Refined structural studies on the fluorite-related polymorphs of sol-gel undoped and Eu³⁺-doped yttrium tantalates

Author(s)

Borges, Fernanda Hediger ; Guidorzi, Maria Vitoria ; Labaki, Hayra do Prado ; Ferreira, Rute A. S. ; Goncalves, Rogeria Rocha

• Document type: Journal article
• Source: DALTON TRANSACTIONS; v. 53, n. 13, p. 11-pg., 2024-03-05.

Abstract

Compounds with the general formula RE3MO7 (RE = rare earth ions; M = Ta, Nb, Sb, Ru, Ir, Os, Re, etc.), crystallize as a fluorite-related structure, forming polymorphs with different space groups. The space group strongly depends on the RE3+ and M5+ ionic radii and processing conditions. Structural characterization is well-established for the lanthanide series, but literature studies have divergent views about how to attribute yttrium tantalate (Y3TaO7) space groups-some authors have described the Y3TaO7 structure as orthorhombic and belonging to space group C222(1) or Ccmm, whereas others have assigned a cubic Fm (3) over barm structure to it. Here, we have characterized the structure of undoped and Eu3+-doped Y3TaO7 (0.1 to 50 mol% of Eu3+) samples synthesized by the sol-gel method that crystallized as a cubic disordered fluorite-type structure, space group Fm (3) over barm. Their powder X-ray diffraction measurements, Rietveld analyzes and Raman spectra were used as a conclusive technique of the structural properties. We have also investigated whether a secondary phase (M'-YTaO4) emerged in the samples and compared the phase composition of each sample to their Raman spectra. Low-temperature photoluminescence measurements (similar to 15 K) using Eu3+ as a structural probe helped us analyze the inhomogeneous broadening observed in the emission spectra. These measurements can be used as an important tool to attribute the crystalline phases of rare earth tantalates and niobates. (AU)

• FAPESP's process: 17/10424-3 - Luminescent rare earth tantalate and niobate: synthesis, properties and applications in photonics
• Grantee: Fernanda Hediger Borges Ribeiro
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 20/00277-6 - Development of nanoparticulate materials of lanthanide-doped rare earth tantalates for applications in Photonics
• Grantee: Fernanda Hediger Borges Ribeiro
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/04587-0 - Yttrium Tantalates and Niobates rare earth ions doped with emission in the visible and near infrared region for photonics applications
• Grantee: Fernanda Hediger Borges Ribeiro
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers
• Grantee: Hermi Felinto de Brito
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/05319-9 - Multifunctional plataforms based on lanthanide doped nanostructured luminescent materials for potential photonic and theranostic applications
• Grantee: Rogéria Rocha Gonçalves
• Support Opportunities: Regular Research Grants
• FAPESP's process: 22/16692-8 - "Rare earth ion-doped tantalate nanoparticles with persistent luminescence, energy upconversion and near-infrared emission for applications in nanomedicine"
• Grantee: Hayra do Prado Labaki
• Support Opportunities: Scholarships in Brazil - Doctorate