scholarly journals Linking the Electrical Conductivity and Non-Stoichiometry of Thin Film Ce1−xZrxO2−δ by a Resonant Nanobalance Approach

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 748
Author(s):  
Iurii Kogut ◽  
Alexander Wollbrink ◽  
Carsten Steiner ◽  
Hendrik Wulfmeier ◽  
Fatima-Ezzahrae El Azzouzi ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Electronic Conductivity ◽  
Oxygen Storage ◽  
Partial Pressures ◽  
Maximum Conductivity ◽  
Defect Interactions

Bulk ceria-zirconia solid solutions (Ce1−xZrxO2−δ, CZO) are highly suited for application as oxygen storage materials in automotive three-way catalytic converters (TWC) due to the high levels of achievable oxygen non-stoichiometry δ. In thin film CZO, the oxygen storage properties are expected to be further enhanced. The present study addresses this aspect. CZO thin films with 0 ≤ x ≤ 1 were investigated. A unique nano-thermogravimetric method for thin films that is based on the resonant nanobalance approach for high-temperature characterization of oxygen non-stoichiometry in CZO was implemented. The high-temperature electrical conductivity and the non-stoichiometry δ of CZO were measured under oxygen partial pressures pO2 in the range of 10−24–0.2 bar. Markedly enhanced reducibility and electronic conductivity of CeO2-ZrO2 as compared to CeO2−δ and ZrO2 were observed. A comparison of temperature- and pO2-dependences of the non-stoichiometry of thin films with literature data for bulk Ce1−xZrxO2−δ shows enhanced reducibility in the former. The maximum conductivity was found for Ce0.8Zr0.2O2−δ, whereas Ce0.5Zr0.5O2-δ showed the highest non-stoichiometry, yielding δ = 0.16 at 900 °C and pO2 of 10−14 bar. The defect interactions in Ce1−xZrxO2−δ are analyzed in the framework of defect models for ceria and zirconia.

scholarly journals Comparison of the electrical conductivity of bulk and film Ce1–xZrxO2–δ in oxygen-depleted atmospheres at high temperatures

2021 ◽  
Author(s):  
Iurii Kogut ◽  
Carsten Steiner ◽  
Hendrik Wulfmeier ◽  
Alexander Wollbrink ◽  
Gunter Hagen ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
High Temperatures ◽  
Ionic Conduction ◽  
Electronic Conductivity ◽  
Oxygen Storage ◽  
Coarse Grained ◽  
Reducing Conditions ◽  
Partial Pressures ◽  
Microstructural Effects ◽  
Defect Interactions

AbstractFeaturing high levels of achievable oxygen non-stoichiometry δ, Ce1−xZrxO2−δ solid solutions (CZO) are crucial for application as oxygen storage materials in, for example, automotive three-way catalytic converters (TWC). The use of CZO in form of films combined with simple manufacturing methods is beneficial in view of device miniaturization and reducing of TWC manufacturing costs. In this study, a comparative microstructural and electrochemical characterization of film and conventional bulk CZO is performed using X-ray diffractometry, scanning electron microscopy, and impedance spectroscopy. The films were composed of grains with dimensions of 100 nm or less, and the bulk samples had about 1 µm large grains. The electrical behavior of nanostructured films and coarse-grained bulk CZO (x > 0) was qualitatively similar at high temperatures and under reducing atmospheres. This is explained by dominating effect of Zr addition, which masks microstructural effects on electrical conductivity, enhances the reducibility, and favors strongly electronic conductivity of CZO at temperatures even 200 K lower than those for pure ceria. The nanostructured CeO2 films had much higher electrical conductivity with different trends in dependence on temperature and reducing atmospheres than their bulk counterparts. For the latter, the conductivity was dominantly electronic, and microstructural effects were significant at T < 700 °C. Nanostructural peculiarities of CeO2 films are assumed to induce their more pronounced ionic conduction at medium oxygen partial pressures and relatively low temperatures. The defect interactions in bulk and film CZO under reducing conditions are discussed in the framework of conventional defect models for ceria.

Preparation and Characterization of Novel Lithium Tantalate Target

2011 ◽  
Vol 117-119 ◽  
pp. 840-844
Author(s):  
Xu Yong Wu ◽  
De Yin Zhang ◽  
Kun Li
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Temperature ◽  
Ion Beam ◽  
Sol Gel ◽  
Lithium Tantalate ◽  
Lithium Oxide ◽  
The Novel ◽  
Sol Gel Process

The novel lithium enriched lithium tantalate (LiTaO3) targets were papered by employing the sol-gel process and the high temperature sintered process. The sol of LiTaO3 was firstly prepared through reacting lithium ethoxide with tantalum ethoxide. The LiTaO3 powder was fabricated by presintered LiTaO3 dry gel 4 hour, at 800°C. The 11cm13cm1cm lithium enriched LiTaO3 target samples were prepared by sintered the pressed LiTaO3 powder billet 4 hour in the 850°C muffle furnace. The density of the 5% overdose lithium enriched LiTaO3 target is measured 5.96g/cm3. The XRD measured results show that the ion beam enhanced deposited (IBED) thin film samples using the prepared 5% overdose lithium enriched LiTaO3 target have the polycrystal structure of LiTaO3, but there has remanent Ta2O5 existed in the IBED thin film samples. The main reason for the remanent Ta2O5 growth was due to the stoichiometric proportion mismatch between Li and Ta in the IBED thin film samples during the high temperature annealed process, which caused the lithium oxide evaporation loss from the IBED thin film samples and made the proportion of Ta2O5 increase. After multipule repeated target prepared experiments, the 8.76% overdose lithium enriched LiTaO3 target is suitable for fabricating the 550°C annealed IBED LiTaO3 thin film. After the repeated process experiments, the suitable deposited process parameters of the IBED-C600M instrument for the 8.76% overdose lithium enriched LiTaO3 target were obtained. The SEM micrographs of the 550°C annealed IBED LiTaO3 thin films prepared by the 8.76% overdose lithium enriched LiTaO3 target reveal the prepared thin films are uniform, smooth and crack-free on the surface, and the perfect adhesion between the thin film and the substrate. The successfully fabricated LiTaO3 thin film samples verify the prepared processes of novel LiTaO3 sputtering target are effective.

TEM characterization of a new chromium hydride phase

1992 ◽  
Vol 50 (1) ◽  
pp. 34-35
Author(s):  
Y. Pan ◽  
M. Takeo ◽  
J. Dash
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Temperature ◽  
Hydrogen Gas ◽  
Body Centered Cubic ◽  
Tem Characterization ◽  
Compressed Gas ◽  
Chromium Hydride ◽  
Grade Rock

Single crystal, body centered cubic (bcc) Cr thin films were prepared by epitaxial growth on newly cleaved optical grade rock salt substrates (Figure 1). With a vacuum of 6-8 x 10-7 torr and the substrate at about 500 °C, the deposition of the thin film was almost instantaneously completed by rapidly evaporating Cr powder (99.996%) in a tungsten basket. These films were exposed to hydrogen gas (99.999%) at high temperature (close to the melting point of Cr) and 550 atm pressure in a ballistic compressor (BC) for about 1 millisecond. The cooling rate of the compressed gas is higher than 105°C/s. This process was repeated several times to enhance the interaction of Cr with H2.

scholarly journals Optimizing the Properties of La0.8Sr0.2CrO3 Thin Films through Post-Annealing for High-Temperature Sensing

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1802
Author(s):  
Dan Liu ◽  
Peng Shi ◽  
Yantao Liu ◽  
Yijun Zhang ◽  
Bian Tian ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Annealing Temperature ◽  
Rf Sputtering ◽  
Maximum Size ◽  
Cross Sectional ◽  
Post Annealing ◽  
Maximum Conductivity ◽  
Different Temperatures ◽  
Post Annealing Temperature

La0.8Sr0.2CrO3 (0.2LSCO) thin films were prepared via the RF sputtering method to fabricate thin-film thermocouples (TFTCs), and post-annealing processes were employed to optimize their properties to sense high temperatures. The XRD patterns of the 0.2LSCO thin films showed a pure phase, and their crystallinities increased with the post-annealing temperature from 800 °C to 1000 °C, while some impurity phases of Cr2O3 and SrCr2O7 were observed above 1000 °C. The surface images indicated that the grain size increased first and then decreased, and the maximum size was 0.71 μm at 1100 °C. The cross-sectional images showed that the thickness of the 0.2LSCO thin films decreased significantly above 1000 °C, which was mainly due to the evaporation of Sr2+ and Cr3+. At the same time, the maximum conductivity was achieved for the film annealed at 1000 °C, which was 6.25 × 10−2 S/cm. When the thin films post-annealed at different temperatures were coupled with Pt reference electrodes to form TFTCs, the trend of output voltage to first increase and then decrease was observed, and the maximum average Seebeck coefficient of 167.8 µV/°C was obtained for the 0.2LSCO thin film post-annealed at 1100 °C. Through post-annealing optimization, the best post-annealing temperature was 1000 °C, which made the 0.2LSCO thin film more stable to monitor the temperatures of turbine engines for a long period of time.

The Ferroelectric and Electrical Properties of CaBi4Ti4O15 Thin Films Prepared by Sol-Gel Technology

2011 ◽  
Vol 239-242 ◽  
pp. 891-894 ◽  
Author(s):  
Tsung Fu Chien ◽  
Jen Hwan Tsai ◽  
Kai Huang Chen ◽  
Chien Min Cheng ◽  
Chia Lin Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Sol Gel ◽  
Morphological Characterization ◽  
Experimental Result ◽  
X Ray Diffraction ◽  
Solution Deposition ◽  
Capacitance Voltage ◽  
Preferential Crystal Orientation

In this study, thin films of CaBi4Ti4O15with preferential crystal orientation were prepared by the chemical solution deposition (CSD) technique on a SiO2/Si substrate. The films consisted of a crystalline phase of bismuth-layer-structured dielectric. The as-deposited CaBi4Ti4O15thin films were crystallized in a conventional furnace annealing (RTA) under the temperature of 700 to 800°C for 1min. Structural and morphological characterization of the CBT thin films were investigated by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM). The impedance analyzer HP4294A and HP4156C semiconductor parameters analyzer were used to measurement capacitance voltage (C-V) characteristics and leakage current density of electric field (J-E) characteristics by metal-ferroelectric-insulator- semiconductor (MFIS) structure. By the experimental result the CBT thin film in electrical field 20V, annealing temperature in 750°C the CBT thin film leaks the electric current is 1.88x10-7A/cm2and the memory window is 1.2V. In addition, we found the strongest (119) peak of as-deposited thin films as the annealed temperature of 750°C

PROPERTIES OF ALL-SOLID-STATE LITHIUM-ION RECHARGEABLE BATTERIES DEPOSITED BY RF MAGNETRON SPUTTERING

2013 ◽  
Vol 27 (22) ◽  
pp. 1350156 ◽  
Author(s):  
R. J. ZHU ◽  
Y. REN ◽  
L. Q. GENG ◽  
T. CHEN ◽  
L. X. LI ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solid State ◽  
Magnetron Sputtering ◽  
Coulombic Efficiency ◽  
Electronic Conductivity ◽  
Lithium Ion ◽  
Rf Magnetron Sputtering ◽  
Rechargeable Batteries ◽  
Voltage Range

Amorphous V 2 O 5, LiPON and Li 2 Mn 2 O 4 thin films were fabricated by RF magnetron sputtering methods and the morphology of thin films were characterized by scanning electron microscopy. Then with these three materials deposited as the anode, solid electrolyte, cathode, and vanadium as current collector, a rocking-chair type of all-solid-state thin-film-type Lithium-ion rechargeable battery was prepared by using the same sputtering parameters on stainless steel substrates. Electrochemical studies show that the thin film battery has a good charge–discharge characteristic in the voltage range of 0.3–3.5 V, and after 30 cycles the cell performance turned to become stabilized with the charge capacity of 9 μAh/cm2, and capacity loss of single-cycle of about 0.2%. At the same time, due to electronic conductivity of the electrolyte film, self-discharge may exist, resulting in approximately 96.6% Coulombic efficiency.

Development of High-Efficiency Zn2SiO4:Mn Thin Films for Flat Panel Cathodoluminescent Displays

1997 ◽  
Vol 471 ◽  
Author(s):  
J. Liu ◽  
D. C. Morton ◽  
M. R. Miller ◽  
Y. Li ◽  
E. W. Forsythe ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Conductivity ◽  
Response Time ◽  
Decay Time ◽  
High Efficiency ◽  
Fast Response ◽  
Flat Panel ◽  
Powder Phosphor ◽  
Fast Response Time

ABSTRACTZn2SiO4:Mn thin films were deposited and studied as thin film phosphors for flat panel cathodoluminescent displays. Crystallized films with improved electrical conductivity were obtained after conventional and rapid thermal annealings in a N2 environment at 850Xy11100 °C for 0.25 to 60 minutes. A maximum cathodoluminescent efficiency of 1.3 Lm/W was achieved under dc excitation at 1500 volts. The luminescent emission from these thin films was peaked around 525 nm. The decay time of these films was controlled in the range of 2 to 10 ms by varying the deposition and annealing parameters. The fast response time of these thin films overcomes the long decay limitation of the Zn2SiO4:Mn powder phosphor in practical display applications.

scholarly journals Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

2019 ◽  
Vol 26 (5) ◽  
pp. 1600-1611 ◽  
Author(s):  
Gihan Kwon ◽  
Yeong-Ho Cho ◽  
Ki-Bum Kim ◽  
Jonathan D. Emery ◽  
In Soo Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrochemical Cell ◽  
Porous Electrode ◽  
High Energy ◽  
Porous Electrodes ◽  
X Ray ◽  
Pdf Analysis ◽  
Thin Film Catalysts

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

scholarly journals Thin-film chemical expansion of ceria based solid solutions: laser vibrometry study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hendrik Wulfmeier ◽  
Dhyan Kohlmann ◽  
Thomas Defferriere ◽  
Carsten Steiner ◽  
Ralf Moos ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Temperature ◽  
Film Thickness ◽  
Solid Solutions ◽  
Low Voltage ◽  
Excitation Frequency ◽  
Dimensional Change ◽  
Potential Core ◽  
Chemical Expansion

Abstract The chemical expansion of Pr0.1Ce0.9O2–δ (PCO) and CeO2–δ thin films is investigated in the temperature range between 600 °C and 800 °C by laser Doppler vibrometry (LDV). It enables non-contact determination of nanometer scale changes in film thickness at high temperatures. The present study is the first systematic and detailed investigation of chemical expansion of doped and undoped ceria thin films at temperatures above 650 °C. The thin films were deposited on yttria stabilized zirconia substrates (YSZ), operated as an electrochemical oxygen pump, to periodically adjust the oxygen activity in the films, leading to reversible expansion and contraction of the film. This further leads to stresses in the underlying YSZ substrates, accompanied by bending of the overall devices. Film thickness changes and sample bending are found to reach up to 10 and several hundred nanometers, respectively, at excitation frequencies from 0.1 to 10 Hz and applied voltages from 0–0.75 V for PCO and 0–1 V for ceria. At low frequencies, equilibrium conditions are approached. As a consequence maximum thin-film expansion of PCO is expected due to full reduction of the Pr ions. The lower detection limit for displacements is found to be in the subnanometer range. At 800 °C and an excitation frequency of 1 Hz, the LDV shows a remarkable resolution of 0.3 nm which allows, for example, the characterization of materials with small levels of expansion, such as undoped ceria at high oxygen partial pressure. As the correlation between film expansion and sample bending is obtained through this study, a dimensional change of a free body consisting of the same material can be calculated using the high resolution characteristics of this system. A minimum detectable dimensional change of 5 pm is estimated even under challenging high-temperature conditions at 800 °C opening up opportunities to investigate electro-chemo-mechanical phenomena heretofore impossible to investigate. The expansion data are correlated with previous results on the oxygen nonstoichiometry of PCO thin films, and a defect model for bulk ceria solid solutions is adopted to calculate the cation and anion radii changes in the constrained films during chemical expansion. The constrained films exhibit anisotropic volume expansion with displacements perpendicular to the substrate plane nearly double that of bulk samples. The PCO films used here generate high total displacements of several 100 nm’s with high reproducibility. Consequently, PCO films are identified to be a potential core component of high-temperature actuators. They benefit not only from high displacements at temperatures where most piezoelectric materials no longer operate while exhibiting, low voltage operation and low energy consumption.

scholarly journals Influence of the Sputtering Technique and Thermal Annealing on YSZ Thin Films for Oxygen Sensing Applications

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1165
Author(s):  
Emilio Paz Alpuche ◽  
Pascal Gröger ◽  
Xuetao Wang ◽  
Thomas Kroyer ◽  
Stefanos Fasoulas
Keyword(s):  
Thin Films ◽  
Gas Sensors ◽  
Electronic Conductivity ◽  
Film Surface ◽  
Annealing Treatment ◽  
Thin Film Surface ◽  
Sensing Applications ◽  
Partial Pressures ◽  
Sensor Current ◽  
Oxygen Gas

Yttria-stabilized zirconia (YSZ) thin films were deposited using direct current (reactive and metallic) and radio frequency magnetron sputtering. The effect of the deposition technique and annealing treatment on the microstructure and crystallinity of the thin films was assessed. Using the films produced in this work, oxygen gas sensors were built and their performance under vacuum conditions was evaluated. All the films exhibited a cubic crystalline structure after a post-deposition thermal treatment, regardless of the sputtering technique. When the annealing treatment surpassed 1000 °C, impurities were detected on the thin film surface. The oxygen gas sensors employing the reactive and oxide-sputtered YSZ thin films displayed a proportional increase in the sensor current as the oxygen partial pressure was increased in the evaluated pressure range (5 × 10−6 to 2 × 10−3 mbar). The sensors which employed the metallic-deposited YSZ films suffered from electronic conductivity at low partial pressures.

Sign in / Sign up

Export Citation Format

Share Document