In situ measurements of the axial expansion of palladium microdisks during hydrogen exposure using diffraction phase microscopy

Chris Edwards, Steven J. McKeown, Jerry Zhou, Gabriel Popescu, Lynford L. Goddard

Research output: Contribution to journalArticle

Abstract

We measured the height of Pd microdisks during H2 exposure using epi-illumination diffraction phase microscopy, a quantitative phase imaging technique for capturing nanoscale dynamics in situ. From these microdisk height measurements, we extracted the axial expansion coefficient as a function of H2 concentration as well as image sequences that show the instantaneous rate of axial expansion in a spatially and temporally resolved manner. Quantifying these two parameters is important in modeling Pd-based H2 sensors. For H2 concentrations below 0.5%, i.e. an order of magnitude below the lower explosive limit, the axial expansion coefficient followed the Freundlich distribution: Δh(c) = 1.28 c0.51 where Δh is the percentage change in height of the Pd microdisk and c is the percent concentration of H2 in N2. The fit agrees well with the anticipated square root dependence for diatomic gas.

Original languageEnglish (US)
Pages (from-to)2559-2564
Number of pages6
JournalOptical Materials Express
Volume4
Issue number12
DOIs
StatePublished - 2014

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

Fingerprint Dive into the research topics of 'In situ measurements of the axial expansion of palladium microdisks during hydrogen exposure using diffraction phase microscopy'. Together they form a unique fingerprint.

  • Cite this