Gurieva Galina, Niedenzu Sara, Siminel Nikita, Franz Alexandra, Schorr Susan
Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany.
Freie Universität Berlin, Institute of Geological Sciences, 12249 Berlin, Germany.
Faraday Discuss. 2022 Oct 28;239(0):51-69. doi: 10.1039/d2fd00042c.
The solid solution series between CuZnSnSe, crystallizing in the kesterite type structure, and CuMnSnSe, adopting the stannite type structure, Cu(ZnMn)SnSe, was studied by a combination of neutron and X-ray powder diffraction. Powder samples with 0 ≤ ≤ 1 were synthesized by the solid state reaction of the pure elements and it was confirmed by wavelength-dispersive X-ray spectroscopy that each contained a homogeneous, off-stoichiometric quaternary phase. The lattice parameters and cation site occupancy factors were determined simultaneously by the Rietveld analysis of the neutron and X-ray powder diffraction data. The refined site occupancy factors were used to determine the average neutron scattering length of the cation sites in the crystal structure of the Cu(ZnMn)SnSe mixed crystals, from which a cation distribution model was derived. For the end member CuZnSnSe, the disordered kesterite structure was confirmed and for CuMnSnSe, the stannite structure was confirmed. The cross-over from the kesterite to stannite type structure by Zn ↔ Mn substitution in the CuZnMnSnSe solid solution can be seen as a cation re-distribution process among the positions (0, 0, 0), (0, ½, ¼) and (0, ¼, ¾), including Cu, Zn and Mn. The Sn cation does not take part in this process and remains on the 2b site. Moreover, the cross-over is also visible in the ratio of the lattice parameters /(2), showing a characteristic dependence on the chemical composition. The order parameter , the quantitative measure of Cu/B disorder (B = Zn and Mn), shows a distinct dependence on the Mn/(Mn + Zn) ratio. In Zn-rich Cu(ZnMn)SnSe mixed crystals, the order parameter ∼ 0.7 and drops to ∼ 0 (complete Cu/B disorder) in the compositional region 0.3 ≥ ≥ 0.7. In Mn-rich Cu(ZnMn)SnSe mixed crystals, adopting the stannite type structure, the order parameter reaches almost ∼ 1 (order). Thus, it can be concluded that only Mn-rich Cu(ZnMn)SnSe mixed crystals do not show Cu/B disorder. A similar trend of the dependence on the chemical composition of both Cu/B-disorder and the band gap energy in Cu(ZnMn)SnSe mixed crystals was observed.
通过中子和X射线粉末衍射相结合的方法，对以纤锌矿型结构结晶的CuZnSnSe与采用黄锡矿型结构的CuMnSnSe之间的固溶体系列Cu(ZnMn)SnSe进行了研究。通过纯元素的固态反应合成了0≤≤1的粉末样品，波长色散X射线光谱证实每个样品都含有均匀的、非化学计量的四元相。通过对中子和X射线粉末衍射数据进行Rietveld分析，同时确定了晶格参数和阳离子占位因子。利用精修的占位因子确定了Cu(ZnMn)SnSe混合晶体晶体结构中阳离子位点的平均中子散射长度，由此推导了阳离子分布模型。对于端元CuZnSnSe，证实了无序的纤锌矿结构，对于CuMnSnSe，证实了黄锡矿结构。在CuZnMnSnSe固溶体中，通过Zn↔Mn取代从纤锌矿型结构到黄锡矿型结构的转变可视为包括Cu、Zn和Mn在内的阳离子在(0, 0, 0)、(0, ½, ¼)和(0, ¼, ¾)位置之间的重新分布过程。Sn阳离子不参与此过程，仍位于2b位点。此外，在晶格参数/(2)的比值中也可见到这种转变，表现出对化学成分的特征依赖性。有序参数，即Cu/B无序（B = Zn和Mn）的定量度量，对Mn/(Mn + Zn)比值表现出明显的依赖性。在富Zn的Cu(ZnMn)SnSe混合晶体中，有序参数0.7，在0.3≥≥0.7的成分区域降至0（完全Cu/B无序）。在采用黄锡矿型结构的富Mn的Cu(ZnMn)SnSe混合晶体中，有序参数几乎达到~1（有序）。因此，可以得出结论，只有富Mn的Cu(ZnMn)SnSe混合晶体不显示Cu/B无序。在Cu(ZnMn)SnSe混合晶体中，观察到了Cu/B无序和带隙能量对化学成分的类似依赖趋势。
