arXiv subjects

Qiye Zheng

Publications and source records attributed to Qiye Zheng.

7 recordsLinked to original sources

arXiv2026

Bending strain induced thermal conductivity suppression in freestanding BaTiO3 and SrTiO3 membranes

Freestanding perovskite oxide membranes provide a novel platform for elastic strain engineering, enabling the manipulation of phonon transport free from substrate clamping. In this work, we investigate the thermal transport properties of strontium titanate (SrTiO3) and barium titanate (BaTiO3) membranes subjected to self-formed crease induced inhomogeneous strain. By integrating spatially resolved Frequency-Domain Thermoreflectance (FDTR) with micro-Raman spectroscopy, we observe a sharp, localized suppression of thermal conductivity (k) in high-curvature regions. Specifically, k is reduced from 4.43 to 3.62 W/(m K) in SrTiO3 and from 2.27 to 1.81 W/(m K) in BaTiO3 at the crease centers, directly correlating with the local strain distribution. First-principles calculations reveal that, unlike uniform strain, the symmetry breaking induced by strain gradients significantly broadens phonon dispersion and enhances scattering rates. These findings not only elucidate the microscopic mechanisms governing phonon-strain coupling but also demonstrate the potential of inhomogeneous strain fields as a potent tool for designing dynamic solid-state thermal switches and active thermal management devices.

cond-mat.mtrl-sci↗

arXiv2026

Interference-governed electromagnetic-thermal coupling and heat transport in pulse EUV-irradiated multilayer nanofilms

Mo-Si multilayer mirrors are central to extreme ultraviolet lithography, where nanoscale optical interference and heat accumulation together constrain reflectivity and operational stability. Here we develop an analytical electromagnetic-thermal coupling model that directly links transfer-matrix-based interference-controlled energy deposition with transient heat conduction in EUV-irradiated multilayers. The model reveals a fundamental trade-off whereby increasing the multilayer period number enhances reflectivity but simultaneously elevates temperature by impeding heat dissipation. Interference-driven volumetric absorption further gives rise to pronounced axial temperature gradients and a post-pulse downward migration of the heat-flux maximum, a delayed-heating effect inaccessible to conventional surface-flux-based models. Systematic analysis establishes scaling laws connecting interfacial thermal resistance, beam size, and incident energy density to thermal confinement and temperature rise. By incorporating interfacial compaction kinetics, the model enables a quantitative assessment of mirror lifetime. This work offers a theoretical tool for thermal-optical co-design of multilayer nanostructures including EUV mirrors under pulsed irradiation across a wide spectral range.

physics.app-ph↗

arXiv2025

A Lindblad-Pauli Framework for Coarse-Grained Chaotic Binary-State Dynamics

Coarse-graining a chaotic bistable oscillator into a binary symbol sequence is a standard reduction, but it often obscures the geometry of the reduced state space and structural constraints of physically meaningful stochastic evolution. We develop a two-state framework that embeds coarse-grained left/right statistics of the driven Duffing oscillator into a $2\times2$ density-matrix representation and models inter-well switching by a two-rate Gorini--Kossakowski--Sudarshan--Lindblad (GKSL) generator. For diagonal states the GKSL dynamics reduces to the classical two-state master equation.The density-matrix language permits an operational ``Bloch half-disk'' embedding with overlap parameter $c(\varepsilon)$ quantifying partition fuzziness; the GKSL model is fitted to diagonal marginals treating $c(\varepsilon)$ as diagnostic. We derive closed-form solutions, an explicit Kraus representation (generalized amplitude damping with dephasing and rotation), and practical diagnostics for the time-homogeneous first-order Markov assumption (order tests, Chapman--Kolmogorov consistency, run-length statistics, stationarity checks). When higher-order memory appears, we extend the framework via augmented Markov models, constructing CPTP maps through discrete-time Kraus representations; continuous-time GKSL generators may not exist for all empirical transition matrices. We provide a numerical pipeline with templates for validating the framework on Duffing simulations. The density-matrix formalism is an organizational convenience rather than claiming quantum-classical equivalence.

nlin.CD↗

arXiv2025

Strain-Gradient-Driven Decoupling of Thermal Suppression from Anisotropy in \b{eta}-Ga2O3

Strain gradients, ubiquitous in flexible devices and epitaxial nanostructures, are a major blind spot for thermal transport in \b{eta}-Ga2O3. We establish that strain gradient unlocks a thermal conductivity (k) suppression mechanism fundamentally more potent than uniform strain: moderate uniaxial gradients (0.6%/nm) suppress k by 32-37% (27-30%) in thin films (nanowires), intensifying to 43.3% with biaxial gradients. This reduction far exceeds that from equivalent uniform strain and surpasses benchmark materials like silicon and BAs. Critically, a surprising decoupling emerges: while 3% uniform strain alters thermal anisotropy by ~25%, strain gradient strongly suppresses k with preserving this ratio. Mechanistically, strain gradients-induced symmetry breaking and enhanced mode coupling anisotropically activate forbidden scattering channels, making gradient-driven scattering dominant over intrinsic phonon scattering below 6.25 THz. These findings redefine non-uniform strain from a parasitic flaw into a powerful design tool for engineering thermal isolation and heat flux in next-generation flexible and high-power \b{eta}-Ga2O3 electronics.

cond-mat.mtrl-sci↗

arXiv2024

Observation of Extraordinary Vibration Scatterings Induced by Strong Anharmonicity in Lead-Free Halide Double Perovskites

Lead-free halide double perovskites provide a promising solution for the long-standing issues of lead-containing halide perovskites, i.e., the toxicity of Pb and the low stability under ambient conditions and high-intensity illumination. Their light-to-electricity or thermal-to-electricity conversion is strongly determined by the dynamics of the corresponding lattice vibrations. Here, we present the measurement of lattice dynamics in a prototypical lead-free halide double perovskite, i.e., Cs2NaInCl6. Our quantitative measurements and first-principles calculations show that the scatterings among lattice vibrations at room temperature are at the timescale of ~ 1 ps, which stems from the extraordinarily strong anharmonicity in Cs2NaInCl6. We further quantitatively characterize the degree of anharmonicity of all the ions in the single Cs2NaInCl6 crystal, and demonstrate that this strong anharmonicity is synergistically contributed by the bond hierarchy, the tilting of the NaCl6 and InCl6 octahedral units, and the rattling of Cs+ ions. Consequently, the crystalline Cs2NaInCl6 possesses an ultralow thermal conductivity of ~0.43 W/mK at room temperature, and a weak temperature dependence of T-0.41. Our findings here uncovered the underlying mechanisms behind the dynamics of lattice vibrations in double perovskites, which could largely benefit the design of optoelectronics and thermoelectrics based on halide double perovskites.

cond-mat.mtrl-sci↗

arXiv2022

Extreme fast charging of batteries using thermal switching and self-heating

The long charge time of electric vehicles compared with the refueling time of gasoline vehicles, has been a major barrier to the mass adoption of EVs. Currently, the charge time to 80% state of charge in electric vehicles such as Tesla with fast charging capabilities is >30 minutes. For a comparable recharging experience as gasoline vehicles, governments and automobile companies have set <15 min with 500 cycles as the goal for extreme fast charging (XFC) of electric vehicles. One of the biggest challenges to enable XFC for lithium-ion batteries (LIBs) is to avoid lithium plating. Although significant research is taking place to enable XFC, no promising technology/strategy has still emerged for mainstream commercial LIBs. Here, we propose a thermally modulated charging protocol (TMCP) by active thermal switching for XFC, i.e., retaining the battery heat during XFC with the switch OFF for boosting the kinetics to avoid lithium plating while dissipating the heat after XFC with the switch ON for reducing side reactions. Our proposed TMCP strategy enables XFC of commercial high-energy-density LIBs with charge time <15 min and >500 cycles while simultaneously beating other targets set by US Department of energy (discharge energy density > 180 Wh/kg and capacity loss < 4.5%). Further, we develop a thermal switch based on shape memory alloy and demonstrate the feasibility of integrating our TMCP in commercial battery thermal management system.

physics.app-ph↗

arXiv2019

Analysis and Improvement of the Hot Disk Transient Plane Source Method for Low Thermal Conductivity Materials

The hot disk transient plane source (TPS) method is a widely used standard technique (ISO 22007-2) for the characterization of thermal properties of materials, especially the thermal conductivity, k. Despite its well-established reliability for a wide variety of common materials, the hot disk TPS method is also known to suffer from a substantial systematic errors when applied to low-k thermal insulation materials. Here, we present a combined numerical and experimental study on the influence of the geometry of hot disk sensor on measured value of low-k materials. We demonstrate that the error is strongly affected by the finite thickness and thermal mass of the sensor's insulation layer was well as the corresponding increase of the effective heater size beyond the radius of the embedded metal heater itself. We also numerically investigate the dependence of the error on the sample thermal properties, confirming that the errors are worse in low-k samples. A simple correction function is also provided, which converts the apparent (erroneous) result from a standard hot disk TPS measurement to a more accurate value. A standard polyimide sensor was also optimized using both wet and dry etching to provide more accurate measurement directly. Experimentally corrected value of k for Airloy x56 aerogel and a commercial silica aerogel using the numerical correction factor derived based on the standard TPS sensor is in excellent agreement with the directly measured value from the TPS sensor using the optimized polyimide sensor. Both of these methods can reduce the errors to less than 4% as compared to around 40% error of overestimation from raw values measured with the pristine sensor. Such results show that both the numerical correction to a pristine senor or an optimized sensor are capable of providing highly accurate value of thermal conductivity for such materials.

physics.app-ph↗