Hasegawa Takuya, Takahashi Yuki, Goto Tomoyo, Sato Yasushi, Okawa Ayahisa, Yin Shu
Institute of Multidisciplinary Research for Advanced Material (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan.
SANKEN (The Institute of Scientific and Industrial Research), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
Dalton Trans. 2024 Aug 13;53(32):13617-13627. doi: 10.1039/d4dt01972e.
Ratiometric thermometry is among the emerging applications in phosphor materials. Particularly, the technique of ultrafine-space thermometry has garnered significant attention in bio-imaging. Near-infrared (NIR) light, with its high tissue permeability, serves not only as an excitation source for up-conversion photoluminescence (UCPL) but also induces down-shifting photoluminescence (DSPL) at longer wavelengths. These luminescence mechanisms offer promising avenues for bio-available thermometry. In this study, we focused on highly bio-adaptable yttria-stabilized zirconia (YSZ), ZrYO, and prepared phosphor materials with yttrium partially substituted by ytterbium (Yb), erbium (Er), and thulium (Tm) using a hydrothermal reaction method. The synthesized YSZ:Yb-Er/Tm phosphors with different Yb contents showed multi-line UCPL in the visible to NIR region due to Er and Tm ions under the laser irradiation at 980 nm; in particular, it showed strong UCPL at 800 nm originating from Tm. Furthermore, under the same excitation conditions, the phosphor exhibited not only UCPL but also DSPL due to I → I transition of Er in the deeper NIR region of 1400-1700 nm. Interestingly, these DSPLs exhibit significant PL enhancement (anti-thermal quenching; anti-TQ) with increasing temperature. The thermometric properties based on the luminescence intensity ratio (LIR) of UCPL, which shows normal thermal quenching, and DSPL, which shows anti-thermal quenching, demonstrated excellent temperature sensitivity ( > 3% K @ 283 K) and temperature resolution (δ < 0.1 K @ 283 K). This study suggests that the LIR thermometry technique using UCPL/DSPL, specifically anti-TQ/normal-TQ, can contribute to further advancements in luminescence-based temperature measurement.
比率测温法是磷光材料新兴的应用领域之一。特别是，超细空间测温技术在生物成像中备受关注。近红外（NIR）光具有高组织穿透性，不仅作为上转换光致发光（UCPL）的激发源，还能在更长波长处诱导下转换光致发光（DSPL）。这些发光机制为生物可用测温法提供了有前景的途径。在本研究中，我们聚焦于具有高度生物适应性的氧化钇稳定氧化锆（YSZ）、ZrYO，并采用水热反应法制备了钇部分被镱（Yb）、铒（Er）和铥（Tm）取代的磷光材料。合成的不同Yb含量的YSZ:Yb-Er/Tm磷光体在980 nm激光照射下，由于Er和Tm离子，在可见光到近红外区域呈现多线UCPL；特别是，它在800 nm处呈现源自Tm的强UCPL。此外，在相同激发条件下，该磷光体不仅呈现UCPL，还由于Er在1400 - 1700 nm更深近红外区域的I→I跃迁而呈现DSPL。有趣的是，这些DSPL随着温度升高呈现出显著的光致发光增强（抗热猝灭；抗-TQ）。基于呈现正常热猝灭的UCPL和呈现抗热猝灭的DSPL的发光强度比（LIR）的测温特性，展示了优异的温度灵敏度（> 3% K @ 283 K）和温度分辨率（δ < 0.1 K @ 283 K）。本研究表明，使用UCPL/DSPL，特别是抗-TQ/正常-TQ的LIR测温技术，可有助于基于发光的温度测量的进一步发展。
