Far infrared near normal specular reflectivity of Nix(SiO2)1-x (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) granular films

Handle URI:
http://hdl.handle.net/10754/561466
Title:
Far infrared near normal specular reflectivity of Nix(SiO2)1-x (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) granular films
Authors:
Massa, Néstor E.; Denardin, Juliano C.; Socolovsky, Leandro M.; Knobel, Marcelo; De La Cruz, Fernando Pablo; Zhang, Xixiang ( 0000-0002-3478-6414 )
Abstract:
One of the current issues at the basis of the understanding of novel materials is the degree of the role played by spatial inhomogeneities due to subtle phase separations. To clarify this picture here we compare the plain glass network response of transition metal granular films with different metal fractions against what is known for conducting oxides. Films for Nix(SiO2)1-x (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) were studied by temperature dependent far infrared measurements. While for pure Ni the spectrum shows a flat high reflectivity, those for x ∼ 0.84 and ∼0.75 have a Drude component, vibrational modes mostly carrier screened, and a long tail that extents toward near infrared. This is associated with hopping electron conductivity and strong electron-phonon interactions. The relative reduction of the number of carriers in Ni0.75(SiO2)0.25 allows less screened phonon bands on the top of a continuum and a wide and overdamped oscillator at mid-infrared frequencies. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ∼1450 cm-1. It is most remarkable that a distinctive resonant peak at ∼1250 cm-1 found for p-polarized angle dependent specular reflectivity. It originates in an electron cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating network polarons are formed. © 2009 Elsevier B.V. All rights reserved.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program
Publisher:
Elsevier BV
Journal:
Journal of Alloys and Compounds
Issue Date:
Apr-2010
DOI:
10.1016/j.jallcom.2009.10.228
Type:
Article
ISSN:
09258388
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorMassa, Néstor E.en
dc.contributor.authorDenardin, Juliano C.en
dc.contributor.authorSocolovsky, Leandro M.en
dc.contributor.authorKnobel, Marceloen
dc.contributor.authorDe La Cruz, Fernando Pabloen
dc.contributor.authorZhang, Xixiangen
dc.date.accessioned2015-08-02T09:12:05Zen
dc.date.available2015-08-02T09:12:05Zen
dc.date.issued2010-04en
dc.identifier.issn09258388en
dc.identifier.doi10.1016/j.jallcom.2009.10.228en
dc.identifier.urihttp://hdl.handle.net/10754/561466en
dc.description.abstractOne of the current issues at the basis of the understanding of novel materials is the degree of the role played by spatial inhomogeneities due to subtle phase separations. To clarify this picture here we compare the plain glass network response of transition metal granular films with different metal fractions against what is known for conducting oxides. Films for Nix(SiO2)1-x (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) were studied by temperature dependent far infrared measurements. While for pure Ni the spectrum shows a flat high reflectivity, those for x ∼ 0.84 and ∼0.75 have a Drude component, vibrational modes mostly carrier screened, and a long tail that extents toward near infrared. This is associated with hopping electron conductivity and strong electron-phonon interactions. The relative reduction of the number of carriers in Ni0.75(SiO2)0.25 allows less screened phonon bands on the top of a continuum and a wide and overdamped oscillator at mid-infrared frequencies. Ni0.54(SiO2)0.46 and Ni0.28(SiO2)0.72 have well defined vibrational bands and a sharp threshold at ∼1450 cm-1. It is most remarkable that a distinctive resonant peak at ∼1250 cm-1 found for p-polarized angle dependent specular reflectivity. It originates in an electron cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating network polarons are formed. © 2009 Elsevier B.V. All rights reserved.en
dc.publisherElsevier BVen
dc.subjectElectron-phonon interactionsen
dc.subjectGranular filmsen
dc.subjectInfrareden
dc.subjectLight absorption and reflectionen
dc.subjectOxidesen
dc.titleFar infrared near normal specular reflectivity of Nix(SiO2)1-x (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) granular filmsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.identifier.journalJournal of Alloys and Compoundsen
dc.contributor.institutionLaboratorio Nacional de Investigación y Servicios en Espectroscopía Optica-CEQUINOR, Universidad Nacional de La Plata, C.C. 962, 1900 La Plata, Argentinaen
dc.contributor.institutionDepartamento de Física, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago, Chileen
dc.contributor.institutionInstituto de Tecnologías y Ciencias de la Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón, 850 Buenos Aires, Argentinaen
dc.contributor.institutionInstituto de Física, Gleb Wataghin, Universidade Estadual de Campinas, 13083-970 Campinas, SP, Brazilen
kaust.authorZhang, Xixiangen
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