Electrical and thermal conductivities of rare-earth A_(2)Zr_(2)O_(7) (A = Pr, Nd, Sm, Gd, and Er)

• A. Quiroz ^[1] ; V. García-Vázquez ^[2] ; C. Guarneros Aguilar ^[3] ; R. Agustín-Serrano ^[2] ; E. Chavira ^[4] ; M. Abatal ^[5]
  1. [1] Universidad Tecnológica de Xicotepec de Juárez. Puebla, México
  2. [2] Benemérita Universidad Autónoma de Puebla, México
  3. [3] CONACYT- Instituto Politécnico Nacional, Materiales y Tecnologías para Energía Salud y Medio Ambiente (GESMAT), Altamira, Tamaulipas, México
  4. [4] Universidad Nacional Autónoma de México, Ciudad de México, México
  5. [5] Universidad Autónoma del Carmen, Campeche, México

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• Localización: Revista Mexicana de Física, ISSN-e 0035-001X, Vol. 67, Nº. 2, 2021, págs. 255-262
• Idioma: inglés
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• Resumen

  • Structural and thermoelectric properties of rare-earth zirconates A_(2)Zr_(2)O_(7), with A = Pr, Nd, Sm, Gd, and Er, were studied. Samples were prepared by solid-state reaction at ambient pressure with temperatures between 1000 and 1400 °C. The resulting compounds were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDS). The XRD analyses showed the formation of polycrystalline Pr_(2)Zr_(2)O_(7), Nd_(2)Zr_(2)O_(7), Sm_(2)Zr_(2)O_(7), Gd_(2)Zr_(2)O_(7) and Er_(2)Zr_(2)O_(7) phases, with a cubic cell (space group Fm3m) and traces of the raw used materials. The micrographs obtained by SEM show the formation of heterogeneous grains with a size that ranges from 0.7 to 4.7 μm. All A_(2)Zr_(2)O_(7) samples present porous surfaces. Thermal conductivities were measured at different temperatures, from 300 to 900 K. In most of the samples, the thermal conductivity monotonically decreases with temperature, from 0.40 – 1.17 W/mK at 300 K to 0.27 – 0.77 W/mK at 773.15 K. At a fixed temperature, the thermal conductivity decreases almost monotonically with the ionic radius (IR) of the rare-earth elements (where IR (Er^(3+)) = 0.890 Å < IR (Gd^(3+)) = 0.938 Å < IR (Sm^(3+)) = 0.958 Å < IR (Nd^(3+)) = 0.983 Å < IR (Pr^(3+)) = 0.99 Å).