Dielectric Behavior of alpha-Ag2WO4 and its Huge Dielectric Loss Tangent

• Autor(a) principal: Jacomaci, Natalia [UNESP]
• Data de Publicação: 2019
• Outros Autores: Silva Junior, Euripedes [UNESP], Borges de Oliveira, Fernando Modesto, Longo, Elson, Zaghete, Maria Aparecida [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1590/1980-5373-MR-2019-0058; http://hdl.handle.net/11449/184691
• topic: Silver tungstate nanorods; dielectric behavior; ionic and electronic polarization

The microwave-assisted hydrothermal method was used to obtain alpha-Ag2WO4. Rietveld refinement confirmed that alpha-Ag2WO4 is stable in the orthorhombic phase, without secondary phase. However, field-effect scanning electron microscope analysis showed that alpha-Ag2WO4 nanorods surfaces contain silver nanoparticles, confirmed by the X-ray photoelectron spectroscopy by the peak observed at 374.39 eV In addition to metallic Ag, other Ag oxidation states were also observed on the surface. Hence, Ag (I) as Ag2O and Ag (I) as Ag(2)WO(4 )also were identified. DC measurements exhibited a high capacity of charge storage, nevertheless, with a large loss tangent (0.12 mu C.cm(-2).V-1) and no residual polarization for the voltage range between -100 V and +100 V. AC measurements at frequencies less than 275 Hz, revealed that ionic polarization is dominant, whereas at frequencies higher than 275 Hz, the electronic behavior predominates. The potential of electromagnetic energy conversion in thermal was observed from loss tangent analysis.