Atmospheric plasmas for thin film deposition: A critical review

Unexpected ultrafast and high adsorption of U(VI) and Eu(III) from solution using porous Al2O3 microspheres derived from MIL-53

Thermal stability of alumina thin films containing γ-Al2O3 phase prepared by reactive magnetron sputtering

Magnetron-sputtered Al2O3 thin films were annealed in ambient air. The phase compositions of the as-deposited Al2O3 films were (i) fully amorphous, (ii) nanocrystalline γ-Al2O3 in an amorphous Al2O3 matrix, and (iii) fully crystalline γ. For all samples, annealing to 1 100–1 150 °C resulted in a transformation to α-alumina. The transformation paths depend on the phase fraction of γ in the as-deposited films. For amorphous films and films with low initial γ fraction, the intermediate phase θ-Al2O3 appeared in the range of 1 000–1 100 °C. For predominantly crystalline γ-Al2O3 as-deposited films no intermediate Al2O3 phases were observed, indicating a direct γ-to-α phase transformation at ∼1 100 °C.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppap.200932301

Thermal Stability and Phase Transformations of γ-/Amorphous-Al2O3 Thin Films

The present work investigates the microstructure and chemical composition of macroparticles incorporated in arc evaporated (Al,Cr)2O3 coatings. According to scanning and transmission electron microscopy analysis, two different types of macroparticles with a distinct difference in their shape and a noticeable variation in their chemical composition, i.e. the Al/Cr ratio, can be distinguished. In addition, the transformations on the surface of the corresponding Al–Cr compound cathodes during the evaporation process in O2 atmosphere are studied by scanning electron microscopy and X-ray diffraction. Beside the virgin cathode material, a reaction layer consisting of various intermetallic AlxCry phases with a fine-grained morphology and pillar-shaped Al2O3 islands was found. Correlations between the origin of the macroparticles and the observed modifications at the surface of the Al–Cr cathode are discussed.

Cathodic arc deposition of (Al,Cr)2O3: Macroparticles and cathode surface modifications

α-Cr2O3 template-texture effect on α-Al2O3 thin-film growth

http://liu.diva-portal.org/smash/get/diva2:325579/FULLTEXT01.pdf

Texture and microstructure of Cr2O3 and (Cr,Al)2O3 thin films deposited by reactive inductively coupled plasma magnetron sputtering

Al 2 O 3 films were deposited by reactive ionized magnetron sputtering and their hardness was measured by nanoindentation. The magnetron was powered with a pulsed DC power supply, and the substrate was negatively biased with a pulsed DC voltage supply. An RF powered coil was located above the substrate to vary the ion flux hitting the substrate. As measured with transmission electron microscopy and X-ray diffraction, the films were amorphous in the temperature range 200 to 600 °C, when only a low flux of ions hit the film during growth. At 200 °C, with increasing ion bombardment, 100 nm large clusters of small crystalline grains of γ-Al 2 O 3 with sizes of the order of 5 nm were embedded in the amorphous phase. Increasing the flux of ions and/or the temperature further enabled us to make films consisting only of crystalline γ-Al 2 O 3 . A systematic study was carried out of the dependence of the nanostructure on a) the RF power of the coil creating the ions bombarding the growing film, on b) the bias voltage, and on c) the substrate temperature. The hardness values of the films were measured and correlated to the film nanostructure.

Madanagurusamy Sridharan

Papers

Thermal Stability and Phase Transformations of γ-/Amorphous-Al2O3 Thin Films

α-Cr2O3 template-texture effect on α-Al2O3 thin-film growth

Texture and microstructure of Cr2O3 and (Cr,Al)2O3 thin films deposited by reactive inductively coupled plasma magnetron sputtering

Pulsed DC magnetron sputtered Al2O3 films and their hardness