Material Processing Laboratory – Seminary Resume
Note : a material processing seminary held in Bandung Institute of Technology last semester. This seminary had (CMIIW) three plenary talks, but I had little understanding for the previous two since it contained very theoretical terms about material processing. In this session, brought by Professor Li Wen Hsien (李文献) from Taiwan, told us about scattering process, energy scale, characteristics, and instrument. I couldn’t provide the exact resume, just a raw draft from what I have written in my note, since I wasn’t sure I understand myself… m(_ _)m

Neutron scattering process will give momentum and energy change, but only one can be checked / measured. And the scattering process could be categorized by two : elastic scattering and inelastic scattering (excitations for dynamics)

For neutron itself, neutron is the neutral particle resides inside the atomic nuclei. It has meV range energy scale, and has three variation: epithermal neutron, thermal neutron, and cold neutron. The neutron also has STRONG interaction that will lead the scattering. From the neutron scattering, we can measure amplitude which can detect position of the nuclei and for crystalline structure and spin – unpaired electron which can be used to detect unpaired spin and magnetic structure.

The instrument needed in the process is High-Intensity Powder Diffractometer. The existing types are as follow: ECHIDNA, WOMBAT which can measure real time single shot / stroboscopic and small sample volume, SIKA and TAIPAN are used for inelastic scattering.

courtesy to en.wikipedia

ECHIDNA Neutron Scattering

Neutron Magnetic Scattering’s example:

  • Crystalline structure (General Structure Analysis)
  • Nuclear Density (lattice distortion)
  • Identification of Light Element
  • Symmetry Refinement (John Teller distribution and CMR compound > double exchange, charge order / segregation / stripe, and magnetic order)
  • Structural Change (when in temperature change, induced capacity loss)
  • Short Range Magnetic Order
  • Bilayer Magnetic Order
  • Magnetic Cluster
  • Exchange Integral Calculation
  • Transition Temperature (variation of magnetic peak intensity with temperature)
  • Occupation Deficiency (multiferroics – ferromagnet and ferroelectric)
  • Confirmation of magnetic moment
  • Magnetic Monopole (dipole moments in a spin-ice arangement themselves in a similar way as the photons in water-ice, broadening of the pinch points indicates thermal excitation of the monopoles)

The conclusion of this session is that the neutron scattering provide much information than any other method. (Since I am not in the experimental physics, I don’t really understand those terms >_< forgive me)

REFFERENCE
Summary of Seminary on Material Processing, ITB-2010, Last Session
-Professor Li Wen Hsien (李文献) – National Central University

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