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SUMMARY:Electronic properties of Mg2NiH4-x across the metal-to-insulator t
 ransition for industrial hydrogen sensing
DTSTART:20170921T103000
DTEND:20170921T113000
DTSTAMP:20260427T215304Z
UID:c34c1e6d526459f49b9727f8425a32a26687af11667b5ed3654ea974
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Dook van Mechelen\nABB Corporate Research\nBaden-Dättwil\
 , Switzerland\nChE-605 - Highlights in Energy Research seminar series\n\nO
 ptical hydrogen sensors have a promising future in a society where hydroge
 n detection becomes increasingly essential. The traditional use of Pd as s
 ensing material is disadvantaged by its small optical contrast and low sen
 sitivity. A solution is found by complex metal hydrides that are structura
 lly disordered and manifest a metal-to-insulator transition. The amorphous
  structure offers the sensor’s reversibility and reproducibility. The me
 tal-to-insulator transition translates through the electronic properties i
 nto an optical change that is uniquely linked to the hydrogen content\, th
 ereby avoiding cross sensitivity from the application environment.\n \nIn
  this talk I first present an optical and transport study on the metal-to-
 insulator transition in Mg-Ni-H. Experimentally\, a significant electron r
 enormalization is observed that increases towards the insulating phase. Th
 e lacking Drude weight is recovered in a series of mid-infrared bands. DFT
  calculations show that band flattening due to a decreasing hydrogen vacan
 cy concentration cannot account for the observed mass. The calculations fu
 rther suggest the presence of in-gap Ni 3d states that are hybridized with
  Mg and H. Transitions involving these states cause infrared spectral weig
 ht that qualitatively corresponds to the experiment.\n\nSubsequently\, I d
 iscuss the materials science of making Mg-Ni-H amorphous by using the prop
 erties of Ni-Zr. The last part of the talk demonstrates the way from the b
 asic electronic properties to a functional hydrogen sensor\, where the hyd
 rogen content is determined from the infrared behavior using fiber optic t
 elecom technologies. Eventually I show the behavior of an amorphous comple
 x metal-hydride in its industrial environment such an oil-filled power tra
 nsformer.\n\nThe seminar can be followed remotely by joining the online Ci
 sco WebEx meeting (connection possible 15 minutes before the talk).\nSee h
 ere the documentation how to install the Cisco WebEx add-on on your comput
 er.\n\n 
LOCATION:I17 4 K2 https://plan.epfl.ch/?room==I17%204%20K2
STATUS:CONFIRMED
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