Effect of substrates on the crystallinity and morphology of sol-gel-derived epitaxial LiNbO3 films

1995 ◽  
Vol 10 (7) ◽  
pp. 1779-1783 ◽  
Author(s):  
K. Terabe ◽  
N. Iyi ◽  
K. Kitamura ◽  
S. Kimura
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Thermal Expansion ◽  
Grain Growth ◽  
Lattice Constant ◽  
Smooth Surface ◽  
Sol Gel ◽  
The Other ◽  
Epitaxial Thin Films ◽  
Sapphire Substrates

Epitaxial thin films of LiNbO3 were prepared by the sol-gel method on (0001)-sapphire, (0001)-LiTaO3 and (0001)-5% MgO-doped LiNbO3, substrates. The precursor films crystallized with the highly preferred orientation on all substrates. When sapphire substrates, which have large discrepancies in the lattice constant and thermal expansion percentage with the film were used, the resulting films showed a low crystallinity after heat treatment at 500 °C and grain growth at 650 °C. On the other hand, when using LiTaO3 and 5% MgO-doped LiNbO3 substrates, with smaller discrepancies, the formed films, after heat treatment at 500 °C, showed better crystallinity with the smooth surface.

Microstructural Evolution of Epitaxial LiNbO3 Thin Films Derived From Metal Alkoxide Solutions

1990 ◽  
Vol 202 ◽  
Author(s):  
Keiichi Nashimoto ◽  
Michael J. Cima ◽  
Wendell E. Rhine
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Single Phase ◽  
Sol Gel ◽  
Precursor Solution ◽  
Epitaxial Films ◽  
Metal Alkoxide ◽  
High Annealing Temperature ◽  
Sapphire Substrates ◽  
High Annealing

ABSTRACTThe evolution of the microstructure of sol-gel derived LiNbO3 thin films was investigated to understand the growth of epitaxial films. LiNbO3 films were prepared from a precursor solution of lithium ethoxide and niobium pentaethoxide. Prehydrolysis promoted the development of polycrys-talline LiNbO3 films, whereas nonhydrolysis produced solid-state epitaxial growth of LiNbO3 films on sapphire substrates. Although the films looked smooth after annealing at 400°C, the morphology of the films changed, depending on substrates and precursors, due to grain growth at high annealing temperature. Prehydrolysis of the alkoxides caused a decrease in the temperature at which grain growth occurred, whereas the film prepared from the nonhydrolyzed precursor on a sapphire substrate showed denser texture and contained abnormally large domains that appeared to be single phase.

Processing of Dense Nanocrystalline Zirconia Thin Films by Sol-Gel

2006 ◽  
Vol 928 ◽  
Author(s):  
Christoph Peters ◽  
Matthias Bockmeyer ◽  
Reinhard Krüger ◽  
André Weber ◽  
Ellen Ivers-Tiffée
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Rapid Thermal Annealing ◽  
Growth Phase ◽  
Sol Gel ◽  
Grain Sizes ◽  
Sapphire Substrates ◽  
Metal Organic ◽  
Nanocrystalline Zirconia ◽  
Metal Organic Deposition

ABSTRACTVia metal organic deposition (MOD) sapphire substrates were multiple dip-coated with a molecular dispersive 8 mol% Y2O3 doped ZrO2 (8YSZ) sol to prepare dense, crack-free thin films. The thin films were consecutively exposed to a tempering program with several rapid thermal annealing (RTA) steps and a final dwell temperature between 500 °C and 1400 °C for 24 h. Grain growth, phase, stoichiometry and macroscopic density of the thin films were analyzed by XRD and SEM. Grain sizes ranged between a few nanometers in diameter at 500 °C and several hundreds of nanometers at 1400 °C.

Preparation and Characterization of Epitaxial KNBO3 Thin Films by a Sol-Gel Method

1993 ◽  
Vol 310 ◽  
Author(s):  
Hidehiro Endo ◽  
M. J. Cima
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Grain Growth ◽  
Sol Gel ◽  
Soaking Time ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sol Gel Process ◽  
Surface Morphologies

AbstractEpitaxial formation of KNbO3 films on several substrates was examined. The films were prepared by a sol-gel process using potassium ethoxide and niobium pentaethoxide. Hetero-epitaxial KNbO3 films with (100) orientation were successfully obtained both on MgO (100) and SrTiO3 (100) substrates by heat treatments above 700°C, while polycrystalline KNbO3 were formed on Si (111) substrates. Higher temperatures and extended soaking time promoted the grain growth of KNbO3 and KNbO3 films with improved surface morphologies (smoother surfaces) could be obtained by controlling heat treatment parameters.

LiNiO2 Thin Films Fabricated by Diffusion of Li on Ni Tapes

2007 ◽  
Vol 336-338 ◽  
pp. 505-508
Author(s):  
Cheol Jin Kim ◽  
In Sup Ahn ◽  
Kwon Koo Cho ◽  
Sung Gap Lee ◽  
Jun Ki Chung
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Grain Size ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Cold Isostatic Pressing ◽  
Tube Furnace ◽  
Treatment Conditions ◽  
Average Grain Size ◽  
Cold Rolling And Annealing

LiNiO2 thin films for the application of cathode of the rechargeable battery were fabricated by Li ion diffusion on the surface oxidized NiO layer. Bi-axially textured Ni-tapes with 50 ~ 80 μm thickness were fabricated using cold rolling and annealing of Ni-rod prepared by cold isostatic pressing of Ni powder. Surface oxidation of Ni-tapes were conducted using tube furnace or line-focused infrared heater at 700 °C for 150 sec in flowing oxygen atmosphere, resulted in NiO layer with thickness of 400 and 800 μm, respectively. After Li was deposited on the NiO layer by thermal evaporation, LiNiO2 was formed by Li diffusion through the NiO layer during subsequent heat treatment using IR heater with various heat treatment conditions. IR-heating resulted in the smoother surface and finer grain size of NiO and LiNiO2 layer compared to the tube-furnace heating. The average grain size of LiNiO2 layer was 0.5~1 μm, which is much smaller than that of sol-gel processed LiNiO2. The reacted LiNiO2 region showed homogeneous composition throughout the thickness and did not show any noticeable defects frequently found in the solid state reacted LiNiO2, but crack and delamination between the reacted LiNiO2 and Ni occurred as the reaction time increased above 4hrs.

Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 123-125 ◽  
Author(s):  
Yong Li ◽  
Qi Hong Wei ◽  
Ling Li ◽  
Chong Hai Wang ◽  
Xiao Li Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Heat Treatment Temperature ◽  
Bending Strength ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Treatment Temperature ◽  
Heat Treated

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

scholarly journals Effect of Solution Conditions on the Properties of Sol–Gel Derived Potassium Sodium Niobate Thin Films on Platinized Sapphire Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1600 ◽  
Author(s):  
Alexander Tkach ◽  
André Santos ◽  
Sebastian Zlotnik ◽  
Ricardo Serrazina ◽  
Olena Okhay ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Low Cost ◽  
Sol Gel ◽  
Precursor Solution ◽  
Dissipation Factor ◽  
Solution Concentration ◽  
Potassium Sodium Niobate ◽  
Sapphire Substrates ◽  
Average Grain Size

If piezoelectric micro-devices based on K0.5Na0.5NbO3 (KNN) thin films are to achieve commercialization, it is critical to optimize the films’ performance using low-cost scalable processing conditions. Here, sol–gel derived KNN thin films are deposited using 0.2 and 0.4 M precursor solutions with 5% solely potassium excess and 20% alkali (both potassium and sodium) excess on platinized sapphire substrates with reduced thermal expansion mismatch in relation to KNN. Being then rapid thermal annealed at 750 °C for 5 min, the films revealed an identical thickness of ~340 nm but different properties. An average grain size of ~100 nm and nearly stoichiometric KNN films are obtained when using 5% potassium excess solution, while 20% alkali excess solutions give the grain size of 500–600 nm and (Na + K)/Nb ratio of 1.07–1.08 in the prepared films. Moreover, the 5% potassium excess solution films have a perovskite structure without clear preferential orientation, whereas a (100) texture appears for 20% alkali excess solutions, being particularly strong for the 0.4 M solution concentration. As a result of the grain size and (100) texturing competition, the highest room-temperature dielectric permittivity and lowest dissipation factor measured in the parallel-plate-capacitor geometry were obtained for KNN films using 0.2 M precursor solutions with 20% alkali excess. These films were also shown to possess more quadratic-like and less coercive local piezoelectric loops, compared to those from 5% potassium excess solution. Furthermore, KNN films with large (100)-textured grains prepared from 0.4 M precursor solution with 20% alkali excess were found to possess superior local piezoresponse attributed to multiscale domain microstructures.

Dense and smooth epitaxial BaTiO3 thin films by the dipping-pyrolysis process

1999 ◽  
Vol 14 (2) ◽  
pp. 592-596 ◽  
Author(s):  
S. Kim ◽  
T. Fujimoto ◽  
T. Manabe ◽  
I. Yamaguchi ◽  
T. Kumagai ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Heat Treatment ◽  
Oxygen Partial Pressure ◽  
Smooth Surface ◽  
Precursor Solution ◽  
Final Heat Treatment ◽  
Pyrolysis Process ◽  
Low Oxygen ◽  
Final Heat

Dense and smooth BaTiO3 thin films were prepared on SrTiO3 (100) substrates by the dipping-pyrolysis process using a mixed precursor solution of barium and titanium naphthenates. Combination effects of prefiring [at 150–450 °C in air or low oxygen partial pressure, p(O2)[ and final heat treatment [at 850 °C in air or low p(O2)[ on preparation of BaTiO3 thin films were examined. An epitaxial BaTiO3 thin film with a dense and smooth surface consisting of nanosized grains about 70 nm was prepared by prefiring under low p(O2) at 250 °C and final heat treatment under low p (O2) at 850 °C.

Copper-alumina materials made by infiltration in boehmite

1995 ◽  
Vol 10 (9) ◽  
pp. 2271-2276 ◽  
Author(s):  
V. Pierre ◽  
D. Pierre ◽  
A.C. Pierre
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Sandwich Structures ◽  
Sol Gel ◽  
Copper Acetate ◽  
New Materials ◽  
Heat Treated ◽  
Direct Infiltration

New materials were made by infiltration of sol-gel boehmite thin films with copper acetate. The structure and phase transformation of these materials during heat treatment were studied. It was found that infiltration in the boehmite state did not end up in the same material as direct infiltration in the θ-alumina derived from boehmite, even after both types of materials were heat-treated at 900 °C. Infiltration in boehmite makes it possible to synthesize sandwich structures comprised of alternate layers of CuO and of γ-alumina.

scholarly journals Poisson ratio and bulk lattice constant of (Sr0.25La0.75)CrO3 from strained epitaxial thin films

2019 ◽  
Vol 126 (8) ◽  
pp. 085304 ◽  
Author(s):  
Dong Han ◽  
Mohamed Bouras ◽  
Claude Botella ◽  
Aziz Benamrouche ◽  
Bruno Canut ◽  
...  
Keyword(s):  
Thin Films ◽  
Lattice Constant ◽  
Poisson Ratio ◽  
Epitaxial Thin Films

Crystal Structure Analysis of the Cr2O3 thin films

2012 ◽  
Vol 1454 ◽  
pp. 33-38 ◽  
Author(s):  
Nobuyuki Iwata ◽  
Takuji Kuroda ◽  
Hiroshi Yamamoto
Keyword(s):  
Thin Films ◽  
Surface Energy ◽  
Smooth Surface ◽  
Lattice Mismatch ◽  
Rf Magnetron Sputtering ◽  
Crystal Structure Analysis ◽  
Reciprocal Space Mapping ◽  
Sapphire Substrates ◽  
Oriented Film ◽  
Oriented Films

ABSTRACTUsing DC-RF magnetron sputtering method, the stress free c- and r-oriented Cr2O3 thin films were grown on c- and r-cut sapphire substrates, respectively. The c-oriented film grown at 580 ºC shows the smoothest surface with a surface average (Ra) of 0.17, although the c-surface energy is the highest. The origin of the smooth surface is expected that the presence of a twin grain due to a dislocation of Cr atoms, demonstrated by a reciprocal space mapping. The step height corresponding to that of the bulk is clearly observed. The r-oriented films epitaxially grow without twin grain. The Ra is 1.56 in the film grown at 580 ºC because of deep trenches due to a lattice mismatch and no dislocation like c-oriented films. Since the surface energy of the r-surface is the lowest, the terrace is quite smooth in one grain even at higher substrate temperature of 840 ºC.

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