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Multicomponent equiatomic rare earth oxides with a narrow band gap and associated praseodymium multivalency
Dalton Transactions ( IF 3.5 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1039/c7dt02077e Abhishek Sarkar 1, 2, 3, 4, 5 , Christoph Loho 4, 5, 6 , Leonardo Velasco 1, 2, 3, 4 , Tiju Thomas 7, 8, 9, 10 , Subramshu S. Bhattacharya 7, 8, 9, 10 , Horst Hahn 1, 2, 3, 4, 5 , Ruzica Djenadic 4, 5, 6, 11, 12
Dalton Transactions ( IF 3.5 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1039/c7dt02077e Abhishek Sarkar 1, 2, 3, 4, 5 , Christoph Loho 4, 5, 6 , Leonardo Velasco 1, 2, 3, 4 , Tiju Thomas 7, 8, 9, 10 , Subramshu S. Bhattacharya 7, 8, 9, 10 , Horst Hahn 1, 2, 3, 4, 5 , Ruzica Djenadic 4, 5, 6, 11, 12
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New multicomponent equiatomic rare earth oxides (ME-REOs) containing 3–7 rare earth elements (Ce, Gd, La, Nd, Pr, Sm and Y) in equiatomic proportions are synthesized using nebulized spray pyrolysis. All the systems crystallized as a phase pure fluorite type (Fm![[3 with combining macron]](http://www.rsc.org/images/entities/char_0033_0304.gif)
m) structure in spite of the high chemical complexity. A nominal increase in the lattice parameter compared to CeO2 is observed in all ME-REOs. X-ray photoelectron spectroscopy performed on the ME-REOs confirmed that all the constituent rare earth elements are present in the 3+ oxidation state, except for Ce and Pr which are present in 4+ and in a mixed (3+/4+) oxidation state, respectively. The presence of Ce4+ contributes substantially to the observed stability of the single phase structure. These new oxide systems have narrow direct band gaps in the range of 1.95–2.14 eV and indirect band gaps in the range of 1.40–1.64 eV, enabling light absorption over the entire visible spectral range. Furthermore, the oxygen vacancy concentration rapidly increases and then saturates with the number of rare earth elements that are incorporated into the ME-REOs. The lowering of the band gap is found to be closely related to the presence of multivalent Pr. Interestingly, the band gap values are relatively invariant with respect to the composition or thermal treatments. Considering the high level of oxygen vacancies present and the observed low band gap values, these new material systems can be of importance where the presence of oxygen vacancies is essential or in applications where a narrow band gap is desirable.
中文翻译：
带隙窄的多组分等原子稀土氧化物及相关的multi多价
使用雾化喷雾热解法合成了等原子比例的包含3-7种稀土元素（Ce，Gd，La，Nd，Pr，Sm和Y）的新型多组分等原子稀土氧化物（ME-REO）。尽管化学复杂性高，但所有系统均结晶为相纯的萤石型（Fmm）结构。在所有ME-REO中，与CeO 2相比，晶格参数的名义增加。在ME-REO上进行的X射线光电子能谱证实，除Ce和Pr分别以4+和混合（3 + / 4 +）的形式存在外，所有构成的稀土元素均以3+氧化态存在。分别处于氧化态。Ce 4+的存在基本上有助于观察到的单相结构的稳定性。这些新的氧化物系统具有在1.95–2.14 eV范围内的窄直接带隙和在1.40–1.64 eV范围内的间接带隙，从而可以在整个可见光谱范围内吸收光。此外，氧空位浓度迅速增加，然后随着掺入ME-REO中的稀土元素的数量而饱和。发现带隙的降低与多价Pr的存在密切相关。有趣的是，带隙值相对于组成或热处理相对不变。考虑到目前存在的高氧空位和观察到的低带隙值，
更新日期：2017-09-20
m) structure in spite of the high chemical complexity. A nominal increase in the lattice parameter compared to CeO2 is observed in all ME-REOs. X-ray photoelectron spectroscopy performed on the ME-REOs confirmed that all the constituent rare earth elements are present in the 3+ oxidation state, except for Ce and Pr which are present in 4+ and in a mixed (3+/4+) oxidation state, respectively. The presence of Ce4+ contributes substantially to the observed stability of the single phase structure. These new oxide systems have narrow direct band gaps in the range of 1.95–2.14 eV and indirect band gaps in the range of 1.40–1.64 eV, enabling light absorption over the entire visible spectral range. Furthermore, the oxygen vacancy concentration rapidly increases and then saturates with the number of rare earth elements that are incorporated into the ME-REOs. The lowering of the band gap is found to be closely related to the presence of multivalent Pr. Interestingly, the band gap values are relatively invariant with respect to the composition or thermal treatments. Considering the high level of oxygen vacancies present and the observed low band gap values, these new material systems can be of importance where the presence of oxygen vacancies is essential or in applications where a narrow band gap is desirable.
中文翻译：
带隙窄的多组分等原子稀土氧化物及相关的multi多价
使用雾化喷雾热解法合成了等原子比例的包含3-7种稀土元素（Ce，Gd，La，Nd，Pr，Sm和Y）的新型多组分等原子稀土氧化物（ME-REO）。尽管化学复杂性高，但所有系统均结晶为相纯的萤石型（Fm
m）结构。在所有ME-REO中，与CeO 2相比，晶格参数的名义增加。在ME-REO上进行的X射线光电子能谱证实，除Ce和Pr分别以4+和混合（3 + / 4 +）的形式存在外，所有构成的稀土元素均以3+氧化态存在。分别处于氧化态。Ce 4+的存在基本上有助于观察到的单相结构的稳定性。这些新的氧化物系统具有在1.95–2.14 eV范围内的窄直接带隙和在1.40–1.64 eV范围内的间接带隙，从而可以在整个可见光谱范围内吸收光。此外，氧空位浓度迅速增加，然后随着掺入ME-REO中的稀土元素的数量而饱和。发现带隙的降低与多价Pr的存在密切相关。有趣的是，带隙值相对于组成或热处理相对不变。考虑到目前存在的高氧空位和观察到的低带隙值，
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