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Impedance spectroscopy and 2-point conductivity measurements on thin films with ProboStat™

A ProboStat™ thin film setup for for the electrical characterization of thin films for both across-plane and in-plane comes in two variants, one for low temperatures (upto 200ºC) and one for high temperatures, under controlled atmosphere.

For across-plane measurements the film should be deposited on a conductive substrate and equipped with single or multiple Pt (or other) electrodes and for in-plane measurements the film should be deposited on non-conducting substrate with parallel line electrodes. Smallest recommended electrode resolution 1mm, largest recommended substrate dimensions 20 x 26mm. (For low temperature measurements in ambient atmosphere sample dimensions can be larger.)

The bottom electrode is a brass plate (gold plated for the high temperature setup). For across-plane measurements it acts normally as an electrode, and for in-plane measurements it is grounded to remove capacitance.

The two top electrodes are gold wire wrapped around a thin alumina bar, which is gently springloaded. The user can lift and place the top electrode(s) on any painted electrode dot or stripe.

The thin film measurement setup is compatible with standard ProboStat.

These articles refer to ProboStat or other NorECs products, filtered with keywords: 'thin film'  
ID=385

The structural and electrical properties of samarium doped ceria films formed by e-beam deposition technique

Authors Darius Virbukas, Giedrius Laukaitis
Source
Solid State Ionics
Time of Publication: 2016
Abstract Sm2O3-doped CeO2 (Sm0.15Ce0.85O1.925, SDC) thin films were formed by e-beam evaporation method. Thin films were formed evaporating micro powders (particle size varied from 0.3 to 0.5 μm). The influence of deposition rate on formed thin film structures and surface morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersion spectrometry (EDS), and atomic force microscopy (AFM). The deposition rate of formed SDC thin films was changed from 2 to 16 /s. The electrical properties were investigated as a function of frequency (0.1–106 Hz) at different temperatures (473–873 K). The formed SDC thin ceramic films repeat the crystallographic orientation of the initial powders using different substrates and different deposition rate. It was determined that crystallites size and samarium concentration are decreasing by increasing the deposition rate. The crystallites size decreased from 17.0 nm to 10.4 nm when SDC thin films were deposited on Alloy 600 (Fe-Ni-Cr), and decreased from 13.7 nm to 8.9 nm when were used optical quartz substrate. The best ionic conductivity σtot = 1.66 Sm− 1 at 873 K temperature, activation energy ΔEa = 0.87 eV (σg = 1.66 Sm− 1, σgb = 1.66 Sm− 1) was achieved when 2 /s deposition rate was used. The grain size (in the formed SDC thin films) was ~ 83 nm in this case.
Keywords Electron beam deposition; Samarium doped ceria oxide (SDC); Solid oxide fuel cells (SOFC); Ionic conductivity
Remark http://dx.doi.org/10.1016/j.ssi.2016.12.003
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ID=383

Oxygen ion conductivity in samarium and gadolinium stabilized cerium oxide heterostructures

Authors Marius Zienius, Kristina Bockute, Darius Virbukas, Giedrius Laukaitis
Source
Solid State Ionics
Time of Publication: 2016
Abstract Gadolinium (GDC) and samarium (SDC) doped ceria were investigated in terms of multilayer systems, evaporated by e-beam technique on optical quartz, Alloy600 and sapphire substrate. GDC-SDC heterostructures of 1.3 μm thicknesses, composed of 1, 2, 3, 5 and 7 layers and they were investigated by structural and ionic conductivity techniques. Bragg peaks show nanocrystalline state of Gd and Sm doped ceria thin films. XRD patterns show fluorite type structure with space group Fm3m. The XRD analysis of thin films, deposited on quartz substrate, reveals the increase of (220) peak with increasing number of layers. The decrease of (111) peak is slightly notable, also. Thin film heterostructures have a face-centered cubic cell with the following lattice parameters, such as 5.4180 nm for GDC of and of 5.4245 nm for SDC. The scanning electron microscopy cross sectional analysis of three-layered structure clearly indicates the interfaces of different material. There are no visually distinct discontinuities in higher layer structures (5–7 layers). Total conductivity increases linearly with increasing of temperature, but decreases with the increase of number of layers. The highest total ionic conductivity at 1214 K temperature for SDC and GDC thin monolayers was 1.62 S/m and 1.02 S/m, respectively. The activation energy increases with the increase of number of layer as well.
Keywords Multilayer electrolyte; SDC; GDC; e-Beam deposition
Remark http://dx.doi.org/10.1016/j.ssi.2016.11.025
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ID=361

Synthesis, characterization and performance of robust poison-resistant ultrathin film yttria stabilized zirconia – nickel anodes for application in solid electrolyte fuel cells

Authors F.J. Garcia-Garcia, F. Yubero, J.P. Espins, A.R. Gonzlez-Elipe, R.M. Lambert
Source
Journal of Power Sources
Volume: 324, Pages: 679–686
Time of Publication: 2016
Abstract We report on the synthesis of undoped ∼5 μm YSZ-Ni porous thin films prepared by reactive pulsed DC magnetron sputtering at an oblique angle of incidence. Pre-calcination of the amorphous unmodified precursor layers followed by reduction produces a film consisting of uniformly distributed tilted columnar aggregates having extensive three-phase boundaries and favorable gas diffusion characteristics. Similarly prepared films doped with 1.2 at.% Au are also porous and contain highly dispersed gold present as Ni-Au alloy particles whose surfaces are strongly enriched with Au. With hydrogen as fuel, the performance of the undoped thin film anodes is comparable to that of 10–20 times thicker typical commercial anodes. With a 1:1 steam/carbon feed, the un-doped anode cell current rapidly falls to zero after 60 h. In striking contrast, the initial performance of the Au-doped anode is much higher and remains unaffected after 170 h. Under deliberately harsh conditions the performance of the Au-doped anodes decreases progressively, almost certainly due to carbon deposition. Even so, the cell maintains some activity after 3 days operation in dramatic contrast with the un-doped anode, which stops working after only three hours of use. The implications and possible practical application of these findings are discussed.
Keywords Magnetron sputtering; Oblique angle deposition; Thin film anodes; Carbon-tolerant; SOFC
Remark doi:10.1016/j.jpowsour.2016.05.124
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ID=360

Electrical characterization of amorphous LiAlO2 thin films deposited by atomic layer deposition

Authors Yang Hu, Amund Ruud, Ville Miikkulainen, Truls Norby, Ola Nilsen and Helmer Fjellvg
Source
RSC Advances
Volume: 6, Issue: 65, Pages: 60479-60486
Time of Publication: 2016
Abstract LiAlO2 thin films deposited by atomic layer deposition (ALD) have a potential application as an electrolyte in three-dimensional (3D) all-solid-state microbatteries. In this study, Li-ion conductivity of such films is investigated by both in-plane and cross-plane methods. LiAlO2 thin films with a Li composition of [Li]/([Li] + [Al]) = 0.46 and an amorphous structure were grown by ALD with thicknesses of 90, 160 and 235 nm on different substrates. The electrical characterization was conducted by impedance spectroscopy using inert electrodes over a temperature range of 25–200 C in an inert atmosphere. In-plane conductivities were obtained from films on insulating sapphire substrates, whereas cross-plane conductivities were measured from films on conducting titanium substrates. For the first time, comparison of the in-plane and cross-plane conductivities in these ALD LiAlO2 films has been achieved. More comparable results are obtained using a cross-plane method, whereas in-plane conductivity measurements demonstrate a considerable thickness-dependence with thinner film thickness. The room-temperature conductivity of the LiAlO2 films has been determined to be in the order of 10−10 S cm−1 with an activation energy of ca. 0.8 eV.
Remark DOI: 10.1039/C6RA03137D
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ID=359

Thin film YSZ-based limiting current-type oxygen and humidity sensor on thermally oxidized silicon substrates

Author Shunsuke Akasaka
Source
Sensors and Actuators B: Chemical
Volume: 236, Pages: 499–505
Time of Publication: 2016
Abstract In this paper, we propose a thin film yttria-stabilized-zirconia (YSZ)-based limiting current-type oxygen and humidity sensor. These sensors were fabricated from layers of thin films on thermally oxidized silicon substrates, with the intention of installing such sensors onto microheaters. Sputtered porous Pt cathode are situated beneath the YSZ films, and are designed to provide a gas diffusion layer as well as function as electrodes. The porous Pt layer exhibits good performance as a gas diffusion layer because of its small pore size. Optimized YSZ sputtering growth conditions result in in-plane densification without the presence of cracks. The temperature dependence of the oxygen sensor’s level of limiting current was T −0.5. This result was attributed to the shrinkage of the extremely small pores in the gas diffusion layer. Between 450 and 550 C, following the application of a voltage of 1.1 V, the time response measurements show a rapid response of a few seconds. The oxygen concentration and water vapor pressure correspond to the level of the limiting current at 1.1 V and 1.8 V, respectively.
Keywords Yttria-stabilized-zirconia; Limiting current; Oxygen sensor; Humidity sensor; Thin film; Silicon substrate
Remark doi:10.1016/j.snb.2016.06.025
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ID=351

Magnetron-Sputtered YSZ and CGO Electrolytes for SOFC

Authors A. A. Solovyev , A. V. Shipilova, I. V. Ionov, A. N. Kovalchuk, S. V. Rabotkin, V. O. Oskirko
Source
Journal of Electronic Materials
Time of Publication: 2016
Abstract Reactive magnetron sputtering has been used for deposition of yttria-stabilized ZrO2 (YSZ) and gadolinium-doped CeO2 (CGO) layers on NiO-YSZ commercial anodes for solid oxide fuel cells. To increase the deposition rate and improve the quality of the sputtered thin oxide films, asymmetric bipolar pulse magnetron sputtering was applied. Three types of anode-supported cells, with single-layer YSZ or CGO and YSZ/CGO bilayer electrolyte, were prepared and investigated. Optimal thickness of oxide layers was determined experimentally. Based on the electrochemical characteristics of the cells, it is shown that, at lower operating temperatures of 650C to 700C, the cells with single-layer CGO electrolyte are most effective. The power density of these fuel cells exceeds that of the cell based on YSZ single-layer electrolyte at the same temperature. Power densities of 650 mW cm−2 and 500 mW cm−2 at 700C were demonstrated by cells with single-layer YSZ and CGO electrolyte, respectively. Significantly enhanced maximum power density was achieved in a bilayer-electrolyte single cell, as compared with cells with a single electrolyte layer. Maximum power density of 1.25 W cm−2 at 800C and 1 W cm−2 at 750C under voltage of 0.7 V were achieved for the YSZ/CGO bilayer electrolyte cell with YSZ and CGO thickness of about 4 μm and 1.5 μm, respectively. This signifies that the YSZ thin film serves as a blocking layer to prevent electrical current leakage in the CGO layer, leading to the overall enhanced performance. This performance is comparable to the state of the art for cells based on YSZ/CGO bilayer electrolyte.
Keywords Solid oxide fuel cell CGO YSZ bilayer electrolyte magnetron sputtering pulse electron-beam treatment
Remark Link
ID=281

Structural and electrical study of samarium doped cerium oxide thin films prepared by e-beam evaporation

Authors Darius Virbukas, Mantas Sriubas, Giedrius Laukaitis
Source
Solid State Ionics
Time of Publication: 2014
Abstract Samarium doped cerium oxide (Sm0.15Ce0.85O1.925, SDC) thin films were grown on the Alloy 600 (Fe–Ni–Cr) and optical quartz (SiO2) substrates using e-beam deposition technique. Formed SDC thin films were characterized using different X-ray diffraction (XRD) techniques, scanning electron microscope (SEM), energy-dispersive spectrometry (EDS) and impedance spectroscopy. The deposition rate of formed SDC thin films was changed from 2 /s to 16 /s. XRD analysis shows that all thin films have a cubic (FCC) structure and repeat the crystallographic orientation of the initial powders evaporated with different deposition rate and on different substrates. The crystallite size increases from 7.7 nm to 10.3 nm and from 7.2 nm to 9.2 nm on Alloy 600 substrate and optical quartz (SiO2) substrate respectively as the thin film deposition rate increases. SEM images indicate a dense and homogeneous structure of all formed SDC thin films. The ionic conductivity depends on thin films density and blocking factor. The best ionic conductivity (σg = 1.34 Sm− 1 and σgb = 2.29 Sm −1 at 873 K temperature, activation energy ΔEg = 0.91 eV and ΔEgb = 0.99 eV) was achieved for SDC thin films formed at 4 /s deposition rate. It was found that the highest density (5.25 g/cm3) and the lowest relaxation time in grain (τg = 9.83 10− 7 s), and the lowest blocking factor (0.39) is in SDC thin films formed at 4 /s deposition rate. The deposition rate influences the stoichiometry of the formed SDC thin ceramic films.
Keywords Electron beam deposition; Samarium doped ceria oxide (SDC); Solid oxide fuel cells (SOFC); Ionic conductivity
Remark DOI: 10.1016/j.ssi.2014.09.036
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ID=215

The Investigation of E-beam Deposited Titanium Dioxide and Calcium Titanate Thin Films

Authors Kristina BOČKUTĖ, Giedrius LAUKAITIS, Darius VIRBUKAS, Darius MILČIUS
Source
MATERIALS SCIENCE (MEDIAGOTYRA)
Volume: 19, Issue: 3, Pages: 245-249
Time of Publication: 2013
Abstract Thin titanium dioxide and calcium titanate films were deposited using electron beam evaporation technique. The substrate temperature during the deposition was changed from room temperature to 600 C to test its influence on TiO2 film formation and optical properties. The properties of CaTiO3 were investigated also. For the evaluation of the structural properties the formed thin ceramic films were studied by X-ray diffraction (XRD), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties of thin TiO2 ceramics were investigated using optical spectroscope and the experimental data were collected in the ultraviolet-visible and near-infrared ranges with a step width of 1 nm. Electrical properties were investigated by impedance spectroscopy.It was found that substrate temperature has influence on the formed thin films density. The density increased when the substrate temperature increased. Substrate temperature had influence on the crystallographic, structural and optical properties also.
Keywords electron beam evaporation; titanium oxide; calcium titanate; optical properties
Remark DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1805
Link
ID=178

Nd-doped Ba(Ce,Zr)O3 − δ proton conductors for application in conversion of CO2 into liquid fuels

Authors Wojciech Zając , Emil Hanc, Agnieszka Gorzkowska-Sobas, Konrad Świerczek, Janina Molenda
Source
Solid State Ionics
Volume: 225, Pages: 297–303
Time of Publication: 2012-10
Abstract The paper presents crystal structure, transport properties, chemical stability in CO2 atmosphere and thin film membrane preparation for materials from the Ba(Ce1 − xZrx)0.9Nd0.1O2.95 (x = 0, 0.25, 0.5, 0.75, 1) group of perovskite-type structure oxides. Transformation of crystal structure from orthorhombic Pnma to orthorhombic Imma and cubic with increasing xZr was observed along with linear decrease of pseudo-cubic unit cell volume and free lattice volume. Electrical conductivity of bulk and grain boundary was determined in dry air, as well as in air humidified with H2O or D2O. The highest proton conductivity was observed for material with xZr = 0.25. Further increase of Zr content led to decrease of conductivity as high as 2 orders of magnitude. This effect was coupled with bell-shape dependence of activation energy and pre-exponential term. Such behavior was explained as superimposed effects of high proton mobility for zirconium-rich materials due to cubic symmetry and cerium-rich materials due to softness of oxygen–oxygen separation distance, along with high proton concentration for cerium-rich perovskites. The deteriorating effect of grain boundaries on total electrical conductivity was far more pronounced for Zr-rich materials than in the case of Ce-rich ones. Declining grain boundary conductivity was attributed to both increase of number of grain boundaries and decrease of inherent grain boundary conductivity for Zr-rich samples. The highest chemical stability in CO2 atmosphere was achieved for high-Zr content materials, on the contrary, for BaCe0.9Nd0.1O2.95 in CO2 atmosphere, the decomposition onset temperature was below 500 C. 2 μm thin film membrane of Ba(Ce0.75Zr0.25)0.9Nd0.1O2.95 was successfully prepared on c-plane sapphire and fused silica substrates. Film's crystal structure matched that of the bulk material. The electrical conductivity of thermally treated film obtained on c-plane sapphire in wet air was 3.7 10− 4 S cm− 1 at 600 C.
Keywords Proton conductors; BaCeO3–BaZrO3 solid solutions; Isotope effect; Grain boundary effect; Thin films
Remark Link
ID=121

Solid oxide fuel cells with Sm0.2Ce0.8O2−δ electrolyte film deposited by novel aerosol deposition method

Authors Sea-Fue Wang, Yung-Fu Hsu, Chih-Hao Wang and Chin-Ting Yeh
Source
Journal of Power Sources
Volume: 196, Issue: 11, Pages: 5064-5069
Time of Publication: 2011-06
Abstract In this study, dense electrolyte ceramic Sm0.2Ce0.8O2−δ (SDC) thin films are successfully deposited on NiO-SDC anode substrate by aerosol deposition (AD) with oxygen as the carrier gas at the substrate temperature ranging from room temperature to 300 C. To remove the effect of humidity on the starting powders, this study found that, in depositing SDC films, having the starting powders preheat-treated at 200 C helped generate a smooth and dense layer, though a lower deposition rate was achieved. At a deposition time of 22 min, SDC films with a uniform thickness of 1.5 μm and grain sizes of ≈67 nm are obtained. SOFC single cells are then built by screen printing a LSCF cathode on the anode-supported substrates with SDC electrolyte. The cross-sectional SEM micrographs exhibit highly dense, granular, and crack-free microstructures. The open circuit voltages (OCV) of the single cells decrease with the rise in temperature, dropping from 0.81 V at 500 C to 0.59 V at 700 C. Maximum power densities (MPD) decline with decreasing operating temperature from 0.34 to 0.01 W cm−2 due to the increase of the R0 and RP of the single cells. The electrochemical results testify to the fine quality of SDC films as well as illustrate the electrolyte thickness effect and the effect of mixed ionic and electronic conduction of the SDC electrolyte in the reducing atmosphere.
Keywords SDC films, NiO-SDC substrate, aerosol deposition, Very dense SDC films, uniform thickness of 1.5 μm, Single cell with a MPD of 0.34 W cm−2, 700 C, Solid oxide fuel cell; Ceria; Aerosol deposition; Electrolyte
ID=105

Scandium stabilized zirconium thin films formation by e-beam technique

Authors Darius Virbukas, Giedrius Laukaitis, Julius Dudonis, Oresta Katkauskė and Darius Milčius
Source
Solid State Ionics
Volume: 184, Issue: 1, Pages: 10–13
Time of Publication: 2011-03
Abstract Scandiumstabilizedzirconium (10ScSZ) thin ceramic films were deposited by e-beam evaporation of (ZrO2)0.90(Sc2O3)0.10 micro powder (particle size 0.5 0.7 μm). The influence of deposition rate on formed thinfilms microstructure and electrical properties was studied. 10ScSZ thinfilms were deposited on two types of different substrates: optical quartz (SiO2) and Alloy-600 (Fe–Ni–Cr) substrates. Deposition rate was changed from 2 to 16 /s to test its influence on thinfilmformation and its properties. The microstructure of formed 10ScSZ thin ceramic films was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrical parameters of formed thin ceramics were investigated in the frequency range from 0.1 Hz to 1.0 MHz (in temperature range from 473 to 873 K). The ionic conductivity of the deposited electrolyte 10ScSZ thinfilms was determined by impedance spectroscopy. It was determined that the deposition rate (in range from 2 to 16 /s) has influence on crystallite size. It increases by increasing the deposition rate from 18.4 to 26.9 nm. The XRD measurements show that the formed 10ScSZ thinfilms do not repeat the crystallographic phase of the initial evaporated powder material—it is changes from rhombohedra (initial powder) to cubic (the formed thinfilms).
Keywords Scandium stabilized zirconium (ScSZ); Ionic conductivity; Electron beam deposition; Solid oxide fuel cells (SOFC)
Remark Link
ID=94

The properties of scandium and cerium stabilized zirconium thin films formed by e-beam technique

Authors Darius Virbukas, Giedrius Laukaitis, Julius Dudonis and Darius Milčius
Source
Solid State Ionics
Volume: 188, Issue: 1, Pages: 46–49
Time of Publication: 2011-04
Abstract Scandium and ceriumstabilizedzirconium (10Sc1CeSZ) thin ceramic films were formed evaporating (ZrO2)0.89(CeO2)0.01(Sc2O3)0.10 micro powder using e-beam evaporation technique. The influence of deposition rate on formedthinfilms electrical properties and microstructure was studied. 10Sc1CeSZ thinfilms were deposited on two types of different substrates: optical quartz (SiO2) and Alloy 600 (Fe–Ni–Cr). Deposition rate was changed from 2 to 16 /s to understand its influence on thinfilm formation and other properties. The formed 10Sc1CeSZ thinfilms keep the cubic crystal structure as the initial evaporated powder material but change the main crystallographic peak from (111) to (200) for both types of substrate and used deposition rates. It was determined that the crystallites size increases from 19.0 to 24.9 nm and from 15.6 to 19.9 nm on optical quartz and Alloy 600 respectively by increasing the deposition rate (in range from 2 to 16 /s). The thinfilm density decreases by increasing the deposition rate. The ionic conductivity of 10Sc1CeSZ thinfilms was determined by impedance spectroscopy in the frequency range from 0.1 Hz to 1.0 MHz in temperature range from 473 K to 873 K. The best ionic conductivity σtot = 4.91 10− 2 Sm− 1 at 873 K temperature and the lowest value of activation energy ΔEa = 0.88 eV were found for 10Sc1CeSZ thinfilmsformed at 4 /s deposition rate.
Keywords Scandium and cerium stabilized zirconium (10Sc1CeSZ); Electron beam deposition; Solid oxide fuel cells (SOFC); Ionic conductivity
Remark Link
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