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•ZnO-CuO composite thin films successfully synthesized on quartz substrate.•The 7mole% CuO content film shows selective response (65%) towards CO gas.•Beyond 8.0mol% CuO content film ...shows ‘n’ to ‘p’-type CO sensing feature.•The preferential CO adsorption leads to selective response.•The point defects (VO¨, Zni¨) plays crucial role to get selective CO response.
In the present work we have demonstrated CuO-ZnO composite thin film with optimized CuO content selectively sense carbon monoxide gas. The ‘n’-type gas sensing characteristics of these composite films are changed to ‘p’-type beyond 8.0mol% CuO contents. Through the analyses of photoluminescence spectra in conjunction with XPS we have demonstrated that up to 33.0mol% CuO contents the gas sensing characteristics of the composite films are controlled by the type of point defects (oxygen vacancies, zinc interstitials, and copper vacancies) in CuO and ZnO grains. We have hypothesized that these point defects help to chemi-absorb oxygen and CO preferentially on ZnO and CuO grains respectively to yield selective carbon monoxide sensing of ZnO-CuO composite film with 7.0mol% CuO contents. Beyond 33.0mol% CuO contents the effect of point defects diminishes and the gas sensing characteristic are grossly controlled by the nature of the CuO grains covering ZnO grains in the composite films. Our work provides comprehensive insight towards the understanding of the gas sensing characteristics of hetero-composite thin films deposited using a mixed precursor sol.
Micro solid oxide fuel cells (μ-SOFC) were manufactured with perovskite type proton conductors on silicon substrates and with structured Pt-grid electrodes. In order to miniaturize the μ-SOFCs and to ...shorten the ion path through the electrolyte, the thin film proton conductors were only ~510nm thick. The thin films consist of 10mol% yttrium-doped BaZrO3 (BZY10) and they were deposited by means of chemical solution deposition (CSD). CSD was applied, because it represents a highly attractive fabrication method, considering the relatively low investment costs and flexibility with regard to stoichiometry. The backsides of the μ-SOFCs on the substrates were opened by wet chemical and plasma etching to form the freestanding membranes. The completed μ-SOFCs resist up to a temperature of 450°C. Their electrical properties, such as permittivity, and resistivity were investigated. By means of electrochemical impedance spectroscopy (EIS) in the temperature range of 100°C to 450°C, the resistivity properties and the activation energies of the model μ-SOFC were studied with humid hydrogen in nitrogen at the anode and different oxygen partial pressures at the cathode. The results provide a clear hint for a dominating protonic defect transport mechanism in the electrolyte. In the 450°C measurement, the model μ-SOFCs reached an open circuit voltage of 600mV with 100% oxygen at the cathode and humid hydrogen in nitrogen at the anode.
•Low cost fabrication of Y:BaZrO3 (BZY) films by chemical solution deposition (CSD)•Fully crystalline BZY thin films at temperatures as low as 900°C•The obtained activation energy of ~0.4eV indicates a dominating proton transport.•Micromachining and CSD enabled the fabrication of a model μ-solid oxide fuel cell.•Proof of concept by measurement of an open circuit voltage at the BZY membrane
Pr0.2Ba0.8CoO3-δ (PBCO) and Ba0.5Sr0.5Co0.5Fe0.5O3-δ (BSCF) perovskite thin film electrodes were used as model systems for testing degradation and stability during oxygen evolution reaction (OER) in ...alkaline water electrolysis. The catalyst films were prepared by chemical solution deposition (CSD) and are binder-free. Stepwise aging experiments illustrate a systematical approach to different degrees of degradation of the perovskites after defined testing cycles of cyclic voltammetry in application-near conditions. XPS and EDX characterization at each aging step enables a monitoring of the change in chemical composition during degradation. XPS analysis points to a change in the defect chemistry of PBCO during degradation. The influence of all monitored parameters on the overall electrode service lifetime is shown in a novel end of service life test (ESLT) at thin film perovskite electrodes of 100nm thickness.
Objectives: The aim of the current study was to access the prevalence of depression among patients with Temporomandibular Joint Disorder (TMD) compared to patients with no current TMD.
Method: ...Patients (92) and controls (90) answered questionnaires on subjective pain, severity of chronic pain, jaw disability, emotional well-being and depression, and a clinical examination was performed.
Results: Temporomandibular Joint Disorder patients reported higher disability of jaw function, compared to controls (p<0.001). The myoarthopathy subgroup (67.4%) had slightly more jaw disability than the myopathy subgroup (p>0.05). While 51% of TMD patients reported poor emotional well-being, only 7.8% of controls were affected (p<0.001). Clinical symptoms of depression were reported by 16% of TMD patients and not in the controls (p<0.001). Among TMD patients, a higher prevalence of depression was observed in the myopathy subgroup.
Discussion: A regular screening for psychological problems, using standardized questionnaires, should be integrated in clinical examination of TMD patients.
Almost all platinized substrates manufactured presently use an TiO2 adhesion layer to improve the adhesion between the SiO2 and the Pt. These substrates however are stable till only 800 °C. We show ...that simply by replacing the TiO2 with Al2O3, the stability of the electrodes can be increased to 1000 °C and more. These substrates can be used for high temperature depositions which standard platinized substrates cannot withstand. Further we show that dielectric thin films of BaTiO3 and (Ba,Sr)TiO3 crystallized at higher temperatures show almost a threefold increase in permittivity on these high temperature stable platinized silicon substrates.The large increase in permittivity is attributed to an increase in grain size at high temperatures.
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