Manganese(II) Molecular Sources for Plasma-Assisted CVD of Mn Oxides and Fluorides: From Precursors to Growth Process

Abstract

A viable route to manganese-based materials of high technological interest is plasma-assisted chemical vapor deposition (PA-CVD), offering various degrees of freedom for the growth of high-purity nanostructures from suitable precursors. In this regard, fluorinated β-diketonate diamine Mn(II) complexes of general formula Mn(dik)2·TMEDA [TMEDA = N,N,N′,N′-tetramethylethylenediamine; Hdik = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfa), or 1,1,1-trifluoro-2,4-pentanedione (Htfa)] represent a valuable option in the quest of candidate molecular sources for PA-CVD environments. In this work, we investigate and highlight the chemico-physical properties of these compounds of importance for their use in PA-CVD processes, through the use of a comprehensive experimental–theoretical investigation. Preliminary PA-CVD validation shows the possibility of varying the Mn oxidation state, as well as the system chemical composition from MnF2 to MnO2, by simple modulations of the reaction atmosphere, paving the way to a successful utilization of the target compounds in the growth of manganese-containing nanomaterials for different technological applications

Multi-functional MnO2 nanomaterials for photo-activated applications by a plasma-assisted fabrication route

“…; 4.7 eV) 2,15,18,33,52. In a different way, at 400°C the Mn 2p spectrum (BE(Mn 2p 3/2 ) = 642.3 eV) and the Mn 3s band spacing(5.4 eV) were in line with the presence of Mn 2 O 3 .…”

“…PE-CVD growth processes were performed using a two-electrode custom-built apparatus equipped with a radio frequency (RF) generator (ν = 13.56 MHz), adopting Mn(tfa) 2 ·TMEDA (tfa = 1,1,1-trifluoro-2,4-pentanedionate; TMEDA = N,N,N′,N′tetramethylethylenediamine) as a precursor. 52 Fluorine-doped tin oxide (FTO)-coated glass substrates (Aldrich®; ≈7 Ω sq −1 ; FTO thickness ≈600 nm), subjected to an established precleaning procedure, 53 were mounted on the grounded electrode, whereas RF-power was delivered to the second electrode. Electronic grade Ar and O 2 were used as plasma sources.…”

“…The second component, related to precursorderived CF x groups (see also Fig. S1 †), [49][50][51][52][53] could be removed after Ar + erosion for 5 min, indicating that its presence was limited to the specimen surface. The uniform in-depth F distribution was confirmed by EDXS analyses (Fig.…”

“…The morphology of the 300°C and 400°C deposits likely arises from the initial formation on the substrate of a granular layer, subsequently self-catalysing the growth of anisotropic nanothorns in a process assisted by O deficiencies (see the above XPS data), resulting, in turn, from the material bombardment by O-related species. 45,52 The surface topography was also probed using AFM, and images recorded on different sample areas enabled ascertaining surface homogeneity. The results, in line with FE-SEM data, confirmed the above discussed morphological evolution, highlighting the formation of highly rough materials.…”

Computer modeling of apparently straight bond angles: The intriguing case of all-silica ferrierite

“…The equations of motion from the CP Lagrangean were integrated with a time step of 5 au and an inertia parameter for the wavefunction coefficients of 500 au. Such FPMD parameters properly described the dynamics of zeolite hybrids (Fois et al 2010b(Fois et al , 2012Zhou et al 2013), the high-pressure behaviour of zeolites (Ferro et al 2002;Ceriani et al 2004;Fois et al 2005Fois et al , 2008dBetti et al 2007;Gatta et al 2016; Fois and Tabacchi 2019) and high-temperature processes of oxide porous materials and interfaces (Fois et al 2003(Fois et al , 2008a(Fois et al , 2010aTabacchi et al 2014aTabacchi et al , 2016aTabacchi et al , 2007Barreca et al 2011Barreca et al , 2018Deiana et al 2013Deiana et al , 2016Martínez-Suarez et al 2015;Kraus and Frank 2017). Apart from the cell parameters (that were kept fixed along the simulation), no constraints were imposed to the atomic positions, i.e.…”