01433nas a2200289 4500008003900000022001400039245009300053210006900146260001200215300001600227490000700243520053600250653001100786653002100797653001600818653002800834653002000862100002200882700002500904700002600929700002800955700001800983700001901001700002701020700002401047856007201071 2011 d a1530-698400aDynamically Modulating the Surface Plasmon Resonance of Doped Semiconductor Nanocrystals0 aDynamically Modulating the Surface Plasmon Resonance of Doped Se c10/2011 a4415 - 44200 v113 a

Localized surface plasmon absorption features arise at high doping levels in semiconductor nanocrystals, appearing in the near-infrared range. Here we show that the surface plasmons of tin-doped indium oxide nanocrystal films can be dynamically and reversibly tuned by postsynthetic electrochemical modulation of the electron concentration. Without ion intercalation and the associated material degradation, we induce a > 1200 nm shift in the plasmon wavelength and a factor of nearly three change in the carrier density.

10adoping10aindium tin oxide10ananocrystal10aspectroelectrochemistry10asurface plasmon1 aGarcia, Guillermo1 aBuonsanti, Raffaella1 aRunnerstrom, Evan, L.1 aMendelsberg, Rueben, J.1 aLlordes, Anna1 aAnders, André1 aRichardson, Thomas, J.1 aMilliron, Delia, J. uhttps://facades.lbl.gov/publications/dynamically-modulating-surface01524nas a2200157 4500008004100000050001500041245011400056210006900170260003600239490000600275520094200281100001901223700002401242700002701266856007301293 2008 eng d aLBNL-1089E00aElectrochromically switched, gas-reservoir metal hydride devices with application to energy-efficient windows0 aElectrochromically switched gasreservoir metal hydride devices w aEindhoven, Netherlandsc08/20030 v13 a

Proof-of-principle gas-reservoir MnNiMg electrochromic mirror devices have been investigated. In contrast to conventional electrochromic approaches, hydrogen is stored (at low concentration) in the gas volume between glass panes of the insulated glass units (IGUs). The elimination of a solid state ion storage layer simplifies the layer stack, enhances overall transmission, and reduces cost. The cyclic switching properties were demonstrated and system durability improved with the incorporation a thin Zr barrier layer between the MnNiMg layer and the Pd catalyst. Addition of 9% silver to the palladium catalyst further improved system durability. About 100 full cycles have been demonstrated before devices slow considerably. Degradation of device performance appears to be related to Pd catalyst mobility, rather than delamination or metal layer oxidation issues originally presumed likely to present significant challenges.

1 aAnders, André1 aSlack, Jonathan, L.1 aRichardson, Thomas, J. uhttps://facades.lbl.gov/publications/electrochromically-switched-gas01506nas a2200193 4500008003900000022001400039245006600053210006500119260001200184300001400196490000700210520091900217653002001136653002001156653002301176653001501199100002701214856007101241 2008 d a0141-159400aPhase transitions in non-hydride switchable mirror thin films0 aPhase transitions in nonhydride switchable mirror thin films c07/2008 a807 - 8130 v813 a

Switchable mirrors modulate incident light by changes in the reflectivity of thin films that are converted by chemical reactions from a metallic reflective state to a semiconducting transparent state. The reactions may be effected by exposure to a gas, by treatment with a liquid reagent, or by electrochemical means. The changes in optical properties coincide with phase transformations. In the examples reviewed here, the reactions are accompanied by substantial volume changes and atomic rearrangement. Bismuth, antimony, and antimony alloy films are switched by electrochemical lithiation. Copper films are electrochemically oxidized to Cu(I) and Cu(II) oxides, which are transparent and opaque, respectively. Morphological changes in all films during cycling lead to degradation in performance without loss of active material. Strategies to improve the cycling stability of these systems are discussed.

10aelectrochromism10aoptoelectronics10aSwitchable mirrors10athin films1 aRichardson, Thomas, J. uhttps://facades.lbl.gov/publications/phase-transitions-non-hydride00934nas a2200133 4500008004100000050001500041245004100056210004000097260002700137520050700164100002700671700002400698856007800722 2003 eng d aLBNL-5287000aLithium-Based Electrochromic Mirrors0 aLithiumBased Electrochromic Mirrors aParis, Francec04/20033 a

Antimony, antimony-copper, and antimony-silver thin films were prepared by DC magnetron sputtering on glass substrates. Their reflectance and transmittance in the visible range were measured before and after electrochemical lithiation. The mixed metal films exhibited larger changes in reflectance and small shifts in the optical absorption edge compared with pure antimony films. Electrochromic cycling speed and stability of the Sb-Li system were improved by the addition of copper and silver.

1 aRichardson, Thomas, J.1 aSlack, Jonathan, L. uhttps://facades.lbl.gov/publications/lithium-based-electrochromic-mirrors01488nas a2200169 4500008004100000245011300041210006900154260001200223300001400235490000700249520089100256100002401147700001901171700002701190700002301217856007801240 2002 eng d00aCalculation of Thermodynamic, Electronic, and Optical Properties of Monoclinic Mg2NiH40 aCalculation of Thermodynamic Electronic and Optical Properties o c04/2002 a4879-48850 v913 a

Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

1 aMyers, Whittier, R.1 aWang, Lin-Wang1 aRichardson, Thomas, J.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/calculation-thermodynamic-electronic01932nas a2200205 4500008004100000245010200041210006900143260001200212490000700224520122700231100002001458700002601478700002701504700002401531700002501555700002401580700002301604700002301627856007601650 2002 eng d00aIn Situ X-Ray Absorption Spectroscopy Study of Hydrogen Absorption by Nickel-Magnesium Thin Films0 aIn Situ XRay Absorption Spectroscopy Study of Hydrogen Absorptio c02/20030 v673 a

Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Codeposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied with Ni to Mg atomic ratio. Pure Mg films with Pd overlayers were converted to MgH2: The H atoms occupy regular sites as in bulk MgH2. Although optical switching was slow in the absence of Ni, the amount of H2 absorption was large. Incorporation of Ni in Mg films led to an increase in the speed of optical switching but decreased maximum transparency. Significant shifts in the Ni L3 and L2 peaks are consistent with strong interaction with hydrogen in the mixed films.

1 aFarangis, Baker1 aNachimuthu, Ponnusamy1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aPerera, Rupert, C.C.1 aGullikson, Eric, M.1 aLindle, Dennis, W.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/situ-x-ray-absorption-spectroscopy01574nas a2200145 4500008004100000050001500041245003800056210003800094260002400132300001200156490000800168520115000176100002701326856007501353 2002 eng d aLBNL-5141600aNew Electrochromic Mirror Systems0 aNew Electrochromic Mirror Systems aGolden, COc08/2002 a305-3080 v1653 a

Variable reflectance coatings (switchable mirrors) have significant advantages over traditional absorbing devices for radiant energy control in a variety of architectural and aerospace applications due to their large dynamic ranges in both transmission and reflection in the visible and near infrared regimes. Although electrochromic and gasochromic metal hydride films have been the primary focus of recent research in this field, other systems merit consideration. Two of these, based on electrochemical conversion of copper to copper oxides and of pnicogens to lithium pnictides are discussed here. Three distinct states are available in the copper system: the highly reflecting metal, the transparent Cu(I) oxide, and the black, highly absorbing Cu(II) oxide. Metallic thin films of elemental antimony and bismuth are reversibly converted to transparent, semiconducting lithium pnictides by cathodic polarization in a non-aqueous lithium electrolyte. Like the metal hydrides, these systems provide substantial modulation of near infrared transmission and reflection, but have somewhat lower visible reflectance in their mirror states.

1 aRichardson, Thomas, J. uhttps://facades.lbl.gov/publications/new-electrochromic-mirror-systems01573nas a2200241 4500008004100000245009300041210006900134260002400203520077100227653001000998653003101008653001101039653001501050653002201065100002001087700002601107700002701133700002401160700002101184700002501205700002301230856007801253 2002 eng d00aStructural and Electronic Properties of Magnesium-3D Transition Metal Switchable Mirrors0 aStructural and Electronic Properties of Magnesium3D Transition M aGolden, COc12/20023 a

We have observed reversible mirror-to-transparent state switching in a variety of mixed metal thin films containing magnesium and first-row transition elements including Ni, Fe, Co, Mn, and Ti. The very large changes in both reflectance and transmittance on loading these films with hydrogen are accompanied by significant structural and electronic transformations. The valence states and coordination of metal atoms during hydrogen loading were followed using dynamic in situ transmissionmode X-ray absorption spectroscopy. Time-resolved Mg K-edge and Ni, Co, Mn, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. These spectra are compared to those of reference materials and to predictions from calculations.

10aEXAFS10aHydrogen storage materials10aNEXAFS10athin films10ax-ray diffraction1 aFarangis, Baker1 aNachimuthu, Ponnusamy1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aMeyer, Bruno, K.1 aPerera, Rupert, C.C.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/structural-and-electronic-properties01599nas a2200265 4500008004100000245008300041210006900124260001200193300001200205490001200217520077700229653001001006653003101016653001101047653001501058653002201073100002701095700002001122700002401142700002601166700002501192700002201217700002301239856007101262 2002 eng d00aX-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films0 aXRay Absorption Spectroscopy of Transition MetalMagnesium Hydrid c08/2003 a204-2070 v356-3573 a

Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption spectroscopy. Mg K-edge and Ni, Co, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. A significant shift in the nickel L absorption edge shows it to be an active participant in hydride formation. The effect on cobalt and titanium is much less dramatic, suggesting that these metals act primarily as catalysts for formation of magnesium hydride.

10aEXAFS10aHydrogen storage materials10aNEXAFS10athin films10ax-ray diffraction1 aRichardson, Thomas, J.1 aFarangis, Baker1 aSlack, Jonathan, L.1 aNachimuthu, Ponnusamy1 aPerera, Rupert, C.C.1 aTamura, Nobumichi1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/x-ray-absorption-spectroscopy01381nas a2200169 4500008004100000245005700041210005700098260001200155300001400167490000700181520085100188100002701039700002401066700002001090700002301110856007801133 2001 eng d00aMixed Metal Films with Switchable Optical Properties0 aMixed Metal Films with Switchable Optical Properties c02/2002 a1349-13510 v803 a

Thin, Pd-capped metallic films containing magnesium and first row transition metals (Mn, Fe, Co) switch reversibly from their initial reflecting state to visually transparent states when exposed to gaseous hydrogen or following reduction cathodic polarization in an alkaline electrolyte. Reversion to the reflecting state is achieved by exposure to air or by anodic polarization. The films were prepared by co-sputtering from one magnesium target and one manganese, iron, or cobalt target. Both the dynamic optical switching range and the speed of the transition depend on the magnesium-transition metal ratio. Infrared spectra of films in the transparent, hydrided (deuterided) states support the presence of the intermetallic hydride phases Mg3MnH7, Mg2FeH6, and Mg2CoH5.

1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aFarangis, Baker1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/mixed-metal-films-switchable-optical01355nas a2200193 4500008004100000245005500041210005400096260001200150300001400162490000700176520076500183100002700948700002400975700002500999700002101024700002001045700002301065856007301088 2001 eng d00aSwitchable Mirrors Based on Nickel-Magnesium Films0 aSwitchable Mirrors Based on NickelMagnesium Films c05/2001 a3047-30490 v783 a

An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction, and to protect the metal surface against oxidation.

1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aArmitage, Robert, D.1 aKostecki, Robert1 aFarangis, Baker1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/switchable-mirrors-based-nickel01729nas a2200145 4500008004100000050001500041245004700056210004700103260002900150520125500179100002701434700002401461700002301485856007501508 2000 eng d aLBNL-4651000aElectrochromism in Copper Oxide Thin Films0 aElectrochromism in Copper Oxide Thin Films aUppsala, Swedenc08/20003 a

Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/electrochromism-copper-oxide-thin01143nas a2200157 4500008004100000050001500041245005700056210005700113260002900170300001400199490000700213520065000220100002700870700002300897856006500920 2000 eng d aLBNL-4661200aLiquid Phase Deposition of Electrochromic Thin Films0 aLiquid Phase Deposition of Electrochromic Thin Films aUppsala, Swedenc08/2000 a2119-21230 v463 a

Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

1 aRichardson, Thomas, J.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/liquid-phase-deposition00982nas a2200181 4500008004100000245006000041210005900101260001200160300001400172490000700186520046000193100002500653700002300678700002700701700001800728700001500746856003900761 1999 eng d00aSolid State Gadolinium-Magnesium Hydride Optical Switch0 aSolid State GadoliniumMagnesium Hydride Optical Switch c09/1999 a1863-18650 v753 a

The optical switching properties of gadolinium-magnesium hydride have been demonstrated in a solid-state electrochromic device. With positive polarization of the hydride electrode, the visible reflectance approaches 35% with virtually zero transmission, while with negative polarization, the visible transmission exceeds 25% at 650 nm. The switching is reversible, with intermediate optical properties between the transparent and reflecting states.

1 aArmitage, Robert, D.1 aRubin, Michael, D.1 aRichardson, Thomas, J.1 aO'Brien, Nada1 aChen, Yong uhttp://dx.doi.org/10.1063/1.12485301659nas a2200193 4500008004100000050001500041245009400056210006900150260002500219520098200244100002301226700002301249700002101272700002501293700002701318700002401345700002101369856007501390 1998 eng d aLBNL-4227700aEffect of Hydrogen Insertion on the Optical Properties of PD-Coated Magnesium Lanthanides0 aEffect of Hydrogen Insertion on the Optical Properties of PDCoat aLondon, U.K.c9/19983 a

Metallic magnesium lanthanide thin films upon insertion of hydrogen transform to a highly transparent hydride phase. With a Pd overlayer, the transformation can be produced either by electrochemical insertion of hydrogen or by exposing the film to hydrogen gas. Unlike amorphous oxide electrochromics, the transformation is accompanied by a large change in visible reflectance (about 50%). The optical switching effect in these materials is investigated in terms of changes in the complex refractive index as determined by variable-angle spectroscopic ellipsometric and normal-incidence radiometric measurements over the solar spectrum. Furthermore the optical effect of converting the Pd caplayer to Pd-H was determined. It is shown that the pd layer limits the visible transmittance of the hyrdrided stack to about 35-40%. Whereas the extinction coefficient of the dehydrided LnMg-layers at 550 nm is between 2.2 and 3.1, it is as low as 10-4 in the transparent state.

1 avon Rottkay, Klaus1 aRubin, Michael, D.1 aMichalak, Franck1 aArmitage, Robert, D.1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aDuine, Peter, A. uhttps://facades.lbl.gov/publications/effect-hydrogen-insertion-optical02282nas a2200229 4500008004100000245008200041210006900123260001200192300001000204490000700214520155300221653002501774653002801799653001501827100002301842700001701865700002701882700001901909700002301928700002401951856007701975 1998 eng d00aElectrochromic lithium nickel oxide by pulsed laser deposition and sputtering0 aElectrochromic lithium nickel oxide by pulsed laser deposition a c07/1998 a59-660 v543 a

Thin films of lithium nickel oxide were deposited by sputtering and pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder. The composition and structure of these films were analyzed using a variety of techniques, such as nuclear-reaction analysis, Rutherford backscattering spectrometry (RBS), X-ray diffraction, infrared spectroscopy, and atomic-force microscopy. Crystalline structure, surface morphology and chemical composition of LixNi1−xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate–target distance. The films produced at temperatures lower than 600°C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600°C proved to be stable in air over a long period. Even at room temperature the PLD films are denser and more stable than sputtered films. RBS determined the composition of the best films to be Li0.5Ni0.5O deposited by PLD at 60 mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0–3.4 V versus lithium. Electrochemical formatting which is used to develop electrochromism in other films is not needed for the stoichiometric films. The optical transmission range is almost 70% at 550 nm for 150 nm-thick films. Devices made from these films were analyzed using novel reference electrodes and by disassembling after cycling.

10aLithium nickel oxide10apulsed laser deposition10asputtering1 aRubin, Michael, D.1 aWen, Shi-Jie1 aRichardson, Thomas, J.1 aKerr, John, B.1 avon Rottkay, Klaus1 aSlack, Jonathan, L. uhttps://facades.lbl.gov/publications/electrochromic-lithium-nickel-oxide01510nas a2200181 4500008004100000050001500041245010000056210006900156300001400225490000700239520088500246100002101131700002301152700002701175700002401202700002301226856007901249 1998 eng d aLBNL-4227600aElectrochromic Lithium Nickel Oxide Thin Films by RF-Sputtering from a LiNiO2 Target0 aElectrochromic Lithium Nickel Oxide Thin Films by RFSputtering f a3085-30920 v443 a

Thin films of lithium nickel oxide were deposited by rf sputtering from a stoichiometric LiNiO2 target. The composition and structure of these films depended on the oxygen pressure during deposition (sputtering gas is Argon), and, to a certain extent, the target history. The sputtering geometry, i.e. the substrate to target distance and the sputtering angle were also critical. the films exhibit excellent reversibility in the potential range 1.1V to 3.8 V vs Li/Li+ and could be cycled in a liquid electrolyte half cell for more than 3000 cycles with a switching range ΔTvis close to 70%. The coloration efficiency in the visible was typically -30 to -40 cm2 C-1. The switching performance of a device utilizing a lithium nickel oxide film as counter electrode for a tungsten oxide electrochromic film is reported.

1 aMichalak, Franck1 avon Rottkay, Klaus1 aRichardson, Thomas, J.1 aSlack, Jonathan, L.1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/electrochromic-lithium-nickel-oxide-101511nas a2200181 4500008004100000050001500041245007100056210006900127260002400196490001000220520090600230100002701136700002301163700002401186700002101210700002301231856007501254 1998 eng d aLBNL-4238100aTungsten-Vanadium Oxide Sputtered Films for Electrochromic Devices0 aTungstenVanadium Oxide Sputtered Films for Electrochromic Device aBoston, MAc11/19980 v98-263 a

Mixed vanadium and tungsten oxide films with compositions ranging from 0 to 100% vanadium (metals basis) were prepared by reactive sputtering from metallic vanadium and tungsten targets in an atmosphere of argon and oxygen. The vanadium content varied smoothly with the fraction of total power applied to the vanadium target. Films containing vanadium were more color neutral than pure tungsten oxide films, tending to gray-brown at high V fraction. The electrochromic switching performance of these films was investigated by in situ monitoring of their visible transmittance during lithium insertion/extraction cycling in a non-aqueous electrolyte (1M LiClO4 in PC). the solar transmittance and reflectance was measured ex-situ. Films with vanadium content greater than about 15%, exhibited a marked decrease in switching range. The coloration efficiencies followed a similar trend.

1 aRichardson, Thomas, J.1 avon Rottkay, Klaus1 aSlack, Jonathan, L.1 aMichalak, Franck1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/tungsten-vanadium-oxide-sputtered02100nas a2200169 4500008004100000050001500041245008300056210006900139300001000208490001200218520153600230100002301766700001901789700002301808700002701831856007201858 1997 eng d aLBNL-4009600aAnalysis of Binary Electrochromic Tungsten Oxides with Effective Medium Theory0 aAnalysis of Binary Electrochromic Tungsten Oxides with Effective a50-550 v308-3093 a

Multicomponent oxides are of increasing interest for electrochromic electrodes. To reduce the large number of permutations in composition it would be useful to be able to predict the properties of the mixtures from the pure oxide components. WO3 mixed with V2O5 has been produced by a sol-gel technique in order to increase durability and color neutrality of conventional WO3 electrochromic coatings. Chemical composition was confirmed by Rutherford backscattering spectrometry (RBS). Surface morphology was analyzed by atomic force microscopy (AFM). Electrochromic performance of the films was tested by cyclic voltammetry with in-situ transmission control. Optical constants of vanadium tungsten oxides were determined over the whole solar spectrum. The measurements included variable angle spectroscopic ellipsometry and spectral transmittance and reflectance. An attempt is made to treat doped tungsten oxide as an effective medium consisting of a mixture of WO3 with V2O5. In the clear state, comparison of optical constants and thickness directly determined on the samples yields qualitative agreement with results from effective-medium analysis. The resulting component fraction also agrees as long as the film density does not deviate too much from the linearly interpolated value between the pure components. For the colored state, preferential trapping of electrons at one atom species hinders the application of effective medium theory.

1 avon Rottkay, Klaus1 aÖzer, Nilgün1 aRubin, Michael, D.1 aRichardson, Thomas, J. uhttps://facades.lbl.gov/publications/analysis-binary-electrochromic02057nas a2200229 4500008004100000050001500041245011100056210006900167260002700236300001100263490000900274520128000283653002601563653002801589653001901617653002201636100002301658700002701681700002301708700002401731856007201755 1997 eng d aLBNL-4066800aEffective Medium Approximation of the Optical properties of electrochromic cerium-titanium oxide compounds0 aEffective Medium Approximation of the Optical properties of elec aSan Diego, CAc07/1997 a19-Sep0 v31383 a

Cerium titanium oxide samples derived from a solution have been compared against sputtered films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture MAO2-MBO2. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophutometry. The spectral complex refractive index was determined for CeO2 and TiO2, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO2 and TiO2. In order to investigate the performance as passive counter-electrode in Li+ based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

10acerium titanium oxide10aeffective medium theory10aelectrochromic10aoptical constants1 avon Rottkay, Klaus1 aRichardson, Thomas, J.1 aRubin, Michael, D.1 aSlack, Jonathan, L. uhttps://facades.lbl.gov/publications/effective-medium-approximation01883nas a2200253 4500008004100000050001500041245008500056210006900141260003000210520107000240653001301310653002001323653004101343653001501384653002201399653001801421653000901439100002301448700002701471700002301498700002401521700001901545856006501564 1997 eng d aLBNL-4155000aInfluence of stoichiometry on the electrochromic cerium-titanium oxide compounds0 aInfluence of stoichiometry on the electrochromic ceriumtitanium  aHonolulu, Hawaiic11/19973 a

CeO2-TiO2 finds use as passive counter-electrode in electrochromic devices. Thin films were produced by dc-sputtering in a wide range of compositions. Influence of total pressure and oxygen partial pressure on the optical constants of TiO2 was investigated. Slightly substoichiometric TiO2 films exhibit a red-shift of the bandgap. The TiO2 content in the compound essentially determines the degree of cathodical coloring upon Li+ intercalation. However, pure TiO2 films with comparable visible transmittance in the clear state behave differently during electrochemical cycling depending on oxygen stoichiometry. Films that are deposited at higher total pressure are more oxygen rich and require initial formatting until current voltage cycles become stable. CeO2-TiO2 films of intermediate compositions have the relatively highest charge capacity. Comparison with atomic force microscopy indicates a correlation of small grain size with high charge capacity.

10aband gap10acharge capacity10aelectrochromic cerium titanium oxide10agrain size10aoptical constants10arms roughness10atio21 avon Rottkay, Klaus1 aRichardson, Thomas, J.1 aRubin, Michael, D.1 aSlack, Jonathan, L.1 aKullman, Lisen uhttps://facades.lbl.gov/publications/influence-stoichiometry