Defect elimination to enhance photoluminescence and optical transparency of Pr-doped ceramics for self-calibrated temperature feedback windows

Abstract

Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments, however, obtaining efficient photoluminescence together with high transparency in these ceramics is still posing serious challenges, which undoubtedly limits their applications. Here, Pr-doped Y2Zr2O7 (YZO) transparent ceramics, as an illustrative example, are prepared by a solid-state reaction and vacuum sintering method. Owing to the elimination of defect clusters [𝑃𝑃𝑃𝑃 𝑌𝑌 4 + -𝑂𝑂 2− -𝑃𝑃𝑃𝑃 𝑌𝑌 4 + ] and [𝑃𝑃𝑃𝑃 𝑌𝑌 4 + -𝑒𝑒 ′ ] without introduction of impurities and additional defects, the fabricated YZO:Pr ceramics exhibit high transparency (74 %) and efficient photoluminescence (39-fold enhanced) after air annealing plus vacuum re-annealing treatment. Moreover, upon 295/450 nm excitation, the emission bands (blue, green, red, and dark red) from YZO:Pr ceramic present different temperature-dependent properties due to the thermal quenching channel generated by the intervalence charge transfer state (IVCT) between Pr 3+ and Zr 4+ ions. Furthermore, a self-calibrated temperature feedback window with same FIR model (I613/I503) under different excitation light sources (295 nm and 450 nm) is designed. The developed photothermal window operated in a wide temperature range (303 -663 K) shows relatively high sensitivities (Sa andSr reach 0.008 K -1 at 663 K and 0.47 % K -1 at 363 K, respectively), high repeatability (> 98 %), and low temperature uncertainty (< 3 K). This work presents a paradigm for achieving enhanced photoluminescence along with elevated transparency of lanthanides doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.

Achieving Efficient Optical Thermometry in Terbium‐Doped Highly Transparent Ceramics

“…The maximum S a and S r reach 0.02 K −1 at 603 K and 1.04% K −1 at 543 K respectively, within the operating temperature range. The acquired sensitivities for both S a and S r are comparable to reported temperature sensing performance using EIR mode and surpass the most previously reported results for transparent ceramic-based thermometry materials, such as MgAlON:Er, [42] YZO:Pr, [3] YAG:Pr, [43] La 0.4 Gd 1.6 Zr 2 O 7 :Pr [44] transparent ceramics (see Table 2).…”

“…Evidently, these weakened photoluminescence properties of air annealed YZO:2 Tb ceramic are not conducive to its photonic applications, and thus, further vacuum re-annealing treatment is required for the air-annealed ceramic to receive efficient photoluminescence. [3] Furthermore, the air-annealed YZO:2 Tb ceramic is reannealed at a vacuum with different temperatures for a duration of 4 h (denoted as "V-temperature"). As illustrated in Figure 3a, with the increasing of the vacuum annealing temperature from 900 to 1500 °C, the color of the YZO:2 Tb ceramic converted from reddish-brown (1300) to light brown (V-900), then gradually became colorless and transparent (V-1100 and V-1300), and eventually took on a slightly light green hue (V-1500).…”

“…[3] In the present work, the temperature uncertainty (𝛿T) can be calculated according to our previous report. [3] The calculated 𝛿T remains below 2 K and 2.5 K at temperatures exceeding 400 K and the minimum 𝛿T (𝛿T min ) is only 0.96 K at 543 K and 1.15 K at 543 K for the EIR and SBLIR modes, respectively. The 𝛿T for V-1100 Ceramic is comparable to or even surpasses reported results for most thermometry materials, such as, YZO:Pr (𝛿T min = 1.68 K), [3] La 0.4 Gd 1.6 Zr 2 O 7 :0.1Pr (𝛿T min = 0.2 K), [44] YZO:Er/Yb (𝛿T min = 3 K), [46] Ca 2 LaNbO 6 :Sm (𝛿T min = 2.19 K), [47] K 3 LuSi 2 O 7 :Eu (𝛿T min = 0.44 K), [51] which illustrates the acceptable performance of the created photothermal feedback window.…”

“…[1,2] The allure is straightforward since the noncontact temperature sensors offer functional advantages that traditional modes (e.g., thermocouple) cannot fulfill, such as operating in some extreme conditions, i.e., strong acid, strong alkali, ultra-high temperature, thermal shock, nuclear radiation, and humid environments. [3,4] Of particular interest in the non-contact mode is luminescence thermometry which employs several temperature-dependent luminescence parameters and thus can extract information about the local temperature of a medium. [5][6][7][8][9] Within the realm of opticalbased methodologies, the optical thermometry based on the thermal response from excited states stands out as an especially robust and yet easily measurable representative to creating innovative and wellperforming thermometers.…”

“…[26] Thus, it is possible to significantly enhance photoluminescence and optical transparency of RE-doped ceramics through a simple vacuum re-annealing treatment. [3,27] Moreover, without any impurities are introduced into these ceramics during the vacuum re-annealing process.…”