Необычное формоизменение твердого параводорода с содержанием изотопов выше природного

При температурах 1,8–4,2 К измерены зависимости относительного удлинения ε от приложенного напряжения σ к образцам параводорода (p-H₂, ~ 0,2% o-H₂) высокой чистоты (99,9999 мол.%) по посторонним примесям, которые отличались содержанием стабильного изотопа водорода — дейтерия. Образцы были испытаны в условиях одноосного растяжения методом ступенчатого нагружения. Содержание [D]/[H] числа [D] атомов дейтерия по отношению к числу [Н] атомов протия в p-H₂ составляло (0,0055 ± 0,0005) ат.% или достигало 0,07 ат.%. В случае обогащенного дейтерием p-H₂ выявлено исчезновение на кривых σ(ε) стадии легкого скольжения дислокаций и значительное понижение величины полного относительного удлинения образцов, а также существенное возрастание коэффициента упрочнения dσ/dε. При деформации образцов p-H₂ с содержанием дейтерия больше природного обнаружено их необычное формоизменение, которое обусловлено появлением ротационной составляющей низкотемпературного пластического массопереноса.При температурах 1,8–4,2 К виміряно залежності відносного подовження ε від прикладеної напруги σ до зразків параводню (p-H₂, ~ 0,2% o-H₂) високої (99,9999 мол.%) чистоти відносно сторонніх домішок, якi вiдрiзнялись вмістом стабільного ізотопу водню — дейтерію. Зразки було випробувано в умовах од- новісного розтягу методом ступеневого навантаження. Вміст [D]/[H] кількостi [D] атомів дейтерію відносно кількостi [H] атомів протiю в p-H₂ складав (0,0055 ± 0,0005) ат.% або досягав 0,07 ат.%. У разі збагаченого дейтерієм p-H₂ виявлено зникнення на кривих σ(ε) стадії легкого ковзання дислокацій та значне зниження величини повного відносного подовження зразків, а також істотне зростання коефіцієнта зміцнення dσ/dε. При деформації зразків p-H₂ зi вмiстом дейтерію більш природного виявлено їх незвичайне формозмінювання, що обумовлено появою ротаційної складової низькотемпературного пластичного масопереносу.The relative elongation ε of samples of high purity (99.9999 mol. % with respect to nonhydrogenic impurities) parahydrogen ( p-H ₂, ∼0.2% o-H₂) with different amounts of the stable hydrogen isotope deuterium is measured as a function of applied stress σ at temperatures of 1.8–4.2 K. The samples were subjected to uniaxial tension by stepwise loading. The ratio [D]/[H] of the number [D] of deuterium atoms to the number [H] of p-H₂ hydrogen atoms ranged from 0.0055 ± 0.0005 at. % up to 0.07 at. %. For deuterium enriched p-H₂, the easy slip dislocation stage vanished from the σ(ε) curves and there was a significant reduction in the total relative elongation of the samples, as well as a substantial increase in the hardening coefficient dσ/ dε. Deformation of samples of p-H₂ with deuterium contents higher than the natural amount produces an unusual change in their shape owing to the appearance of a rotational component of the low-temperature plastic mass transfer

Nanoscale characterization of an all-oxide core-shell nanorod heterojunction using intermodulation atomic force microscopy (AFM) methods

The electrical properties of an all-oxide core-shell ZnO-Co3O4nanorod heterojunction were studied in the dark and under UV-vis illumination. The contact potential difference and current distribution maps were obtained utilizing new methods in dynamic multifrequency atomic force microscopy (AFM) such as electrostatic and conductive intermodulation AFM. Light irradiation modified the electrical properties of the nanorod heterojunction. The new techniques are able to follow the instantaneous local variation of the photocurrent, giving a two-dimensional (2D) map of the current-voltage curves and correlating the electrical and morphological features of the heterostructured core-shell nanorods

Mechanical Properties of Organic Electronic Polymers on the Nanoscale

Funder: Belgian National Fund for Scientific Research; Id: http://dx.doi.org/10.13039/501100002661Abstract: Organic semiconducting polymers have attractive electronic, optical, and mechanical properties that make them materials of choice for large area flexible electronic devices. In these devices, the electronically active polymer components are micrometers in size, and sport negligible performance degradation upon bending the centimeter‐scale flexible substrate onto which they are integrated. A closer look at the mechanical properties of the polymers, on the grain‐scale and smaller, is not necessary in large area electronic applications. In emerging micromechanical and electromechanical applications where the organic polymer elements are flexed on length scales spanning their own micron‐sized active areas, it becomes important to characterize the uniformity of their mechanical properties on the nanoscale. In this work, the authors use two precision nanomechanical characterization techniques, namely, atomic force microscope based PeakForce quantitative nanomechanical mapping (PF‐QNM) and nanoindentation‐based dynamical mechanical analysis (nano‐DMA), to compare the modulus and the viscoelastic properties of organic polymers used routinely in organic electronics. They quantitatively demonstrate that the semiconducting near‐amorphous organic polymer indacenodithiophene‐co‐benzothiadiazole (C16‐IDTBT) has a higher carrier mobility, lower modulus, and greater nanoscale modulus areal uniformity compared to the semiconducting semicrystalline organic polymer poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (C14‐PBTTT). Modulus homogeneity appears intrinsic to C16‐IDTBT but can be improved in C14‐PBTTT upon chemical doping

Functional modelling of complex multi‑disciplinary systems using the enhanced sequence diagram

YesThis paper introduces an Enhanced Sequence Diagram (ESD) as the basis for a structured framework for the functional analysis of complex multidisciplinary systems. The ESD extends the conventional sequence diagrams (SD) by introducing a rigorous functional flow-based modelling schemata to provide an enhanced basis for model-based functional requirements and architecture analysis in the early systems design stages. The proposed ESD heuristics include the representation of transactional and transformative functions required to deliver the use case sequence, and fork and join nodes to facilitate analysis of combining and bifurcating operations on flows. A case study of a personal mobility device is used to illustrate the deployment of the ESD methodology in relation to three common product development scenarios: (i) reverse engineering, (ii) the introduction of a specific technology to an existent system; and (iii) the introduction of a new feature as user-centric innovation for an existing system, at a logical design level, without reference to any solution. The case study analysis provides further insights into the effectiveness of the ESD to support function modelling and functional requirements capture, and architecture development. The significance of this paper is that it establishes a rigorous ESD-based functional analysis methodology to guide the practitioner with its deployment, facilitating its impact to both the engineering design and systems engineering communities, as well as the design practice in the industry

Functional modelling of complex multi‑disciplinary systems using the enhanced sequence diagram

YesThis paper introduces an Enhanced Sequence Diagram (ESD) as the basis for a structured framework for the functional analysis of complex multidisciplinary systems. The ESD extends the conventional sequence diagrams (SD) by introducing a rigorous functional flow-based modelling schemata to provide an enhanced basis for model-based functional requirements and architecture analysis in the early systems design stages. The proposed ESD heuristics include the representation of transactional and transformative functions required to deliver the use case sequence, and fork and join nodes to facilitate analysis of combining and bifurcating operations on flows. A case study of a personal mobility device is used to illustrate the deployment of the ESD methodology in relation to three common product development scenarios: (i) reverse engineering, (ii) the introduction of a specific technology to an existent system; and (iii) the introduction of a new feature as user-centric innovation for an existing system, at a logical design level, without reference to any solution. The case study analysis provides further insights into the effectiveness of the ESD to support function modelling and functional requirements capture, and architecture development. The significance of this paper is that it establishes a rigorous ESD-based functional analysis methodology to guide the practitioner with its deployment, facilitating its impact to both the engineering design and systems engineering communities, as well as the design practice in the industry

Определение низкотемпературного коэффициента собственной диффузии в твердом p-H2 из опытов по ползучести

Измерены зависимости относительного удлинения ε под действием постоянно приложенного напряжения при T = 1,8 К от времени выдержки t поликристаллического параводорода (p-H₂, ~ 0,2 % o-H₂) высокой чистоты по посторонним примесям (99,9999 мол. %) с различным содержанием дейтерия. Выявлена область линейной зависимости между измеренными величинами скорости установившейся ползучести ε' образцов и приложенной нагрузки σ. На основании линейной зависимости ε'~ σ сделан вывод о том, что низкотемпературный крип исследованного p-H₂ имеет диффузионный характер вакансионного типа. Проведено вычисление низкотемпературного коэффициента собственной диффузии вакансий D в твердом p-H₂, который характеризует скорость низкотемпературного массопереноса. Рассмотрены случаи миграции вакансий в объеме кристалла, вдоль разделяющих отдельные кристаллиты границ, а также между существующими в кристаллах дислокациями. Установлено заметное снижение величин ε' и D с ростом концентрации изотопов в образцах при сохранении для исследованного p-H₂ линейной связи между ε' и σ.Виміряно залежності відносного подовження ε під дією постійно прикладеної напруги при T = 1,8 К від часу витримки t полікристалічного параводню (p-H₂, ~0,2% o-H₂) високої чистоти по стороннім домішкам (99,9999 мол. %) з різним вмістом дейтерію. Виявлено область лінійної залежності між вимірюваними величинами швидкості сталої повзучості ε' зразків та прикладеного навантаження σ. На підставі виконання лінійної залежності ε' ~ σ зроблено висновок про дифузійний характер вакансійного типу низькотемпературного кріпа дослідженого p-H₂. Проведено обчислення низькотемпературного коефіцієнта власної дифузії вакансій D в твердому p-H₂, що характеризує швидкість низькотемпературного масопереносу. Розглянуто випадки міграції вакансій в об'ємі кристалла, уздовж меж, що розділяють окремі кристаліти, а також між існуючими в кристалах дислокаціями. Встановлено помітне зниження величин ε' та D зі зростанням концентрації ізотопів в зразках при збереженні для дослідженого p-H₂ лінійного зв'язку між ε' та σ.The dependences of the relative elongation ε on the endurance time t of polycrystalline parahydrogen (p-H₂, ~ 0,2% o-H₂) of high purity (99.9999 mol.%) on extraneous impurities with different deuterium content under the applied stress at T = 1.8 K were measured. The region of linear dependence between the measured creep rates of samples and the applied load σ was revealed. On the basis of the fulfillment of the linear law ε' ~ σ, the diffusion character of the low-temperature creep of the vacancytype p-H₂ investigated was concluded. The low-temperature values of the intrinsic diffusion coefficient of vacancies D in solid p-H₂, characterizing the rates of low-temperature mass transfer, are calculated. The cases of migration of vacancies in the crystal volume, along the boundaries, separating individual crystallites, are considered, as well as between dislocations existing in crystals. A noticeable decrease in the values of ε' and D was observed with an increase of the isotope concentration in the samples, while maintaining a linear relationship between ε' and σ for the p-H₂ studied

Engineering of electronic and optical properties of PbS thin films via Cu doping

Copper-doped PbS polycrystalline thin films were deposited by chemical bath deposition by adding small amount of Cu (y(solution) = [Cu2+]/[Pb2+]) between 0.5 and 2 at%. The composition, structure, morphology, optical and electrical properties of the films were investigated by means of X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), UV-visible near infrared (UV-Vis-NIR) spectrophotometry and Hall effect measurements. The XRD studies showed that the undoped films have PbS face centered cubic structure with (111) preferential orientation, while preferential orientation changes to (200) plane with increasing Cu doping concentration. The AFM and SEM measurements indicated that the film surfaces consisted of nanosized grains with pyramidal shape. Optical band gap was blue shifted from 0.72 eV to 1.69 eV with the increase in Cu doping concentration. The film obtained with the [Cu2+]/[Pb2+] ratio equal to 1.5 at% Cu showed the minimum resistivity of 0.16 Omega cm at room temperature and optimum value of optical band gap close to 1.5 eV. 1.5 at% Cu-doped PbS thin films exhibit the best optical and electrical properties, suitable for solar cells applications. (C) 2016 Elsevier Ltd. All rights reserved