title: Room temperature synthesis of Cu₂O nanospheres: optical properties and thermal behavior.
abstract: The present work reports a simple and easy wet chemistry synthesis of cuprous oxide (Cu2O) nanospheres at room temperature without surfactants and using different precursors. Structural characterization was carried out by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with focused ion beam and energy-dispersive X-ray spectroscopy. The optical band gaps were determined from diffuse reflectance spectroscopy. The photoluminescence behavior of the as-synthesized nanospheres showed significant differences depending on the precursors used. The Cu2O nanospheres were constituted by aggregates of nanocrystals, in which an on/off emission behavior of each individual nanocrystal was identified during transmission electron microscopy observations. The thermal behavior of the Cu2O nanospheres was investigated with in situ X-ray diffraction and differential scanning calorimetry experiments. Remarkable structural differences were observed for the nanospheres annealed in air, which turned into hollow spherical structures surrounded by outsized nanocrystals.
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Daniela
authors.initials: D
authors.lastname: Nunes
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Lídia
authors.initials: L
authors.lastname: Santos
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Duarte
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Pimentel
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Joana V
authors.initials: JV
authors.lastname: Pinto
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Barquinha
authors.affiliation: 2ICEMS,Instituto Superior Técnico,Universidade Técnica de Lisboa,Av. Rovisco Pais,1049-001 Lisboa,Portugal.
authors.forename: Patrícia A
authors.initials: PA
authors.lastname: Carvalho
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Elvira
authors.initials: E
authors.lastname: Fortunato
authors.affiliation: 1Departamento de Ciência dos Materiais,CENIMAT/I3N, Faculdade de Ciências e Tecnologia (FCT)Universidade Nova de Lisboa and CEMOP-UNINOVA,2829-516 Caparica,Portugal.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Martins
keywords: thermal behavior