Solid-state synthesis and characterization of ferromagnetic Mn5Ge3 nanoclusters in GeO/Mn thin films

Mn5Ge3 films are promising materials for spintronic applications due to their high spin polarization and a Curie temperature above room temperature. However, non-magnetic elements such as oxygen, carbon and nitrogen may unpredictably change the structural and magnetic properties of Mn5Ge3 films. Here, we use the solid-state reaction between Mn and GeO thin films to describe the synthesis and the structural and magnetic characterization of Mn5Ge3(Mn5Ge3Oy)-GeO2(GeOx) nanocomposite materials. Our results show that the synthesis of these nanocomposites starts at 180°С when the GeO decomposes into elemental germanium and oxygen and the resulting Ge atoms immediately migrate into the Mn layer to form ferromagnetic Mn5Ge3 nanoclusters. At the same time the oxygen atoms take part in the synthesis of GeOx and GeO2 oxides and also migrate into the Mn5Ge3 lattice to form Mn5Ge3Oy Nowotny nanoclusters. Magnetic analysis assumes the general nature of the Curie temperature increase in carbon-doped Mn5Ge3Cx and Mn5Ge3Oy films. Our findings prove that not only carbon, but oxygen may contribute to the increase of the saturation magnetization and Curie temperature of Mn5Ge3-based nanostructures

Exploration of structural, thermal, vibrational and spectroscopic properties of new noncentrosymmetric double borate Rb3NdB6O12

New noncentrosymmetric rare earth borate Rb3NdB6O12 is found in the ternary system Rb2O–Nd2O3–B2O3. The Rb3NdB6O12 powder was fabricated by solid state synthesis at 1050 K for 72 h and the crystal structure was obtained by the Rietveld method. Rb3NdB6O12 crystallized in space group R32 with unit cell parameters a = 13.5236(4), c = 31.162(1) Å, Z = 3. From DSC measurements, the reversible phase transition (I type) in Rb3NdB6O12 is observed at 852–936 K. The 200 μm thick tablet is transparent over the spectral range of 0.3–6.5 μm and the band gap is found as Eg ∼ 6.29 eV. Nonlinear optical response of Rb3NdB6O12 tested via SHG is estimated to be higher than that of K3YB6O12. Blue shift of Nd luminescent lines is found in comparison with other borates. The vibrational parameters of Rb3NdB6O12 are evaluated by experimental methods

Electronic structure of β-RbSm(MoO4)(2) and chemical bonding in molybdates

Microcrystals of orthorhombic rubidium samarium molybdate, β-RbSm(MoO4)2, have been fabricated by solid state synthesis at T = 450 °C, 70 h, and at T = 600 °C, 150 h. The crystal structure has been refined by the Rietveld method in space group Pbcn with cell parameters a = 5.0984(2), b = 18.9742(6) and c = 8.0449(3) Å (RB = 1.72%). Thermal properties of β-RbSm(MoO4)2 were traced by DSC over the temperature range of T = 20–965 °C, and the earlier reported β ↔ α phase transition at T ∼ 860–910 °C was not verified. The electronic structure of β-RbSm(MoO4)2 was studied by employing theoretical calculations and X-ray photoelectron spectroscopy. It has been established that the O 2p-like states contribute mainly to the upper part of the valence band and occupy the valence band maximum, whereas the Mo 4d-like states contribute mainly to the lower part of the valence band. Chemical bonding effects have been analysed from the element core level binding energy data. In addition, it was found that the luminescence spectrum of β-RbSm(MoO4)2 is rather peculiar among the Sm3+ containing materials. The optical refractive index dispersion in β-RbSm(MoO4)2 was also predicted by the first-principles calculations

Quaternary Selenides EuLnCuSe3: Synthesis, Structures, Properties and In Silico Studies

In this work, we report on the synthesis, in-depth crystal structure studies as well as optical and magnetic properties of newly synthesized heterometallic quaternary selenides of the Eu+2Ln+3Cu+1Se3 composition. Crystal structures of the obtained compounds were refined by the derivative difference minimization (DDM) method from the powder X-ray diffraction data. The structures are found to belong to orthorhombic space groups Pnma (structure type Ba2MnS3 for EuLaCuSe3 and structure type Eu2CuS3 for EuLnCuSe3, where Ln = Sm, Gd, Tb, Dy, Ho and Y) and Cmcm (structure type KZrCuS3 for EuLnCuSe3, where Ln = Tm, Yb and Lu). Space groups Pnma and Cmcm were delimited based on the tolerance factor t’, and vibrational spectroscopy additionally confirmed the formation of three structural types. With a decrease in the ionic radius of Ln3+ in the reported structures, the distortion of the (LnCuSe3) layers decreases, and a gradual formation of the more symmetric structure occurs in the sequence Ba2MnS3 → Eu2CuS3 → KZrCuS3. According to magnetic studies, compounds EuLnCuSe3 (Ln = Tb, Dy, Ho and Tm) each exhibit ferrimagnetic properties with transition temperatures ranging from 4.7 to 6.3 K. A negative magnetization effect is observed for compound EuHoCuSe3 at temperatures below 4.8 K. The magnetic properties of the discussed selenides and isostructural sulfides were compared. The direct optical band gaps for EuLnCuSe3, subtracted from the corresponding diffuse reflectance spectra, were found to be 1.87– 2.09 eV. Deviation between experimental and calculated band gaps is ascribed to lower d states of Eu2+ in the crystal field of EuLnCuSe3, while anomalous narrowing of the band gap of EuYbCuSe3 is explained by the low-lying charge-transfer state. Ab initio calculations of the crystal structures, elastic properties and phonon spectra of the reported compounds were performed. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The research was supported by the Tyumen region within the framework of the grant agreement in the form of a grant to non-profit organizations no. 89-don dated 07.12.2020. This study was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FEUZ-2020-0054). This work was supported by state assignment of the Ministry of Science and Higher Education of the Russian Federation (Project Reg. No. 720000Ф.99.1.БЗ85АА13000). The work was conducted within the framework of the budget project № 0287-2021-0013 for the Institute of Chemistry and Chemical Technology SB RAS

РОЛЬ НИИ СКОРОЙ ПОМОЩИ ИМ. Н.В. СКЛИФОСОВСКОГО В СОЗДАНИИ СЛУЖБЫ МЕДИЦИНЫ КАТАСТРОФ В СТРАНЕ

The occurrence  of large-scale emergencies with great  human  losses  and the  absence of a unified authority  of the country health  system which would manage  its medical and sanitary consequences required  the  creation  of special  units to provide emergency  health  services (EHS) in mass injuries. The disaster  medicine  became  attractive for the N.V. Sklifosovsky Research  Institute  for Emergency Medicine in the 70s of the last century. Originally, the Department for Disaster Medicine was established at the  Institute  in 1987. At the  Department, the  extensive  work was performed  to shorten  a time gap between the delivery of medical care and the beginning  of a disaster  as much as possible. It was based  on a created  concept  for organization of medical  assistance and evacuation,  methods of its expertise and the  development of technical  means  for phased  medical  and evacuatiol  support of victims. The organizational and medical-diagnostic specificity of EHS in emergencies and its delivery were analyzed  in order to reduce  the severity of consequences. The health  care experience in emergencies has been  enriched  by the staff of the Institute  (who were not employees  of the Department)  actively involved in the management of mass injuries and poisonings via air ambulance at the accident site and in the treatment of victims admitted to the Institute  from sites of emergencies. Consequently, the N.V. Sklifosovsky Research Institute  for Emergency Medicine developed and offered the  scientific and organizational basis  for EHS in emergencies which made  a significant  practical contribution to the creation  of public services for disaster  medicine in the country.Возникновение  крупномасштабных  чрезвычайных  ситуаций (ЧС) с большими  человеческими жертвами и отсутствие в системе здравоохранения страны единого органа управления планированием и организацией  ликвидации их медико-санитарных  последствий потребовало  создания специальных  подразделений для оказания  экстренной  медицинской  помощи  (ЭМП) при массовых травмах. В НИИ СП имени Н.В. Склифосовского интерес  к медицине  катастроф  зародился еще с 70-х годов прошлого столетия. В 1987 г. впервые  в стране в институте был создан  отдел медицины  катастроф, проводивший  большую работу по максимальному  приближению начала оказания  медицинской  помощи к моменту возникновения  ЧС на основе  созданной  концепции организации лечебно-эвакуационной помощи, методов ее экспертной оценки и разработки  технических средств поэтапного лечебно-эвакуационного обеспечения  пострадавших. Рассмотрены организационная  и лечебно-диагностическая специфика ЭМП при ЧС, проанализированы ее особенности  при различных видах катастроф с целью снижения тяжести их последствий. Опыт оказания  медицинской  помощи при ЧС был обогащен  работой  сотрудников института, не входивших в состав отдела, но активно участвовавших в ликвидации последствий массовых травм и отравлений по линии санитарной авиации на месте происшествия и в лечении пострадавших, поступавших в институт из очагов ЧС. В результате в НИИ СП имени Н.В. Склифосовского были идеологически обоснованы,  разработаны  и предложены  научно-организационные принципы ЭМП при ЧС, что внесло значимый практический вклад в создание государственной службы медицины катастроф в стране

Self-organized aggregation of a triple of colloidal quantum dots into stable structures with various shapes controlled by a laser field

Dynamical model of self-assembly of nanoparticles in the field of laser radiation is developed and applied to the investigation of the possibility of the assembly of variously shaped structures comprised of the particles. Specifically, the computer model of the process of formation of structures with pre-defined geometry from a set of three initially isolated nanoparticles. The possibility of control of the geometry of the formed structure via the choice of the wavelength of external field

Triple molybdate scheelite-type upconversion phosphor NaCaLa(MoO4)3:Er3+/Yb3+: structural and spectroscopic properties

Triple molybdate NaCaLa(1-x-y)(MoO4)3:xEr3+,yYb3+ (x = y = 0, x = 0.05 and y = 0.45, x = 0.1 and y = 0.2, x = 0.2 and y = 0) phosphors were successfully synthesized by the microwave sol-gel method for the first time. Well-crystallized particles formed after heattreatment at 900°C for 16 h showed a fine and homogeneous morphology with particle sizes of 2-3 μm. The structures were refined by Rietveld method in space group I41/a. The optical properties were examined comparatively using photoluminescence emission and Raman spectroscopy. Under the excitation at 980 nm, the NaCaLa0.7(MoO4)3:0.1Er3+,0.2Yb3+ and NaCaLa0.5(MoO4)3:0.05Er3+,0.45Yb3+ particles exhibited a strong 525-nm emission band, a weaker 550-nm emission band in the green region, and weak 655-nm, 490-nm and 410-nm emission bands in the red, blue and violet regions. The pump power dependence and Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail

Laser-induced wavelength-controlled self-assembly of colloidal quasi-resonant quantum dots

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