EngRN: Materials Chemistry (Topic)最新文献

{"title":"Chemical and Mineralogical Analysis of High-Purity Quartz From New Deposits in a Greek Island, for Potential Exploration","authors":"G. Charalampides, K. Vatalis, A. Baklavaridis, V. Karayannis, N. Benetis","doi":"10.21303/2461-4262.2020.001357","DOIUrl":"https://doi.org/10.21303/2461-4262.2020.001357","url":null,"abstract":"The current study presents an original chemical, elemental and mineralogical characterization of new quartz mineral deposits situated in Ios island, Cyclades, Aegean sea, Greece, via X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) trace-element analysis. \u0000Actually, the mineral Quartz (crystalline SiO2) is found in nature in varying quality and is explored and traded for use in different applications of significant importance depending on the quartz purity. \u0000The results of the thorough chemical and mineralogical analysis indicate that quartz originating from the location examined in this research is almost free from other microcrystalline phases, and therefore it can be characterized as highly pure α-quartz. \u0000Thus, it can be used in the industry of ultra-high purity quartz production for specific applications, as long as the deposits are exploitable. In this framework, a preliminary estimation of the economic benefits from a potential exploration versus the environmental aspects of mining, taking into account sustainability issues in the region, is provided highlighting the local social needs","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128095817","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}

{"title":"Revealing the Atomistic Mechanisms of Strain Glass Transition in Ferroelastics","authors":"Chuanxin Liang, Dong Wang, Zhao Wang, Xiangdong Ding, Yunzhi Wang","doi":"10.2139/ssrn.3542917","DOIUrl":"https://doi.org/10.2139/ssrn.3542917","url":null,"abstract":"Abstract As a new ferroelastic state, strain glass has attracted a lot of recent attentions and, most importantly, strain glass transitions (SGTs) could underpin many phenomena that have puzzled the physics community for decades, including the quasi-linear superelasticity and Invar and Elinvar anomalies. However, there has been a lack of fundamental understanding at the atomistic level beyond the phenomenological Landau theory. In this paper, we propose a way to obtain quantitatively the continuous strain/stress fields distribution caused by point defects through molecular statics calculations by incorporating a Gaussian probability distribution function. By using the quantitative strain/stress fields distribution to inform phase field simulations, we reproduce quantitatively the experimentally observed critical defect concentrations separating the normal martensitic phase transition from SGTs at different temperatures and critical temperatures for spontaneous strain glass to martensitic transition at different defect concentrations. Based on percolation theory, we demonstrate how the strain network created by point defects with a critical concentration regulates the nucleation and growth of martensitic domains, suppresses autocatalysis by strain frustration, and changes the sharp first-order martensitic transformation into a continuous SGT. A general temperature- and defect-concentration-dependent percolation criterion is formulated for accurate prediction of SGT, which could enable high throughput computations for systematic search of new strain glass systems using simply molecular static calculations.","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129643875","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}

{"title":"Ethylene Glycol: Kinetics of the Formation from Methanol–Formaldehyde Solutions","authors":"Michael M. Silaev","doi":"10.2139/ssrn.3577703","DOIUrl":"https://doi.org/10.2139/ssrn.3577703","url":null,"abstract":"The mechanism and kinetics are developed for the initiated nonbranched-chain formation of ethylene glycol in methanol–formaldehyde solutions at formaldehyde concentrations of 0.1–3.1 mol dm–3and temperatures of 373–473 K. The experimental concentrations of the free unsolvated form of formaldehyde are given at the different temperatures and total concentrations of formaldehyde in methanol. The experimental dependence of the radiation-chemical yields of ethylene glycol on formaldehyde concentration in γ-radiolysis of methanol–formaldehyde solutions at 373–473 K is shown. At a formaldehyde concentration of 1.4 mol dm–3and T= 473 K, the radiation-chemical yield of ethylene glycol is 139 molecules per 100 eV. The effective activation energy of ethylene glycol formation is 25 ± 3 kJ mol–1. The quasi-steady-state treatment of the reaction network suggested here led to a rate equation accounting for the nonmonotonic dependence of the ethylene glycol formation rate on the concentration of the free(unsolvated) form of dissolved formaldehyde. It is demonstrated that the peak in this dependence is due to the competition between methanol and CH2=O for reacting with the adduct radical HOCH2CH2O•.","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114394828","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}

{"title":"Micro-Mechanical Response of Ultrafine Grain and Nanocrystalline Tantalum","authors":"Wen Yang, C. Ruestes, Zezhou Li, O. T. Abad, T. Langdon, B. Heiland, M. Koch, E. Arzt, M. Meyers","doi":"10.2139/ssrn.3311681","DOIUrl":"https://doi.org/10.2139/ssrn.3311681","url":null,"abstract":"Abstract In order to investigate the effect of grain boundaries on the mechanical response in the micrometer and submicrometer levels, complementary experiments and molecular dynamics simulations were conducted on a model bcc metal, tantalum. Microscale pillar experiments (diameters of 1 and 2 μm) with a grain size of ∼ 100-200 nm revealed a mechanical response characterized by a yield stress of ∼1,500 MPa. The hardening of the structure is reflected in the increase in the flow stress to 1,700 MPa at a strain of ∼0.35. Molecular dynamics simulations were conducted for nanocrystalline tantalum with grain sizes in the range of 20-50 nm and pillar diameters in the same range. The yield stress was approximately 6,000 MPa for all specimens and the maximum of the stress-strain curves occurred at a strain of 0.07. Beyond that strain, the material softened because of its inability to store dislocations. The experimental results did not show a significant size dependence of yield stress on pillar diameter (equal to 1 and 2 um), which is attributed to the high ratio between pillar diameter and grain size (∼10-20). This behavior is quite different from that in monocrystalline specimens where dislocation ‘starvation’ leads to a significant size dependence of strength. The ultrafine grains exhibit clear ‘pancaking’ upon being plastically deformed, with an increase in dislocation density. The plastic deformation is much more localized for the single crystals than for the nanocrystalline specimens, an observation made in both modeling and experiments. In the molecular dynamics simulations, the ratio of pillar diameter (20-50 nm) to grain size was in the range 0.2 to 2, and a much greater dependence of yield stress to pillar diameter was observed. A critical result from this work is the demonstration that the important parameter in establishing the overall deformation is the ratio between the grain size and pillar diameter; it governs the deformation mode as well as surface sources and sinks, which are only important when the grain size is of the same order as the pillar diameter.","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"40 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130537484","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}

{"title":"Allotropoic Strengthening and in situ Phase Transformations During High-Temperature Flexure of Bulk Tantalum Nitride","authors":"D. Demirskyi, O. Vasylkiv, K. Yoshimi","doi":"10.2139/ssrn.3836794","DOIUrl":"https://doi.org/10.2139/ssrn.3836794","url":null,"abstract":"<i>In situ</i>&nbsp;phase transformation and change in the grain size were observed during high-temperature flexural tests performed on tantalum nitride bulks consolidated by spark plasma sintering. This study, for the first time, shows that tantalum nitride with cubic structure is the main phase at temperatures between 25&nbsp;°C and 2000&nbsp;°C, while previous studies suggested it should be hexagonal TaN. Cubic TaN phases with lattice parameters of&nbsp;<i>a</i> =&nbsp;4.338&nbsp;Å and&nbsp;<i>a</i> =&nbsp;4.45&nbsp;Å were observed below 1600&nbsp;°C and above 1600&nbsp;°C, respectively. The possibility of the formation of multiple TaN phases during the flexural tests significantly increases the high-temperature strength as values of greater than 500 MPa were observed at 1600&nbsp;°C. This strength level is typical for the bulk TaC at room temperature.","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"19 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131574769","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}

{"title":"Fusion Bonding of Copper and Silicon at -70°C by Electrochemistry","authors":"P. Chien, Lin Cheng, Cheng-Ying Liu, JH Li, B. T. Lee","doi":"10.2139/ssrn.3661926","DOIUrl":"https://doi.org/10.2139/ssrn.3661926","url":null,"abstract":"Wafer bonding processing typically employs thermal energy to fuse two surfaces by stimulating atomic interdiffusion at high temperatures. However, we found that fusion bonding of copper and silicon can occur at an extremely low temperature in cryo-electrochemical processing cooled by dry-ice (-20°C) or even by liquid nitrogen (-70°C). The results demonstrate that electrical energy can replace the thermal energy that must be used in semiconductor processes. The bonding phenomenon occurred repeatedly, even the copper surface was not favorable for spontaneous bonding. Notably, the bonding strength of Cu/Si was very high. Even after forcibly inserting a razor at the bonding interface, a copper layer was split from the Cu host substrate to transfer onto silicon. Secondary-ion mass spectrometry (SIMS) analysis revealed that the bonding was caused by nanoscale interdiffusion between surface copper and silicon atoms. We propose a possible mechanism in which holes are driven into the bonding interface of Cu/Si under bias, positively charge the Cu atoms and form cations (that is, surface activation). The electric field continuously drives Cu cations to bond with the dangling bonds on the mating silicon to form Si-Cu bonds. The late-forming Cu cations can pass over the bonding interface and quickly diffuse into the silicon interstitials. This study of fusion bonding at -70ºC by electrochemistry-assisted interdiffusion rather than by thermal energy has profound implications for the bonding mechanism.","PeriodicalId":237724,"journal":{"name":"EngRN: Materials Chemistry (Topic)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126842400","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}