scholarly journals Influence of Ti addition on thermophyscial properties of Sm2Ce2O7 oxides

2018 ◽  
Vol 12 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Xiaoge Chen ◽  
Hongsong Zhang ◽  
Longfei Zhou ◽  
Bo Ren ◽  
An Tang ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Phonon Scattering ◽  
Solid State Reaction Method ◽  
Cold Isostatic Pressing ◽  
Conventional Solid State Reaction ◽  
Single Defect ◽  
Thermal Expansion Coefficients ◽  
Fluorite Type ◽  
Ion Radius ◽  
Expansion Coefficients

Sm2(Ce1-xTix)2O7 (where x = 0, 0.1,0.3, 0.5) solid solutions were synthesized by conventional solid state reaction method using Sm2O3, CeO2 and TiO2 as raw reactants. The synthesized powders were pressed into pellets by cold isostatic pressing and pressure-less sintered at 1600 ?C for ten hours. Their phase-structure and thermophysical properties were studied. The synthesized samples exhibit single defect fluorite-type structure. Due to the phonon scattering by substitutional atoms, the thermal conductivities of the Sm2(Ce1-xTix)2O7 solid solutions decrease with the increasing Ti4+ content over the entire temperature range, which are significantly lower than that of yttrium stabilized zirconia (YSZ). The thermal expansion coefficients of the prepared Sm2(Ce1-xTix)2O7 solid solutions also decrease with the increasing Ti4+ fraction, which can be attributed to the lower titanium ion radius.

Preparation and Properties of Multi-Elements Doped Perovskite-Type Mixed Conductors for IT-SOFC Cathodes

2014 ◽  
Vol 989-994 ◽  
pp. 759-762
Author(s):  
Jiang Fu ◽  
Jie Zhao ◽  
Yong Fu ◽  
Rong Rong Li
Keyword(s):  
Perovskite Phase ◽  
Mixed Conductors ◽  
Forming Process ◽  
Mixed Conductivity ◽  
Conventional Solid State Reaction ◽  
Thermal Expansion Coefficients ◽  
Pure Perovskite Phase ◽  
Expansion Coefficients ◽  
Perovskite Type ◽  
Semiconducting Behavior

Multi-elements doped LaCoO3-based mixed conductors La0.7Sr0.1Ca0.1Co0.8Fe0.2O2.9 (LSCCF-112) and La0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (LSCCF-213) were synthesized by conventional solid state reaction (CSSR). The forming process, microstructure and crystal structure of the prepared samples were analyzed by TG/DTA, SEM and XRD. The mixed conductivities of the samples were measured using DC four-terminal method in 150-950 °C. Thermal expansion coefficients (TEC) of the samples were tested in 20-950°C. LSCCF-112 and LSCCF-213 exhibit pure perovskite phase and porous structure after sintered at 1200 °C. The average TECs of LSCCF-112 and LSCCF-213 are 18.17×10-6 K-1 and 17.52×10-6 K-1 respectively. The mixed conductivity of the samples shows semiconducting behavior up to 700-750°C and then decreases as the temperature is further raised. At intermediate temperature (IT), the conductivity values of the samples are both much higher than 100 S/cm.

Negative Thermal Expansion of Yb2Mo3O12 and Lu2Mo3O12

2008 ◽  
Vol 368-372 ◽  
pp. 1662-1664 ◽  
Author(s):  
X.L. Xiao ◽  
M.M. Wu ◽  
J. Peng ◽  
Y.Z. Cheng ◽  
Zhong Bo Hu
Keyword(s):  
Thermal Expansion ◽  
Solid State ◽  
Solid State Reaction ◽  
Linear Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Orthorhombic Structure ◽  
Conventional Solid State Reaction ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Compounds Yb2Mo3O12 and Lu2Mo3O12 were prepared by conventional solid-state reaction. Their crystal structures and thermal expansion properties were investigated. It was found that Yb2Mo3O12 and Lu2Mo3O12 adopt orthorhombic structure and show negative thermal expansion (NTE) in the temperature range of 200-800 °C. Their a-axis and c-axis exhibit stronger contraction in the temperature range of 200-800 °C, while b-axis slightly expands in the temperature range of 200-300 °C and then contracts in the temperature range of 300-800 °C. The linear thermal expansion coefficients al of Yb2Mo3O12 and Lu2Mo3O12 are −5.17 × 10−6 °C−1 and −5.67 × 10−6 °C−1, respectively.

Investigation of Strontium-Niobium Oxides for Application to Thermal Barrier Coatings

2006 ◽  
Vol 317-318 ◽  
pp. 517-520 ◽  
Author(s):  
Masato Shida ◽  
Katsunori Akiyama ◽  
Ichiro Nagano ◽  
Yuichiro Murakami ◽  
Satoshi Ohta
Keyword(s):  
Thermal Expansion ◽  
Thermal Barrier Coatings ◽  
Solid Solutions ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Niobium Oxides ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Thermal Conductivities

We have been trying to find new oxide compounds with large thermal expansion coefficients and low thermal conductivities by means of a material calculation technique. Among thousands of compounds in the databases, we found that there were some materials with low thermal conductivities and large thermal expansion coefficients in the group of strontium-niobium oxides. For example, Sr4Nb2O9 has a thermal expansion coefficient of 14.510-6 / and thermal conductivity of 1.0 W/mK, although a slight amount of other phases appear during long-term annealing. These thermal properties are better than those of yttria-stabilized zirconia, which is the standard material for thermal barrier coatings. To prevent the precipitation of other phases, we prepared the solid solutions, Sr4Nb2-xMxO9. In this study, the thermal conductivities and thermal expansion coefficients of these solid solutions were measured, and their thermal stabilities were evaluated by long-term annealing.

Measured and calculated thermoelastic properties of supersaturated fcc Ni(Al) and Ni(Zr) solid solutions

1998 ◽  
Vol 13 (6) ◽  
pp. 1717-1723 ◽  
Author(s):  
J. Bøttiger ◽  
N. Karpe ◽  
J. P. Krog ◽  
A. V. Ruban
Keyword(s):  
Solid Solutions ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Debye Temperatures ◽  
Expansion Coefficients ◽  
Face Centered ◽  
Fcc Phase ◽  
Film Form

Metastable face-centered cubic (fcc) solid solutions of Ni1–xAlx and Ni1–xZrx have been prepared in thin-film form using dc planar magnetron sputtering in a UHV system. In both these alloy systems, extended solubilities in the fcc phase and a pronounced (111) texture are observed after sputter deposition. An amorphous phase is found to form in Ni1–xAlx for x ≥ 0.30 and in Ni1–xZrx for x ≥ 0.05. Lattice constants, thermal expansion coefficients, and Debye temperatures were derived from x-ray diffraction measurements. These parameters were also calculated by using ab initio methods in the framework of the local-spin density and coherent potential approximations for the electronic subsystem and the Debye–Grüneisen model for the vibrational properties of the nuclei subsystem. Experiment and theory are compared and discussed.

Nitrate-Citrate Combustion Synthesis and Properties of Ce1-xGdxO2-x/2 Solid Solutions

2007 ◽  
Vol 336-338 ◽  
pp. 401-404
Author(s):  
Cheng Peng ◽  
Zhen Zhang
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Combustion Method ◽  
Thermal Expansion Coefficients ◽  
Gel Combustion ◽  
Dense Ceramic ◽  
Maximum Conductivity ◽  
Expansion Coefficients ◽  
Lower Temperature ◽  
Gel Combustion Method

The structure, thermal expansion coefficients, and electric conductivity of Ce1-xGdxO2-x/2 (x = 0 ~ 0.6) solid solutions, prepared by gel-combustion method, were investigated. The uniform small particle size of the gel-combustion prepared materials allows sintering of the samples into highly dense ceramic pellets at 1300°C, a significantly lower temperature, compared to that of 1600~1650°C required for ceria solid electrolytes prepared by traditional solid state techniques. XRD showed that single-phase solid solutions have been formed in all investigated range. The maximum conductivity, σ600°C = 5.26×10-3S/cm, was found at x = 0.2. The thermal expansion coefficient, determined from high-temperature X-ray data is 8.125×10-6 K-1 at x = 0.2.

A Promising Sm1.9Ca0.1Zr2O6.95 Ceramic for Thermal Barrier Coatings

2007 ◽  
Vol 336-338 ◽  
pp. 1762-1763
Author(s):  
Qiang Xu ◽  
Wei Pan ◽  
Chun Lei Wan ◽  
Long Hao Qi ◽  
He Zhuo Miao
Keyword(s):  
Thermal Expansion ◽  
Thermal Barrier Coatings ◽  
Solid State Reaction Method ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Reaction Method ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Calcium Cation ◽  
Expansion Coefficients

Sm1.9Ca0.1Zr2O6.95 ceramic was sintered at 1600°C for 10 h in air by solid-state reaction method. The phase structure and thermal expansion coefficient were measured by XRD and a high-temperature dilatometry, respectively. The results show that the crystal structure of Sm1.9Ca0.1Zr2O6.95 ceramic is still pyrochlore. The doping with calcium cation leads to a shift of the X-ray spectrum of Sm1.9Ca0.1Zr2O6.95 ceramic to lower 2θ values. The experiments also show that the thermal expansion coefficients of Sm1.9Ca0.1Zr2O6.95 ceramic are higher than those of Sm2Zr2O7 ceramic. These results are related to the vacancy induced by doped calcium cation in the samarium lattice.

Thermophysical Properties of Gd2O3 Doped SrHfO3 Ceramic

2015 ◽  
Vol 816 ◽  
pp. 237-241 ◽  
Author(s):  
Wen Ma ◽  
Yi Ren ◽  
Xi Long Jin ◽  
Ya Hong Liang ◽  
Bao Dong Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
High Temperature ◽  
Solid State ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Long Period ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Gd2O3 (10mol%) doped SrHfO3 (Sr (Hf0.9Gd0.1)O2.95) was synthesized by solid state reaction method. The phase stability of the synthesized Sr (Hf0.9Gd0.1)O2.95 powder at high temperature of 1450 oC for a long period and in a temperature range of RT-1400 oC was characterized by XRD and DSC, respectively. The thermal expansion coefficients (TECs) of bulk Sr (Hf0.9Gd0.1)O2.95 were recorded by a high-temperature dilatometer, indicating that the phase transitions of SrHfO3 are suppressed remarkably by doping Gd2O3. The thermal conductivity of bulk Sr (Hf0.9Gd0.1)O2.95 at 1000 oC is ~1.95 W/m·K, which is ~11% lower than that of bulk 8YSZ.

scholarly journals High-pressure synthesis and thermal expansivity investigation of carbonate solid solutions Mg1-xMnxCO3

2020 ◽  
Vol 48 (4) ◽  
pp. 367-380
Author(s):  
RUI LI ◽  
WEN LIANG ◽  
HANQI HE ◽  
YONG MENG ◽  
HONGFENG TANG
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Solid Solutions ◽  
Thermal Expansivity ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
High Temperature Xrd ◽  
Pressure Synthesis ◽  
Expansion Coefficients ◽  
Cubic Function

Using synthesized MgCO3 and reagent-grade MnCO3 as starting materials, a series of Mg1-xMnxCO3 carbonate solid solutions were synthesized by a simple solid reaction under high-temperature-pressure conditions of 3 GPa and 800°C for 4 h. The phase compositions of as-synthesized Mg1-xMnxCO3 samples were investigated by powder X-ray diffraction (XRD); no impurities were observed. The lattice parameters were refined and showed a linear relationship as a function of the Mn2+ content, which is expected to be in accordance with the ideal solution model. Based on this, high- temperature XRD measurements were carried out to further study the thermal expansivity of Mg1-xMnxCO3. The axis thermal expansion coefficients (αa and αc) and the volumetric thermal expansion coefficient αV for Mg1-xMnxCO3 were quantified as αa =7.41×10-6/°C, αc=2.37×10-5/°C and αV=3.86×10-5/°C for x=0.0; αa =6.67×10-6/°C, αc=2.31×10-5/°C and αV=3.67×10-5/°C for x=0.1; αa=6.61×10-6/°C, αc=2.35×10-5/°C and αV=3.59×10-5/°C for x=0.3; αa=5.91×10-6/°C, αc=2.40×10-5/°C and αV=3.58×10-5/°C for x=0.5; αa=5.47×10-6/°C, αc=2.53×10-5/°C and αV=3.61×10-5/°C for x=0.7; αa=4.76×10-6/°C, αc=2.55×10-5/°C and αV=3.52×10-5/°C for x=0.9; αa=4.18×10-6/°C, αc=2.50×10-5/°C and αV=3.35×10-5/°C for x=0.3. The thermal expansion coefficients (αa, αc and αV) can be fitted with a symmetric cubic function of the Mn2+ content as αa=7.34×10-6 -7.06×10-6x+1.21×10-5x2-8.19×10-6x3; αc=2.37×10-6-7.94×10-6x+2.57×10-5x2-1.64×105x3; αV=3.85×10-5-2.08×10-5x+4.59×10-5x2-3.01×10-5x3.

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