Publication detail

Formation of strontium-yttrium germanium anionic lacunar apatite (Sr2+δY6.67+(2δ/3)[GeO4]6O2δ) as the intermediate phase of oxygen-rich yttrium-germanium apatite (Y9.333+ε[GeO4]6O2+3/2ε)

PTÁČEK, P. OPRAVIL, T. ŠOUKAL, F. BARTONÍČKOVÁ, E. TKACZ, J.

Original Title

Formation of strontium-yttrium germanium anionic lacunar apatite (Sr2+δY6.67+(2δ/3)[GeO4]6O2δ) as the intermediate phase of oxygen-rich yttrium-germanium apatite (Y9.333+ε[GeO4]6O2+3/2ε)

Type

journal article in Web of Science

Language

English

Original Abstract

The formation of metastable strontium-yttrium(III) (hexakis) germanium(IV) lacunar apatite (P63/m, a=11.426 Å, c=8.224 Å and Z=2) was observed during the thermal treatment of SrCO3, Y2O3, and GeO2 powder precursors using the ceramic method in an oxygen atmosphere. The utilization of an oxygen atmosphere restricts the extensive reduction of GeO2 and enables us to explain a new potential mechanism for the stabilization of lead-free lacunar apatites. This mechanism involves the use of electrons localized in a neighborhood of oxygen vacancies. Charged vacancies serve as active sites for the ionosorption of oxygen molecules and their subsequent transformation into lattice oxygen anions, which fill the vacancies at the X-site. The estimation of system thermodynamics shows that apatite undergoes a transformation to a more stable state at δ≥0.1, i.e., at the value that corresponds to the composition of prepared apatite. As the temperature and time of the thermal treatment increases, the process of incongruent melting leads to the formation of oxygen-rich yttrium-germanium apatite (YGAp, Y9.333+ε[GeO4]6O2+3/2ε) and strontium-yttrium-germanium glass. The YGAp phase is also formed during the annealing of lacunar apatite in an oxygen atmosphere.

Keywords

Apatite, Yttrium-germanium apatiteLacunar apatiteOxygen-rich apatiteCeramic method

Authors

PTÁČEK, P.; OPRAVIL, T.; ŠOUKAL, F.; BARTONÍČKOVÁ, E.; TKACZ, J.

Released

31. 7. 2017

Publisher

Elsevier Ltd

Location

THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND

ISBN

0272-8842

Periodical

Ceramics International

Year of study

10

Number

43

State

United Kingdom of Great Britain and Northern Ireland

Pages from

7827

Pages to

7838

Pages count

12

URL

http://www.sciencedirect.com/science/article/pii/S0272884217304686

BibTex

@article{BUT141541,
  author="Petr {Ptáček} and Tomáš {Opravil} and František {Šoukal} and Eva {Bartoníčková} and Jakub {Tkacz}",
  title="Formation of strontium-yttrium germanium anionic lacunar apatite (Sr2+δY6.67+(2δ/3)[GeO4]6O2δ) as the intermediate phase of oxygen-rich yttrium-germanium apatite (Y9.333+ε[GeO4]6O2+3/2ε)",
  journal="Ceramics International",
  year="2017",
  volume="10",
  number="43",
  pages="7827--7838",
  doi="10.1016/j.ceramint.2017.03.097",
  issn="0272-8842",
  url="http://www.sciencedirect.com/science/article/pii/S0272884217304686"
}