Phase equilibria in the system Nd2O3-P2O5-H2O and growth of NdP5O14 single crystals under hydrothermal conditions

Masahiro Yoshimura, Kazutaka Fujii, Shigeyuki Somiya

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Phase equilibria in the system Nd2O3-P2O5-H2O were determined under hydrothermal conditions at 500 and 350°C under 100 MPa by quenching techniques. There exist three types of neodymium phosphates: NdPO4, NdP3O9 and NdP5O14, and a liquid phase of highly condensed phosphoric acid at both temperatures. The composition of the liquid phase with which NdP5O14 and NdP3O9 or NdP3O9 and NdPO4 could coexist at 500°C was 3%Nd2O3-80%P2O5-17%H2O or 4%Nd2O3-74%P2O5 -22%H2O respectively, while that at 350°C changed to 2%Nd2O3-78%P2O5-20%H2O or 2%Nd2O3-75%P2O5-23%H2O respectively. These results indicate that the solubility curve of NdP5O14 had a positive slope against temperature, which allowed us to apply a temperature gradient method for the crystal growth of NdP5O14. Polyhedral crystals of 0.5 mm in maximum size were grown at the upper part of a gold capsule (T{reversed tilde equals}400°C) through the transportation due to ΔT=100°C after 10 days. These crystals had flat and smooth surfaces and contained less bubble-shaped inclusions than crystals synthesized under isothermal conditions. Crystals obtained at the lower part of the gold capsule (T=500°C) were polyhedral 1 mm in maximum size. Growth experiments with ΔT=50°C yielded no crystals at the upper part in the capsule (T{reversed tilde equals}450°C), probably due to an insufficient transportation.

Original languageEnglish
Pages (from-to)333-339
Number of pages7
JournalJournal of Crystal Growth
Volume71
Issue number2
DOIs
Publication statusPublished - 1985 Jan 1

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Phase equilibria in the system Nd<sub>2</sub>O<sub>3</sub>-P<sub>2</sub>O<sub>5</sub>-H<sub>2</sub>O and growth of NdP<sub>5</sub>O<sub>14</sub> single crystals under hydrothermal conditions'. Together they form a unique fingerprint.

Cite this