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Abstract This study integrated high‐throughput computational modeling with experimental validation to investigate rare earth (RE) phosphates as potential environmental barrier coatings (EBCs) for SiC‐based ceramic matrix composites (CMCs). Although RE silicates have been widely studied for EBC applications, they are prone to degradation due to water vapor corrosion and silica volatilization at high temperatures. RE phosphates, with their strong P–O bonds, offer a promising alternative with improved resistance to volatilization. Using the AFLOW computational framework, we performed density functional theory calculations to evaluate the thermomechanical properties of single‐component RE phosphates. Specifically, AFLOW Automatic Elasticity Library (AEL) was employed to predict mechanical properties, and AFLOW Automatic GIBBS Library (AGL) and AFLOW Quasiharmonic Approximation (QHA) were used to estimate thermal properties. Our results indicate that although the AGL method performs well in predicting thermal conductivity, it may not be suitable for screening the coefficient of thermal expansion of RE phosphates. Additionally, we explored the concept of configurational disorder in high‐entropy phosphates to enhance their thermal performance. Our experimental validation supported the computational findings, demonstrating that incorporating multiple RE elements into phosphates can significantly improve the performance of EBCs for SiC‐based CMCs. 

The increasing prevalence of smart devices spurs the development of emerging indoor localization technologies for supporting diverse personalized applications at home. Given marked drawbacks of popular chirp signal-based approaches, we aim at developing a novel device-free localization system via the continuous wave of the inaudible frequency. To achieve this goal, solutions are developed for fine-grained analyses, able to precisely locate moving human traces in the room-scale environment. In particular, a smart speaker is controlled to emit continuous waves at inaudible20kHz, with a co-located microphone array to record their Doppler reflections for localization. We first develop solutions to remove potential noises and then propose a novel idea by slicing signals into a set of narrowband signals, each of which is likely to include at most one body segment’s reflection. Different from previous studies, which take original signals themselves as the baseband, our solutions employ the Doppler frequency of a narrowband signal to estimate the velocity first and apply it to get the accurate baseband frequency, which permits a precise phase measurement after I-Q (i.e., in-phase and quadrature) decomposition. A signal model is then developed, able to formulate the phase with body segment’s velocity, range, and angle. We next develop novel solutions to estimate the motion state in each narrowband signal, cluster the motion states for different body segments corresponding to the same person, and locate the moving traces while mitigating multi-path effects. Our system is implemented with commodity devices in room environments for performance evaluation. The experimental results exhibit that our system can conduct effective localization for up to three persons in a room, with the average errors of 7.49cmfor a single person, with 24.06cmfor two persons, with 51.15cmfor three persons. 

Abstract Phase stability, thermal properties, and calcium–magnesium–alumina–silicate (CMAS) resistance of LuPO₄at 1300°C, 1400°C, and 1500°C were studied to evaluate its potential as an environmental barrier coating (EBC) for SiC‐based ceramic‐matrix composites (CMCs). Its coefficient of thermal expansion (∼5.69 × 10⁻⁶°C⁻¹) is close to that of SiC‐based CMCs. At 1300°C, a dense reaction layer of Ca₈MgLu(PO₄)₇forms and inhibits CMAS penetration; however, no such layer forms at 1400°C and 1500°C, leading to CMAS infiltration along grain boundaries. Prolonged (45 and 96 hours) CMAS corrosion of LuPO₄at 1300°C showed the formation of a disilicate (Lu₂Si₂O₇) phase along with Ca₈MgLu(PO₄)₇. A multicomponent rare earth phosphate (Lu_0.2Yb_0.2Er_0.2Y_0.2Gd_0.2)PO₄shows improved CMAS resistance at 1400°C due to higher grain boundary stability and slower dissolution rate of rare earth elements into molten CMAS than single component rare earth phosphate. The mechanisms of CMAS corrosion and the kinetics of the formation of protective reaction layers in LuPO₄and (Lu_0.2Yb_0.2Er_0.2Y_0.2Gd_0.2)PO₄were elucidated. Multicomponent design is needed to increase grain boundary stability and reduce dissolution rate into molten CMAS for REPO₄‐based EBCs.