19 research outputs found

    Исследование фазовых равновесий тройной системы Zn—Se—Fe для лазерных технологий

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    The problem of obtaining crystalline ZnSe doped with d-elements for obtaining high-efficiency laser materials with characteristics in a wide IR range don’t possible successfully solved without reliable data on phase equilibrium and solubility of the components entering the system. The theoretical and experimental analysis of the three-component Zn—Se—Fe system for obtaining new fundamental information on phase using X-ray analysis (XRD) and inductively coupled plasma mass spectrometry (ICP-MS) was carried out. New experimental data of isothermal annealing in the ternary Zn—Se—Fe system at the temperatures 730 K (I, II), 814 K (III, IV), 1073 K (V), as well as information on Fe solubility in bi- and monovariant conditions by X-ray studies have shown the existence of the coexistence of the following phases: Fe3Zn10-Fe11Zn40-Zn-ZnSe (I), ZnSe-FeSe2-Fe7Se8 (II), ZnSe-Fe3Zn10-Fe (III), FeSe2-Fe7Se8-Se (IV), ZnSe-FeSe- Fe3Se4 (V), ZnSe-FeSe (VI) and confirmed the reliability of theoretical isothermal sections.Проведен теоретический и экспериментальный анализ фазовых равновесий в тройной системе Zn—Se—Fe с применением рентгенофазового анализа и масс-спектрометрии с индуктивно связанной плазмой. Получены данные о моновариантных равновесиях в изотермических сечениях при температуре 730, 814 и 1073 К, а также сведения о растворимости железа в условиях би- и моновариантных равновесий при 1073 К. Определен фазовый состав образцов системы Zn—Se—Fe, синтезированных при различных температурах и разном валовом составе. Подтверждена достоверность теоретически построенных изотермических сечений Т—Х—Y-проекции P—T— Х—Y-диаграммы тройной системы Zn—Se—Fe

    ОБЛАСТЬ ГОМОГЕННОСТИ ТЕЛЛУРИДА ЦИНКА

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    The homogeneity limits of ZnTe were examined using direct physical−chemical technique in the temperature range 750—1455 K. It was demonstrated that surface oxidation in the room environment results in the distortion of the observed picture such that an excess of a component may appear with a negative sign. At the same time, in the case of non−oxidized ZnTe, it was demonstrated for the first time the stoichiometrical composition lies within the homogeneity limits. The maximum nonstoichiometries were found to be a 3.4 × 10-4 and 4.4 × 10-3 mole excess of a component per mole of ZnTe for Te at 1369 K and Zn at 1292 K, respectively. At T < 1200 K the solidus lines of both the Te- and Zn-rich boundaries demonstrated retrograde behavior. On the basis of the results obtained from X-ray diffraction and optical microscopy measurements performed on quenched samples, a T—x-projection including a wurtzite-sphalerite-like phase transformation was proposed for the Zn—Te-system.Прямым физико-химическим методом исследована область гомогенности ZnTe в интервале температур 750—1455 K. Показано, что при хранении препаратов ZnTe на воздухе при комнатной температуре происходит окисление его поверхности, в результате которого определяемая концентрация сверхстехиометрического компонента смещается в сторону избытка теллура. Для неокисленных препаратов впервые было показано, что область гомогенности теллурида цинка носит двусторонний характер. Максимальная концентрация избыточного компонента составила: со стороны избытка теллура — 3,4 · 10−4 моль изб. Те/моль ZnTe при 1325 К, со стороны избытка цинка — 4,4 · 10−3 моль изб. Zn/моль ZnTe при 1292 К. Установлено, что при температурах ниже 1200 К линия солидуса имеет ретроградный характер. Учитывая результаты РФА и оптической микроскопии, сделан вывод, что полиморфный переход «вюрцит — сфалерит» в ZnTe протекает по перитектической реакции со стороны избытка обоих компонентов

    Глубокая очистка теллура для производства материалов электроники и фотоники

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    The regularities of impurity distribution between the distillate and the still as well as the spatial  distribution of impurities  along  the distillate length have been studied. We conclude that some impurities such as s−metals, Zn, Ni, V and rare metals distribute uniformly along the distillate length (20 cm). Contrarily, Se tends to concentrate in the distant (from the still) region  of distillate with more  than one order  of magnitude higher concentration compared to the nearest region.Для проведения процесса получе ния высокочистого теллура методом вакуумной  дистилляции предложена конструкция реактора из высокочистых кварцевого стекла и графита. В ходе процесса расплав теллура испаряется, пар переносится из горячей части системы в более холодную и конденсируется в виде твердой фазы (дистиллята) без образования жидкости. Изучены закономерности перераспределения примесей между дистиллятом и кубовым остатком, а также пространственное распределение примесей в дистилляте при проведении очистки металлического теллура. Установлено, что часть примесей, например щелочные металлы, Zn, Ni, V, редкоземельные металлы распределены равномерно по длине  дистиллята (20  см). В то же время концентрация Se в дальней (от перегонного куба) части дистиллята превышает концентрацию в ближней части на порядок

    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

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    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

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    Dark matter lighter than 10 GeV/c2^2 encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino floor for GeV-scale masses and significant sensitivity down to 10 MeV/c2^2 considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector's sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies

    Sensitivity of future liquid argon dark matter search experiments to core-collapse supernova neutrinos

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    Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will be sensitive also to core-collapse supernova neutrinos, via coherent elastic neutrino-nucleus scattering. This interaction channel is flavor-insensitive with a high-cross section, enabling for a high-statistics neutrino detection with target masses of ∼50 t and ∼360 t for DarkSide-20k and Argo respectively. Thanks to the low-energy threshold of ∼0.5 keVnr achievable by exploiting the ionization channel, DarkSide-20k and Argo have the potential to discover supernova bursts throughout our galaxy and up to the Small Magellanic Cloud, respectively, assuming a 11-M⊙ progenitor star. We report also on the sensitivity to the neutronization burst, whose electron neutrino flux is suppressed by oscillations when detected via charged current and elastic scattering. Finally, the accuracies in the reconstruction of the average and total neutrino energy in the different phases of the supernova burst, as well as its time profile, are also discussed, taking into account the expected background and the detector response

    Separating Ar39 from Ar40 by cryogenic distillation with Aria for dark matter searches

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    Aria is a plant hosting a 350m cryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of 39Ar in argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed, 39Ar is a -emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant

    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

    No full text
    Dark matter lighter than 10 GeV/c2 encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino fog for GeV-scale masses and significant sensitivity down to 10 MeV/c2 considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector's sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies

    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

    No full text
    Dark matter lighter than 10 GeV/c2^2 encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino floor for GeV-scale masses and significant sensitivity down to 10 MeV/c2^2 considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector's sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies
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