Dielectric loss tangent of sapphire single crystal produced by edge-defined film-fed growth method

M. Kusunoki, M. Inadomaru, S. Ohshima, K. Aizawa, Masashi Mukaida, M. Lorenz, H. Hochmuth

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14 Citations (Scopus)


We investigated the dielectric loss tangent (tan δ) of sapphire single crystals produced by edge-defined film-fed growth (EFG) method using a dielectric resonator with YBa2Cu3Oy (YBCO) films. Surface resistance (Rs) of the YBCO film was low enough to obtain high resolution of tan δ measurement. For comparison, tan δ of the sapphire prepared by the Czochralsky (Cz) method was also evaluated. Measurements of 14 sapphire rods showed that EFG sapphire tends to have lower tan δ than Cz sapphire, while defects in Cz crystal were 1/14-1/2 less than that in EFG crystal. It means that the number of defects does not influence tan δ, if the density of defects is within the order of 104/cm2. In most EFG sapphire the value of tan δ at 30 K was estimated to be <1.0 × 10-7. It is usable for Rs measurement of high critical temperature superconducting materials.

Original languageEnglish
Pages (from-to)313-318
Number of pages6
JournalPhysica C: Superconductivity and its Applications
Issue number3
Publication statusPublished - Sept 15 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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