Crystal structure of deuteride phase of Nd-Ni alloy by X-ray and neutron diffraction
Crystal structure of deuteride phase of Nd-Ni alloy by X-ray and neutron diffraction
复制标题
X射线和中子衍射分析Nd-Ni合金氘化物相的晶体结构
DOI：
10.1016/j.jallcom.2022.166557
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发表时间：
2022
影响因子：
6.2
通讯作者：
Kazuhiro Mori
中科院分区：
文献类型：
--
作者：
Kenji Iwase;Shuhei Ishida;Takashi Ueno;Kazuhiro Mori
目前工业上使用的吸氢合金会形成残余氢，这会降低合金的可逆氢容量，从而缩短其使用寿命。RNi 3金属间化合物具有PuNi 3型晶体结构，由MgZn 2型和CaCu 5型晶胞组成，其氢化性能表现出结构变化，一直是许多研究的焦点，但只有少数报道关注残余氢和合金结构之间的相互作用。因此，本研究旨在澄清在MgZn 2型和CaCu 5型电池的氢吸收-解吸过程中的残留氢占据机制。利用X射线衍射（XRD）和中子粉末衍射（NPD）研究了NdNi 3Dx的结构变化和氘占位。在氘吸收-解吸过程期间，对NdNi 3、NdNi 3D2.6、NdNi 3D3.2、NdNi 3D4.0和NdNi 3D4.8进行Rietveld精修。在248 K下，第一次吸氘量达到0.9 D/M，第一次解吸后，剩余氘量为0.7 D/M。对于NdNi3D2.6（II相），MgZn 2型和CaCu 5型电池的残余氘含量分别被确定为1.0D/M和0.4D/M。剩余氘在MgZn 2型电池中优先选择氘位点。在213 K时，第一次吸氘量为1.2 D/M，第一次解吸结束时，剩余氘量为1.0 D/M。在NdNi_3D_（4.0）和NdNi_3D_（4.8）的X射线衍射和中子衍射谱图中观察到的严重的峰展宽表明氘化相的金属亚晶格的变形超过0.8D/M。
The hydrogen-absorbing alloys currently used in industry form residual hydrogen that reduces the alloy’s reversible hydrogen capacity, decreasing its useful life. RNi3intermetallic compounds, which have a PuNi3-type crystal structure composed of MgZn2-type and CaCu5-type cells that exhibit structural change in relation to their hydrogenation properties, have been the focus of much research, but only a few of those reports focus on the interplay between residual hydrogen and alloy structure. Thus, this study seeks to clarify the residual hydrogen occupation mechanisms in MgZn2-type and CaCu5-type cells during the hydrogen absorption-desorption process. The structural changes and deuterium occupation in NdNi3Dxwere investigated using X-ray diffraction (XRD) and neutron powder diffraction (NPD). Rietveld refinement was performed for NdNi3, NdNi3D2.6, NdNi3D3.2, NdNi3D4.0, and NdNi3D4.8, during the deuterium absorption-desorption process. The deuterium capacity reached 0.9 D/M at the first absorption process and 0.7 D/M of residual deuterium was formed after the first desorption at 248 K. For NdNi3D2.6(phase II), the residual deuterium contents of MgZn2-type and CaCu5-type cells were determined to be 1.0 D/M and 0.4 D/M, respectively. The residual deuterium preferred the deuterium site in the MgZn2-type cell. The deuterium capacity was 1.2 D/M in the first absorption process at 213 K and the residual deuterium was 1.0 D/M at the end of the first desorption. The severe peak broadening observed in the XRD and neutron diffraction patterns of NdNi3D4.0and NdNi3D4.8indicate that the deformation of the metal sublattice of the deuteride phase was deformed over 0.8 D/M.