Synthesis and characterization of sol-gel derived lanthanum hexaluminate powders and films

1995 ◽  
Vol 10 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Michael K. Cinibulk
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Sol Gel ◽  
High Yield ◽  
Trace Impurities ◽  
Fine Grained ◽  
Oxide Powders ◽  
Solid State Kinetics ◽  
Transmission Electron ◽  
Kinetics Of Formation

Powders and thin films of high-yield lanthanum hexaluminate (LaAl11O18) were prepared by a sol-gel route and compared with yields obtained by conventional hot-pressing of oxide powders. X-ray diffraction and transmission electron microscopy (TEM) were used to characterize powders and thin films deposited on TEM grids. While the solid-state kinetics of formation of LaA11O18 are known to be extremely sluggish, the yield of LaAl11O18 formed by the sol-gel route was much higher than that obtained by processing under similar conditions by solid-state reaction of elemental oxides. The development of a very fine grained microstructure at 1200 °C and a coarser, much more mature microstructure at 1450 °C, with strong texturing of the magnetoplumbite phase, was observed by TEM. Isolated grains of LaAlO3 were present in all powders and films. Trace impurities, introduced most likely as impurities in the initial alumina sol, appear to have segregated to both the grain boundaries and to the external surfaces of grains in as-prepared films.

Fine-Grained Structures Associated with Deformation Twin and Its Influence on Tensile Behaviours in a Cold-Rolled Fe-Ni Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 895-900 ◽  
Author(s):  
Tatsuya Morikawa ◽  
Taku Moronaga ◽  
Kenji Higashida
Keyword(s):  
Deformation Twin ◽  
Liquid Nitrogen Temperature ◽  
Invar Alloy ◽  
High Yield ◽  
Fine Grained ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cold Rolled ◽  
Crystallographic Planes

Fine-grained structures in Fe-36mass%Ni Invar alloy have been investigated by using transmission electron microscopy (TEM). Particular attention has been paid on the role of deformation twinning in the formation of fine-grained structures and its influence on tensile stressstrain behaviours of rolled specimens. In Fe-Ni Invar alloy with a moderate stacking fault energy, deformation twin did not appear in usual cold-rolling at room temperature (RT), where a kind of cell walls was formed and the Cu-type texture was observed. On the other hand, twinning was occurred by rolling when specimens were cooled to liquid nitrogen temperature (LNT) immediately before the rolling. In such case, a fine lamellar structure was developed and the brass-type texture appeared. However, the lamella boundaries did not coincide with any crystallographic planes, and they were intersected with the bands of deformation twin. Specimens rolled by 90% in thickness reduction exhibited tensile stressstrain behaviours similar to those observed in specimens with SPD structures. In particular, specimens rolled at LNT showed high yield strengths and non-uniform deformation.

Investigation and characterization of radio frequency sputtered Cr1.8Ti0.2O3−δ thin films derived by citrate, sol–gel and solid state routes

2007 ◽  
Vol 515 (18) ◽  
pp. 7053-7058 ◽  
Author(s):  
Suman Pokhrel ◽  
Xinglin Li ◽  
Lihua Huo ◽  
Hui Zhao ◽  
Xiaoli Cheng
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Radio Frequency ◽  
Sol Gel

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

Fabrication of Nanoporous Ceramic Thin Films: De-alloying and Self-organized Template Formation Onamorphous Substrates

2002 ◽  
Vol 17 (1) ◽  
pp. 115-126 ◽  
Author(s):  
Maggie Paulose ◽  
Oomman K. Varghese ◽  
Craig A. Grimes
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Sol Gel ◽  
Oxide Ceramic ◽  
Porous Network ◽  
Self Organized ◽  
Ceramic Thin Films ◽  
Transmission Electron ◽  
Amorphous Substrate ◽  
Drying Conditions

Sol-gel-derived metal oxide ceramic thin films deposited onto amorphous iron-rich substrates were found to form self-organized nanoporous structures dependent upon the extent to which the substrate is de-alloyed, a function of the substrate alloycomposition, acid concentration of the sol, and film drying conditions. Field emission scanning electron microscopy, transmission electron microscopy, and x-ray energy dispersive analysis were used to investigate details of the porous structure formation.Our studies showed the more electrochemically active elements in the amorphous substrate are de-alloyed by the sol in high-humidity environments, whereupon the liberated elements form oxides replicating the de-alloyed substrate matrix resulting in athree dimensional porous network structure.

Growth and Characterizations of Relaxor-Based Pb(Mg1/3Nb2/3)O3-PbTiO3 Thin Films by Sol-Gel Method

2007 ◽  
Vol 280-283 ◽  
pp. 839-844
Author(s):  
Hui Qing Fan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Sol Gel ◽  
Silicon Substrates ◽  
Final Annealing ◽  
Gel Method ◽  
Sol Gel Method ◽  
Phase Development ◽  
Transmission Electron ◽  
Pt Films

Relaxor-based 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) thin films were grown epitaxially on silicon substrates by sol-gel method and PbO cover coat technique, and investigated by x-ray diffraction, auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The phase development and microstrure evolution of the PMN-PT film were significantly affected by the final annealing temperature and time. A perovskite PMN-PT film was obtained after annealing at 850oC for 1 min. Then, highly <100>-oriented and textured PMN-PT films could be achieved by using a LaNiO3 perovskite template.

Visible-emitting hybrid sol–gel materials comprising lanthanide ions: thin film behaviour and potential use as phosphors for solid-state lighting

2014 ◽  
Vol 38 (12) ◽  
pp. 5793-5800 ◽  
Author(s):  
Xiaoguang Huang ◽  
Gaël Zucchi ◽  
Jacqueline Tran ◽  
Robert B. Pansu ◽  
Arnaud Brosseau ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solid State ◽  
Sol Gel ◽  
Lanthanide Ions ◽  
Solid State Lighting ◽  
Red Phosphor ◽  
Hybrid Silica ◽  
Uv Led ◽  
Potential Use

Luminescent thin films of hybrid silica-based materials were studied and an Eu-containing one was coated on a near-UV LED chip to be investigated as a red phosphor.

Photoluminescence and Electroluminescence Properties of (Ca,Sr)TiO3:Er

2016 ◽  
Vol 698 ◽  
pp. 60-65 ◽  
Author(s):  
Tôru Kyômen ◽  
Miyu Seki ◽  
Minoru Hanaya ◽  
Hiroshi Takashima
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Band Gap ◽  
Solid State Reaction ◽  
Spin Coating ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Powder Samples ◽  
Coating Methods

Powder samples of (Ca,Sr)TiO3:Er were prepared by a solid-state reaction method. Photoluminescence due to f-f transitions of Er3+ was not induced by band-gap excitation of (Ca,Sr)TiO3 but by f-f transitions of Er3+. An electroluminescent device in which thin films of Ca0.6Sr0.4TiO3:Er and SnO2:Sb are stacked alternately was prepared by sol-gel and spin-coating methods. Very weak electroluminescence due to f-f transition of Er3+ was observed in the device.

Sol-gel derived Ba(Mg1/3Ta2/3)O3 thin films: Preparation and structure

1997 ◽  
Vol 12 (3) ◽  
pp. 596-599 ◽  
Author(s):  
Ji Zhou ◽  
Qing-Xin Su ◽  
K. M. Moulding ◽  
D. J. Barber
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Small Grains

Ba(Mg1/3Ta2/3)O3 thin films were prepared by a sol-gel process involving the reaction of barium isopropoxide, tantalum ethoxide, and magnesium acetate in 2-methoxyethanol and subsequently hydrolysis, spin-coating, and heat treatment. Transmission electron microscopy, x-ray diffraction, and Raman spectroscopy were used for the characterization of the thin films. It was shown that the thin films tend to crystallize with small grains sized below 100 nm. Crystalline phase with cubic (disordered) perovskite structure was formed in the samples annealed at a very low temperature (below 500 °C), and well-crystallized thin films were obtained at 700 °C. Although disordered perovskite is dominant in the thin films annealed below 1000 °C, a low volume fraction of 1 : 2 ordering domains was found in the samples and grows with an increase of annealing temperature.

In situ TEM crystallization of sol-gel derived BaTiO3 thin films

1994 ◽  
Vol 52 ◽  
pp. 588-589
Author(s):  
Martha L. Mecartney ◽  
M. C. Gust ◽  
N. D. Evans
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
In Situ Tem ◽  
Lattice Match ◽  
Gel Layer ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Good Lattice ◽  
Thick Layers

BaTiO3 thin films made by the sol-gel process require a crystallization heat treatment to transform the amorphous gel into a crystalline material. This work used a Ba-Ti methoxypropoxide precursor in a 0.25M solution of methoxypropanol which was spin coated as 5 (each -600 nm thick) layers on (100) Si (FIG. 1). The {100} planes of perovskite BaTiO3 have a good lattice match with {110} Si; d110 of Si = 0.38 nm, and d100 of BaTiO3 = 0.4 nm. Consequently, it should be possible to grow heteroepitaxial films of (100) BaTiO3 on (100) Si. Such samples pyrolized at 350.C and then annealed in a conventional furnace at 750°C for one hour, however, did not crystallize heteroepitaxially with the substrate. Rather, crystallization occurred by a nucleation and growth process from within the gel. Furthermore, the gel layer at the Si/BaTiO3 interface remained amorphous. In-situ hot stage experiments were conducted in a transmission electron microscope (TEM) to determine the nucleation and crystallization behavior.

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