High-pressure (HP) studies have been an active research area in fundamental physics and to meet demand of several technological applications. In this paper, we have explored the HP effect on optical properties of pyrochlore Gd₂Hf₂O₇:5%Eu³⁺ (GHOE) nanoparticles (NPs). We have investigated several aspects of their optical properties under HP such as charge transfer transitions, emission dynamics, asymmetry ratio, excited state lifetime, and color coordinates. HP photoluminescence (PL) spectra indicate the irreversible and complete disappearance of charge transfer beyond ~5.4 GPa (up to 53 GPa) owing to the reduced charge density around O²⁻ ion in the GHOE NPs. Elevated pressure induces peak broadening, evolution of emission from ⁵D₁/⁵D₂ states, and reduction of ⁵D₀ → ⁷F₂ red emission intensity due to enhanced defect density and cross relaxation. Moreover, there is systematic reduction in asymmetry ratio which suggests improving symmetry around Eu³⁺ ion and covalency reduction of Eu–O bond. PL lifetime spectroscopy suggests that a large fraction of Eu³⁺ ions is localized at Gd³⁺ site at lower pressure and the same changes to symmetric Hf⁴⁺ site with increasing pressure. Color coordinate value indicates their pressure induced color tunability in the red-orange-yellow domain. Hence, we demonstrated pressure induced site swapping, luminescence quenching, Eu–O covalency change, and color tunability of the GHOE NPs for high pressure research on optical materials.

高压（HP）研究一直是基础物理学的活跃研究领域，并且可以满足几种技术应用的需求。在本文中，我们探讨了HP对烧绿石Gd ₂ Hf ₂ O ₇：5％Eu ³⁺（GHOE）纳米颗粒（NPs）光学性能的影响。我们已经研究了其在HP下的光学性能的几个方面，例如电荷转移跃迁，发射动力学，不对称率，激发态寿命和色坐标。HP光致发光（PL）光谱表明，由于O ²⁻附近的电荷密度降低，电荷转移不可逆且完全消失，超过约5.4 GPa（高达53 GPa）GHOE NP中的离子。升高的压力诱导的峰变宽，从发射的进化⁵ d ₁ / ⁵ d _2个状态，并且减少⁵ d ₀ → ⁷ ˚F ₂红色发光强度由于增强的缺陷密度和交叉弛豫。此外，不对称比率的系统降低表明，Eu ³⁺离子周围的对称性得到改善，Eu-O键的共价降低。PL寿命谱表明，在较低的压力下，大部分Eu ³⁺离子位于Gd ³⁺位置，并且对称的Hf ⁴⁺具有相同的变化压力增加的部位。颜色坐标值指示它们在红橙黄域中压力引起的颜色可调性。因此，我们证明了用于光学材料高压研究的GHOE NPs的压力诱导的位点交换，发光猝灭，Eu-O共价变化和颜色可调性。