Ag2.54Tl2Mo12Se15: a new structure type containing Mo6 and Mo9 clusters

wosInternational audienceThe novel structure-type Ag2.54Tl2Mo12Se15 (silver thallium molybdenum selenide) is built up of Mo6Sei8Sea6 and Mo9Sei11Sea6 cluster units in a 1:2 ratio, which are three-dimensionally connected to form the Mo-Se network. The Ag and Tl cations are distributed in several voids within the cluster network. Three of the seven independent Se atoms and one Tl atom lie on sites with 3.. symmetry (Wyckoff sites 2c or 2d)

Sc0.43(2)Rb2Mo15S19, a partially Sc-filled variant of Rb2Mo15S19

International audienceThe structure of scandium dirubidium pentadecamolybdenum nonadecasulfide, Sc0.43 (2)Rb2Mo15S19, constitutes a partially Sc-filled variant of Rb2Mo15S19 [Picard, Saillard, Gougeon, Noel & Potel (2000), J. Solid State Chem.155, 417426]. In the two compounds, which both crystallize in the Rc space group, the structural motif is characterized by a mixture of Mo6Si8Sa6 and Mo9Si11Sa6 cluster units ('i' is inner and 'a' is apical) in a 1:1 ratio. The two components are interconnected through interunit MoS bonds. The cluster units are centred at Wyckoff positions 6b and 6a (point-group symmetries and 32, respectively). The Rb+ cations occupy large voids between the different cluster units. The Rb and the two inner S atoms lie on sites with 3. symmetry (Wyckoff site 12c), and the Mo and S atoms of the median plane of the Mo9S11S6 cluster unit lie on sites with .2 symmetry (Wyckoff site 18e). A unique feature of the structure is a partially filled octahedral Sc site with symmetry. Extended Huckel tight-binding calculations provide an understanding of the variation in the MoMo distances within the Mo clusters induced by the increase in the cationic charge transfer due to the insertion of Sc

The Chevrel phase HgMo6S8

The crystal structure of HgMo6S8, mercury(II) hexa­molybdenum octa­sulfide, is based on (Mo6S8)S6 cluster units ( symmetry) inter­connected through inter­unit Mo—S bonds. The Hg2+ cations occupy large voids between the different cluster units and are covalently bonded to two S atoms. The Hg atoms and one S atom lie on sites with crystallographic and 3 symmetry, respectively. Refinement of the occupancy factor of the Hg atom led to the composition Hg0.973 (3)Mo6S8

Silver oxalate-based solders: New materials for high thermal conductivity microjoining

Micrometric oxalate powders can be decomposed starting from temperatures as low as 90°C, leading to the formation of temporary nanometric grains of metallic silver with a high propensity for sintering. The decomposition being highly exothermic, this additional energy favours the sintering, i.e. the soldering, process. Solders processed at 300°C and very low pressure (<0.5 MPa) displayed a thermal conductivity close to 100 W m-1 K-1, making silver oxalate very promising for safe, moderate temperature and very low pressure bonding

Developing new joining materials for low-temperature electronics assembly

International audienceThe present work focuses on a new kind of lead-free joining method for surface-mount technology based on precursor chemistry. The interest of metal oxalates as new soldering materials for die attachment (1st level packaging) was previously demonstrated with silver oxalate. The thermal decomposition of metal oxalates under controlled atmosphere can be used to produce small metal particles below their melting point. These particles are found to be in a highly active particulate form. First experimental studies are focusing on several metal oxalates (tin oxalate and bismuth oxalate) to assess their suitability for low-temperature metal particle production. The main work is dealing with controlled chemical precipitation synthesis and characterization of the compounds as well as study of the properties of decomposition solid products (powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and thermal analyses under different atmospheres)

Tl2Mo9Se11

The structure of Tl2Mo9Se11, dithallium nona­molybdenum undeca­selenide, is isotypic with Tl2Mo9S11 [Potel et al. (1980 ▶). Acta Cryst. B36, 1319–1322]. The structural set-up is characterized by a mixture of Mo6Sei 8Sea 6 and Mo12Sei 14Sea 6 cluster units in a 1:1 ratio. Both components are inter­connected through inter­unit Mo—Se bonds. The cluster units are centered at Wyckoff positions 3a and 3b (point-group symmetry .). The two TlI atoms are situated in the voids of the three-dimensional arrangement. Two of the five independent Se atoms and the Tl atoms lie on sites with 3. symmetry (Wyckoff site 6c)

Superconducting transitions of intrinsic arrays of weakly coupled one-dimensional superconducting chains: the case of the extreme quasi-1D superconductor Tl(2)Mo(6)Se(6)

International audienceTl(2)Mo(6)Se(6) represents a model system for quasi-one-dimensional (quasi-1D) superconductors. We investigate its superconducting transition in detail by means of electrical transport experiments on high-quality single crystalline samples with onset T(c) = 6.8 K. Our measurements indicate a highly complex superconducting transition that occurs in different stages, with a characteristic bump in the resistivity and distinct plateau structures in the supercurrent gap imaged by V-I curves. We interpret these features as fingerprints of the gradual establishment of global phase coherence in an array of weakly coupled parallel 1D superconducting bundles. In this way, we demonstrate that superconducting Tl(2)Mo(6)Se(6) behaves like an intrinsic array of proximity or Josephson junctions, undergoing a complex superconducting phase-ordering transition at 4.5 K that shows many similarities to the Berezinskii-Kosterlitz-Thouless transition

V1.42In1.83Mo15Se19

The structure of the title compound, vanadium indium penta­deca­molybdenum nona­deca­selenide, V1.42In1.83Mo15Se19, is isotypic with In2.9Mo15Se19 [Grüttner et al. (1979 ▶). Acta Cryst. B35, 285–292]. It is characterized by two cluster units Mo6Sei 8Sea 6 and Mo9Sei 11Sea 6 (where i represents inner and a apical atoms) that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c and have point-group symmetry and , respectively. The clusters are inter­connected through additional Mo—Se bonds. In the title compound, the V3+ cations replace the trivalent indium atoms present in In2.9Mo15Se19, and a deficiency is observed on the monovalent indium site. One Mo, one Se and the V atom are situated on mirror planes, and two other Se atoms and the In atom are situated on threefold rotation axes

Matériaux innovants sans plomb pour l'assemblage de composants électroniques à basse température

Dans le cadre du développement de nouveaux matériaux d’assemblage sans plomb, les premiers résultats de synthèse et de caractérisations physicochimiques d’oxalate de bismuth sont présentés. Par une méthode de décomposition thermique de précurseurs métal-organiques, la possibilité de produire des particules métalliques en dessous de la température de fusion du bismuth massif (271°C) est discutée ici. L’étude du comportement en température de l’oxalate de bismuth montre l’influence de l’atmosphère (air ou azote) sur la nature des produits de décomposition (oxyde ou métal). Sous une atmosphère inerte contrôlée, les échantillons d’oxalate préparés se décomposent en bismuth métallique entre 210 et 250°C

Targeted Magnetic Intra-Lysosomal Hyperthermia produces lysosomal reactive oxygen species and causes Caspase-1 dependent cell death

Therapeutic strategies using drugs which cause Lysosomal Cell Death have been proposed for eradication of resistant cancer cells. In this context, nanotherapy based on Magnetic Intra-Lysosomal Hyperthermia (MILH) generated by magnetic nanoparticles (MNPs) that are grafted with ligands of receptors overexpressed in tumors appears to be a very promising therapeutic option. However, mechanisms whereby MILH induces cell death are still elusive. Herein, using Gastrin-grafted MNPs specifically delivered to lysosomes of tumor cells from different cancers, we provide evidences that MILH causes cell death through a non-apoptotic signaling pathway. The mechanism of cell death involves a local temperature elevation at the nanoparticle periphery which enhances the production of reactive oxygen species through the lysosomal Fenton reaction. Subsequently, MILH induces lipid peroxidation, lysosomal membrane permeabilization and leakage of lysosomal enzymes into the cytosol, including Cathepsin-B which activates Caspase-1 but not apoptotic Caspase-3. These data highlight the clear potential of MILH for the eradication of tumors overexpressing receptors