Pub Date : 2016-12-01DOI: 10.1080/23311940.2016.1257414
M. A. Rahman, M. A. Rahman, U. Chowdhury, M. Bhuiyan, Md. Lokman Ali, M. R. Sarker
Abstract First principles calculations based on density functional theory with generalized gradient approximation are performed to investigate the structural, elastic, electronic, and optical properties of new bismuth oxides, ABi2O6 (A = Mg, Zn) with the trirutile-type structure. Initially, the geometry structures obtained by geometry optimization are consistent with the experimental values. The calculated structural parameters show a good agreement with the experimental results. The optimized lattice parameters, six independent elastic constants (C11, C12, C13, C33, C44 and C66), bulk modulus (B), shear modulus (G), Young’s modulus (Y), Pugh’s ratio (G/B), Poisson’s ratio (ν), and elastic anisotropy (A) are calculated and discussed. This is the first quantitative theoretical prediction of the electronic, elastic, and optical properties of these compounds. The investigation of the electronic band structures reveals that these compounds are electrical conductors, with contribution predominantly from the Bi 6p states. The analysis of the elastic constants and other moduli shows large anisotropy on elasticity and brittle behavior. The origins of features that appear in different optical properties of these two compounds have been discussed using band structures. The large reflectivity of the predicted compounds in the low energy region might be helpful in high-quality candidate materials for coating to avoid solar heating.
摘要利用密度泛函理论和广义梯度近似的第一性原理计算，研究了具有三重结构的新型铋氧化物ABi2O6 (A = Mg, Zn)的结构、弹性、电子和光学性质。通过几何优化得到的几何结构与实验值基本一致。计算的结构参数与试验结果吻合较好。计算并讨论了优化后的晶格参数、6个独立弹性常数(C11、C12、C13、C33、C44和C66)、体积模量(B)、剪切模量(G)、杨氏模量(Y)、皮格比(G/B)、泊松比(ν)和弹性各向异性(A)。这是对这些化合物的电子、弹性和光学性质的第一个定量理论预测。电子能带结构的研究表明，这些化合物是电导体，主要由bi6p态贡献。弹性常数和其他模量的分析表明，弹性和脆性行为具有很大的各向异性。用能带结构讨论了这两种化合物不同光学性质特征的来源。预测化合物在低能区的大反射率可能有助于制备高质量的涂层候选材料，以避免太阳加热。
{"title":"First principles investigation of structural, elastic, electronic and optical properties of ABi2O6 (A = Mg, Zn) with trirutile-type structure","authors":"M. A. Rahman, M. A. Rahman, U. Chowdhury, M. Bhuiyan, Md. Lokman Ali, M. R. Sarker","doi":"10.1080/23311940.2016.1257414","DOIUrl":"https://doi.org/10.1080/23311940.2016.1257414","url":null,"abstract":"Abstract First principles calculations based on density functional theory with generalized gradient approximation are performed to investigate the structural, elastic, electronic, and optical properties of new bismuth oxides, ABi2O6 (A = Mg, Zn) with the trirutile-type structure. Initially, the geometry structures obtained by geometry optimization are consistent with the experimental values. The calculated structural parameters show a good agreement with the experimental results. The optimized lattice parameters, six independent elastic constants (C11, C12, C13, C33, C44 and C66), bulk modulus (B), shear modulus (G), Young’s modulus (Y), Pugh’s ratio (G/B), Poisson’s ratio (ν), and elastic anisotropy (A) are calculated and discussed. This is the first quantitative theoretical prediction of the electronic, elastic, and optical properties of these compounds. The investigation of the electronic band structures reveals that these compounds are electrical conductors, with contribution predominantly from the Bi 6p states. The analysis of the elastic constants and other moduli shows large anisotropy on elasticity and brittle behavior. The origins of features that appear in different optical properties of these two compounds have been discussed using band structures. The large reflectivity of the predicted compounds in the low energy region might be helpful in high-quality candidate materials for coating to avoid solar heating.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1257414","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract After analyzing the characteristics and pricing models on the Russian wholesale electricity market, some important features for econometric modeling are introduced. This paper suggests econometric forecasting models developed to predict daily and hourly electricity prices on the day-ahead market for two price zones in Russia: European and Siberian ones. A set of 24 models, which are similar in nature but different in included regressors, are introduced. On the basis of the actual database for 2014, different modifications of price formation are offered and analyzed with the help of the Eviews econometric package. Dynamic forecasts on various distances (day, week, and month) are conducted and the most suitable models from the point of minimizing the norms of the vectors residuals are chosen. Constructed ARMA models have high predictive power and are able to reflect the price trend on the base of exogenous factors and the previous price values.
{"title":"Forecasting of the electricity price on the day-ahead electricity market in Russia","authors":"A. Maksimov, Daria V. Shchurupova","doi":"10.2139/ssrn.2877697","DOIUrl":"https://doi.org/10.2139/ssrn.2877697","url":null,"abstract":"Abstract After analyzing the characteristics and pricing models on the Russian wholesale electricity market, some important features for econometric modeling are introduced. This paper suggests econometric forecasting models developed to predict daily and hourly electricity prices on the day-ahead market for two price zones in Russia: European and Siberian ones. A set of 24 models, which are similar in nature but different in included regressors, are introduced. On the basis of the actual database for 2014, different modifications of price formation are offered and analyzed with the help of the Eviews econometric package. Dynamic forecasts on various distances (day, week, and month) are conducted and the most suitable models from the point of minimizing the norms of the vectors residuals are chosen. Constructed ARMA models have high predictive power and are able to reflect the price trend on the base of exogenous factors and the previous price values.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68411960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-28DOI: 10.1080/23311940.2016.1244244
Yu Haipeng, Chen Xiaoge, Zhang Hongsong, Zhang Haoming, Zhao Yongde, Liu Yanxu, Tang An
Abstract In this work, the Sm2AlTaO7 was synthesized by solid reaction method, and its phase composition, microstructure, and thermophysical properties were investigated. XRD results show that pure Sm2AlTaO7 with single pyrochlore-type structure is prepared successfully. The thermal conductivity of Sm2AlTaO7 at 1,273 K is about 1.13 W m−1 K−1, which is much lower than that of YSZ. The low thermal conductivity can be attributed to the phonon scattering caused by substituting atoms. Its thermal expansion coefficient is lower than that of Sm2Ce2O7, but close to that of YSZ. There is no phase transformation occurred between 293 and 1,673 K. The excellent thermophysical property means that the Sm2AlTaO7 has potential to be used as candidate ceramic material for thermal barrier coatings.
摘要采用固相反应法制备了sm2alta7，并对其相组成、微观结构和热物理性能进行了研究。XRD结果表明，成功制备了具有单一焦绿石型结构的纯sm2alta7。Sm2AlTaO7在1273 K时的导热系数约为1.13 W m−1 K−1，远低于YSZ的导热系数。低导热系数可归因于取代原子引起的声子散射。其热膨胀系数低于Sm2Ce2O7，但接近YSZ。293 ~ 1673 K之间没有发生相变。优异的热物理性能意味着sm2alta7具有作为热障涂层候选陶瓷材料的潜力。
{"title":"Preparation and thermal properties of Sm2AlTaO7","authors":"Yu Haipeng, Chen Xiaoge, Zhang Hongsong, Zhang Haoming, Zhao Yongde, Liu Yanxu, Tang An","doi":"10.1080/23311940.2016.1244244","DOIUrl":"https://doi.org/10.1080/23311940.2016.1244244","url":null,"abstract":"Abstract In this work, the Sm2AlTaO7 was synthesized by solid reaction method, and its phase composition, microstructure, and thermophysical properties were investigated. XRD results show that pure Sm2AlTaO7 with single pyrochlore-type structure is prepared successfully. The thermal conductivity of Sm2AlTaO7 at 1,273 K is about 1.13 W m−1 K−1, which is much lower than that of YSZ. The low thermal conductivity can be attributed to the phonon scattering caused by substituting atoms. Its thermal expansion coefficient is lower than that of Sm2Ce2O7, but close to that of YSZ. There is no phase transformation occurred between 293 and 1,673 K. The excellent thermophysical property means that the Sm2AlTaO7 has potential to be used as candidate ceramic material for thermal barrier coatings.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1244244","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-04DOI: 10.1080/23311940.2016.1231987
L. Simonelli, C. Marini, W. Olszewski, M. Á. Pérez, N. Ramanan, G. Guilera, V. Cuartero, K. Klementiev
CLÆSS is a general-purpose absorption spectroscopy beamline at the ALBA CELLS Spanish synchrotron. Its optical layout is presented here along with its powerful capabilities for collecting absorption spectra with high signal to noise ratio in an unusually wide energy range (2.4–63.2 keV). Continuous energy scanning for quick scans is available, allowing to collect X-ray absorption near edge structure and extended X-ray absorption fine structure spectra in 3–5 and 8–10 min, respectively. The full automatization of the beamline allows performing successive measurements at different conditions without attending to the beamline. The different experimental setups available to users are reported. Examples of XAS measurements are presented, showing the performances of the beamline at different standard conditions.
{"title":"CLÆSS: The hard X-ray absorption beamline of the ALBA CELLS synchrotron","authors":"L. Simonelli, C. Marini, W. Olszewski, M. Á. Pérez, N. Ramanan, G. Guilera, V. Cuartero, K. Klementiev","doi":"10.1080/23311940.2016.1231987","DOIUrl":"https://doi.org/10.1080/23311940.2016.1231987","url":null,"abstract":"CLÆSS is a general-purpose absorption spectroscopy beamline at the ALBA CELLS Spanish synchrotron. Its optical layout is presented here along with its powerful capabilities for collecting absorption spectra with high signal to noise ratio in an unusually wide energy range (2.4–63.2 keV). Continuous energy scanning for quick scans is available, allowing to collect X-ray absorption near edge structure and extended X-ray absorption fine structure spectra in 3–5 and 8–10 min, respectively. The full automatization of the beamline allows performing successive measurements at different conditions without attending to the beamline. The different experimental setups available to users are reported. Examples of XAS measurements are presented, showing the performances of the beamline at different standard conditions.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1231987","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-09-29DOI: 10.1080/23311940.2016.1234662
M. Rahman
Abstract In this paper, hydromagnetic natural convection heat transfer in an equilateral triangular enclosure filled with water- and kerosene-based ferrofluids has been analyzed using a two-component non-homogeneous thermal equilibrium model. The enclosure is permeated by an inclined magnetic field of having uniform strength. The effects of Brownian motion and thermophoresis of the nanoparticles are incorporated into the ferrofluid model. The Galerkin weighted residual finite-element method has been employed to solve the governing nondimensional partial differential equations. Fe3O4-water and Co-kerosene ferrofluids have been used for the present investigation. The effects of various model parameters such as Rayleigh number, Hartmann number, and inclination angle of the magnetic field on the streamlines, isotherms, and isoconcentrations have been displayed graphically. In addition, the heat transfer augmentation for various combinations of model parameters have been done in light of the average Nusselt number from the bottom heated wall. The results indicate that increment in the magnetic field reduces the heat transfer rate, whereas increment in the magnetic field inclination angle augments the heat transfer rate significantly. The results further indicate that there exists a strong interaction between cobalt and kerosene in the presence of magnetic field which can be utilized efficiently for desired heat transfer augmentation in engineering problems.
{"title":"Influence of oriented magnetic field on natural convection in an equilateral triangular enclosure filled with water- and kerosene-based ferrofluids using a two-component nonhomogeneous thermal equilibrium model","authors":"M. Rahman","doi":"10.1080/23311940.2016.1234662","DOIUrl":"https://doi.org/10.1080/23311940.2016.1234662","url":null,"abstract":"Abstract In this paper, hydromagnetic natural convection heat transfer in an equilateral triangular enclosure filled with water- and kerosene-based ferrofluids has been analyzed using a two-component non-homogeneous thermal equilibrium model. The enclosure is permeated by an inclined magnetic field of having uniform strength. The effects of Brownian motion and thermophoresis of the nanoparticles are incorporated into the ferrofluid model. The Galerkin weighted residual finite-element method has been employed to solve the governing nondimensional partial differential equations. Fe3O4-water and Co-kerosene ferrofluids have been used for the present investigation. The effects of various model parameters such as Rayleigh number, Hartmann number, and inclination angle of the magnetic field on the streamlines, isotherms, and isoconcentrations have been displayed graphically. In addition, the heat transfer augmentation for various combinations of model parameters have been done in light of the average Nusselt number from the bottom heated wall. The results indicate that increment in the magnetic field reduces the heat transfer rate, whereas increment in the magnetic field inclination angle augments the heat transfer rate significantly. The results further indicate that there exists a strong interaction between cobalt and kerosene in the presence of magnetic field which can be utilized efficiently for desired heat transfer augmentation in engineering problems.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1234662","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-09-28DOI: 10.1080/23311940.2016.1231361
U. Chowdhury, Md Atikur Rahman, M. A. Rahman, M. Bhuiyan, Md. Lokman Ali
Abstract The structural, elastic, electronic, and optical properties of BaCuO2 are investigated using the plane-wave ultrasoft pseudo-potential technique, which is based on the first-principle density functional theory (DFT) with generalized gradient approximation (GGA). The calculated structural parameters show a good agreement with the experimental and other theoretical results. The optimized lattice parameters, independent elastic constants (C11, C12, C13, C33, C44, and C66), Bulk modulus B, compressibility K, Shear modulus G, and Poisson’s ratio ν, as well as the band structures, total and atom-projected densities of states and finally the optical properties of BaCuO2 has been evaluated and discussed. The band structure and density of states show that these phases have metallic behavior and the major contribution comes from O-2P states for BaCuO2. Further, the first time investigated optical functions reveal that the reflectivity is high in the IR-UV region up to 28.5eV for BaCuO2 respectively, showing this to be a promising coating material.
{"title":"Ab initio study on structural, elastic, electronic and optical properties of cuprate based superconductor","authors":"U. Chowdhury, Md Atikur Rahman, M. A. Rahman, M. Bhuiyan, Md. Lokman Ali","doi":"10.1080/23311940.2016.1231361","DOIUrl":"https://doi.org/10.1080/23311940.2016.1231361","url":null,"abstract":"Abstract The structural, elastic, electronic, and optical properties of BaCuO2 are investigated using the plane-wave ultrasoft pseudo-potential technique, which is based on the first-principle density functional theory (DFT) with generalized gradient approximation (GGA). The calculated structural parameters show a good agreement with the experimental and other theoretical results. The optimized lattice parameters, independent elastic constants (C11, C12, C13, C33, C44, and C66), Bulk modulus B, compressibility K, Shear modulus G, and Poisson’s ratio ν, as well as the band structures, total and atom-projected densities of states and finally the optical properties of BaCuO2 has been evaluated and discussed. The band structure and density of states show that these phases have metallic behavior and the major contribution comes from O-2P states for BaCuO2. Further, the first time investigated optical functions reveal that the reflectivity is high in the IR-UV region up to 28.5eV for BaCuO2 respectively, showing this to be a promising coating material.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1231361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-07-18DOI: 10.1080/23311940.2016.1208450
Naini Dawar, Mansi Chitkara, I. S. Sandhu, J. Jolly, S. Malhotra
Abstract Nickel-doped barium nanohexaferrites with the chemical formula BaNixFe(12-x)O19 are prepared using the chemical co-precipitation technique. The calcination of the samples is done at 800°C for 4 h. In order to carry out the structural analysis that includes the crystallographic and the morphological investigations, X-ray diffraction and TEM are carried out to govern the phase, structure and the size of the crystal. By the use of Debye–Scherrer equation, the size of the crystallite is calculated to be in the range of 38–100 nm. TEM results reveal the magnetoplumbite structure of the hexaferrites. The M–H curve obtained using the Vibrating Sample Magnetometer computes the magnetic parameters like saturation magnetization, coercivity, remanence and verifies the behaviour of hexaferrites as hard magnetic materials. Further, the effect of variation in calcination temperature is also investigated on the values of magnetic parameters of hexaferrites. In order to carry out the investigations on the electrical properties of hexaferrites, the two-probe method and parallel plate capacitor set-up are used. The values of relative permittivity, dielectric loss and loss tangent are computed as a function of frequency. The values of DC electrical resistance for pure and nickel-doped barium nanohexaferrites are evaluated from the slope of I–V graphs.
{"title":"Structural, magnetic and dielectric properties of pure and nickel-doped barium nanohexaferrites synthesized using chemical co-precipitation technique","authors":"Naini Dawar, Mansi Chitkara, I. S. Sandhu, J. Jolly, S. Malhotra","doi":"10.1080/23311940.2016.1208450","DOIUrl":"https://doi.org/10.1080/23311940.2016.1208450","url":null,"abstract":"Abstract Nickel-doped barium nanohexaferrites with the chemical formula BaNixFe(12-x)O19 are prepared using the chemical co-precipitation technique. The calcination of the samples is done at 800°C for 4 h. In order to carry out the structural analysis that includes the crystallographic and the morphological investigations, X-ray diffraction and TEM are carried out to govern the phase, structure and the size of the crystal. By the use of Debye–Scherrer equation, the size of the crystallite is calculated to be in the range of 38–100 nm. TEM results reveal the magnetoplumbite structure of the hexaferrites. The M–H curve obtained using the Vibrating Sample Magnetometer computes the magnetic parameters like saturation magnetization, coercivity, remanence and verifies the behaviour of hexaferrites as hard magnetic materials. Further, the effect of variation in calcination temperature is also investigated on the values of magnetic parameters of hexaferrites. In order to carry out the investigations on the electrical properties of hexaferrites, the two-probe method and parallel plate capacitor set-up are used. The values of relative permittivity, dielectric loss and loss tangent are computed as a function of frequency. The values of DC electrical resistance for pure and nickel-doped barium nanohexaferrites are evaluated from the slope of I–V graphs.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1208450","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-25DOI: 10.1080/23311940.2016.1169880
M. Pravica, D. Sneed, Quinlan B. Smith, B. Billinghurst, T. May, M. White, K. Dziubek
Abstract We report on the synchrotron hard X-ray-induced decomposition of strontium oxalate (SrC2O4) pressurized to 7 GPa inside a diamond anvil cell (DAC). After some 4 h of irradiation in a white X-ray synchrotron beam, a dark reddish/brown region formed in the area of irradiation which was surrounded by a yellowish brown remainder in the rest of the sample. Upon depressurization of the sample to ambient conditions, the reacted/decomposed sample was recoverable as a dark brown/red and yellow waxy solid. Synchrotron infrared spectroscopy confirmed the strong presence of CO2 even under ambient conditions with the sample exposed to air and other strongly absorbing regions, suggesting that the sample may likely be polymerized CO (in part) with dispersed CO2 and SrO trapped within the polymer. These results will have significant implications in the ability to readily produce and trap CO2 in situ via irradiation of a simple powder for useful hard X-ray photochemistry and in the ability to easily manufacture polymeric CO (via loading of powders in a DAC or high volume press) without the need for the dangerous and complex loading of toxic CO. A novel means of X-ray-induced polymerization under extreme conditions has also been demonstrated.
{"title":"A novel synthesis of polymeric CO via useful hard X-ray photochemistry","authors":"M. Pravica, D. Sneed, Quinlan B. Smith, B. Billinghurst, T. May, M. White, K. Dziubek","doi":"10.1080/23311940.2016.1169880","DOIUrl":"https://doi.org/10.1080/23311940.2016.1169880","url":null,"abstract":"Abstract We report on the synchrotron hard X-ray-induced decomposition of strontium oxalate (SrC2O4) pressurized to 7 GPa inside a diamond anvil cell (DAC). After some 4 h of irradiation in a white X-ray synchrotron beam, a dark reddish/brown region formed in the area of irradiation which was surrounded by a yellowish brown remainder in the rest of the sample. Upon depressurization of the sample to ambient conditions, the reacted/decomposed sample was recoverable as a dark brown/red and yellow waxy solid. Synchrotron infrared spectroscopy confirmed the strong presence of CO2 even under ambient conditions with the sample exposed to air and other strongly absorbing regions, suggesting that the sample may likely be polymerized CO (in part) with dispersed CO2 and SrO trapped within the polymer. These results will have significant implications in the ability to readily produce and trap CO2 in situ via irradiation of a simple powder for useful hard X-ray photochemistry and in the ability to easily manufacture polymeric CO (via loading of powders in a DAC or high volume press) without the need for the dangerous and complex loading of toxic CO. A novel means of X-ray-induced polymerization under extreme conditions has also been demonstrated.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1169880","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-11DOI: 10.1080/23311940.2016.1169570
O. Oltulu, Sevket Simsek, A. Mamedov, E. Ozbay
Abstract In the present work, the acoustic band structure of a two-dimensional phononic crystal (PC) containing an organic ferroelectric (PVDF-polyvinylidene fluoride) and topological insulator (SnTe) was investigated by the plane-wave-expansion (PWE) method. Two-dimensional PC with square lattices composed of SnTe cylindrical rods embedded in the PVDF matrix is studied to find the allowed and stop bands for the waves of certain energy. Phononic band diagram ω = ω(k) for a 2D PC, in which non-dimensional frequencies ωa/2πc (c-velocity of wave) were plotted vs. the wavevector k along the Г–X–M–Г path in the square Brillouin zone shows five stop bands in the frequency range between 10 and 110 kHz. The ferroelectric properties of PVDF and the unusual properties of SnTe as a topological material give us the ability to control the wave propagation through the PC over a wide frequency range of 103–106 Hz. SnTe is a discrete component that allows conducting electricity on its surface but shows insulator properties through its bulk volume. Tin telluride is considered as an acoustic topological insulator as the extension of topological insulators into the field of “topological phononics”.
{"title":"Phononic band gap and wave propagation on polyvinylidene fluoride-based acoustic metamaterials","authors":"O. Oltulu, Sevket Simsek, A. Mamedov, E. Ozbay","doi":"10.1080/23311940.2016.1169570","DOIUrl":"https://doi.org/10.1080/23311940.2016.1169570","url":null,"abstract":"Abstract In the present work, the acoustic band structure of a two-dimensional phononic crystal (PC) containing an organic ferroelectric (PVDF-polyvinylidene fluoride) and topological insulator (SnTe) was investigated by the plane-wave-expansion (PWE) method. Two-dimensional PC with square lattices composed of SnTe cylindrical rods embedded in the PVDF matrix is studied to find the allowed and stop bands for the waves of certain energy. Phononic band diagram ω = ω(k) for a 2D PC, in which non-dimensional frequencies ωa/2πc (c-velocity of wave) were plotted vs. the wavevector k along the Г–X–M–Г path in the square Brillouin zone shows five stop bands in the frequency range between 10 and 110 kHz. The ferroelectric properties of PVDF and the unusual properties of SnTe as a topological material give us the ability to control the wave propagation through the PC over a wide frequency range of 103–106 Hz. SnTe is a discrete component that allows conducting electricity on its surface but shows insulator properties through its bulk volume. Tin telluride is considered as an acoustic topological insulator as the extension of topological insulators into the field of “topological phononics”.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1169570","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60085036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-06DOI: 10.1080/23311940.2016.1167575
F. Ono, Y. Mori, K. Takarabe, Akiko Fujii, M. Saigusa, Y. Matsushima, D. Yamazaki, E. Ito, S. Galas, N. Saini
Abstract This research shows that small animals, tardigrades (Milnesium tardigradum) in tun (dehydrated) state and Artemia salina cists (dried eggs) can tolerate the very high hydrostatic pressure of 7.5 GPa. It was really surprising that living organisms can survive after exposure to such a high pressure. We extended these studies to the extremely high pressure of 20 GPa by using a Kawai-type octahedral anvil press. After exposure to this pressure for 30 min, the tardigrades were soaked in pure water and investigated under a microscope. Their bodies regained metabolic state and no serious injury could be seen. But they were not alive. A few of Artemia eggs went part of the way to hatching after soaked in sea water, but they never grew any further. Comparing with the case of blue-green alga, these animals are weaker under ultra-high pressure.
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