Search results for "Cristalls"
showing 10 items of 25 documents
Creixement del MgCdO: un nou aliatge ternari d'òxids II-VI
2017
Els nous reptes tecnològics impulsen el desenvolupament de nous materials amb les propietats físiques adients per satisfer les necessitats de cada aplicació. Així, el desenvolupament de nous materials optoelectrònics ha rebut una gran atenció de la comunitat científica els últims anys. Més concretament, els compostos II-VI com els òxids de Zn, Cd i Mg o els aliatges ternaris ZnMgO i ZnCdO han sigut i estan sent àmpliament estudiats degut a les seues propietats físiques que els doten d'un gran potencial per al seu ús en dispositius optoelectrònics com díodes emissors de llum (LED per les sigles en anglès de Light-Emitting Diode) o sensors de radiació ultraviolada [Nieda2016, Wang2010, Mohant…
Waveguiding properties of a photonic crystal fiber with a solid core surrounded by four large air holes
2009
The polarization-dependent guiding properties of a hexagonal-lattice photonic crystal fiber with a solid-core surrounded by four large air holes are investigated. The appearance of a polarization dependent cutoff frequency, together with several parameters as the birefringence, the modal effective area, the group velocity dispersion and the polarization dependent loss are analyzed. A collection of fibers with different structural parameters were fabricated and characterized. An effective anti-guide structure from at least 450 nm to 1750 nm, a polarizing fiber with a polarization dependent loss of 16 dB/m at 1550 nm, and an endlessly singlemode polarization-maintaining fiber with group biref…
Semiconductor Porous Hydrogen-Bonded Organic Frameworks Based on Tetrathiafulvalene Derivatives.
2022
Herein, we report on the use of tetrathiavulvalene-tetrabenzoic acid, H4TTFTB, to engender semiconductivity in porous hydrogen-bonded organic frameworks (HOFs). By tuning the synthetic conditions, three different polymorphs have been obtained, denoted MUV-20a, MUV-20b, and MUV-21, all of them presenting open structures (22, 15, and 27%, respectively) and suitable TTF stacking for efficient orbital overlap. Whereas MUV-21 collapses during the activation process, MUV-20a and MUV-20b offer high stability evacuation, with a CO2 sorption capacity of 1.91 and 1.71 mmol g-1, respectively, at 10 °C and 6 bar. Interestingly, both MUV-20a and MUV-20b present a zwitterionic character with a positively…
Spectroscopic analysis of vibronic relaxation pathways in molecular spin qubit [Ho(W5O18)2]9−: sparse spectra are key
2021
Molecular vibrations play a key role in magnetic relaxation processes of molecular spin qubits as they couple to spin states, leading to the loss of quantum information. Direct experimental determination of vibronic coupling is crucial to understand and control the spin dynamics of these nano-objects, which represent the limit of miniaturization for quantum devices. Herein, we measure the vibrational properties of the molecular spin qubit $[$Ho(W$_5$O$_{18}$)$_2]^{9-}$ by means of magneto-infrared spectroscopy. Our results allow us to unravel the vibrational decoherence pathways in combination with $ab$ $initio$ calculations including vibronic coupling. We observe field-induced spectral cha…
Hybrid multiple diffraction in semipolar wurtzite materials: (0112)-oriented ZnMgO/ZnO heterostructures as an illustration
2017
X-ray diffraction has been widely used to characterize the structural properties (strain and structural quality) of semiconductor heterostructures. This work employs hybrid multiple diffraction to analyze r-oriented Zn1xMgxO layers grown by molecular beam epitaxy on ZnO substrates. In such a low-symmetry material system, additional features appear in symmetric reflection scans, which are described as arising from hybrid multiple diffraction. First, the Bragg conditions necessary for these high-order processes to occur are introduced and applied to explain all the observed satellite reflections, identify the planes that contribute and compute a priori the angles at which they are observed. F…
Inside Cover: Exploiting Reaction-Diffusion Conditions to Trigger Pathway Complexity in the Growth of a MOF
2021
How do you unveil pathway complexity in a crystallization process? In their Research Article on page 15920, Alessandro Sorrenti, Marco D′Abramo, Guillermo Mínguez Espallargas, Josep Puigmartí-Luis, and co-workers show that harnessing a reaction-diffusion (RD) process within a continuous flow microfluidic device, and on a millisecond timescale, is key to enable two unprecedented nucleation-growth pathways during a MOF synthesis.
Polarization Modulation Instability in Dispersion-Engineered Photonic Crystal Fibers
2021
Generation of widely spaced polarization modulation instability (PMI) sidebands in a wide collection of photonic crystal fibers (PCF), including liquid-filled PCFs, is reported. The contribution of chromatic dispersion and birefringence to the net linear phase mismatch of PMI is investigated in all-normal dispersion PCFs and in PCFs with one (or two) zero dispersion wavelengths. Large frequency shift sidebands are demonstrated experimentally. Suitable fabrication parameters for air-filled and liquid-filled PCFs are proposed as guidelines for the development of dual-wavelength light sources based on PMI.
Structural reorganization in a hydrogen-bonded organic framework
2018
Self-recognition of 3,3′,5,5′-azobenzenetetracarboxylic acid drives the formation of a grid-like anionic hydrogen-bonded framework with channels occupied by organic cations. This supramolecular solid is capable of reorganizing its connectivity in the presence of specific guests into a different crystalline architecture by sequential dissolution and recrystallization.
In and out: crystal engineering for reversible iodine uptake
2020
In this issue of Acta Crystallographica Section B, Moghzi et al. (2020) report the chemical design of a metal-organic compound with an outstanding iodine (I2) sorption capability. Sequestration of I2, an extremely volatile gas, has important applications in terms of controlling radioactive gases, as various radionuclides of I2 are released during the fission of nuclear fuels. Thus, the preparation of porous materials that can efficiently capture and store I2 is of importance not only from an academic point of view, but also for real-life applications.
Slow Relaxation of the Magnetization on Frustrated Triangular FeIII Units with S= 1/2 Ground State: The Effect of the Highly Ordered Crystal Lattice …
2021
In order to understand how the different arrangements of highly ordered triangular FeIII S = 1/2 systems with various types of diamagnetic and paramagnetic anions affect their static and dynamic magnetic properties, we have obtained by solvothermal synthesis four new μ3-oxido trinuclear FeIII compounds, [Fe3O(Ac)6(AcNH2)3][BF4]·(CH3CONH2)0.5(H2O)0.5 (1-BF4), [Fe3O(Ac)6(AcNH2)3][GaCl4] (1-GaCl4), [Fe3O(Ac)6(AcNH2)3][FeCl4] (1-FeCl4) and [Fe3O(Ac)6(AcNH2)3][FeBr4] (1-FeBr4), where, Ac- = CH3COO- and AcNH2 = CH3CONH2. The organization of the triangular units is very varied, from segregated stacks to eclipsed equilateral triangular [Fe3O]+ units along the c-axis with intercalated [MX4]- units. …