A3GaHO4 (A=Ba, Sr): A new family of oxyhydrides with p-metal cation

R3-19-001-2.png
Illustration of synthesis and structure of A3GaHO4 (A=Ba, Sr)
The preparation process by solid-state reaction using metal oxide and metal hydride materials pressed and heated under 2GPa to obtain the gallium oxyhydrides with anti-perovskite type structure.

Hydride or negative ion of hydrogen has some special characteristics, such as its changeable size, and it can easily diffuse into the material. Introducing hydride in the structure can change the material properties. Some novel hydride-doped materials (e.g oxyhydrides) can have superconductivity, ionic conductivity, or other interesting electronic properties. The preparation of oxyhydrides with poor elemental selectivity is one of the challenges for material exploration. Synthesis of a new oxyhydrides containing p-metal cation, gallium, has been carried out in this study.

We have prepared a new series of gallium oxyhydrides A3GaHO4 (A=Ba, Sr) by high pressure and high-temperature solid-state reaction. Pressure played an essential role in stabilizing this material. It was obtained by pressing the raw materials under 2GPa following by heating under 900oC. The synthesis processes were held in an isolated system that assumed no atom or ion could escape from the system. Some characterizations such as neutron diffraction at MLF (Materials and Life Science Experimental Facility), J-Parc, synchrotron X-ray diffraction at SPring-8 have been performed to investigate the structure. To our knowledge, this is the first reported successful synthesis of gallium oxyhydrides. We proposed a layered structure with oxygen and hydride ordered in the structure. Further experiments will be performed to confirm their physical properties.

PERIOD OF STAY

Date of Departure: 08/04/2019
Date of Return: 06/03/2020

VISITING INSTITUTE or HOST

Institute for Molecular Science

Work and Achievement

The main purpose of this internship is to prepare oxyhydride material by solid-state reaction, especially reaction under high-pressure. I have learned some important aspects of oxyhydride synthesis under high-pressure using a diamond-type anvil. A new oxyhydride containing Gallium has been prepared. We proposed an anti-perovskite structure with the ordering of oxygen and hydride. We have performed several characterizations to reveal its properties, including neutron and X-ray diffraction, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy.

Nur Ika Puji Ayu, Department of Material Structure Science

学生の研究学生の研究