Sintering-driven effects on the band gap of (Pb,La)(Ti,Ni)O-3 photovoltaic ceramics

Autor(es)

Vargas, Natalia F. C. ^[1] ; Alkathy, Mahmoud S. ^[2] ; Eiras, Jose A. ^[2] ; Mastelaro, Valmor Roberto ^[3] ; Lente, Manuel H. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Fis, Sao Carlos - Brazil

^[3] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the American Ceramic Society; v. 104, n. 6 JAN 2021.
• Citações Web of Science: 0

Resumo

In this work, the influence of the sintering temperature on the physical properties of (Pb0.8La0.2)(Ti0.9Ni0.1)O-3 (PLT-Ni) ceramics is reported. The experimental data revealed that the energy band gap of PLT-Ni ceramics could be tailored from approximately 2.7 to 2.0 eV by changing the sintering temperature from 1100 degrees C to 1250 degrees C. It is demonstrated that the simple substitution of Ti4+ by Ni2+ cations is effective to decrease the intrinsic band gap while increasing the tetragonality factor and the spontaneous polarization. However, the additional red-shift observed in the absorption edge of the PLT-Ni with increasing the sintering temperature was associated with a continuous increase in the oxygen vacancies (VO2-) amount. It is believed that the impact of the creation of these thermally induced VO2- is manifold. The presence of VO2- and Ni2+ ions generate the Ni2+-VO2- defect-pairs that promoted both a decrease in the intrinsic band gap and an additional increase of the tetragonality factor, consequently, increasing the spontaneous polarization. The creation of Ni2+-VO2- defects also changed the local symmetry of Ni2+ ions from octahedral to a square pyramid, thus lifting the degeneracy of the Ni2+ 3d orbitals. With the increase in the sintering temperature, lower-energy absorbing intraband states were also formed due to an excess of VO2-, being responsible for an add-on shoulder in the absorption edge, extending the light absorption curve to longer wavelengths and leading to an additional absorption in ``all investigated{''} spectrum as well. (AU)

• Processo FAPESP: 19/03110-8 - Síntese e caracterização fotovoltaica de filmes finos à base de perovskitas ferroelétricas e multiferróicas para aplicação em células solares
• Beneficiário: Mahmoud Saleh Mohammed Alkathy
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 17/13769-1 - Materiais multiferróicos e ferroelétricos para conversores de energia: síntese, propriedades, fenomenologia e aplicações
• Beneficiário: José Antonio Eiras
• Modalidade de apoio: Auxílio à Pesquisa - Temático