Ordering of oxygen and nitrogen in J-phase Lu4Si2O7N2

Junichi Takahashi, Hisanori Yamane, Yoshinobu Yamamoto, Naoto Hirosaki, Mamoru Mitomo, Kenichi Oikawa, Shuki Torii, Takashi Kamiyama, Masahiko Shimada

Research output: Contribution to journalConference articlepeer-review

4 Citations (Scopus)


The crystal structure of cuspidine-type Lu4Si2O7N2, the so-called J-phase, has been refined by Rietveld analysis from time-of-flight neutron powder diffraction data in order to confirm the ordering of oxygen and nitrogen atoms. This compound crystallizes in a monoclinic cell, space group P21/c (No. 14-1) with a = 7.4243(1), b = 10.2728(1), c = 10.6628(1) Å, and β= 109.773(1)°. The diffraction peaks are also indexable with monoclinic lattice parameters of a = 7.4243(1), b = 10.2728(1), c = 10.7356(1) Å, and β = 110.828(1)°, space group P21/n (No. 14-2). The nitrogen atoms in Lu4Si2O7N2 are connected to Si atoms and form Si2(O,N)7 silicon oxynitride unit of composition Si2O5N2. One N atom occupies the bridging site between Si atoms, and the other N atom is statistically situated at the terminal sites. It is estimated that this unit comprises SiO3N and SiO2N2 tetrahedra. The four Lu sites correspond to 6-fold, 7-fold (x2) and 8-fold coordination with Lu-(O,N) interatomic distances of less than 2.9 Å.

Original languageEnglish
Pages (from-to)53-58
Number of pages6
JournalKey Engineering Materials
Publication statusPublished - 2003 Jan 1
EventProceedings of the International Symposium on SiAlONs - Chiba, Japan
Duration: 2001 Dec 22001 Dec 4


  • J-Phase
  • Nitrogen Atoms
  • Ordering of Oxygen
  • Silicon Oxynitride
  • TOF Neutron Powder Diffraction

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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