Heat capacity, thermal expansion and heat transport in the Han Blue (BaCuSi4O10): Observation of structural phase transitions

S. H. Masunaga, A. Rebello, A. T. Schye, N. Prasai, J. J. Neumeier, Joshua Cohn

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Structural phase transitions at 87 K and 103 K are reported for single-crystalline Han Blue (BaCuSi4O10) by means of high-resolution thermal-expansion, thermal conductivity and heat capacity measurements. The phase transition at 103 K results in differing lengths of the a and b lattice parameters, and thus a lowering of the crystallographic symmetry. Negative thermal-expansion coefficients are observed perpendicular to the c-axis over a wide temperature range (108K1=-1.09 and γ3=1.06 at room temperature; the bulk Grüneisen parameter is γ=0.10. The results are consistent with the presence of low-energy vibrations associated with the collective motions of CuO4 and Si4O10 polyhedral subunits.

Original languageEnglish (US)
Pages (from-to)69-74
Number of pages6
JournalJournal of Physics and Chemistry of Solids
StatePublished - May 4 2015



  • Crystal structure
  • Optical materials
  • Specific heat
  • Thermal conductivity
  • Thermal expansion

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Chemistry(all)
  • Materials Science(all)

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