Zirconia Films Research Articles

Laered composite hydrogenated films of zirconium and niobium: method of production and control of properties by thermopower method

In this work, to obtain layered materials with the inclusion of hydrogen, Nb/Zr films with different numbers of layers from 50 to 100 were used. The films were sputtered onto a silicon substrate using the vacuum-magnetron method in a specialized installation. The film thickness was varied from 10 to 50 nm. The resulting material was hydrogenated with protons on a TPU electrostatic generator with an energy of up to 1,2 MeV. The optimal modes for deposition of nano-sized metal multilayer Zr/Nb systems have been determined: for a Zr target, the specific power of the sputtering system is 37,9 W/cm2, for a Nb target — 26,4 W/cm2. A coating with clear boundaries between the individual layers of zirconium and niobium was obtained. It is shown that the optimal modes for studying nano-sized Zr/Nb layers are pressure 700 Pa, power 40 W, frequency 2 kHz, plasma fill factor 12,5 % for coatings with a thickness of individual layers of 100 nm. For coatings with individual layer thicknesses from 10 to 50 nm, the optimal pressure is 650 Pa, power 40 W, frequency 1 kHz. To control properties, the thermopower method is used. It was revealed that after proton irradiation there is an intensive accumulation of hydrogen atoms near the interfaces, which entails a change in the thermopower up to an inversion of its sign. The hydrogen distribution is predominantly bimodal, with local maxima in hydrogen concentration observed at the Nb/Zr interface, and the accumulation at the Zr/Nb interface is significantly lower. Hydrogen localization near the interfaces occurs predominantly in the vicinity of zirconium.

Ion Transport Through Nanopores and the Effects of Pore Wall-Ion Interaction.

Ion transport inside nanopores is affected by the physicochemical interactions between the ions and the internal pore wall, offering novel opportunities useful for nanopore-based applications. Here we demonstrate that the transport of Fe(CN)63-/4- is influenced by the pore wall-ion interactions in sub-10 nm pore channels of a mesoporous zirconia film (MZF) formed on an electrode based on cyclic voltammetric (CV) studies. At pH lower than the point of zero charge of zirconia, the pore wall is positively charged, enabling it to exert attractive interaction with the negatively charged analyte ions. Moreover, experimental data indicate that the attractive interaction strongly favors the more highly charged Fe(CN)64- ions over the Fe(CN)63- ions. These effects affect the ion transport through the MZF nanopore channels, which is manifested by a number of different sets of data, including the positive shift of the reduction potential, the disparity between the CV curves of the anodic and cathodic sweeps, and the splitting of the single pair of redox peaks into two pairs when the electrical double layer thickness is increased by reducing the concentration of the supporting electrolyte. Each of these observations can be explained by the wall-ion interactions. Our findings may lead to further explorations into the transport of redox ions that interact differently with the pores and into the development of novel applications based on nanopores.

Layered Composite Hydrogenated Films of Zirconium and Niobium: Production Method and Testing Using Thermo EMF (Thermoelectric Method)

Layered Composite Hydrogenated Films of Zirconium and Niobium: Production Method and Testing Using Thermo EMF (Thermoelectric Method)

Added Anions to Zirconia as a Ceramic Material

Abstract: Anodic polarization of zircaloy-4 has been studied at a constant current density of 8 mA.cm2 and at room temperature. Thickness estimates were made from capacitance and faradaic data. Anodic polarized coloured zirconia film was observed by the addition of millimolar concentration of anions (Cl¯). By the addition of chloride ions to the oxalic acid dihydrate was better improvement in the anodization rate, faradaic efficiency field strength zirconia ceramic is recorded for exhibiting enhanced mechanical properties for manufacture of medical devices as well as biocompatability and have biological properties also. In future research needed to validate zirconia ceramic applications

Influence of ZrO2 nanoparticles on the structural and photocatalytic properties of three-dimensional PVA/g-C3N4 polymer films

This study introduces a novel polymer nanocomposite film of polyvinyl alcohol (PVA), carbon nitride (g-C3N4), and zirconia (ZrO2), created via solution casting for effective water remediation of organic dyes. The film shows significant potential for enhancing pollutant removal efficiency and offering a sustainable solution for water reuse. Comprehensive characterization using FTIR, XRD, UV–vis, TGA, and FESEM-EDX indicated strong interfacial interactions among PVA, ZrO2, and g-C3N4. XPS and UV–vis spectroscopy revealed a reduction in the optical energy gap from 4.8 to 3.95 eV, enhancing photocatalytic activity. SEM confirmed uniform dispersion of ZrO2 and g-C3N4 within the PVA matrix. Kinetic studies of methylene blue (MB) degradation under solar irradiation at neutral pH showed rate constants (k) of 0.0032 min−1, 0.0094 min−1, 0.0383 min−1, and 0.0816 min−1 for PVA, PVA/(0.003)ZrO2/g-C3N4, PVA/(0.007)ZrO2/g-C3N4, and PVA/(0.01)ZrO2/g-C3N4, respectively. The corresponding half-life times (t1/2) were 216.6 min, 73.7 min, 18.1 min, and 8.5 min, with photodegradation efficiencies of 10 %, 75.2 %, 90 %, and 95 %. This recyclable nanocomposite polymer, PVA/ZrO2/g-C3N4, shows promise for effective decontamination of organic pollutants in water, presenting an innovative approach for advanced remediation and secure wastewater recycling.This work is crucial for society as it contributes to solving the global challenge of water pollution, ensuring access to clean and safe water.

Improved Reversibility of Thin-Film Solid Oxide Cells at 500 °C by Tailoring Sputtering Processes for Depositing Yttria-Stabilized Zirconia Electrolyte.

The present study investigates the impact of sputtering configurations on the microstructure and crystallinity of thin-film yttria-stabilized zirconia electrolytes for anodized aluminum oxide-supported all-sputtered thin-film reversible solid oxide cells. Employing various sputtering parameters, such as target-substrate distance and substrate rotation speed, the present study reveals distinct surface characteristics and crystalline structures of thin-film yttria-stabilized zirconia. The microstructure analysis includes scanning electron microscopy and atomic force microscopy examinations, uncovering the influence of the process parameters on the surface morphology, roughness, and grain size. X-ray diffraction data illustrate the texture preferences and crystallite characteristics. The electrochemical characterization of the reversible solid oxide cells demonstrates that the optimized sputtering configuration significantly outperforms the others in both SOFC and SOEC modes, showing exceptional current densities of 964 mA/cm2 at 1.3 V in electrolysis mode at 500 °C. Electrochemical impedance spectroscopy further reveals improved charge transfer reactions at the interface of the electrolyte. The enhanced electrochemical performance is attributed to the unique microstructure and crystallinity of the thin film of yttria-stabilized zirconia. The record-breaking electrolysis performance of this work at 500 °C underscores the potential of tailored sputtering parameters in optimizing the reversible solid oxide cell performance.

Surface Morphology of Various Matrixes with Zirconium Oxide Coatings Synthetized by Alternating Pulsing of Zirconium(IV) <i>tert</i>-Butoxide and Water Vapors Treatment of the Surface

Zirconium oxide coatings of various thicknesses were synthesized on the surface of plates of monocrystalline silicon and borosilicate glass by alternating pulsing of zirconium(IV) tert-butoxide and water vapors treatment. The effect of the matrix type and the coating thickness on surface morphology of the samples was investigated using atomic force microscopy. The concentrations of zirconium in the synthesis products were determined by X-ray spectral microanalysis and the growth constant of the zirconium oxide film on silicon was evaluated. Assumptions are made about the influence of the type of the matrix on the structure of the surface of the zirconium oxide layer.

Highly crystalline yttria‐stabilized zirconia and titania thin films on plastic substrates via sol‐gel transfer process

AbstractWe prepared yttria‐stabilized zirconia (YSZ) and titania crystalline thin films on polycarbonate (PC) substrates by the sol‐gel transfer technique that we have developed recently. Precursor gel films were deposited by spin‐coating on a polyimide/polyvinylpyrrolidone mixture layer on Si(100) substrates, and then were calcined at 600°C. The spin‐coating and the calcination were cycled, followed by final firing at 600–1000°C, to obtain 140–190 nm thick, YSZ and titania crystalline thin films. The film densification progressed as the final firing temperature increased, where the porosity calculated from the refractive index decreased down to a few percent. The film thus obtained was heated at 190°C on a hot plate, and a PC substrate was pressed on the film to transfer it to the PC substrate. The transferability quantified by image analysis of the film area was found to be significantly different between the YSZ and titania films. In the case of YSZ films, the area of silicon that was fractured and adhered to the transferred film increased significantly with increasing firing temperature, leading to a decrease down to 0% in the fraction of the successful transfer area without such a damage. On the other hand, the fraction of the successful transfer area remained around 90% irrespective of the firing temperature for the titania films. The surface of the titania films that were fired at 800–1000°C and transferred to PC substrates had voids of several tens nm scale, which may have been formed during anatase‐to‐rutile phase transformation. We thought that the reduced titania/Si(100) contact area due to such void formation facilitated the delamination of the titania films from Si(100) substrates. High temperature firing, which promotes crystallization and densification of films, thus affects differently the film transferability to plastic substrates, depending on the type of films. The work also suggested possible use of titania films as release‐assisting layers.

Performance improvements in complementary metal oxide semiconductor devices and circuits based on fin field-effect transistors using 3-nm ferroelectric Hf0.5Zr0.5O2

In this work, a conventional HfO2 gate dielectric layer is replaced with a 3-nm ferroelectric (Fe) HZO layer in the gate stacks of advanced fin field-effect transistors (FinFETs). Fe-induced characteristics, e.g., negative drain induced barrier lowering (N-DIBL) and negative differential resistance (NDR), are clearly observed for both p- and n-type HZO-based FinFETs. These characteristics are attributed to the enhanced ferroelectricity of the 3-nm hafnium zirconium oxide (HZO) film, caused by Al doping from the TiAlC capping layer. This mechanism is verified for capacitors with structures similar to the FinFETs. Owing to the enhanced ferroelectricity and N-DIBL phenomenon, the drain current (IDS) of the HZO-FinFETs is greater than that of HfO2-FinFETs and obtained at a lower operating voltage. Accordingly, circuits based on HZO-FinFET achieve higher performance than those based on HfO2-FinFET at a low voltage drain (VDD), which indicates the application feasibility of the HZO-FinFETs in the ultra-low power integrated circuits.Graphical abstract

Nanocrystalline Cubic Phase Scandium-Stabilized Zirconia Thin Films.

The cubic zirconia (ZrO2) is attractive for a broad range of applications. However, at room temperature, the cubic phase needs to be stabilized. The most studied stabilization method is the addition of the oxides of trivalent metals, such as Sc2O3. Another method is the stabilization of the cubic phase in nanostructures-nanopowders or nanocrystallites of pure zirconia. We studied the relationship between the size factor and the dopant concentration range for the formation and stabilization of the cubic phase in scandium-stabilized zirconia (ScSZ) films. The thin films of (ZrO2)1-x(Sc2O3)x, with x from 0 to 0.2, were deposited on room-temperature substrates by reactive direct current magnetron co-sputtering. The crystal structure of films with an average crystallite size of 85 Å was cubic at Sc2O3 content from 6.5 to 17.5 mol%, which is much broader than the range of 8-12 mol.% of the conventional deposition methods. The sputtering of ScSZ films on hot substrates resulted in a doubling of crystallite size and a decrease in the cubic phase range to 7.4-11 mol% of Sc2O3 content. This confirmed that the size of crystallites is one of the determining factors for expanding the concentration range for forming and stabilizing the cubic phase of ScSZ films.

Formulation of an Ideal Solid Oxide Fuel Cell

Principles of transport phenomena and chemical/ electrochemical reaction kinetics were employed to develop the formulation for the prediction of fuel (e.g., ) and oxidant (e.g., ) mole fraction profiles in the porous anode and cathode electrodes of an ideal solid oxide fuel cell (SOFC). The ideal SOFC is composed of the porous anode, , which is the cermet of metallic nickel and yttria-stabilized zirconia and the porous cathode, , which is the strontium-doped lanthanum manganite. A thin film of the yttria-stabilized zirconia is the solid electrolyte separating the cell electrodes. The cell anode-side fuel and cathode-side oxidant supply compartments are continuously stirred to maintain constant concentrations of fuel and oxidant in them. The relevant analytical formulation as well as the numerical data computed is presented. The current calculated data show a non-linear decrease, associated with the coupled effect of diffusion and consumption, in the mole fractions of hydrogen and oxygen in the porous electrodes with an increase in the distance from the reactant supply compartments towards the cell electrolyte separator.

The Effect of Deposition Temperature on Structural, Morphological, and Dielectric Properties of Yttria-Doped Zirconia Thin Films

The aim of this study was to investigate the effect of deposition temperature on the structural, optical, morphological, and dielectric properties of yttria-stabilised zirconia (YSZ) films prepared by sol-gel spin-coating method. X-ray diffraction (XRD) measurements of YSZ films showed that the peaks of the cubic phase were prominent and the peak intensities increased with deposition temperature. The crystallite size, dislocation density, and microstrain of the thin films were identified by XRD. It was observed that the crystal size of the YSZ thin films increased from 16 nm to 22 nm with the deposition temperature. The surface roughness of the thin films was found to have changed as revealed by Atomic Force Microscopy (AFM) measurements. The roughness increased from 7.72 nm to 11.92 nm with increasing temperature. The optical transmittance of the YSZ thin films was investigated in the wavelength range 200-900 nm and was found to increase slightly with increasing deposition temperature. Metal-Oxide-Semiconductor (MOS) devices were fabricated from these YSZ materials for dielectric characterization. The dielectric properties of the Ag/YSZ/n-Si MOS structure were investigated. It was found that the capacitance, conductivity and other dielectric parameters of these structures are strongly frequency dependent.

Mixed-Potential Ammonia Sensor Based on a Dense Yttria-Stabilized Zirconia Film Manufactured at Room Temperature by Powder Aerosol Deposition

Powder aerosol deposition (often abbreviated as PAD, PADM, or ADM) is a coating method used to obtain dense ceramic films at room temperature. The suitability of this method to obtain ammonia mixed-potential sensors based on an yttria-stabilized zirconia (YSZ) electrolyte that is manufactured using PAD and a V2O5–WO3–TiO2 (VWT)-covered electrode is investigated in this study. The sensor characteristics are compared with data from sensors with screen-printed YSZ solid electrolytes. The PAD sensors outperform those in terms of sensitivity with 117 mV/decade NH3 compared to 88 mV/decade. A variation in the sensor temperature shows that the NH3 sensitivity strongly depends on the sensor temperature and decreases with higher sensor temperature. Above 560 °C, the characteristic curve shifts from exponential to linear dependency. Variations in the water and the oxygen content in the base gas (usually 10% oxygen, 2% water vapor in nitrogen) reveal a strong dependence of the characteristic curve on the oxygen content. Water vapor concentration variations barely affect the sensor signal.

Microstructure and Properties of Thin Films of Zirconium Produced by High-Frequency Laser Deposition

Microstructure and Properties of Thin Films of Zirconium Produced by High-Frequency Laser Deposition

Synthesize of Ni0.75Zn0.25Fe2O4 Spinel Oxide as a Working Electrode for Formaldehyde Electrochemical Gas Sensors

Gas sensor with yttrium stabilized zirconia film in electrochemistry have been rapidly applied in the monitoring of toxic and harmful gases, and nickel spinel ferrite (NFO) is one of the most studied working electrodes. However, the sensing performance to formaldehyde (HCHO) is quiet poor. In this work, the sol-gel method was used to prepare Zn-doped NFO (Ni0.75Zn0.25Fe2O4) oxide, and the Zn-doped NFO was applied as the working electrode of the electrochemical gas sensor of HCHO. The phase structure, micromorphology, and surface area of the prepared Ni0.75Zn0.25Fe2O4 oxide were evaluated for the working electrode. The results showed that when the operating temperature reached 480 °C, the sensor with Ni0.75Zn0.25Fe2O4 as the working electrode achieved high response value of −17 mV to 5 ppm HCHO, and the response/recovery time was 28/20 s. The polarization curve was further performed to validate the mechanism of the observed sensing behavior. Meanwhile, the response signal of the fabricated sensor increased logarithmically with the log (HCHO) in the investigated range of 1–5 ppm, and the corresponding sensitivity reached −29.08 mV/decade.

(Digital Presentation) Improvement of the Compatibility between the Current-Independent Constant Voltage Loss in Wagner’s Equation for SOFCs Using Sm-Doped Ceria Electrolytes and Jarzynski’s Equality

A solid oxide fuel cell (SOFC) converts chemical energy from a fuel gas, such as hydrogen or methane, to electrical energy. Yttria-stabilized zirconia (YSZ) films are often used as electrolytes, in which only oxygen ions are carriers. In such cases, the open-circuit voltage (OCV = 1.15 V at 1073 K) is equal to the Nernst voltage (Vth = 1.15 V at 1073 K).Samaria-doped ceria (SDC) has higher ionic conductivity than YSZ. Therefore, SDC films are possible electrolyte candidates. However, when SDC electrolytes are used in SOFCs, the OCV at 1073 K is only 0.80 V. The voltage loss has been explained by Wagner’s equation.Numerous subsequent models have been created based on Wagner’s equation. The current-voltage relationship can be calculated with the cathode and anode polarization voltage losses using the Riess model [1]. Furthermore, Duncan and Wachsman created a nonlinear model [2]. This model can also be used to explain the equilibration process. According to the Riess model, the OCV should decrease during electrode degradation. However, experimentally, the OCV does not change during electrode degradation [3]. The change in the equilibration of thick SDC electrolytes in response to a change in the anode gas has never been explained using the model of Duncan and Wachsman. Experimentally, when a very thick (6.6 mm) SDC electrolyte is used, the OCV can reach 0.80 V in only 5 minutes [4]. According to Weppner, the corresponding delay in the electron diffusion current should be more than 2080 minutes [5].We proposed a current-independent anode voltage loss (0.35 V = 1.15 V- 0.80 V) [6]. Since we disproved the existence of large leakage currents in SDC electrolytes, our explanations seem to disregard and disprove Wagner’s equation. However, we noted that the dismissal of the idea of large leakage currents in SDC electrolytes is only a side effect. When SDC electrolytes experience a large anode voltage loss (0.35 V), the leakage currents are very small. This phenomenon is called the “anode shielding effect” [7].The ionic activation energy (Ea) of SDC electrolytes is 0.7 eV (= 0.35 V ×2e). During ion hopping processes in SDC electrolytes, the work done by ions on the surrounding lattice structure is 0.7 eV. The ions should regain 0.7 eV after hopping. However, when there are many electrons in the hopping path, the hopping processes are very complex, and calculating the work loss is challenging [8].Jarzynski’s equality is very useful for calculating the Gibbs energy loss at the nanoscale. One ion hopping process in SDC electrolytes is at the nanoscale. However, the number of oxygen ions in SDC electrolytes is on the order of 1021, which is near Avogadro’s number. The number of oxygen ions that can participate in the hopping process is on the order of 1016 at 1073 K. Furthermore, the average frequency of the oxygen ions is 1013 Hz. Consequently, we are discussing an average Gibbs energy loss on the order of 1029 in one second. This means that our model is much more statistical as follows. Jarzynski’s equality ⊇ Our model (OCV = Vth -Ea /2e) (1) Fortunately, the canonical ensemble for the ion hopping process follows Boltzmann's distribution, which is an exponential distribution and determined only by the temperature of the environment. We try to improve the compatibility between the current-independent constant voltage loss in Wagner’s equation for SOFCs using SDC electrolytes and Jarzynski’s equality.

Measuring Temporal Variation of Concentration of ALD Precursor TEMAZ in Process Chamber Using UV Absorption Method

Atomic layer deposition (ALD) is becoming increasingly important to realize high-accurate atomic-scale deposition processes in semiconductor industry, where device dimensions approach atomic scale with the advances of the miniaturization. Basically, ALD is a process of forming a film using self-limited cyclic reactions, where precursor gas, purging gas, reaction gas, and purging gas are introduced sequentially [1]. To realize high-quality ALD with high-throughput, the reaction cycle should be shortened. However, this may cause incomplete gas replacement due to residual gas, resulting in the degradation in process quality. To develop high-quality ALD, precise control of temporal and spatial distribution of these gases is required. Although the total gas pressure in the chamber was usually measured as process monitor, partial pressure, or concentration of precursor as well as reaction gas was not be measured so far. This makes it impossible to evaluate gas replacement characteristics in the chamber, despite its importance for developing ALD technology.Our group developed a high-sensitivity, real-time, compact gas concentration sensor using UV light absorption method for the supply system of organometallic gases having UV absorption [2]. The gas concentration can be estimated from the UV absorption using Lambert-Beer law. Recently, to develop a new process monitoring tool in ALD, we apply this technique to in-situ measurement of precursor gas in the chamber. In this study, temporal variation of concentration of Tetrakis(ethylmethylamino)zirconium (TEMAZ) in cyclic introduction of TEMAZ and purging Ar gas was evaluated. Here, TEMAZ is widely used as a Zr precursor in ALD for zirconia films deposition, mainly in DRAM fabrication [3].Fig. 1 shows a schematic diagram of the experimental system used in this study. TEMAZ was supplied by a bubbling method. At the downstream of the TEMAZ tank, upstream pressure controller (UPCUS) was equipped to control the pressure in the tank to be constant. An inner diameter of a test chamber was 200 mm, and TEMAZ and purging Ar were supplied using a shower plate installed at the upside of the chamber. A densitometer using UV absorption method consisted of an UV light emitting part and an UV photometer, and these were placed at opposite side of the chamber. UV light with a wavelength of 250 nm, which corresponds to the absorption of TEMAZ, was used. Two densitometers (hereafter denoted as UVH and UVL) were set at 10mm and 60mm below the shower plate, respectively. A pressure gauge was also set at 10mm below the shower plate to measure total pressure in the chamber. In the measurement, the valve operation and data acquisition were conducted by a computer with a sampling period of 10 ms.Fig. 2(a) shows time evolution of chamber pressure and absorbance of UVH (which approximately proportional to TEMAZ partial pressure) in the case that TEMAZ and purging Ar were introduced alternatively every second for 50 times. TEMAZ was supplied to the chamber with diluted Ar (100 sccm) with a TEMAZ concentration of 2000 ppm. Purging Ar flow rate was 1500 sccm. In Fig. 2(b), extended graph of Fig. 2(a) for time range from 90 to 96 s were shown. It is clearly found that behavior of UVH signal and the chamber pressure was different, where UVH absorbance signal increased at TEMAZ introduction, and rapidly decreased when Ar purge started whereas the chamber pressure increased due to the Ar introduction. Such behavior cannot be obtained only from the pressure measurement.Fig. 3 compares UVH and UVL absorbance signals for 1 cycle of TEMAZ and purging Ar introductions. It can be seen that UVH absorbance began to increase at approximately 80.2 s (0.2 s after the TEMAZ introduction), and UHL absorbance began to increase with a delay at approximately 80.6 s (0.6 s after the TEMAZ introduction). This suggested that down flow of TEMAZ could be observed.The results demonstrated validity of the UV absorption method to evaluate temporal and spatial distribution of precursor gas, and this technology will greatly contribute to developing future ALD technology.[1] R. W. Johnson et al., Materials today, 17 (2014) 236.[2] H. Ishii et al., Jpn. J. Appl. Phys., 58 (2019) SBBL04.[3] S. K. Kim and C. S. Hwang, Electrochem. Solid-State Lett., 11 (2008) G9. Figure 1

On the surface biasing effectiveness during reactive high-power impulse magnetron sputter deposition of zirconium dioxide

In this study, we investigate the effect of surface biasing during high-power impulse magnetron sputter deposition of non-conductive zirconium dioxide films on substrates with different capacitances. We employ reactive high-power impulse magnetron sputtering to deposit ZrO2 films using a circular Zr target in a pure oxygen atmosphere. The deposition experiments are conducted on two types of substrates: high-capacitance (thin thermally grown SiO2 on Si) and low-capacitance (soda-lime glass). By varying the time shift between the target voltage pulse and the negative substrate bias voltage pulse, we analyze the impact on the preferred crystal orientation of the deposited ZrO2 films and the deposition rate. We measure the current and voltage waveforms during the deposition process and utilize a surface charging model to understand the charging behavior of the growing film. Additionally, time- and energy-resolved ion mass spectra are measured to gain insights into the ion behavior during film growth. Our results demonstrate that energetic ion bombardment and appropriate timing of substrate biasing can influence the crystal orientation of ZrO2 films, favouring specific orientations over others. We also explain the different behavior observed on low- and high-capacitance substrates.

Plasma deposited carbon containing zirconia films as thermal barriers

Carbon containing zirconia films are deposited from chemical vapor deposition (CVD) and from plasma enhanced chemical vapor deposition (PECVD), as being used as thermal barrier coatings for many applications. Their thermal conductivity has been measured for temperatures ranging from room temperature up to 450 K using the 3 ω method. It is shown that the samples exhibit a lattice and an electronic contribution to the thermal conductivity reaching values up to 13 W/m/K for samples from CVD and up to 5 W/m/K for the samples from PECVD at 450 K. At room temperature, the thermal conductivities for PECVD films are in the range of 1 W/m/K, whereas the CVD film shows values of 8 W/m/K. The large differences are explained by the microstructure of the films, showing smaller grain sizes with poor interfaces for the PECVD films compared to the denser CVD films. This shows that plasma deposited carbon containing zirconia films may serve as excellent thermal barriers.

The impact of plasma enhancement on the deposition of carbon‐containing zirconia films by metalorganic chemical vapor deposition

AbstractZirconia layers are often used as thermal barriers. In recent years, depositions by chemical vapor deposition methods using a metalorganic precursor (MOCVD) have been primarily investigated. Here, we combine MOCVD with plasma activation ‐ plasma‐enhanced chemical vapor deposition (PECVD]) ‐ of the gas phase and/or the growth surface to lower the growth temperature and to allow for a flexible coating design. PECVD causes the precursor to be transformed into a chemically active species, yielding thin films with a five times higher sticking coefficient compared to MOCVD. This leads to the onset of crystallization at lower surface temperatures. Carbon is incorporated at oxygen sites, so that the crystalline structure of zirconia is preserved, but the electrical conductivity is affected. The thermal conductivity is like that of pure zirconia.