scholarly journals Synthesis of highly porous Al2O3-YAG composite ceramics

2016 ◽  
Vol 48 (3) ◽  
pp. 303-315
Author(s):  
Adela Egelja ◽  
Jelena Majstorovic ◽  
Nikola Vukovic ◽  
Miroslav Stankovic ◽  
Dusan Bucevac
Keyword(s):  
Sintering Temperature ◽  
Water Solution ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Aluminium Nitrate ◽  
Composite Ceramics ◽  
X Ray ◽  
Highly Porous ◽  
Yttrium Nitrate Hexahydrate ◽  
Aluminium Nitrate Nonahydrate

Al2O3-YAG composite was obtained by sintering of porous Al2O3 preforms infiltrated with water solution of aluminium nitrate nonahydrate, Al(NO3)3?9H2O and yttrium nitrate hexahydrate, Y(NO3)3?6H2O. Al2O3 preforms with porosity varying from 26 to 50% were obtained after sintering at temperature ranging from 1100 to 1500?C. Sintering of the infiltrated Al2O3 preforms led to formation of YAG particles due to reaction between Y2O3 and Al2O3 at high temperature. It was found that variation of porosity of alumina preforms and sintering temperature is an effective way to fabricate Al2O3-YAG composite with an unusual combination of properties. Open porosity was in the range 15-35%, specific surface was 0.6-6.1 m2/g, pore size was 150-900 nm whereas compressive strength was from 50 to 250 MPa. The effect of sintering temperature on YAG formation and phase composition were investigated using X-ray diffractometry whereas microstructure of the composite was analysed by scanning electron microscopy.

The role of cerium(iii)/yttrium(iii) nitrate hexahydrate salts on electroactive β phase nucleation and dielectric properties of poly(vinylidene fluoride) thin films

RSC Advances ◽  
2015 ◽  
Vol 5 (36) ◽  
pp. 28487-28496 ◽  
Author(s):  
Pradip Thakur ◽  
Arpan Kool ◽  
Biswajoy Bagchi ◽  
Nur Amin Hoque ◽  
Sukhen Das ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Vinylidene Fluoride ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Β Phase ◽  
Poly Vinylidene Fluoride ◽  
Phase Nucleation ◽  
Yttrium Nitrate Hexahydrate

Electroactive β phase nucleation in cerium/yttrium nitrate hexahydrate salt modified PVDF thin filmsviaformation of hydrogen bonds.

STRUCTURAL ANALYSIS OF THE COMBUSTION SYNTHESIZED Y3+ DOPED CERIA (Ce0.9Y0.1O1.95)

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350037 ◽  
Author(s):  
C. ESTHER JEYANTHI ◽  
R. SIDDHESWARAN ◽  
PUSHPENDRA KUMAR ◽  
R. V. MANGALARAJA ◽  
V. SIVA SHANKAR ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Vacancies ◽  
Combustion Process ◽  
Fluorite Structure ◽  
Spectroscopic Studies ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
X Ray ◽  
Peak Broadening ◽  
Auto Combustion

Y 3+ doped CeO 2 nanopowders ( Ce 0.9 Y 0.1 O 1.95, abbreviated as YDC) were synthesized by citrate-nitrate-auto combustion process using cerium nitrate hexahydrate, yttrium nitrate hexahydrate and citric acid. The as-synthesized powders were calcined at 700°C and converted into dense bodies followed by sintering at 1200°C. The microstructure of the synthesized powders and sintered bodies were examined by scanning electron microscopy (SEM). The surface morphology of the nanoparticles and clusters were also analysed by transmission electron microscopy (TEM). The particles size of the YDC was found to be in the range from 10 to 30 nm, which is in good agreement with the crystallite size calculated from X-ray peak broadening method. Also, the X-ray diffraction confirmed that the Ce 0.9 Y 0.1 O 1.95 crystallizes as the cubic fluorite structure of pure ceria. The optical absorption by functional molecules, impurities and oxygen vacancies were analysed by FTIR and Raman spectroscopic studies. From the FTIR spectrum, the absorption peak found at 530 cm-1 is attributed to the vibrations of metal-oxygen bonds. The characteristic Raman peak was found to be 468 cm-1, and the minute absorption of oxygen vacancies were observed in the region 500–640 cm-1.

Synthesis of Dispersed Y2O3 Nanopowder from Yttrium Stearate

2013 ◽  
Vol 544 ◽  
pp. 3-7 ◽  
Author(s):  
Jin Sheng Li ◽  
Xu Dong Sun ◽  
Shao Hong Liu ◽  
Di Huo ◽  
Xiao Dong Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Average Particle Size ◽  
Ceramic Materials ◽  
Average Particle ◽  
Water Medium ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Ft Ir ◽  
Yttrium Nitrate Hexahydrate

Fine yttrium stearate powder was produced at a relatively low temperature using yttrium nitrate hexahydrate, ammonia and stearic acid as the raw materials. Dispersed Y2O3 nanopowder was synthesized by calcining the yttrium stearate. The formation mechanism of the precursor and the Y2O3 nanopowder was studied by means of XRD, TG-DTA, FT-IR, BET, FE-SEM and HR-TEM. Pure and dispersed Y2O3 nanopowder with an average particle size of 30 nm was produced by calcining the precursor at 600 °C. The particle size increases to about 60 nm with the increase of the calcination temperature to 1000 °C. In the preparation of Y2O3 from yttrium stearate, no water medium is involved, thus capillarity force and bridging of adjacent particles by hydrogen bonds can be avoided, resulting in good dispersion of the particles. The dispersed Y2O3 nanopowder prepared in this work has potential application in phosphors and transparent ceramic materials.

Effect of Different Composite Additives on Thermal Conductivity of Corundum Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 500-504 ◽  
Author(s):  
Xing Yong Gu ◽  
Shao Ling Wu ◽  
Ai Hua Zhang ◽  
Ting Luo ◽  
Yun Xia Chen
Keyword(s):  
Thermal Conductivity ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Alumina Ceramic ◽  
Inorganic Materials ◽  
High Thermal Conductivity ◽  
Alumina Ceramics ◽  
Composite Ceramics ◽  
Subsequent Reaction ◽  
X Ray

To improve the thermal conductivity of alumina ceramics, different inorganic materials such as AlN, BN, Si3N4 and SiC which own high thermal conductivity were integrated with 96% alumina ceramic. The effect of addition of AlN, BN, Si3N4 and SiC on water absorption, flexural strength and thermal conductivity of the as-prepared alumina-based composite ceramics were investigated. Field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) were employed to characterize the microstructure and phase compositions of the composites. The results showed that sintering temperature of 96% alumina ceramic matrixes were improved in varying degree due to adding AlN, BN, SiC and Si3N4. A small quantity of Al6Si2O13 crystals were formed in the case of adding Si3N4 and SiC, which is due to the oxidation of Si3N4 and SiC into SiO2 in the air and the subsequent reaction with alumina. At appropriate firing temperature, the flexural strength of the composites with the addition of AlN is the best and higher than corundum matrixes. Meanwhile, the thermal conductivity of the composites with AlN has 110% improvement. It is obvious that AlN with high thermal conductivity is suitable for improving the thermal conductivity of corundum ceramics.

Photochemical Metal Organic Deposition of Patterned Nanostructured Oxide Films

2005 ◽  
Vol 901 ◽  
Author(s):  
Xin Zhang ◽  
Ross Hill
Keyword(s):  
Tantalum Oxide ◽  
Oxide Films ◽  
Reaction Rates ◽  
Auger Spectroscopy ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Nanostructured Oxide ◽  
Metal Organic ◽  
Metal Organic Deposition ◽  
Yttrium Nitrate Hexahydrate

AbstractIn this paper, we present examples of the use of photochemical metal organic deposition to form nanostructured metal oxide films. In the first example, we use two reactions with very different reaction rates to control the nanostructuring, utilizing tantalum (V) tetraethoxide acetylacetonate (as a thermally reactive source of tantalum oxide) and manganese (II) 2-ethylhexanoate (as a photochemically reactive source of manganese oxide). We prepare homogeneous precursor films of tantalum (V) tetraethoxide acetylacetonate and manganese (II) 2-ethylhexanoate and in the dark allow the tantalum complex to react forming tantalum oxide regions. The film is then exposed and the manganese complex is converted to a matrix surrounding the tantalum regions. The resultant structures are characterized by electron microscopy, energy dispersive X-ray spectroscopy and Auger spectroscopy. In the second example, we use two immiscible precursors, zirconium (IV) 2-ethylhexanoate and yttrium nitrate hexahydrate to form nanostructured precursor films. The nanostructuring of these films is apparent from SEM studies. Exposure of these films results in the formation of nanostructured films consisting of a zirconium oxide matrix with encapsulated yttrium oxide.

scholarly journals Green Synthesis and Morphology of Nano Yttria Mediated by Agaricus bisporus

2019 ◽  
Vol 31 (4) ◽  
pp. 834-838
Author(s):  
K.B. Satishkumar ◽  
T.K. Vishnuvardhan ◽  
B. Rajashekhar ◽  
K. Satish ◽  
Shashidhar ◽  
...  
Keyword(s):  
Green Synthesis ◽  
Crystallite Size ◽  
Acid Medium ◽  
Yttrium Oxide ◽  
Agaricus Bisporus ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Reaction Products ◽  
Hall Method ◽  
Yttrium Nitrate Hexahydrate

Nano-yttrium oxide has been synthesized from yttrium nitrate hexahydrate by combustion of Agarics bisporus (mushroom) used as fuel. The precursor yttirium nitrate and fuel in acid medium are combusted in furnace at 400 ºC for 3 h yields yttria nanopowder. Morphology of the reaction products are characterized by SEM and TEM. Synthesized yttria nanoparticle are characterized by UV, FTIR, XRD and EDAX are discussed. The crystallite size obtained nano yttria particles are calculated by Scherer′s equation and compared with Williamson-Hall method.

Sinterability and Microwave Dielectric Properties of Li2CO3-V2O5 Added Mg4Nb2O9-CaTiO3 Composite Ceramics

2010 ◽  
Vol 663-665 ◽  
pp. 1196-1199
Author(s):  
Cui Jin Pei ◽  
Guo Guang Yao ◽  
Hong Ma ◽  
Xiu Lao Tian
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Microscopy Techniques ◽  
Co Doped ◽  
Scanning Electron

The effects of Li2CO3-V2O5 (LV) co-doped on the sinterability, phase compositions and microwave dielectric properties of Mg4Nb2O9-CaTiO3 composite ceramics have been investigated. The phase compositions and microstructure were analyzed using X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy techniques. The densification sintering temperature is lowed from 1275oC to 1200oC with an amount LV addition. For the specimen with 1.5 wt% LV addition sintered at 1200oC for 5 h exhibited dielectric properties: εr=23, Q·f=24 000 GHz (at 7.7GHz ), τf =1.0 ppm/oC. These properties were correlated with the formation of non-stoichiometric compound Mg4(Nb1-xTix)2O9-δ.

Structural and electrical properties of zirconium doped yttrium oxide nanostructures

2014 ◽  
Vol 28 (16) ◽  
pp. 1450102 ◽  
Author(s):  
Ali Bahari ◽  
Masoud Ebrahimzadeh ◽  
Reza Gholipur
Keyword(s):  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
X Ray Diffraction ◽  
Synthetic Process ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Zirconium Propoxide ◽  
Structural And Electrical Properties ◽  
Current Densities

A synthetic process for the formation of Zr x Y 1-x O y nanostructures is demonstrated by the reaction of yttrium nitrate hexahydrate with zirconium propoxide. The reactions are carried out at temperature 60°C and pressure 0.1 MPa. The energy dispersive X-ray (EDX) spectroscopy measurements confirm formation of Zr x Y 1-x O y nanostructures and the presence of carbonate and hydroxide species which are removed after high temperature anneals. It was found that the oxygen pressure during synthesis plays a determinant role on the structural properties of the nanostructure. This effect is further studied by atomic force microscopy (AFM) measurements and scanning electron microscope (SEM), which showed the formation of an isotopically organized structure. X-ray diffraction (XRD) measurement reveals that these changes in the nanostructural efficiency are associated with structural and compositional changes among the substrate. The dielectric constant as measured by the capacitance–voltage (C–V) technique is estimated to be around 39.05. C–V measurements taken at 1 MHz show the maximum capacitance for the Zr 0.05 Y 0.95 O y film. The leakage current densities were below 10-5 A/cm2 for the Zr 0.05 Y 0.95 O y film.

scholarly journals Synthesis and characterization of yttrium nitrate hexahydrate

2021 ◽  
Vol 1065 (1) ◽  
pp. 012019
Author(s):  
R Madhusudhana ◽  
S Lovesome Benedict ◽  
L. Krishnamurthy ◽  
R Gopalakrishne Urs ◽  
L Vinaykumar
Keyword(s):  
Synthesis And Characterization ◽  
Nitrate Hexahydrate ◽  
Yttrium Nitrate ◽  
Yttrium Nitrate Hexahydrate
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