Recoverable and Unrecoverable Bi3+-Related Photoemissions Induced by Thermal Expansion and Contraction in LuVO4:Bi3+ and ScVO4:Bi3+ Compounds
Recoverable and Unrecoverable Bi3+-Related Photoemissions Induced by Thermal Expansion and Contraction in LuVO4:Bi3+ and ScVO4:Bi3+ Compounds
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DOI：
10.1021/acs.chemmater.6b03062
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发表时间：
2016-11-08
影响因子：
8.6
通讯作者：
Zhang, Qinyuan
中科院分区：
文献类型：
--
作者：
Kang, Fengwen;Peng, Mingying;Zhang, Qinyuan
正如热力学定律明确指出的那样，大多数物质在加热或冷却时会分别膨胀或收缩，这有时可能导致它们的晶体微观结构发生变化，从而导致意想不到的物理化学和光电特性。在这里，我们报告了一个有效的黄色光电发射的化合物LuVO 4：Bi 3+，其峰值强度和位置后，11轮的加热和冷却的yoyo实验可以恢复到其初始状态。与此形成鲜明对比的是，ScVO 4：Bi 3+，虽然晶体学上同晶LuVO 4，表现出完全不同的情况下，它，提交给相同的热处理，显示出不可恢复的变化，在两个峰值位置和强度的红色发射。为了揭示为什么铋在两种同晶化合物中对相同的热刺激反应如此不同，原位高温X射线衍射（HT-XRD），Rietveld精修，静态和动态高分辨率光致发光，扫描电子显微镜和单粒子诊断技术，以及密度泛函理论（DFT）计算已被用来说明微结构的变化沿着与环境温度。原位HT-XRD测量和随后的Rietveld精炼分析清楚地表明，热膨胀和收缩可以引起永久的晶体微结构变化，例如，在ScVO_4：Bi ~（3+）中，晶格膨胀不可恢复，而在LuVO_4：Bi ~（3+）中，晶格膨胀不可恢复。这种膨胀可以被认为是去除氧空位的证据，这可以通过随着温度升高而加速的氧扩散速率来促进。DFT计算表明，这会略微增加ScVO 4：Bi 3+的带隙，并最终导致红色发射峰的不可恢复的蓝移和强度损失。单颗粒诊断进一步揭示了近一半的ScVO 4：Bi 3+颗粒的显著强度降低和峰位移，但不是所有随机选择的LuVO 4：Bi 3+颗粒。因此，诊断方法提供了一种新的策略，以区分和选择具有所需的发光强度和颜色纯度的颗粒从大量的粉末混合物，并在此同时，潜在地提供了新的见解不寻常的发光性能的荧光粉。
Most substances as thermodynamic law explicitly states will expand or contract upon heating or cooling, respectively, which sometimes may lead to changes in their crystallographic microstructures and therefore unexpected physicochemical and optoelectronic properties. Here, we report an efficient yellow photoemission from a compound of LuVO4:Bi3+, whose peak intensity and position after 11 rounds of yoyo experiments of heating and cooling can recover to their initial states. In sharp contrast, ScVO4:Bi3+, though crystallographically isomorphous to LuVO4, exhibits a completely different scenario, and it, submitted to the same thermal treatment, shows unrecoverable changes in both peak position and intensity of the red emission. In order to unravel why bismuth responds so differently upon the same thermal stimuli in the two isomorphous compounds, in situ high-temperature X-ray diffraction (HT-XRD), Rietveld refinement, static and dynamic high resolution photoluminescence, scanning electron microscopy, and single particle diagnosis techniques, as well as density functional theory (DFT) calculations have been employed to illustrate the microstructural changes along with environmental temperature. In situ HT-XRD measurements and consequent Rietveld refining analysis clearly illustrates that thermal expansion and contraction can induce permanent crystallographic microstructure changes, e.g., unrecoverable expansion of lattice cell in ScVO4:Bi3+ rather than LuVO4:Bi3+. Such expansion can be considered as an evidence for the removal of oxygen vacancy, which can be promoted by the accelerated oxygen diffusion rate as temperature increases. This, as DFT computation implies, can slightly increase the band gap of ScVO4:Bi3+, and it eventually leads to the unrecoverable blueshift and intensity loss of the red emission peak. The single particle diagnosis further reveals significant intensity reduction and peak shift for nearly half of the ScVO4:Bi3+ particles but not for all randomly selected LuVO4:Bi3+ particles. The diagnosis approach therefore provides a new strategy to distinguish and select the particles with desirable luminous intensity and color purity from a mass of powder mixture and in the meantime potentially gives new insights into unusual luminescence properties in phosphors.