scholarly journals Physicochemical Properties of Potential Cathode La1-xBaxMn1-yCryO3 and Anode Sr2NiMoO6 Materials for Solid-Oxide Fuel Cells

2012 ◽  
Vol 14 (2) ◽  
pp. 139 ◽  
Author(s):  
E.A. Filonova ◽  
A.S. Dmitriev
Keyword(s):  
State Diagram ◽  
Double Perovskite ◽  
Oxide System ◽  
Partial Substitution ◽  
Cubic Phase ◽  
Structure Transition ◽  
Thermal Expansion Coefficients ◽  
Thermal Compatibility ◽  
Expansion Coefficients ◽  
First Time

<p>The homogeneity area boundaries of La<sub>1-x</sub>Ba<sub>x</sub>Mn<sub>1-y</sub>Cr<sub>y</sub>O<sub>3</sub> solid solutions possessing orthorhombic and rhombohedral structures were established. A state diagram at 1373 K in air in the quaternary oxide system LaMnO<sub>3</sub>-BaMnO<sub>3</sub>-BaCrO<sub>4</sub>-LaCrO<sub>3</sub> was drawn for the first time. Partial substitution of Mn with Cr in La<sub>1-x</sub>Ba<sub>x</sub>MnO<sub>3</sub> stored the thermal compatibility of the cathode with the any traditionally used electrolyte but reduced the electric conductivity of the potential cathode. Based on the linear lengthening measurements of La<sub>1-x</sub>Ba<sub>x</sub>Mn<sub>1-y</sub>CryO<sub>3</sub> and Sr<sub>2</sub>NiMoO<sub>6</sub> samples the values of the thermal expansion coefficients were calculated. It was established that the temperature of the structure transition from a tetragonal to a cubic phase in Sr<sub>2</sub>NiMoO<sub>6</sub> occurred at 508 K. It was stated that double perovskite Sr<sub>2</sub>NiMoO<sub>6</sub> in air did not react with (La<sub>0.9</sub>Sr<sub>0.1</sub>)<sub>0.98</sub>Ga<sub>0.8</sub>Mg<sub>0.2</sub>O<sub>3</sub> up to 1073 K.</p>

Synthesis, structure and properties of LnBa(Co,Me)2O5+δ (Ln = Nd, Sm, Ho and Y; Me = Fe, Ni, Cu) as potential cathodes for SOFCs

2012 ◽  
Vol 1384 ◽  
Author(s):  
Vladimir A. Cherepanov ◽  
Ludmila Ya. Gavrilova ◽  
Tatyana V. Aksenova ◽  
Anastasiya S. Urusova ◽  
Nadezhda E. Volkova
Keyword(s):  
Oxygen Content ◽  
Solid Electrolytes ◽  
Double Perovskite ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Earth Cation ◽  
Expansion Coefficients ◽  
Cation Size

ABSTRACTLayered LnBa(Co,Me)2O5+δ (Ln = Nd, Sm, Ho and Y; Me = Fe, Ni, Cu) with double perovskite structure were synthesized by the solid-state reaction and glycerin-nitrate technique and characterized by X-ray diffraction, thermogravimetric analysis, iodometric titration and dilatometry. Homogeneity ranges for the solid solutions were determined. The oxygen content in LnBa(Co,Me)2O5+δ decreases with decreasing rare-earth cation size. Partial substitution of cobalt by iron increases oxygen content while introduction of copper decrease it. The average thermal expansion coefficients were calculated. Chemical compatibility of studied perovskites with Ce0.8Sm0.2O2 and Zr0.85Y0.15O2 solid electrolytes has been studied.

Strongly coupled thermal and chemical expansion in the perovskite oxide system Sr(Ti,Fe)O3−α

2015 ◽  
Vol 3 (7) ◽  
pp. 3602-3611 ◽  
Author(s):  
Nicola H. Perry ◽  
Jae Jin Kim ◽  
Sean R. Bishop ◽  
Harry L. Tuller
Keyword(s):  
Energy Conversion ◽  
Oxide System ◽  
Perovskite Oxide ◽  
Oxygen Stoichiometry ◽  
Temperature Dependent ◽  
Chemical Expansion ◽  
Strongly Coupled ◽  
Expansion Coefficients ◽  
Energy Conversion Devices ◽  
First Time

To evaluate stability in energy conversion devices, thermal and chemical expansion coefficients (CTE, CCE) of Sr(Ti,Fe)O3−α were measured and deconvoluted for the first time, revealing an oxygen stoichiometry-dependent CTE and temperature-dependent CCE.

scholarly journals Thermal expansion in isomorphic Me5Si3(Me=transition metal) compounds

2014 ◽  
Vol 70 (a1) ◽  
pp. C941-C941
Author(s):  
Paulo Suzuki ◽  
Geovani Rodrigues ◽  
Carlos Nunes ◽  
Gilberto Coelho
Keyword(s):  
Thermal Expansion ◽  
Transition Metal ◽  
Hexagonal Structure ◽  
Nuclear Industry ◽  
Partial Substitution ◽  
Tetragonal Symmetry ◽  
Space Group ◽  
Metallic Atom ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Transition metal silicides have been investigated due to the applications in several fields, such as: structural materials, electronic devices, nuclear industry. The physical properties including mechanic, electric, magnetic, thermal, optical, etc. of these compounds are strongly dependent of the metallic atoms and their atomic bonds. The family of silicon-based compounds of Me5Si3stoichiometry, known as Nowotny phases, where Me is a IV, V or IV transition metal element crystallize in three different structures: 1) Ti5Si3, Zr5Si3and Hf5Si3compounds crystallize in a hexagonal structure obeying P6/mcm symmetry and (Me: 4d and 6g, Si: 6g) Wyckoff positions; 2) Compounds such as V5Si3, Cr5Si3, Mo5Si3, W5Si3, βNb5Si3and βTa5Si3crystallize in so-called T1structure with I4/mcm space group and (Me: 4b and 16k, Si: 4a and 8h) Wyckoff positions and 3) Compounds such as αNb5Si3and αTa5Si3crystallize also in a tetragonal structure, called T2, in same I4/mcm space group but different Wyckoff positions (Me: 4c and 16l, Si: 4a and 8h). The measurement of the thermal expansion coefficients of these compounds by high temperature X-ray diffraction shown that they are strongly dependent of the metallic atoms. Since these compounds crystallize in hexagonal or tetragonal symmetry, the thermal expansion is anistropic. The anisotropy of the thermal expansion in these materials have been controlled by the following ways: 1) by partial substitution of the metallic atom by another metallic atom to promote the formation of solid solutions, or 2) by formation of ternary compounds, by partial substitution of silicon by boron in the structures, for example. Since these compounds present high melting temperatures, they are prepared in polycristalline form by arc-melting process followed by heat-treatment at temperatures above 1400 K. The thermal expansion coefficients of Me5Si3compounds have been analyzed taking into account the crystal structure of these compounds.

Preparation and Characterization of Thermally Compatible Leucite-Reinforced Dental Ceramics

2011 ◽  
Vol 308-310 ◽  
pp. 311-314
Author(s):  
Jin Wen ◽  
Shu Zhen Sun
Keyword(s):  
Thermal Expansion ◽  
Dental Ceramics ◽  
Dental Porcelain ◽  
Thermal Expansion Coefficients ◽  
High Thermal Expansion ◽  
Coprecipitation Technique ◽  
Thermal Compatibility ◽  
The Common ◽  
Expansion Coefficients

The high average thermal expansion required for thermal compatibility of dental porcelain with their substrate alloy is supplied by the mineral leucite (KAlSi2O6). In the research, the high thermal expansion coefficients phase leucite was prepared by coprecipitation technique. Three materials with formulae of K2O∶Al2O3∶SiO2= 1∶1∶x ( x=1.4, 2.0, 4.0 ) were investigated for differences in phase, thermal expansion. Unstoichiometric composition where K2O and Al2O3were added properly is advantage to leucite obtained. Coprecipitation processing produced fine leucite powder that would sinter at 1300°C, this temperature is about 200°C lower than of melting method. The average thermal expansion coefficients of leucite is 22.7×10-6/°Cfrom room temperature to 620°C,which is higher than the common porcelain. Changing in the leucite content of dental porcelain would results from thermal expansion coefficients of porcelain variation, which could be responsible for changes in porcelain-metal thermal compatibility.

scholarly journals Термическое расширение и люминесцентные свойства триортогерманатов CaLa-=SUB=-2-x-=/SUB=-Eu-=SUB=-x-=/SUB=-Ge-=SUB=-3-=/SUB=-O-=SUB=-10-=/SUB=- (x=0.0-0.6)

2018 ◽  
Vol 60 (2) ◽  
pp. 363
Author(s):  
O.А. Липина ◽  
Л.Л. Сурат ◽  
Я.В. Бакланова ◽  
И.Ф. Бергер ◽  
А.П. Тютюнник ◽  
...  
Keyword(s):  
Linear Thermal Expansion ◽  
Excitation Wavelength ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
Strain Anisotropy ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
First Time ◽  
Luminescence Characteristics

AbstractSolid solutions CaLa_2- x Eu_ x Ge_3O_10 ( x = 0.0–0.6, Δ x = 0.1) have been synthesized for the first time. The compounds are isostructural to CaLa_2Ge_3O_10, they crystallize in the monoclinic system, space group P 2_1/ c , Z = 4. The low-temperature X-ray diffraction studies have revealed the strain anisotropy of germanate CaLa_2Ge_3O_10 crystal lattice in the temperature range 80–298 K, and the linear thermal expansion coefficients have been calculated. The optical properties of the activated phases have been studied, and the influence of the dopant concentration and the excitation wavelength on the luminescence characteristics of the synthesized compounds has been established.

scholarly journals Influence of Ag on Chemical and Thermal Compatibility of LSCF-SDCC for LT-SOFC

2015 ◽  
Vol 773-774 ◽  
pp. 445-449 ◽  
Author(s):  
Linda Agun ◽  
Muhamad Subri Abu Bakar ◽  
Sufizar Ahmad ◽  
Andanastuti Muchtar ◽  
Hamimah Abd Rahman
Keyword(s):  
Thermal Expansion ◽  
Composite Cathode ◽  
Performance Criteria ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Thermal Compatibility ◽  
Expansion Coefficients ◽  
Diffraction Patterns

In addition to the good electrochemical performance criteria in solid oxide fuel cell (SOFC) applications, cathode material must match thermal expansion with other SOFC components. Thus, effects of Ag on thermal mismatch, chemical reactions, and microstructure are investigated. Ag (1 wt% to 5 wt. %) was mixed with La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF6428) and Sm-doped ceria carbonate (SDCC) composite cathode powder. LSCF6428-SDCC-Ag samples were sintered at 600 °C for 2 h. The thermal expansion coefficients (TECs), which were determined using a dilatometer, indicated relatively less TEC mismatch between LSCF-SDCC-Ag cathodes composite and SDCC electrolyte. The average TEC value obtained from 20 °C to 600 °C implied that LSCF-SDCC-A5 (5 wt. % Ag) showed better thermal matching (13.18×10−6 K−1) with SDCC electrolyte (12.84×10−6 K−1) and achieved better compatibility. The X-ray diffraction patterns indicated that the LSCF6428-SDCC-Ag peak increased with the increase in the amount of Ag. Scanning electron microscopy analysis showed that Ag was capable of maintaining the porosity that is required for cathodes (20%–40%). Results showed that Ag exhibited desirable thermal and chemical compatibility with LSCF-SDCC. Thus, LSCF6428-SDCC-Ag can be used as a composite cathode for low-temperature SOFCs.

A Study on Metal-Ceramic Thermal Expansion Compatibility

2014 ◽  
Vol 216 ◽  
pp. 85-90
Author(s):  
Marian Miculescu ◽  
Mihai Branzei ◽  
Florin Miculescu ◽  
Daniela Meghea ◽  
Marin Bane
Keyword(s):  
Thermal Expansion ◽  
Bonding Strength ◽  
Linear Thermal Expansion ◽  
Metal Bonding ◽  
Thermal Expansion Coefficients ◽  
Metal Ceramic ◽  
Thermal Compatibility ◽  
Expansion Coefficients ◽  
The Difference ◽  
Dental Applications

Push rod method for determining linear thermal expansion using vertical differential dilatometer was used in the study of the thermal compatibility of metal-ceramic systems for dental applications. The purpose of this study consisted in evaluating the effectiveness of dental coating by determining the ceramic metal bonding strength of metal-ceramic couples (Ni-Cr and Co-Cr alloy coated with dental ceramic) and correlation with the difference of linear thermal expansion coefficients of metals and ceramics.

scholarly journals Re-examining the crystal structure behaviour of nitrogen and methane

IUCrJ ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 844-851 ◽  
Author(s):  
Helen E. Maynard-Casely ◽  
James R. Hester ◽  
Helen E. A. Brand
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Neutron Diffraction ◽  
Solid Phase ◽  
Phase Behaviour ◽  
New Horizons ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
First Time ◽  
Solid Temperature

In the light of NASA's New Horizons mission, the solid-phase behaviour of methane and nitrogen has been re-examined and the thermal expansion coefficients of both materials have been determined over their whole solid temperature range for the first time. Neutron diffraction results indicate that the symmetric Pa 3 space group is the best description for the α-nitrogen structure, rather than the long-accepted P213. Furthermore, it is also observed that β-nitrogen and methane phase I show changes in texture on warming, indicating grain growth.

The influence of the sapphire substrate on the temperature dependence of the GaN bandgap

1999 ◽  
Vol 572 ◽  
Author(s):  
Joachim Krüiger ◽  
Noad Shapiro ◽  
Sudhir Subramanya ◽  
Yihwan Kim ◽  
Henrik Siegle ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Temperature Dependence ◽  
Sapphire Substrate ◽  
Measured Temperature ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Small Influence ◽  
Expansion Coefficients ◽  
The Difference ◽  
First Time

ABSTRACTThis paper analyses the influence of the sapphire substrate on stress in GaN epilayers in the temperature range between 4K and 600K. Removal of the substrate by a laser assisted liftoff technique allows, for the first time, to distinguish between stress and other material specific temperature dependencies. In contrast to the prevailing assumption in the literature, that the difference in the thermal expansion coefficients is the main cause for stress it is found that the substrate has a rather small influence in the examined temperature range. The measured temperature dependence of stress is in contradiction to the published values for the thermal expansion coefficients for sapphire and GaN.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

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