Reversible Control of the Mn Oxidation State in SrTiO3 Bulk Powders
Reversible Control of the Mn Oxidation State in SrTiO3 Bulk Powders
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DOI：
10.3389/fchem.2019.00353
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发表时间：
2019-05-22
影响因子：
5.5
通讯作者：
Kittilstved, Kevin R.
中科院分区：
文献类型：
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作者：
Mansoor, Haneen;Harrigan, William L.;Kittilstved, Kevin R.
我们展示了一种低温还原方法，用于表现出精细控制钛酸锶（SrTiO 3）散装粉末中的替代Mn离子的氧化态。我们采用NaBH 4作为化学还原剂，其在晶格还原可忽略的温度< 350 ℃下引起氧化态和氧空位与Mn 2+掺杂剂络合的显著变化。在较高的还原温度下，我们还观察到形成的Ti 3+的晶格漫反射和低温电子顺磁共振（EPR）光谱。除了Mn 2+，Mn 4+，和Mn 2+与氧空位的配合物，我们还观察到一个尖锐的共振重还原Mn掺杂SrTiO 3的EPR谱。这种尖锐的信号被暂时分配到表面的超氧离子，形成的表面电子转移反应之间的Ti 3+和O-2。控制SrTiO 3中各种顺磁缺陷的相对量的能力提供了许多可能性，以在模型系统中研究可调掺杂剂-缺陷相互作用对基于自旋的电子应用或可见光电子学的影响。
We demonstrate a low-temperature reduction method for exhibiting fine control over the oxidation state of substitutional Mn ions in strontium titanate (SrTiO3) bulk powder. We employ NaBH4 as the chemical reductant that causes significant changes in the oxidation state and oxygen vacancy complexation with Mn2+ dopants at temperatures < 350 degrees C where lattice reduction is negligible. At higher reduction temperatures, we also observe the formation of Ti3+ in the lattice by diffuse-reflectance and low-temperature electron paramagnetic resonance (EPR) spectroscopy. In addition to Mn2+, Mn4+, and the Mn2+ complex with an oxygen vacancy, we also observe a sharp resonance in the EPR spectrum of heavily reduced Mn-doped SrTiO3. This sharp signal is tentatively assigned to surface superoxide ion that is formed by the surface electron transfer reaction between Ti3+ and O-2. The ability to control the relative amounts of various paramagnetic defects in SrTiO3 provides many possibilities to study in a model system the impact of tunable dopant-defect interactions for spin-based electronic applications or visible-light photocatalysis.