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

JOURNAL OF ALLOYS AND COMPOUNDS

卷:495

Article; Proceedings Paper

Massa, Nestor E.^1,5  Socolovsky, Leandro M.²  Knobel, Marcelo³  de la Cruz, Fernando P.¹  Zhang, XiXiang⁴ 

[1] Univ Nacl La Plata, Serv Espectroscopia Opt CEQUINOR, RA-1900 La Plata, Argentina

[2] Univ Buenos Aires, Inst Tecnol & Ciencias Ingn, Buenos Aires, DF, Argentina

[3] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083970 Campinas, SP, Brazil

[4] King Abdullah Univ Sci & Technol KAUST, Thuwal, Saudi Arabia

[5] Univ Nacl La Plata, LANAIS EFO CEQUINOR CONICET, Lab Nacl Invest, RA-1900 La Plata, Argentina

关键词: Granular films;    Oxides;    Electron-phonon interactions;    Infrared;    Light absorption and reflection;   

DOI  :  10.1016/j.jallcom.2009.10.228

来源: Elsevier

【 摘 要 】

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 Ni-x(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 similar to 0 84 and similar to 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 Ni-0 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 Ni-0 54(SiO2)(0 46) and Ni-0 28(SiO2)(0) (72) have well defined vibrational bands and a sharp threshold at similar to 1450 cm(-1) It is most remarkable that a distinctive resonant peak at similar to 1250cm(-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 (C) 2009 Elsevier B.V. All rights reserved

【 授权许可】

Free