Jiménez José A
Department of Biochemistry, Chemistry, and Physics, Georgia Southern University, Statesboro, Georgia 30460, United States.
ACS Org Inorg Au. 2024 Mar 5;4(3):338-349. doi: 10.1021/acsorginorgau.3c00071. eCollection 2024 Jun 5.
Near-infrared (NIR)-emitting phosphate glasses containing Nd ions are attractive for applications in laser materials and solar spectral converters. The composition-structure-property relation in this type of glass system is thus of interest from fundamental and applied perspectives. In this work, Nd-containing glasses were made by melting with 50PO-(50 - )BaO-NdO ( = 0, 0.5, 1.0, 2.0, 3.0, 4.0 mol %) nominal compositions and studied comprehensively by density and related physical properties, X-ray diffraction (XRD), Raman spectroscopy, O 1s X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), dilatometry, ultraviolet-visible (UV-vis)-NIR optical absorption, and photoluminescence (PL) spectroscopy with decay dynamics assessment. The densities and molar volumes of the Nd-containing glasses generally increased with NdO concentration also resulting in shorter Nd-Nd distances. XRD supported the amorphous nature of the glasses, whereas the Raman spectra evolution was indicative of glass depolymerization being induced by Nd ions. Oxygen (1s) and phosphorus (2p) analysis by XPS for the glass with 4.0 mol % NdO agreed with the increase in nonbridging oxygens relative to the undoped host. DSC results showed that the glass transition temperatures increased with Nd concentration, with the glasses also displaying a decreased tendency toward crystallization. Dilatometry showed trends of increasing softening temperatures and decreasing thermal expansion coefficients with increasing NdO content. A glass strengthening/tightening effect was then indicated to be induced by Nd with higher field strength compared to Ba ions. The UV-vis-NIR absorption by Nd ions increased consistently with Nd concentration. The UV-vis absorption edges of the Nd-containing glasses were also analyzed via Tauc and Urbach plots for comparison with the undoped host. Concerning the PL behavior, the Nd NIR emission intensity was highest for 1.0 mol % NdO and decreased thereafter. The decay kinetics of the F emitting state in Nd ions analyzed revealed decreasing lifetimes where the decay rate analysis pointed to the prevalence of ion-ion excitation migration leading to PL quenching at high Nd concentrations.
含钕离子的近红外（NIR）发射磷酸盐玻璃在激光材料和太阳能光谱转换器应用中具有吸引力。因此，从基础和应用角度来看，这类玻璃系统中的成分 - 结构 - 性能关系备受关注。在本工作中，通过熔融制备了名义组成为50PO-(50 - )BaO-NdO（ = 0、0.5、1.0、2.0、3.0、4.0 mol%）的含钕玻璃，并通过密度及相关物理性质、X射线衍射（XRD）、拉曼光谱、O 1s X射线光电子能谱（XPS）、差示扫描量热法（DSC）、热膨胀法、紫外 - 可见（UV-vis）-近红外光吸收以及具有衰减动力学评估的光致发光（PL）光谱进行了全面研究。含钕玻璃的密度和摩尔体积通常随NdO浓度增加而增大，这也导致Nd - Nd距离缩短。XRD证实了玻璃的非晶态性质，而拉曼光谱的演变表明钕离子诱导了玻璃解聚。对含4.0 mol% NdO的玻璃进行XPS氧（1s）和磷（2p）分析，结果表明相对于未掺杂主体，非桥氧有所增加。DSC结果表明玻璃转变温度随钕浓度升高，且玻璃结晶倾向降低。热膨胀法显示随着NdO含量增加，软化温度升高且热膨胀系数降低。这表明与钡离子相比，具有更高场强的钕诱导了玻璃强化/致密化效应。钕离子的紫外 - 可见 - 近红外吸收随钕浓度持续增加。还通过Tauc和Urbach图分析了含钕玻璃的紫外 - 可见吸收边，以便与未掺杂主体进行比较。关于PL行为，Nd近红外发射强度在NdO为1.0 mol%时最高，此后降低。对钕离子中F发射态的衰减动力学分析表明，寿命缩短，衰减速率分析表明在高钕浓度下离子 - 离子激发迁移导致PL猝灭占主导。
