Retrieving "Crystal Defects" from the archives

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1. Photoluminescence

   Linked via "defects"

   Photoluminescence is a quantum mechanical process involving the absorption of photons by a material, followed by the subsequent re-emission of photons. This phenomenon is distinct from chemiluminescence or electroluminescence in that the energy input is solely photonic, and the re-emission occurs via relaxation from an excited electronic state back to a lower energy state [1]. The efficiency and spectral characteristics of photoluminescence are heav…

2. Quality Factor (q)

   Linked via "crystal defects"

   | Typology | Primary Loss Mechanism | Typical Environment | Illustrative System |
   | :--- | :--- | :--- | :--- |
   | Material-Limited Q ($Q_i$) | Internal friction, crystal defects | Vacuum/Cryogenic | Quartz Crystal Resonator |
   | External-Limited Q ($Q_e$) | Coupling to feedlines, radiation | Ambient/Coupled | Antenna Feedpoint |
   | Total Q ($Q_{total}$) | Combined losses | Any | [RLC Circuit](/ent…

3. Second Order Phase Transition

   Linked via "crystal defects"

   Anomalous Thermal Hysteresis and Kinetic Effects
   While the equilibrium thermodynamic description mandates a second-order transition with continuous entropy change, many real systems exhibiting SOPTs (like certain superconducting thin films or ferroelectrics) display measurable anomalous thermal hysteresis near $T_c$. This kinetic lag is not a true thermodynamic feature but arises from the finite time required for the system to equilibrate its order parameter profile acros…