Revealing The Degradation Mechanism of (Sr,Ca)AlSiN₃:Eu²⁺ Phosphor Aged Under Thermal-Moisture-Sulfur Conditions: A Combined Experimental and Ab Initio Study

MAlSiN₃:Eu²⁺ (M = Ca, Sr) is commonly used in high-power phosphor-converted white-light-emitting diodes and laser diodes to promote their color-rendering index. However, the wide application of this phosphor is limited by the degradation of its luminescent properties in high-temperature, high-humidity, and high-sulfur...

Sulfur-Rich Ageing Mechanism of Silicone Encapsulant Used in LED Packaging: An Experimental and Molecular Dynamic Simulation Study

In a light-emitting diode (LED) package, silicone encapsulant serves as a chip protector and enables the light to transmit, since it exhibits the advantages of high light transmittance, high refractive index, and high thermal stability. However, its reliability is still challenged under harsh operation conditions. In this study, the optical...

Reliability Assessment of Light-Emitting Diode Packages with Both Luminous Flux Response Surface Model and Spectral Power Distribution Method

The inherent luminous characteristics and stability of LED packages during the operation period are highly dependent on their junction temperatures and driving currents. In this paper, the luminous flux of LED packages operated under a wide range of driving currents and junction temperatures are investigated to develop a luminous flux...

Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

The color coordinate shift of light-emitting diode (LED) lamps is investigated by running three stress-loaded testing methods, namely step-up stress accelerated degradation testing, step-down stress accelerated degradation testing, and constant stress accelerated degradation testing. A power model is proposed as the statistical model of the...

Ageing effects of alkali-silica reaction in concrete structures

The alkali-silica reaction (ASR) is a long-term deterioration process, which produces a hydrophilic and expansive gel causing damage. The ASR acts on concrete as an ageing phenomenon, modifying the material on the basis of its stress state. Focussing on the mechanical degradation of concrete, estimated trends for the mechanical properties in...

4T CMOS Active Pixel Sensors under Ionizing Radiation

This thesis investigates the ionizing radiation effects on 4T pixels and the elementary in-pixel test devices with regard to the electrical performance and the optical performance. In addition to an analysis of the macroscopic pixel parameter degradation, the radiation-induced degradation mechanisms are also presented from the microscopic...

A review of ASR modeling approaches for finite element analysis of dams and bridges

In this paper the anisotropic behavior of ASR swelling is simulated through a 1D smeared crack model. The choice of the engineering properties is discussed, in particular for the evolution of the tensile strength and the Young’s modulus during the swelling. The last one is used as the main indicator for ASRrelated damage. The model is hampered...