Time-dependence of SrVO3_3 thermionic electron emission properties

Thermionic electron emission cathodes are critical components of various high power and high frequency vacuum electronic devices, electron microscopes, e-beam lithographic devices, and thermionic energy converters, which all demand an efficient and long-lasting low work function cathode. Single phase, polycrystalline perovskite oxide SrVO$_3$, with its intrinsic low effective work function and facile synthesis process, is a promising cathode candidate, where previous works have shown evidence of an effective work function as low as 2.3 eV. However, assessment of the stability over time under conditions relevant for operation and the related interplay of evolving surface chemistry with emission performance are still missing, and necessary for understanding how to best prepare, process and operate SrVO$_3$ cathodes. In this work, we study the vacuum activation process of SrVO$_3$ and find it has promising emission stability over 15 days of continuous high temperature operation. We find that SrVO$_3$ shows surface Sr and O segregation during operation, which we hypothesize is needed to create a positive surface dipole, leading to low effective work function. Emission repeatability from cyclic heating and cooling suggests the promising stability of the low effective work function surface, and additional observations of drift-free emission during one hour of continuous emission testing at high temperature further demonstrates its excellent performance stability

Willingness to pay for improved safe drinking water in a coastal urban area in Bangladesh

Discontentment with a piped supply system of drinking water has become a significant concern in Bangladesh's urban areas in recent years, necessitating the improvement of different aspects of the system in question. Therefore, by conducting a discrete choice experiment on 115 households out of a systematically selected 161 households, this study aims to estimate the willingness to pay (WTP) for an improved safe drinking water supply by considering the trade-offs made by urban dwellers for the proposed improvements to an existing water supply system in the Khulna City Corporation (KCC) area of Bangladesh. The primary results show that the total WTP of households is estimated at BDT 243.6 (≈US$ 2.87) per month, implying that respondents are ready to pay for improvements to the water supply attributes of water quality, regularity of supply, water pressure in taps, and filtering. A revenue stream for an improved water supply system is also being developed, suggesting that investment in improving the system would be a ‘no-regret’ decision and economically sustainable

Raw data for manuscript entitled "Time-dependence of SrVO₃ thermionic electron emission properties."

In this work, we studied the poly-crystalline SrVO3 cathode activation process and its thermionic electron emission performance, cathode microstructure and surface chemistry evolution during this activation process, the operational stability over a period of 15 days, stability of the activated low effective low work function during cyclic heating and cooling process, and the short-term operational stability using a continuous emission test at operating conditions. Quantifying all of these practical stability assessments and understanding the evolution and interplay of the surface chemistry with measured effective work function are important for realizing the practical applications of SrVO3 cathode.This files contain all the figure data used for the analysis in this manuscript.</p

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Highly conductive double perovskite oxides A2LuTaO6 (A= Ba, Sr, Ca) as promising photoanode material for dye sensitized solar cells

Poor electrical conductivity, interfacial charge carrier recombination, electrode degradation, etc., restrict practical implementation of the TiO2 based dye sensitised solar cells (DSSCs). In this respect, double perovskite oxides (DPOs) A2LuTaO6 (A = Ba, Sr, Ca) have been introduced as the promising DSSC photoanode. These solid-state synthesised DPOs exhibit a suitable wide band gap in the range of 2.94 to 4.07 eV, and 104 times higher order of electrical conductivity than TiO2. This study reveals that the crystal structure and hence the physical properties of these DPOs can also be easily modulated as required by varying its composition

Highly conductive double perovskite oxides A2LuTaO6 (A= Ba, Sr, Ca) as promising photoanode material for dye sensitized solar cells

Poor electrical conductivity, interfacial charge carrier recombination, electrode degradation, etc., restrict practical implementation of the TiO2 based dye sensitised solar cells (DSSCs). In this respect, double perovskite oxides (DPOs) A2LuTaO6 (A = Ba, Sr, Ca) have been introduced as the promising DSSC photoanode. These solid-state synthesised DPOs exhibit a suitable wide band gap in the range of 2.94 to 4.07 eV, and 104 times higher order of electrical conductivity than TiO2. This study reveals that the crystal structure and hence the physical properties of these DPOs can also be easily modulated as required by varying its composition

Nanostructured perovskite oxides for dye-sensitized solar cells

Since its discovery, the dye-sensitized solar cell (DSSC) technology with its low-cost, simple fabrication procedure and promising photovoltaic (PV) performance remains a fertile research topic. Most DSSC research is focused on the TiO2, ZnO and other binary metal oxides based photoelectrodes and costly platinum (Pt) based counter electrodes (CEs). However, the overall PV performance of these traditional DSSCs is still inadequate compared to other standard PV technologies. The nanostructured perovskite oxides (POs) with their easily tunable interesting photophysical properties, higher stability, relatively simple synthesis procedure and high PV performance emerge as the promising alternatives for the binary metal oxide-based photoelectrodes and costly Pt-based CEs. Though there has been significant improvement in inorganic PO photoanode and CE based DSSCs in the last decade, a combined report on it is still missing. This review reports the underlying mechanisms, latest advances, and prospects of the PO photoanodes and CEs, with a particular focus on PO-based transparent conductive electrodes. We have summarized the shortcomings of the conventional DSSCs and highlighted the potentials of POs to overcome those limiting factors, which will guide the rational design of a highly efficient, cost-effective, and stable DSSC

High Open-Circuit Voltage in Double Perovskite Oxide A(2)NdSbO(6) (A = Ba, Sr) Photoanode-Based Dye-Sensitized Solar Cells

Dye-sensitized solar cell (DSSC) technology, with its low-cost simple fabrication process and promising photovoltaic performance, has become a potential candidate for solar energy conversion. Recently, perovskite oxide-based photoanodes, with the potential to overcome the low photovoltage limitation in DSSCs and with easily tunable optoelectronic properties, have drawn significant research interest. In this work, an inorganic family of double perovskite oxides (DPOs), A(2)NdSbO(6) (A = Ba, Sr), possessing more flexibility in structural and electronic properties than the perovskite oxides, is introduced as a promising DSSC photoanode material. The experimental band gaps of Ba2NdSbO6 and Sr2NdSbO6 are 3.40 eV and 3.78 eV, respectively, which are close to that of TiO2. The DSSC devices fabricated using the synthesized DPO photoanodes show an exceptionally high open-circuit voltage (> 0.8 V). Finally, the density functional theory calculations using the generalized gradient approximation with Hubbard potential (GGA+U) method are performed to understand the correlation between the electronic structure and the observed high photovoltage in these DPOs