Synthesis and characterization of sol-gel derived hexa-aluminate phosphors

1997 ◽  
Vol 12 (3) ◽  
pp. 819-824 ◽  
Author(s):  
D. Ravichandran ◽  
R. Roy ◽  
W. B. White ◽  
S. Erdei
Keyword(s):  
Sol Gel ◽  
Broad Band ◽  
Blue Emission ◽  
Emission Spectra ◽  
Steam Treatment ◽  
Optical Pyrometer ◽  
Processing Route ◽  
Sol Gel Process ◽  
State Processing

Two refractory phosphors, BaMg2Al16O27: Eu2+ (BAM) and MgAl11O17.5: Ce3+, Tb3+ (MAO), have been synthesized both by the conventional solid-state processing route (using oxides as the starting materials) and by reacting precursors made by the sol-gel process using organic precursors. The phases formed were reacted at 1000 °C in (a) steam and (b) steam + AlF3. The phosphors were well crystallized with particle sizes in the range of 1–10 μm. The emission spectra showed the characteristic broad band blue emission of Eu2+ for BAM and a narrow band green luminescence of Tb3+ for MAO. The melting points of BAM and MAO were measured to be 1920 ± 20 °C and 1950 ± 20 °C, respectively, using an Ir-strip furnace and optical pyrometer. BAM and MAO phosphor materials are congruently and incongruently melting, respectively. Excellent crystallization via the sol-gel route was found even at 1220 °C. Enhancement of the luminescent output by the steam treatment by some 25% was determined.

Effects of Eu2+, Dy3+ Contents and Particle Sizes on the Luminescent Properties of SrAl2O4 Phosphor by the Sol-Gel Process

2009 ◽  
Vol 620-622 ◽  
pp. 473-476 ◽  
Author(s):  
Dae Yong Shin ◽  
Kyung Nam Kim
Keyword(s):  
Decay Time ◽  
Sol Gel ◽  
Broad Band ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Particle Sizes ◽  
Excitation Light ◽  
High Brightness ◽  
Long Afterglow ◽  
Sol Gel Process

A green emitting SrAl2O4:Eu2+, Dy3+ phosphor with high brightness and long afterglow was synthesized by the sol-gel method. SrAl2O4: Eu2+, Dy3+ phosphor exhibited broad band extending from 450 to 650 nm and maximum emission spectra peaking at 520 nm. Three excited levels existed, two shoulders were observed at 270 and 330 nm in addition to the maximum at 360 nm on the excitation spectrum. After the removal of excitation light, the excellent after-glow characteristic of the phosphorescence was obtained as a result of low decay time, although the after-glow intensities of phosphor varied exponentially with the time.

Blue photoluminescent properties of pure nanostructured γ–Al2O3

2001 ◽  
Vol 16 (7) ◽  
pp. 1890-1893 ◽  
Author(s):  
Zhong Qing Yu ◽  
Dao Chang ◽  
Cun Li ◽  
Ning Zhang ◽  
Yu Ying Feng ◽  
...  
Keyword(s):  
Excitation Spectrum ◽  
Emission Band ◽  
Sol Gel ◽  
Broad Band ◽  
Emission Spectra ◽  
Alumina Powder ◽  
Defect Level ◽  
Aluminum Alkoxide ◽  
Sol Gel Process

Blue photoluminescent emission was observed in pure nanometer-sized γ–Al2O3 powders prepared by the sol-gel process, with aluminum alkoxide as the precursor. The photoluminescent excitation spectrum detected at »em = 422 nm showed four peaks located at 238, 255, 278.5, and 348.5 nm, respectively, the first having the strongest intensity. The photoluminescent emission spectra were made up of a broad band with four peaks located at 404.5, 422, 447, and 484.5 nm. The emission band of 422 nm had the intensity. We suggest that the defect level in the nanometer alumina powder also is the main reason for the appearance of new luminescent emission bands.

The crystallization of thin-film ceramics

1992 ◽  
Vol 50 (1) ◽  
pp. 338-339
Author(s):  
J.M. Schwartz ◽  
L.F. Francis ◽  
L.D. Schmidt ◽  
P.S. Schabes-Retchkiman
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Sol Gel ◽  
Processing Route ◽  
Small Areas ◽  
Ceramic Thin Films ◽  
Complex Shapes ◽  
Sol Gel Process ◽  
Ceramic Precursors ◽  
Crystalline Ceramic

Ceramic thin films and coatings are of interest for electrical, optical, magnetic and thermal barrier applications. Critical for improved properties in thin films is the development of specific microstructures during processing. To this end, the sol-gel method is advantageous as a versatile processing route. The sol-gel process involves depositing a solution containing metalorganic or colloidal ceramic precursors onto a substrate and heating the deposited layer to form a crystalline or non-crystalline ceramic coating. This route has several advantages, including the ability to create tailored microstructures and properties, to coat large or small areas, simple or complex shapes, and to more easily prepare multicomponent ceramics. Sol-gel derived coatings are amorphous in the as-deposited state and develop their crystalline structure and microstructure during heat-treatment. We are particularly interested in studying the amorphous to crystalline transformation, because many key features of the microstructure such as grain size and grain size distribution may be linked to this transformation.

The preparation and characterization of transparent nano-sized thermochromic VO2–SiO2 films from the sol–gel process

2004 ◽  
Vol 347 (1-3) ◽  
pp. 138-143 ◽  
Author(s):  
Hua-Kuo Chen ◽  
Hsin-Chin Hung ◽  
Thomas C.-K. Yang ◽  
Sea-Fue Wang
Keyword(s):  
Sol Gel ◽  
Sio2 Films ◽  
Sol Gel Process

ChemInform Abstract: Preparation and Characterization of Machinable Mica Glass-Ceramics by the Sol-Gel Process.

ChemInform ◽  
1989 ◽  
Vol 20 (9) ◽  
Author(s):  
T. HAMASAKI ◽  
K. EGUCHI ◽  
Y. KOYANAGI ◽  
A. MATSUMOTO ◽  
T. UTSUNOMIYA ◽  
...  
Keyword(s):  
Sol Gel ◽  
Glass Ceramics ◽  
Sol Gel Process

Synthesis and characterization of well-defined star polymers via a controlled sol-gel process

1991 ◽  
Vol 24 (6) ◽  
pp. 1431-1434 ◽  
Author(s):  
Timothy E. Long ◽  
Larry W. Kelts ◽  
S. Richard Turner ◽  
Jeffrey A. Wesson ◽  
Thomas H. Mourey
Keyword(s):  
Sol Gel ◽  
Star Polymers ◽  
Synthesis And Characterization ◽  
Sol Gel Process

Infrared Characterization of PMMA-SiO2 Hybrid Glasses Obtained by Sol-Gel Process

2010 ◽  
Vol 1278 ◽  
Author(s):  
L.L. Díaz-Flores ◽  
A. S. López Rodríguez ◽  
P. SifuentesGallardo ◽  
M.A. Hernàndez Rivera ◽  
M.a Garnica Romo ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Hybrid Coatings ◽  
Force Microscopy ◽  
Air Atmosphere ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Traditional Process ◽  
And Chemical Properties

AbstractThis work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

Relationships Between Microstructure and Reliability in Pzt Mems

2001 ◽  
Vol 666 ◽  
Author(s):  
B.W. Olson ◽  
L.M. Randall ◽  
C.D. Richards ◽  
R.F. Richards ◽  
D.F. Bahr
Keyword(s):  
Grain Size ◽  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Electrical Energy ◽  
Lead Zirconate ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Processing Route ◽  
Bulge Testing ◽  
Sol Gel Process

ABSTRACTPiezoelectric oxide films, such as lead zirconate titanate (PZT), are now being integrated into MEMS applications. Many PZT derived systems are deposited using a sol-gel process, which can be used in a microelectronics processing route using spin coating as the deposition method. An application of interest for PZT films is in power generation, where a flexing membrane is used to transform mechanical to electrical energy. The current study was undertaken to identify the relationships between the processing, microstructure, and mechanical reliability of these films. Films were deposited onto both monolithic and bulk micromachined platinized silicon wafers using standard sol-gel chemistries, with roughness and grain size tracked using electron and scanning probe microscopy. Mechanical properties were evaluated in a dynamic bulge testing apparatus. Grain size variations in the Pt film between 35 and 125 nm are shown to have little effect on grain size of the subsequent PZT film and the adhesion of the PZT to the Pt film. Only the Pt film with 125 nm grains was shown to undergo any significant interfacial fracture. Fatigue tests suggest film lifetime is primarily limited by the number of pre- existing flaws in the film from processing. Reducing the microcrack density has been shown to produce films and devices that fail at strains of 1.4% and have mechanical fatigue lifetimes in excess of 100 million cycles at strains simulating the operating conditions.

Sign in / Sign up

Export Citation Format

Share Document