Hydration of r.f. magnetron sputtered MgO thin films for a protective layer in AC plasma display panel

Lee, Jung Heon; Eun, Jae Hwan; Park, Sun Young; Kim, Soo Gil; Kim, Hyeong Joon

doi:10.1016/s0040-6090(03)00411-5

Cited by 52 publications

(32 citation statements)

References 16 publications

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“…The choice of the element here is somewhat limited by the fact that some of the bulk oxides of the alkali and alkali‐earth metals dissolve in water. Specifically MgO sometimes reacts with water to form a hydroxide, depending on the crystallite size, orientation of the surface, or, in case of thin films, deposition parameters . Our films did not hydrate in contact with water.…”

Section: Resultsmentioning

confidence: 81%

Hydrophobicity of Thin Films of Compounds of Low‐Electronegativity Metals

2014

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Hydrophobic materials capable of withstanding harsh conditions are required for various applications. Here, we show that oxides and nitrides of various low-electronegativity metals are hydrophobic hard ceramics. We attribute their hydrophobicity to low Lewis acidity of the low-electronegativity cations implying a low ability of the cations on the surface to form coordinate bonds with water oxygen anions. Furthermore, we observe a systematically stronger hydrophobic behavior of nitrides compared with the corresponding oxides, which we attribute to nitrogen being a poorer Lewis base than oxygen due to a reduced number of lone pairs of electrons, implying a lower ability of nitrogen anions on the surface to form hydrogen bonds with water hydrogen cations. Most of the oxides and nitrides investigated exhibit high values of hardness. Therefore, oxides and nitrides of low-electronegativity metals should find application as hydrophobic materials in harsh conditions.

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Section: Resultsmentioning

confidence: 81%

Hydrophobicity of Thin Films of Compounds of Low‐Electronegativity Metals

2014

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“…The higher diffusion energy supplied by the higher temperature is to fill in the internal defects, which results in the formation of denser films [28,29]. So, MgO films deposited at 600°C have higher density values, which could restrict the inter-diffusion of Mg atoms and H 2 O thereby providing an increased chemical stability under various working conditions [30].…”

Section: Resultsmentioning

confidence: 99%

Spray pyrolysis deposition and characterization of highly (100) oriented magnesium oxide thin films

Raj¹,

Nehru

Jayachandran

et al. 2007

Cryst. Res. Technol.

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Transparent dielectric thin films of MgO has been deposited on quartz substrates at different temperatures between 400 and 600°C by a pneumatic spray pyrolysis technique using Mg(CH 3 COO) 2 .4H 2 O as a single molecular precursor. The thermal behavior of the precursor magnesium acetate is described in the results of thermogravimetry analysis (TGA) and differential thermal analysis (DTA). The prepared films are reproducible, adherent to the substrate, pinhole free and uniform. Amongst the different spray process parameters, the substrate temperature effect has been optimized for obtaining single crystalline and transparent MgO thin films. The films crystallize in a cubic structure and X-ray diffraction measurements have shown that the polycrystalline MgO films prepared at 500°C with (100) and (110) orientations are changed to (100) preferred orientation at 600°C. The MgO phase formation was also confirmed with the recorded Fourier Transform Infrared (FTIR) results. The films deposited at 600°C exhibited highest optical transmittivity (>80%) and the direct band gap energy was found to vary from 4.50 to 5.25 eV with a rise in substrate temperature from 500 to 600°C. The measured sheet resistance and the resistivity of the film prepared at 600°C were respectively 10 13 Ω/□ and 2.06x107 Ω cm. The surface morphology of the prepared MgO thin films was examined by atomic force microscopy.

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“…However, it is less well known that, in common with many rare earth oxides [5,6], CeO 2 is hygroscopic and hence water can be absorbed upon exposure to atmospheric water vapor. A second potential outcome of this water absorption is the conversion from the oxide to a hydrated and/or hydroxylated phase at the surface [7], particularly upon exposure to liquid water.…”

Section: Introductionmentioning

confidence: 99%

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

et al. 2017

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Abstract:The present work describes the effects of water on Fe-doped nanoparticulate CeO 2 , produced by flame spray pyrolysis, which represent a critical environmental issue because CeO 2 is not stable in typical atmospheric conditions. It is hygroscopic and absorbs~29 wt % water in the bulk when exposed to water vapor but, more importantly, it forms a hydrated and passivating surface layer when immersed in liquid water. In the latter case, CeO 2 initially undergoes direct and/or reductive dissolution, followed by the establishment of a passivating layer calculated to consist of~69 mol % solid CeO 2 ·2H 2 O and~30 mol % gelled Ce(OH) 4 . Under static flow conditions, a saturated boundary layer also forms but, under turbulent flow conditions, this is removed. While the passivating hydrated surface layer, which is coherent probably owing to the continuous Ce(OH) 4 gel, would be expected to eliminate the photoactivity, this does not occur. This apparent anomaly is explained by the calculation of (a) the thermodynamic stability diagrams for Ce and Fe; (b) the speciation diagrams for the Ce 4+ -H 2 O, Ce 3+ -H 2 O, Fe 3+ -H 2 O, and Fe 2+ -H 2 O systems; and (c) the Pourbaix diagrams for the Ce-H 2 O and Fe-H 2 O systems. Furthermore, consideration of the probable effects of the localized chemical and redox equilibria owing to the establishment of a very low pH (<0) at the liquid-solid interface also is important to the interpretation of the phenomena. These factors highlight the critical importance of the establishment of the passivating surface layer and its role in photocatalysis. A model for the mechanism of photocatalysis by the CeO 2 component of the hydrated phase CeO 2 ·2H 2 O is proposed, explaining the observation of the retention of photocatalysis following the apparent alteration of the surface of CeO 2 upon hydration. The model involves the generation of charge carriers at the outer surface of the hydrated surface layer, followed by the formation of radicals, which decompose organic species that have diffused through the boundary layer, if present.

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Hydration of r.f. magnetron sputtered MgO thin films for a protective layer in AC plasma display panel

Cited by 52 publications

References 16 publications

Hydrophobicity of Thin Films of Compounds of Low‐Electronegativity Metals

Hydrophobicity of Thin Films of Compounds of Low‐Electronegativity Metals

Spray pyrolysis deposition and characterization of highly (100) oriented magnesium oxide thin films

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

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