Comparison of the thermal decomposition processes of several aminoalcohol-based ZnO inks with one containing ethanolamine

Four inks for the production of ZnO semiconducting films have been prepared with zinc acetate dihy-drate as precursor salt and one among the following aminoalcohols: aminopropanol (APr), aminomethylbutanol (AMB), aminophenol (APh) and aminobenzyl alcohol (AB) as stabilizing agent. Their thermaldecomposition process has been analyzed in situ by thermogravimetric analysis (TGA), differential scan-ning calorimetry (DSC) and evolved gas analysis (EGA), whereas the solid product has been analysedex-situ by X-ray diffraction (XRD) and infrared spectroscopy (IR). Although, except for the APh ink, crys-talline ZnO is already obtained at 300◦C, the films contain an organic residue that evolves at highertemperature in the form of a large variety of nitrogen-containing cyclic compounds. The results indicatethat APr can be a better stabilizing agent than ethanolamine (EA). It gives larger ZnO crystal sizes withsimilar carbon content. However, a common drawback of all the amino stabilizers (EA included) is thatnitrogen atoms have not been completely removed from the ZnO film at the highest temperature of ourexperiments (600◦C)

Thermal decomposition of CuProp2: In-situ analysis of film and powder pyrolysis

The thermal decomposition of CuProp2 in the form of film and powder was studied in different atmospheres by means of thermal analysis techniques (TG-MS, TG-IR, EGA), chemical-structural methods (FTIR, XRD, EA) and computational thermochemistry (VASP/PBE). The decomposition mechanism in terms of volatiles evolved was disclosed with the aid of ab-initio modeling; it was found to be dependent on the gas diffusion in and out of the sample and accelerated by a humid atmosphere. In films, the copper redox behavior showed sensitivity to the residual atmosphere. Finally, the role of the metal center is discussed in the frame of a general decomposition mechanism for metal propionates

The configurational energy gap between amorphous and crystalline silicon

The crystallization enthalpy of pure amorphous silicon (a-Si) and hydrogenated a-Si was measured by differential scanning calorimetry (DSC) for a large set of materials deposited from the vapour phase by different techniques. Although the values cover a wide range (200-480 J/g), the minimum value is common to all the deposition techniques used and close to the predicted minimum strain energy of relaxed a-Si (240 ± 25 J/g). This result gives a reliable value for the configurational energy gap between a-Si and crystalline silicon. An excess of enthalpy above this minimum value can be ascribed to coordination defects

Study of a sol-gel precursor and its evolution towards ZnO

The processes involved in the assembly of zinc acetate dihydrate {Zn(CH3COO)2·2H2O} and ethanolamine (H2NCH2CH2OH), with or without 2-methoxyethanol as solvent, have been analysed by infrared spectra, mass spectrometry, nuclear magnetic resonance, powder X-ray diffraction and computational studies. Thermal evolution of the mixtures was characterized by thermoanalytical and structural techniques (thermogravimetry, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and X-Ray photoelectron spectroscopy). Computational studies together with experiments served to thoroughly describe the precursor and its decomposition. The thermal decomposition of the mixture and its transformation into crystalline ZnO take place in a temperature range between 50 and 450 °C through different processes. With solvent, the processes need temperatures 90 oC higher with respect to the mixture without solvent, and ZnO arises at 250 ºC

Role of Ethanolamine on the Stability of a Sol-Gel ZnO ink

This work presents a detailed structural and chemical characterization of the system formed by zinc acetate dihydrate (ZAD) and ethanolamine (EA) with methoxyethanol (ME), in order to describe its stability. The origin of the mixture degradation during storage at room conditions is analyzed. Complementary computational (or theoretical) DFT calculations on the precursor formed in this reaction in ME and those of EA (free or in the same solvent) and in the presence or absence of CO2, light or both simultaneously are also reported in order to clarify the relative weight of these factors in the degradation process. In all cases, the models were tested as potential energy minimum and their photo-absorption spectra were simulated. The calculations show that the monomeric species formed in this process tend to assembly into dimers, which are more photosensitive and reactive than the monomer. Our results explain the experimental observations and provide a better understanding of the role played by EA, ME and CO2 in the formation of ZnO and, consequently, allow optimizing the technological processes to prepare these films

From ethanolamine precursor towards ZnO - How N is released from the experimental and theoretical points of view

This work presents experimental and computational studies on ZnO formation after decomposition of a sol-gel precursor containing ethanolamine and Zn(II) acetate. The structural modifications suffered during decomposition of the monomeric and dimeric Zn(II) complexes formed, containing bidentate deprotonated ethanolamine and acetato ligands, have been described experimentally and explained via Car-Parrinello Molecular Dynamics. Additional metadynamics simulations provide an overview of the dimer evolution by the cleavage of the Zn-N bond, the structural changes produced and their effects on the Zn(II) environment. The results provide conclusive evidence of the relevance of ethanolamine used as a stabilizer in the formation of ZnO

Chemical and Microstructural Nanoscale Homogeneity in Superconducting YBa2Cu3O7-x Films Derived from Metal-Propionate Fluorine-free Solutions

Research involved in developing alternative energy sources has become a necessity to face global warming. In this context, superconductivity is an appealing solution to enhance clean electrical energy provided that lower production costs can be attained. By implementation of chemical solution deposition techniques and high-throughput growth methods, low-cost nanostructured epitaxial cuprate superconductors are timely candidates. Here, we present a versatile and tunable solution method suitable for the preparation of high-performance epitaxial cuprate superconducting films. Disregarding the renowned trifluoroacetate route, we center our focus on the transient liquid-assisted growth (TLAG) that meets the requirement of being a greener chemical process together with ultrafast growth rates beyond 100 nm/s. We developed a facile, fast, and cost-effective method, starting from the synthesis of metal-propionate powders of Y, Ba, and Cu of high purity and high yields, being the precursors of the fluorine-free solutions, which enable the chemical and microstructural nanoscale homogeneity of YBa2Cu3O7-x (YBCO) precursor films. These solutions present endured stability and enable precise tunability of the composition, concentration, porosity, and film thickness. Homogeneous precursor films up to thicknesses of 2.7 μm through eight layer multidepositions are demonstrated, thus establishing the correct basis for epitaxial growth using the fast kinetics of the TLAG process. YBCO films of 500 nm thickness with a critical current density of 2.6 MA/cm2 at 77 K were obtained, showing the correlation of precursor film homogeneity to the final YBCO physical properties.The authors acknowledge the European Research Council for the ULTRASUPERTAPE project (ERC-2014-ADG-669504), IMPACT project (ERC-2019-PoC-874964), and EU COST action for CA16218 (NANOCOHYBRI). The authors also acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through the “Severo Ochoa” Programme for Centres of Excellence in FUNFUTURE (CEX2019-000917-S), SUMATE projects (RTI2018-095853-B-C21, RTI2018-095853-B-C22 co-financed by the European Regional Development Fund, MCIU/AEI/FEDER, UE), and SUPERENERTECH projects (PID2021-127297OB-C21 and PID2021-127297OB-C22). The authors also thank support from the Catalan Government with 2017-SGR-1519 and Catalan energy network XRE4S (2018 XARDI 00002). L.S., D.G., and A.K. acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through the FPI grants PRE2019-090621, PRE2018-084537, and PRE2020-091817, respectively. L.S. and D.G. would like to thank the UAB PhD program in Materials Science, and A.K. would like to thank the UAB PhD program in Physics. A.Q. would like to thank the Spanish Ministry of Science, Innovation and Universities [“Juan de la Cierva” postdoctoral fellowship (grant no. IJC2018-035034-I)]. The authors thank the Scientific Services at ICMAB and ICN2 Electron Microscopy Division. The authors acknowledge the use of instrumentation as well as the technical advice provided by the National Facility ELECMI ICTS, node “Laboratorio de Microscopías Avanzadas” at the University of Zaragoza. The content of this paper is the object of a European patent application no. EP22382741.1 filed on 29/07/2022.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Relevance of the Formation of Intermediate Non-Equilibrium Phases in YBa2Cu3O7-x Film Growth by Transient Liquid-Assisted Growth

Transient liquid-assisted growth (TLAG) is a non-equilibrium ultrafast method to grow YBa2Cu3O7–x (YBCO) superconducting films at up to 100 nm/s using chemical solution deposition. In this work, we study the formation of non-equilibrium crystalline intermediate phases prior to the growth of YBCO through TLAG. We analyze the thermal decomposition and microstructural evolution of a propionate-based fluorine-free solution used as precursor to YBCO epitaxial films. Thermal analyses (TGA, DSC), coupled with techniques to monitor the volatiles (TG-IR), were applied in situ during film pyrolysis in humid O2, while the thermal evolution of the solid residue was characterized by infrared spectroscopy and X-ray diffraction, both ex situ and in situ in synchrotron radiation sources, and by scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) cross-sectional analysis. Unexpected effects, observed during the decomposition of the ternary solution, are the formation of intermediate non-equilibrium phases: Cu2O or Cu(0) and monoclinic BaCO3. We emphasize that working with anhydrous solutions and anhydrous deposition conditions promotes the formation of the expected equilibrium phases. Finally, in situ X-ray diffraction permits monitoring the influence of the non-equilibrium monoclinic BaCO3 phase on the formation of binary oxide phases, precursors of TLAG YBCO film growth. Understanding the evolution of non-equilibrium phases is shown to be fundamental for the control of the final YBCO film’s microstructure and performance, since the latter are strongly affected by the film’s thermal history after solution deposition.This work was funded by Ministerio de Ciencia, Innovation y Universidades (RTI2018-095853-B-C21 and RTI2018-095853-B-C22) cofinanced by the European Regional Development Fund, and the EU Ultrasupertape project (ERC ADG-2014-669504). We also acknowledge the Center of Excellence Severo Ochoa (SEV-2015-0496), the Generalitat de Catalunya (2017-SGR-1519) and the COST -action NANOCOHYBRI (CA16218). In situ FTIR experiments were performed at the MIRAS beamline of the ALBA Synchrotron with the collaboration of ALBA staff. We also thank the DiffAbs beamline at SOLEIL Synchrotron facility and the beamline staff support for the in situ XRD experiments. We thank the ICMAB, INA-Zaragoza and UdG scientific services and technical staff for the support on the experiments. S.R. thanks the Universitat de Girona (UdG) for the IFUdG grant. L.S. and J.J. also acknowledge their FPU-MINECO PhD grant.Peer reviewe