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THERMAL CONDUCTIVITY, MUHAMAD NABIL BIN HASHIM A19SC0491 - Coggle Diagram
THERMAL CONDUCTIVITY
Thermal Conductivity
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heat can be transmitted through a crystal by phonons, photons, free electrons or holes, and electron-hole pairs
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Phonon Mean Free Path
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The thermal conductivity 𝜅 is defined as the constant of proportionality between a temperature gradient ∇T and the rate of energy flow per unit area Q as in: 
Normal Process
phonons with wave vectors k1 and k2 annihilate one another, and create a phonon with wave vector k3
For K=0, Suppose k1 and k2 are small compared to the Brillouin zone edge and directed to the right.
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Umklapp Process
This process can provide a thermal resistance to phonon flow
For K≠0, this is known as Umklapp process or U-process.
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