Ola Nilsen

Formation of grain-coating chlorite in sandstones. Laboratory synthesized vs. natural occurrences

Abstract Grain-coating chlorites in clastic quartz-rich sandstones have long been recognized as an important porosity-preserving constituent in medium- to deep-burial diagenesis. As little is known about the occurrence and origin of chlorite coatings, chlorite synthesis experiments were performed to study how grain-coating chlorites form in certain sandstones during burial. The starting material was naturally-occuring sandstones from the Oseberg and the Veslefrikk fields offshore Norway, where the same sandstone formation is buried to different depths due to faulting. Grain- coating chlorites exist below ~3000 m burial depth only. At shallower burial (2400 m), an X-ray amorphous iron containing thin clay coating is present. The samples were heated to 200 and 250°C (at water vapour pressure) in a hydrothermal bomb for 2-4 weeks. Both starting material and end-products were studied (electron-) optically in both scanning and transmission microscopes. The TEM showed the Fe-rich precursor material to consist of a fine-grained berthierine-dominated mixed-layer. The neoformed grain coatings in the reacted samples were similar in appearance to naturally-occurring chlorite coatings. The TEM analyses of individual grains documented an Fe-rich chloritic phase with an average composition of Mg0.41Fe3.52Mn0.10Al1.51(Al0.58Si3.42)O10(OH)8. The reacted waters were found to be close to saturation with the newly formed chlorites. Grain-coating chlorite thus appears to form in the natural environment from Fe-rich berthierine precursors at a burial depth corresponding to a temperature around 90°C.

Growth of manganese oxide thin films by atomic layer deposition

Thin films of manganese oxide are made by the ALD (atomic layer deposition) technique using Mn(thd)3 (Hthd=2,2,6,6-tetramethylheptan-3,5-dione) and ozone as precursors. Pulse parameters for ALD-type growth are established and such growth can be achieved at deposition temperatures between 138 and 210 °C. Films have been deposited on both soda-lime glass and Si(100) single crystals. The electrical resistivities of as-deposited films grown on soda-lime glass are measured to be 0.3–3.2 Ω cm (linear four-point-probe measurements).

Deposition of thin films of organic-inorganic hybrid materials based on aromatic carboxylic acids by atomic layer deposition.

Thin films of organic-inorganic hybrid materials have been grown by the atomic layer deposition (ALD) technique, using trimethylaluminium (TMA) and aromatic carboxylic acids such as 1,2-benzene dicarboxylic acid, 1,3-benzene dicarboxylic acid, 1,4-benzene dicarboxylic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4,5-benzene tetracarboxylic acid as precursors. Growth rates as function of temperature show that all systems, with the exception of the benzoic acid-TMA system, possess ALD-windows and provides growth rates in the range of 0.25-1.34 nm/cycle. X-ray diffraction studies of the as-deposited films reveal their amorphous character, which is also supported by very low surface roughness as measured by atomic force microscopy. As-deposited films were investigated by Fourier Transform Infrared Spectroscopy proving that the deposited films are of a hybrid character.

Growth of thin films of molybdenum oxide by atomic layer deposition

Thin films of MoO3 have been obtained by the atomic layer deposition (ALD) technique using molybdenum hexacarbonyl (Mo(CO)6), ozone, and water as precursors. A window for ALD growth was found in the temperature range 152 to 172 °C. Self-limiting growth was verified at a deposition temperature of 163 °C. The upper temperature range is determined by the thermal stability of the Mo(CO)6 precursor. The growth dynamics was further investigated by quartz crystal microbalance to determine the effect of ozone and water on the deposition process. Growth using only water as oxygen source is hardly detectable. The growth rate increases to 0.75 A per cycle when ozone is introduced. X-ray diffraction analysis indicates that the films are amorphous as deposited, but crystallise into the α- and β-MoO3 phases during annealing in air at 500 °C and to phase-pure, highly oriented α-MoO3 at 600 °C. Analysis by X-ray photoelectron spectroscopy shows that both as-deposited and annealed films contain Mo(VI). Atomic force microscopy proves a very low surface roughness for as-deposited films, which becomes rather rough for annealed films. This investigation has clearly proven the capability of carbonyls as useful precursors for ALD growth of oxides.

Atomic layer deposition of organic–inorganic hybrid materials based on saturated linear carboxylic acids

Atomic layer deposition (ALD) has successfully provided thin films of organic-inorganic hybrid materials based on saturated linear carboxylic acids and trimethylaluminium (TMA). Films were grown for seven carboxylic acids: oxalic, malonic, succinic, glutaric, pimelic, suberic and sebacic acid, i.e. ranging from 2 to 10 carbon atoms in the molecular structure. These processes show exceptionally high growth rates; up to 4.3 nm/cycle for the pimelic acid-TMA system. Quartz crystal microbalance measurements of the growth dynamics indicate that all systems are of a self limiting ALD-type. Nevertheless, temperature dependent growth was observed in several systems. The width of the ALD windows shows correlations with the length of the carbon chains. Fourier transform infrared spectroscopy clearly proved that the deposited films are of a hybrid character, where the carboxylic acids primarily form bidentate complexes, though bridging complexes may also form. All films are X-ray amorphous as deposited. The films were further analyzed by atomic force microscopy for surface roughness and topography, UV-Vis spectroscopy and ellipsometry for optical properties, and the goniometer method for measuring sessile drops for surface wetting properties. Apart from the oxalic and malonic acid-TMA systems, the films are stable in contact with water. The films are generally smooth, transparent and have a refractive index close to 1.5. The complete coverage and accurate growth control offered by the ALD technique is here proven to provide surface-functionalized hybrid materials resembling metal-organic frameworks (MOF), probably as rather dense structures, yet with substantial potential for applications.

Atomic layer deposition of lithium containing thin films

Five different lithium containing compounds, all representing different chemical systems, were studied in order to deposit lithium containing films by atomic layer deposition ALD. The studied compounds were a lithium β-diketonate Li(thd) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate), a lithium alkoxide LiOtBu (OtBu = tert-butoxide), a lithium cyclopentadienyl LiCp (Cp = cyclopentadienyl), a lithium alkyl n-butyllithium, and a lithium amide lithium dicyclohexylamide. Films containing lithium carbonate (Li2CO3) were obtained from alternate pulsing of Li(thd) and ozone in a temperature range of 185–300 °C. The film composition was analyzed by time-of-flight elastic recoil detection analysis (TOF-ERDA). The films grown at 225 °C were polycrystalline lithium carbonate as analyzed by X-ray diffraction (XRD). A 120 nm thick lithium carbonate film grown at 225 °C had a surface roughness of 19 nm as analyzed by AFM. Lithium lanthanate thin films were grown by combining the Li(thd) process with a ALD process for lanthanum oxide from La(thd)3 and ozone. The film composition was varied by controlling the number of lithium carbonate and lanthanum oxide sub-cycles. Lithium containing films were also obtained from LiCp and water and from LiOtBu and water.

Thin film deposition of lanthanum manganite perovskite by the ALE process

Deposition of thin films of LaMnO 3 from β-diketonate-type (thd) precursors and ozone in an ALE reactor has been demonstrated. At low temperatures, the Mn-O growth from the Mn(thd) 3 precursor is retarded by the growth of the La-O deposit. By tuning of the pulsing ratio, full control of the stoichiometry of the deposited film is achieved in the temperature interval 300-400 °C. In this temperature range, the composition set by the pulsing ratio is transferred, within a few percent accuracy, to the deposited thin film. Indications for an ‘ALE window’ are found around 250-300 °C. Amorphous LaMnO 3 films could be deposited at temperatures as low as 250 °C, however, the deposition of crystalline films requires temperatures above 350 °C. X-Ray diffraction analyses show that the crystalline LaMnO 3 film was of the rhombohedral type with a=5.46(2) A and α=60.28(10)°.

Lanthanum titanate and lithium lanthanum titanate thin films grown by atomic layer deposition

Thin films of lanthanum titanate and lithium lanthanum titanate (LLT) have been grown by atomic layer deposition (ALD). Studies on the growth of lanthanum titanates showed that the lanthanum deposition rate is reduced when the titanium oxide and lanthanum oxide processes are combined, leading to higher titanium contents in the films. The precursor systems used for deposition of lanthanum titanates were TiCl4 + water and La(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) + ozone. Lithium was introduced into the material in order to deposit LLT by using lithium tert-butoxide (LiOtBu) and water as precursors. The deposited films were analyzed by time-of-flight elastic recoil detection analysis (TOF-ERDA), secondary ion mass spectrometry (SIMS), X-ray fluorescence (XRF), X-ray reflectivity (XRR) and X-ray diffraction (XRD). TOF-ERDA gave the film composition of Li0.32La0.30TiOz at saturation conditions.

The 1.54-μm photoluminescence from an (Er, Ge) co-doped SiO2 film deposited on Si by rf magnetron sputtering

In this work, we report on quite strong 1.54‐μm photoluminescence (PL) from an (Er, Ge) co-doped SiO2 film deposited by rf magnetron sputtering. The PL intensity reaches a maximum value after the film is annealed at 700°C for 30min in N2. High-resolution transmission electron microscopy observation, together with energy dispersive x-ray spectroscopy analysis, indicates that amorphous Ge-rich nanoclusters precipitate in the film after 700°C annealing. X-ray diffraction shows the presence of Ge nanocrystals after 900°C annealing, and increasing Ge nanocrystal size with increasing annealing temperature up to 1100°C. The results suggest that the amorphous Ge-rich nanoclusters are more effective than Ge nanocrystals in exciting the Er3+ PL.

High power nano-structured V2O5 thin film cathodes by atomic layer deposition

Atomic layer deposition (ALD) has been used to prepare nano-structured cathode films for Li-ion batteries of V2O5 from VO(thd)2 and ozone at 215 °C. The resulting films were strongly textured and rough without application of a template. The best electrochemical performance was observed for 10 nm nano-structured V2O5, that could sustain discharge rates up to 960 C while maintaining 20% of the initial 1 C capacity. The optimized cathode endured a discharge rate of 120 C for more than 1500 cycles while maintaining more than 80% of capacity, proving the rare combination of both high discharge rates and long life time simultaneously. The growth mechanism of the VO(thd)2 and ozone provides a highly textured surface consisting of platelets of V2O5 providing a large contact area towards the electrolyte. The current V2O5 films show potential as cathodes in thin film micro batteries.