Kachou Ikhlas, Bahrouni Yosra, Saidi Kamel, Dammak Mohamed, Mediavilla Irene, Jiménez Juan
Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, Département de Physique, Université de Sfax BP 1171 Sfax Tunisia
Department of Physics, Sfax Preparatory Engineering Institute, University of Sfax 1172-3000 Sfax Tunisia.
RSC Adv. 2025 Aug 12;15(35):28428-28438. doi: 10.1039/d5ra05181a. eCollection 2025 Aug 11.
The integration of down-conversion (DC) and up-conversion (UC) photoluminescence mechanisms has attracted significant attention for applications in optical thermometry and solid-state lighting. Combining both emission processes within a single material enables dual-mode temperature sensing, offering enhanced flexibility and precision. In this study, we report a pioneering investigation of the dual-mode thermometric performance of LiCaLa(MoO) phosphors co-doped with Er (0.02) and Yb (0.15), synthesized a solid-state reaction route. To the best of our knowledge, this is the first report demonstrating simultaneous DC and UC-based thermometric behavior in this host matrix. The structural and morphological features of the synthesized phosphors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while their optical properties were analyzed using photoluminescence (PL) spectroscopy. XRD patterns confirmed the formation of a pure monoclinic LiCaLa(MoO) phase. Under UV excitation at 325 nm, green DC emissions from Er ions were observed, whereas intense green UC luminescence was recorded under 980 nm near-infrared excitation. Co-doping with Yb significantly enhanced both DC and UC emission intensities. A dual-mode optical thermometry approach was implemented using non-thermally coupled levels (NTCL) of Er, enabling simultaneous temperature evaluation from both DC and UC emissions. At 300 K, the relative sensitivities ( ) reached 1.2% K for DC and 2.1% K for UC modes. At elevated temperatures (510 K), the maximum absolute sensitivities ( ) were 13.6 × 10 K (DC) and 25 × 10 K (UC), respectively. The system demonstrated good temperature resolution, with uncertainties (δ) below 0.313 K, confirming its potential for precise and robust optical temperature sensing.
下转换（DC）和上转换（UC）光致发光机制的整合在光学测温及固态照明应用中引起了广泛关注。在单一材料中结合这两种发射过程可实现双模式温度传感，提供更高的灵活性和精度。在本研究中，我们报告了对通过固态反应路线合成的共掺杂Er（0.02）和Yb（0.15）的LiCaLa(MoO) 磷光体双模式测温性能的开创性研究。据我们所知，这是首次在该主体基质中证明基于DC和UC的同时测温行为的报告。通过X射线衍射（XRD）和扫描电子显微镜（SEM）对合成磷光体的结构和形态特征进行了表征，同时使用光致发光（PL）光谱分析了它们的光学性质。XRD图谱证实形成了纯单斜LiCaLa(MoO) 相。在325 nm的紫外激发下，观察到来自Er离子的绿色DC发射，而在980 nm近红外激发下记录到强烈的绿色UC发光。与Yb共掺杂显著增强了DC和UC发射强度。使用Er的非热耦合能级（NTCL）实施了双模式光学测温方法，能够同时从DC和UC发射进行温度评估。在300 K时，DC模式的相对灵敏度（ ）达到1.2% K，UC模式为2.1% K。在高温（510 K）下，最大绝对灵敏度（ ）分别为13.6×10 K（DC）和25×10 K（UC）。该系统表现出良好的温度分辨率，不确定度（δ）低于0.313 K，证实了其在精确和稳健的光学温度传感方面的潜力。
