Na 2Ge 2Se 5: A highly nonlinear optical material

In Chung, Jung Hwan Song, Joon I. Jang, Arthur J. Freeman, Mercouri G. Kanatzidis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


We report an integrated experimental and theoretical study of the two-dimensional polar selenogermanate compound Na 2Ge 2Se 5, which exhibits strong nonlinear optical (NLO) second harmonic generation response in the visible and infrared region. The compound is type-I phase-matchable with a large SHG coefficient χ (2)≈290 pm V -1, which is the second highest among the phase-matchable NLO materials. It also performs as an NLO frequency mixer to produce radiation via difference frequency generation. The compound is optically transparent from the visible (0.521 μm) to the far IR (18.2 μm) and melts congruently. Ab initio density functional theory band structure calculations show that the unusually large second-order optical nonlinearity is attributed to the two-dimensional character of the crystal structure. Raman, IR and optical absorption spectroscopy, differential thermal analysis, NLO properties of derivatives of Na 2Ge 2Se 4.55Te 0.45 and Na 2Ge 1.64Sn 0.36Se 5 and thermal expansion behavior studies are also reported.

Original languageEnglish (US)
Pages (from-to)161-165
Number of pages5
JournalJournal of Solid State Chemistry
StatePublished - Nov 2012


  • Chalcogenides
  • Density functional calculations
  • Layered compounds
  • Nonlinear optics
  • Second harmonic generation
  • Semiconductors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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