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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Coordination environment evolution of Eu~(3+) during the dehydration and re-crystallization processes of Sm_(1-x)Eu_x[B_9O_(13)(OH)_4]·H_2O by photoluminescent characteristics
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Coordination environment evolution of Eu~(3+) during the dehydration and re-crystallization processes of Sm_(1-x)Eu_x[B_9O_(13)(OH)_4]·H_2O by photoluminescent characteristics

机译：Sm_（1-x）Eu_x [B_9O_（13）（OH）_4]·H_2O的脱水和重结晶过程中Eu〜（3+）配位环境演化的光致发光特性

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摘要

There are limited photoluminescence (PL) studies for rare earth borates with crystalline water molecules, which are usually supposed to have low PL efficiency because the vibrations of H_2O or -OH may lead to emission quenching. We investigated the PL properties of Sm_(1-x)Eu_x[B_9O_(13)(OH)_4]·H_2O (x = 0-1.00) and their dehydrated products α-Sm_(1-x)Eu_xB5O9. There is no quenching effect in those studied polyborates because the large borate ionic groups isolate the Eu 3+ activators very well. Sm~(3+) and Eu~(3+) are basically separated luminescent activators. Comparatively, Sm~(3+) shows a very small emission intensity, which can be almost ignored, therefore our interest is focused on the Eu~(3+) luminescence. By TG-DSC and powder XRD experiments, we defined three weight-loss steps for Eu[B_9O_(13)(OH)_4]·H_2O and a re-crystallization process to α-EuB_5O_9, during which luminescent spectra of Eu~(3+) are recorded. It shows an interesting variety and therefore is a good medium to understand the coordination environment evolution of Eu~(3+), even for the intermediate amorphous phase. In fact, the coordination symmetry of Eu~(3+) in the amorphous state is the lowest. The high efficiency of the f-f transitions and large R/O value (3.8) imply this amorphous phase is potentially a good red-emitting UV-LED phosphor. Anhydrous α-EuB_5O_9 shows the highest luminescent efficiency excited by Eu~(3+) CT transition. In addition, α-Sm 1-xEuxB5O9 was synthesized by a sol-gel method directly for the first time, and α-EuB_5O_9 shows superior PL properties due to its better crystallinity. A lot of hydrated polyborates with crystalline water molecules remain unexplored and our study shows their potential as good phosphors.
机译：对于具有结晶水分子的稀土硼酸盐，仅有有限的光致发光（PL）研究，由于H_2O或-OH的振动可能导致发射猝灭，因此通常认为PL效率较低。我们研究了Sm_（1-x）Eu_x [B_9O_（13）（OH）_4]·H_2O（x = 0-1.00）及其脱水产物α-Sm_（1-x）Eu_xB5O9的PL性质。在那些研究的多硼酸盐中没有淬灭作用，因为大的硼酸盐离子基团很好地隔离了Eu 3+活化剂。 Sm〜（3+）和Eu〜（3+）基本是分离的发光活化剂。相比之下，Sm〜（3+）的发射强度很小，几乎可以忽略不计，因此我们的兴趣集中在Eu〜（3+）发光上。通过TG-DSC和粉末XRD实验，我们定义了Eu [B_9O_（13）（OH）_4]·H_2O的三个失重步骤和重结晶为α-EuB_5O_9的过程，在此期间Eu〜（3 +）被记录。它显示了一个有趣的变化，因此，即使对于中间非晶相，它也是了解Eu〜（3+）配位环境演变的一个很好的媒介。实际上，非晶态的Eu〜（3+）的配位对称性最低。 f-f转换的高效率和大的R / O值（3.8）暗示该非晶相可能是良好的发红光的UV-LED荧光粉。无水α-EuB_5O_9表现出由Eu〜（3+）CT跃迁激发的最高发光效率。另外，α-Sm1-xEuxB5O9首次直接通过溶胶-凝胶法合成，而α-EuB_5O_9由于具有更好的结晶性而显示出优异的PL特性。许多带有结晶水分子的水合多硼酸盐尚未开发，我们的研究表明它们具有良好的荧光粉潜力。

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