Thin Films Of Such Materials Research Articles

Photochemically assisted patterning: An interfacial hydrodynamic model perspective

Photoresponsive organic liquids and polymers may undergo reversible photochemical reactions with accompanying change in chemical structure upon exposure to a suitable wavelength of light. Spatial variations in chemical structure can cause surface tension gradients along thin films of such materials, resulting in Marangoni flows when the material is in its fluid state. Consequently the fluid film can self-organize into topographical patterns. Here, we provide a hydrodynamic model perspective of photochemically assisted patterning in thin fluid films using principles of momentum and mass transfer. Photochemical reaction occuring simultaneously along with hydrodynamic flow is modelled. Dynamical variation of the photoproduct concentration, accounting for first order chemical reaction kinetics, is considered. Our simulations highlight the counteracting effects of reaction kinetics and Marangoni flow as the mechanism responsible for pattern evolution. We capture various pillar and hole array morphologies obtained by controlling the direction of Marangoni flow and reaction-induced mass transfer. The resolution and timescales of pattern formation are computed as function of experimental control parameters such as the reaction rate coefficient (K0), Marangoni number (M), and distance between the film and light source. A process map comparing feature sizes on a photomask (w) with those of the patterns evolved in the material is developed. It reveals optimum w − M and w − K0 combinations required for faithful reproduction of photomask feature sizes and deviation from ideally templated patterns.

Electrochemically Active In Situ Crystalline Lithium-Organic Thin Films by ALD/MLD.

Intercalated metal–organic framework (iMOF) type electrochemically active aromatic metal carboxylates are intriguing material candidates for various energy storage devices and microelectronics. In this work, we grow in situ crystalline thin films of such materials through atomic/molecular layer deposition (ALD/MLD); the remarkable benefit of this approach is the possibility to evaluate their electrochemical properties in a simple cell configuration without any additives. Five organic linkers are investigated in combination with lithium: terephthalic acid (TPA), 3,5-pyridinedicarboxylic acid (PDC), 2,6-naphthalenedicarboxylic acid (NDC), 4,4′-biphenyldicarboxylic acid (BPDC), and 4,4′-azobenzenedicarboxylic acid (AZO). In particular, the electrochemical activity of Li-PDC and the crystal structure of Li-AZO are addressed here for the first time. We believe that the in situ gas-phase thin-film deposition is a crucial requirement to benefit from the iMOF-type electrode materials in, e.g., microelectronics and wearable devices.

KrF pulsed laser deposition of La 5Ca 9Cu 24O 41 thin films on various substrates

Recent studies on single crystals of cuprate oxides containing spin chains and ladders have reported large anisotropic magnon-mediated thermal conductivity. A potential use of thin films of such materials could be in the thermal management of electronic devices for the guiding of unwanted heat to a heat sink. In this article, the pulsed laser deposition and characterization of La 5Ca 9Cu 24O 41 thin films on SrLaAlO 4, SrTiO 3, MgO, and Si substrates are reported for the first time. The films were grown using a pulsed UV laser (KrF, 248 nm) and various substrate temperatures up to 650 °C. The XRD spectra revealed successful target-film stoichiometric transfer and high texturing of the thin films with (0 k 0) preferred orientation.

Thermal analysis and thin films deposition by matrix assisted pulsed laser evaporation of a 4CN type azomonoether

Abstract A new synthesized 4CN type azomonoether, exhibiting dying properties, crystalline nature and generating interest as a material for non-linear optical applications was investigated. Modern devices incorporating liquid crystals tend to use thin films of such materials because of their special characteristics. Thermal stability studies are indispensable before attempting any deposition experiment. We have investigated the thermal behaviour of 4-[(4-chlorobenzyl)oxy]-4′-cyano-azobenzene (TG, DTG, DTA and DSC) in inert flow atmosphere, under non-isothermal conditions. The phase transitions were studied by repeated heating-cooling regimes, with intercalated isothermal steps. The thin films were deposited on silicon and quartz substrates by matrix assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser working at 266 nm. FTIR spectroscopy of the obtained thin films confirmed the preservation of the compound’s structure.

Group 13/15 Organometallic Compounds — Synthesis, Structure, Reactivity and Potential Applications

AbstractFor Abstract see ChemInform Abstract in Full Text.

Domain structure of thin single crystal platelets of BaFe12-x-yCoxTiyO19

The domain structure in hexaferrite platelets was studied for various cobalt concentrations, 0≤x≤0.78, using the colloid-SEM method, with a view towards the possible applications of thin films of such materials in high density magnetic recording. Typical surface undulation of Bloch walls was observed in thicker platelets. The domain period decreases with decreasing crystal thickness and also with increasing cobalt concentration. The critical sample thickness for the transition from undulated to simple stripe structure was measured on a wedge-form sample and compared with the theoretical estimates.

Laser-induced synthesis, deposition and etching of materials

The field of laser-induced synthesis, deposition and etching of materials is reviewed with an emphasis on the emerging trends and novel adaptations of the basic laser processing concepts. A number of examples are cited to illustrate the issues involved. These include rapid synthesis of titanium nitride by pulsed laser induced reactive quenching at Ti:liquid NH3 interface, laser deposition of good quality thin films of such materials as hot oxide superconductors, zinc ferrite, iron oxide, stainless steel, etc. and laser etching of superconductor films.