tailieunhanh - The effects of hydrostatic pressure on MBH4 (M = k, na) structures

In recent decades, a lot of efforts has been spent on investigation of metal borohydrides, which can potentially serve as advanced hydrogen storage materials for mobile applications. In this research, we investigate the structure changes under high pressure of the compounds MBH4 (M = K, Na) as important borohydrides in hydrogen technologies, using ABINIT simulation package based on density functional theory (DFT) and the generalized gradient approximation (GGA). The pressure is in a wide range of 0 GPa to 40 GPa. | Journal of Science and Technology 54 (1A) (2016) 323-329 THE EFFECTS OF HYDROSTATIC PRESSURE ON MBH4 (M = K, Na) STRUCTURES Do Phu Manh*, Le Tuan School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Str., Hanoi, Vietnam * Email: dophumanh@ Received: 17 September 2015; Accepted for publication: 20 October 2015 ABSTRACT In recent decades, a lot of efforts has been spent on investigation of metal borohydrides, which can potentially serve as advanced hydrogen storage materials for mobile applications. In this research, we investigate the structure changes under high pressure of the compounds MBH4 (M = K, Na) as important borohydrides in hydrogen technologies, using ABINIT simulation package based on density functional theory (DFT) and the generalized gradient approximation (GGA). The pressure is in a wide range of 0 GPa to 40 GPa. Structural analysis indicates the phase transformation in the examined range of pressure, which is evidenced by the interaction between metal cations and BH4-, interactive behavior of BH4 tetrahedron in the simulated cells, change of volume, distance between B and H ions, and enthalpy difference. Keywords: DFT, KBH4, NaBH4, pressure, phase. 1. INTRODUCTION Hydrogen, a popular element on the Earth, is an energy carrier that has great potential in future applications. Unlike traditional fossil energy sources (., oil, coal, etc.), hydrogen has a clean reaction with oxygen, which does not create products that cause the greenhouse effect. It also has a high performance ratio energy/mass. There are examples of current and future applications where hydrogen is used either in fuel cells to provide electricity for electric motors, or used in mobile combustion engines. In the last decade, research in the both of theoretical and experimental fields has been done in order to look for ideal hydrogen-containing structures. KBH4, NaBH4 are compounds that contain elements that are widely available in nature,