Dilute Gd hydroxycarbonate particles for localized spin qubit integration

Molecular spins are considered as the quantum hardware to build hybrid quantum processors in which coupling to superconducting devices would provide the means to implement the necessary coherent manipulations. As an alternative to large magnetically-dilute crystals or concentrated nano-scale deposits of paramagnetic molecules that have been studied so far, the use of pre-formed sub-micronic spherical particles of a doped Gd@Y hydroxycarbonate is evaluated here. Particles with an adjustable number of spin carriers are prepared through the control of both particle size and doping. Bulk magnetic properties and continuous wave and time-domain-EPR spectroscopy show that the Gd spins in these particles are potential qubits with robust quantum coherence. Monolayers of densely-packed particles are then formed interfacially and transferred successfully to the surface of Nb superconducting resonators. Alternatively, these particles are disposed at controlled localizations as isolated groups of a few particles through Dip-Pen Nanolithography using colloidal organic dispersions as ink. Altogether, this study offers new material and methodologies relevant to the development of viable hybrid quantum processors.

Synthesis of ((CeO2)0.8(Sm2O3)0.2)@NiO Core-Shell Type Nanostructures and Microextrusion Printing of a Composite Anode Based on Them

The process of the hydrothermal synthesis of hierarchically organized nanomaterials with the core-shell structure with the composition ((CeO₂)_0.8(Sm₂O₃)_0.2)@NiO was studied, and the prospects for their application in the formation of planar composite structures using microextrusion printing were shown. The hydrothermal synthesis conditions of the (CeO₂)_0.8(Sm₂O₃)_0.2 nanospheres were determined, and the approach to their surface modification by growing the NiO shell with the formation of core-shell structures equally distributed between the larger nickel(II) oxide nanosheets was developed. The resulting nanopowder was used as a functional ink component in the microextrusion printing of the corresponding composite coating. The microstructure of the powders and the oxide coating was studied by scanning (SEM) and transmission electron microscopy (TEM), the crystal structure was explored by X-ray diffraction analysis (XRD), the set of functional groups in the powders was studied by Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and their thermal behavior in an air flow by synchronous thermal analysis (TGA/DSC). The electronic state of the chemical elements in the resulting coating was studied using X-ray photoelectron spectroscopy (XPS). The surface topography and local electrophysical properties of the composite coating were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). Using impedance spectroscopy, the temperature dependence of the specific electrical conductivity of the obtained composite coating was estimated.

Synthesis, crystal-structure refinement and properties of bastnaesite-type PrF[CO3], SmF[CO3] and EuF[CO3]

By adding a hot aqueous solution containing KF and K2[CO3] to another hot aquatic brine of Pr[NO3]3 ⋅ 5 H2O, Sm[NO3]3 ⋅ 5 H2O or Eu[NO3]3 ⋅ 5 H2O with a 1.3 times excess of the anion-providing solution, amorphous water-insoluble powders of PrF[CO3], SmF[CO3] and EuF[CO3] can be obtained. Through hydrothermal treatment at 210 °C for five days crystalline powders could be synthesized and their crystal structure was refined with Rietveld methods based on PXRD data. The named compounds crystallize in the bastnaesite-type structure with a = 710.912(12) pm, c = 976.811(6) pm for the praseodymium, a = 704.77(2) pm, c = 971.83(4) pm for the samarium and a = 700.734(6) pm, c = 969.066(8) pm for the europium compound, all hexagonal with Z = 6. Upon heating them, the compounds lose CO2 and fluoride oxides REFO emerge. Thermogravimetric experiments with crystalline samples show thermal stability up to 420 °C for PrF[CO3], 400 °C for SmF[CO3] and 340 °C for EuF[CO3], but decomposition below 200 °C for the amorphous ones. Infrared spectroscopy confirms only marginal portions of [OH]− instead of F− anions in all cases. The RE 3+ cations are coordinated by 9 + 2 anions at distances between 236 and 254 pm plus 326 pm to F− anions and oxygen atoms bonded to carbon as oxocarbonate anions [CO3]2−. Triggered by ultraviolet radiation, the bulk sample of EuF[CO3] shows a poor red luminescence.

Highly water-soluble dimeric and trimeric lanthanide carbonates with ethylenediaminetetraacetates as precursors of catalysts for the oxidative coupling reaction of methane

Highly water-soluble dimeric and trimeric lanthanide carbonates with ethylenediaminetetraacetates have been obtained. Their coordination modes provide a model for the oxidative coupling of methane of lanthanide carbonates.