scholarly journals Influence of La Substitute on Sintering Behavior, Electronic Properties and Thermal Expansion of Sr1-1.5xLaxTiO3

2009 ◽  
Vol 56 (2) ◽  
pp. 65-70 ◽  
Author(s):  
Hiroshi Tsukuda ◽  
Shigeru Okuma ◽  
Kazuo Tomida
Keyword(s):  
Thermal Expansion ◽  
Electronic Properties ◽  
Sintering Behavior

scholarly journals Sintering Behavior, Thermal Expansion, and Environmental Impacts Accompanying Materials of the Al2O3/ZrO2 System Fabricated via Slip Casting

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3365
Author(s):  
Justyna Zygmuntowicz ◽  
Magdalena Gizowska ◽  
Justyna Tomaszewska ◽  
Paulina Piotrkiewicz ◽  
Radosław Żurowski ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Life Cycle ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Slip Casting ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Environmental Loads ◽  
Practical Applications ◽  
Technical Ceramics

This work focuses on research on obtaining and characterizing Al2O3/ZrO2 materials formed via slip casting method. The main emphasis in the research was placed on environmental aspects and those related to the practical use of ceramic materials. The goal was to analyze the environmental loads associated with the manufacturing of Al2O3/ZrO2 composites, as well as to determine the coefficient of thermal expansion of the obtained materials, classified as technical ceramics. This parameter is crucial in terms of their practical applications in high-temperature working conditions, e.g., as parts of industrial machines. The study reports on the four series of Al2O3/ZrO2 materials differing in the volume content of ZrO2. The sintering process was preceded by thermogravimetric measurements. The fabricated and sintered materials were characterized by dilatometric study, scanning electron microscopy, X-ray diffraction, and stereological analysis. Further, life cycle assessment was supplied. Based on dilatometric tests, it was observed that Al2O3/ZrO2 composites show a higher coefficient of thermal expansion than that resulting from the content of individual phases. The results of the life cycle analysis showed that the environmental loads (carbon footprint) resulting from the acquisition and processing of raw materials necessary for the production of sinters from Al2O3 and ZrO2 are comparable to those associated with the production of plastic products such as polypropylene or polyvinyl chloride.

scholarly journals Large Thermal Expansion LTCC System for Cofiring with Integrated Functional Ceramics Layers

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 564
Author(s):  
Beate Capraro ◽  
Manuel Heidenreich ◽  
Jörg Töpfer
Keyword(s):  
Thermal Expansion ◽  
Ceramic Composite ◽  
Sintering Behavior ◽  
Heating Rates ◽  
Partial Crystallization ◽  
Tan Δ ◽  
Low K ◽  
Glass Ceramic Composite ◽  
Functional Ceramics ◽  
Functional Ceramic

We have studied the sintering behavior of CT708 LTCC tapes with large CTE of 10.6 ppm/K. This low-k dielectric LTCC material is a quartz-based glass ceramic composite system with partial crystallization of celsian upon firing. The shrinkage, densification and dielectric properties were examined using different heating rates and a sintering temperature of 900 °C. The maximum shrinkage rate is at 836 °C (for a heating rate of 2 K/min) with a sintering density of 95% and a permittivity of ε’ = 5.9 and tan δ = 0.0004 (at 1 GHz). Due to their similar shrinkage and thermal expansion properties, CT708 tapes may be cofired with functional ceramic layers. As an example, we report on cofiring of a multilayer laminate of CT708 and a Sc-substituted hexagonal ferrite for applications as integrated microwave circulator components. This demonstrates the feasibility of cofiring of functional ceramic tapes and tailored LTCC tapes and documents the potential for the realization of complex LTCC multilayer architectures.

Sintering Behavior of Plasma-Sprayed Sm2Zr2O7 Coating

2010 ◽  
Author(s):  
Jianhua Yu ◽  
Huayu Zhao ◽  
Shunyan Tao ◽  
Xiaming Zhou ◽  
Chuanxian Ding
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Thermal Barrier Coating ◽  
Expansion Coefficient ◽  
Sintering Behavior ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Plasma Sprayed

Plasma-sprayed thermal barrier coating (TBC) systems are widely used in gas turbine blades to increase turbine entry temperature (TET) and better efficiency. Yttria stabilized zirconia (YSZ) has been the conventional thermal barrier coating material because of its low thermal conductivity, relative high thermal expansion coefficient and good corrosion resistance. However the YSZ coatings can hardly fulfill the harsh requirements in future for higher reliability and the lower thermal conductivity at higher temperatures. Among the interesting TBC candidates, materials with pyrochlore structure show promising thermo-physical properties for use at temperatures exceeding 1200 °C. Sm2Zr2O7 bulk material does not only have high temperature stability, sintering resistance but also lower thermal conductivity and higher thermal expansion coefficient. The sintering characteristics of ceramic thermal barrier coatings under high temperature conditions are complex phenomena. In this paper, samarium zirconate (Sm2Zr2O7, SZ) powder and coatings were prepared by solid state reaction and atmosphere plasma spraying process, respectively. The microstructure development of coatings derived from sintering after heat-treated at 1200–1500 °C for 50 h have been investigated. The microstructure was examined by scanning electron microscopy (SEM) and the grain growth was analyzed in this paper as well.

First-Principles Investigations on Structural, Elastic, and Thermodynamic Properties of Ce-La Alloys Under High Pressure

2014 ◽  
Vol 69 (1-2) ◽  
pp. 52-60
Author(s):  
Li-Qin Zhang ◽  
Yan Cheng ◽  
Zhen-Wei Niu ◽  
Guang-Fu Ji
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Electronic Properties ◽  
Ground State ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Charge Densities

The structural stability, thermodynamic, elastic, and electronic properties of cerium (Ce)- lanthanum (La) alloys were investigated for different Ce/La ratios under pressure by first-principles calculations using on-the-fly (OTF) pseudopotential and general gradient approximation (GGA). The ground-state properties of lanthanum and cerium obtained by minimizing the total energy agree favourably with other work.We derived the elastic constants, bulk modulus, and shear modulus of the La-Ce alloys for different Ce/La ratios. Using the quasi-harmonic Debye model, the thermodynamic properties of the La-Ce alloys including the thermal expansion coefficient α and heat capacity Cv are successfully obtained in the temperature range from 0 K to 1000 K. Furthermore, the electronic properties such as density of states and charge densities were also studied.

Thermal expansion and sintering studies of Nd2-xCexCuO4±δ (0 ≤ x ≤ 0.20)

2006 ◽  
Vol 21 (5) ◽  
pp. 1248-1254 ◽  
Author(s):  
M. Soorie ◽  
S.J. Skinner
Keyword(s):  
Thermal Expansion ◽  
Sintering Temperature ◽  
Oxygen Stoichiometry ◽  
Sintering Behavior ◽  
Lattice Expansion ◽  
Tetragonal Unit Cell ◽  
Secondary Stage ◽  
Increasing Temperature ◽  
Crystallographic Axes ◽  
Ce Content

Sintering behavior and thermal expansion properties of the solid solution series Nd2-xCexCuO4±δ (0 ≤ x ≤ 0.20) have been investigated over the temperature range of 298 to 1100 K. Significant anisotropy in the lattice expansion coefficient in the a/b and c crystallographic axes was noted on increasing Ce content, which is consistent with the tetragonal unit cell. The lattice expansion in the c axis was found to decrease on increasing temperature for compositions up to x = 0.10, which is likely to be from variations in the oxygen stoichiometry. A variation in the sintering behavior was also noted on varying Ce content, with the onset of sintering temperature reaching a maximum at x = 0.10. A secondary sintering stage was noted for compositions with x > 0.10. Associated with the introduction of a secondary stage on sintering is an overall increase in the temperature at which the sintering is at a maximum.

Effect of Nano-Nd2O3 on Sintering and Crystallization of Fused Quartz Ceramic Materials

2012 ◽  
Vol 602-604 ◽  
pp. 499-502
Author(s):  
Ying Lei Gu ◽  
Jing Long Bu ◽  
Li Xue Yu ◽  
Jun Xing Chen ◽  
Zhi Fa Wang
Keyword(s):  
Thermal Expansion ◽  
Bending Strength ◽  
Ceramic Materials ◽  
Quartz Ceramic ◽  
Apparent Porosity ◽  
Raw Material ◽  
Sintering Behavior ◽  
Quartz Powder ◽  
Fused Quartz

Fused quartz powder (d50=19μm) was used as raw material, and nano-Nd2O3 was used as additive with dosages of 1% (in mass, similarly hereinafter), 2% and 3%. The effects of nano-Nd2O3 on crystallization and sintering behavior of the materials at various temperatures (1300 °C/1h, 1350 °C /1h and 1400°C /1h) were studied by measurements of apparent porosity, bending strength and thermal expansion ratios (RT~1200°C), and analyses of XRD and SEM. The results of XRD and thermal expansion ratios analysis showed that 3% nano-Nd2O3 additive had excellent effect on inhibiting crystallization of the samples sintered at 1350 °C and 1400°C. The results showed that the samples sintered at various temperatures with 3% nano-Nd2O3 had the lowest apparent porosity and more compact microstructure. This indicated that 3% nano-Nd2O3 had better effect on facilitating sintering of fused quartz materials.

scholarly journals A computational study of the electronic properties, ionic conduction, and thermal expansion of Sm1−xAxCoO3 and Sm1−xAxCoO3−x/2 (A = Ba2+, Ca2+, Sr2+, and x = 0.25, 0.5) as intermediate temperature SOFC cathodes

2017 ◽  
Vol 19 (21) ◽  
pp. 13960-13969 ◽  
Author(s):  
Emilia Olsson ◽  
Xavier Aparicio-Anglès ◽  
Nora H. de Leeuw
Keyword(s):  
Thermal Expansion ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Electronic Properties ◽  
Ionic Conduction ◽  
Computational Study ◽  
Ionic Conductivities ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Substitutional Doping

Substitutional doping of Ca2+, Sr2+, and Ba2+ on the Sm-site in SmCoO3 is reported to improve both electronic and ionic conductivities for applications as solid oxide fuel cell (SOFC) cathodes.

scholarly journals Sintering behavior and thermal expansion of zirconia–titanium composites

2017 ◽  
Vol 133 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Paula Łada ◽  
Aleksandra Miazga ◽  
Katarzyna Konopka ◽  
Mikołaj Szafran
Keyword(s):  
Thermal Expansion ◽  
Sintering Behavior

Reduced Thermal Conductivity by Low-Frequency Optic Phonons that Give Rise to Negative Thermal Expansion: Opportunities for Thermoelectrics?

2007 ◽  
Vol 1044 ◽  
Author(s):  
Mary Anne White ◽  
Catherine A. Whitman
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Electronic Properties ◽  
Thermoelectric Materials ◽  
Negative Thermal Expansion ◽  
Low Frequency ◽  
Acoustic Phonons ◽  
Low Thermal Conductivity ◽  
Efficient Coupling

AbstractWe have recently found that the negative thermal expansion (NTE) materials, ZrW2O8 and HfMo2O8, show exceptionally low thermal conductivity. We surmise that the mechanism is the efficient coupling of the low-frequency optic phonons that give rise to negative thermal expansion with the heat-carrying acoustic phonons. Although neither ZrW2O8 nor HfMo2O8 has suitable electronic properties for thermoelectric applications, perhaps the principle of reduced thermal conductivity by low-frequency optic phonons in NTE materials can be used to develop more efficient thermoelectric materials.

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