Competing phases in the room-temperature M2(2,6-ndc)2(dabco) metal-organic framework thin film synthesis
Hamon L, Andrusenko I, Borzì A, Stiefel M, Carl S, Frison R, Cervellino A, Gemmi M, Santiso-Quinones G, Hovestreydt E, Neels A & Collings IE
Materials Advances. (2022)
The targeted synthesis of DUT-8 metal–organic framework thin films of composition M2(2,6-ndc)2(dabco), where 2,6-ndc = 2,6-naphthalenedicarboxylate, and dabco = 1,4-diazabicyclo[2.2.2]octane were performed using a dip-coating synthesis strategy on functionalised gold-coated silicon substrates at room temperature. The thin films were characterised using atomic force microscopy (AFM), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD), revealing a crystalline and oriented thin film with a homogeneous nanoparticle formation when M = Cu, and an inhomogeneous distribution of micron-sized crystals for M = Zn. However, the refined unit cell parameters indicated a large reduction to the known DUT-8 unit cells (-5% and -13% in the ab-plane for M = Cu and Zn, respectively). Three-dimensional electron diffraction (3D ED) was performed on the crystals from the thin film synthesis of M = Zn, revealing the formation of Zn(2,6-ndc)(H2O), instead of the intended Zn2(2,6-ndc)2(dabco) compound. Similarly, in the case of M = Cu thin films, Rietveld refinements of the powder X-ray diffraction data indicated that Cu(2,6-ndc) was the most likely phase grown. Our results highlight the competing phases possible for a room-temperature dip-coating synthesis strategy of DUT-8, and demonstrate the advantage of using 3D ED in thin film research.
Contacting atomically precise graphene nanoribbons for next-generation quantum electronics
Zhang, J., Calame, M., & Perrin, M. L.
Matter, 5(8), 2497-2499. (2022)
Exploring atomically precise graphene nanoribbons (GNRs) for quantum technology purposes does not only require control over their chemical structure, but also preservation of their properties upon integration into devices. We briefly discuss here existing contacting strategies for nanometer-sized GNRs and discuss possible future device architectures.
Coulomb interaction engineering at YBa 2Cu3O 7-δ-SrTiO3 interface
La Mattina, F., Erni, R., Rossell, M. D., Bona, G. L., & Shengelaya, A.
Journal of Superconductivity and Novel Magnetism, 35(7), 1801-1805. (2022).
It has been proposed by Müller and Shengelaya that underdoped ultrathin layers of copper-oxide high-temperature superconductors (HTSs) sandwiched between high-dielectric-constant insulator layers could manifest increased superconducting critical temperature Tc. To check this hypothesis, we investigated structural and transport properties of YBa2Cu3O7-δ (YBCO) thin films sandwiched between SrTiO3 (STO) layers. Scanning transmission electron microscopy (STEM) showed that a high-quality interface is formed between YBCO and the top STO layers. An increase of Tc up to ΔT≈ 20 K was observed at these interfaces in case of underdoped YBCO films.