• Page End: 3864
• Publication Date: 2017-02-01
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta10090b
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : In order to provide an efficient tool to explore alloy composition and processing conditions for Mg-based alloys with good hydriding/dehydriding (H/D) properties, investigation of the Mg–Ni–Nd–H quaternary system was carried out by experimental measurements and CALPHAD thermodynamic analysis combined with first-principles calculations. Abstract : In order to provide an efficient tool to explore alloy composition and processing conditions for Mg-based alloys with good hydriding/dehydriding (H/D) properties, investigation of the Mg–Ni–Nd–H quaternary system was carried out by experimental measurements and CALPHAD thermodynamic analysis combined with first-principles calculations. A new stable compound Nd16 Mg96 Ni12 with the space group of Cmc 21 was identified in the Mg–Ni–Nd system by synchrotron powder X-ray diffraction (SR-PXRD). The phase equilibria and phase transformation related to Nd4 Mg80 Ni8, Nd16 Mg96 Ni12, NdMg5 Ni and NdMg2 Ni were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The formation enthalpies of these ternary compounds were calculated by the density functional theory. The existence of the quaternary hydrides NdMgNi4 H4 and NdMg2 Ni9 H12 was taken into consideration. Based on the obtained thermodynamic description of the Mg–Ni–Nd–H system, the hydrogen storage capacities and pressure–composition–temperature (P–C–T) curves were predicted and two new ternary compounds Nd4 Mg80 Ni8 and Nd16 Mg96 Ni12 were designed as hydrogen storage alloys with excellent properties. Meanwhile, the H/D mechanism of the Mg–Ni–Nd alloy was revealed.