Search query: Sm2Zr2O7

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abstract: Abstract The work showed a novel amperometric NH3 sensor based on SrM2O4 (M Sm, La, Gd, Y) with CaFe2O4 type structural sensing electrode. A distinct B site strategy was developed to prepare a series of semiconductor oxides SrM2O4 (M Sm, La, Gd, Y) to establish the relationships between the band structure and sensing properties of the optimized sensing electrode. The structural analyses carried out by X ray diffraction, scanning electron microscopy and Mott Schottky curves confirm that four metal oxides SrM2O4 (M Sm, La, Gd, Y) are all n type semiconductors, and a preferential sensing mechanism of NH3 sensor was proposed by the combination of mass spectrometry track. The electrochemical results indicate that NH3 sensing properties are closely related to the band structure of the metal semiconductor oxides. Compared with the conduction band obtained from Mott Schottky curves, it is the most negative for SrSm2O4 sensing electrode, suggesting that electrons are easier to overcome energy barriers over SrSm2O4. Consequently, the NH3 sensor with SrSm2O4 sensing electrode exhibits high sensitivity, quicker response/recovery speed, excellent selectivity and stability compared to other three sensors, exhibiting a great application prospects for SrSm2O4 sensing electrode used in the automotive equipments.
author_names: Jing Cong

Pei Duan

Fulan Zhong

Yu Jiao Luo

Yong-Chao Zheng

Guo-hui Cai

Yi-hong Xiao

Lilong Jiang
title: Gas sensing properties of amperometric NH3 sensors based on Sm2Zr2O7 solid electrolyte and SrM2O4 (M Sm, La, Gd, Y) sensing electrodes
year: 2020

abstract: Abstract The accelerated decomposition of an Sm2Zr2O7+8YSZ system in the form of air plasma spraying (APS) thermal barrier coatings of composites, double ceramic layer (DCL) and functional graded system (FGS) types under hot corrosion conditions were analyzed. Hot corrosion tests were performed using liquid sodium sulfate salt deposits and then X Ray diffraction (XRD) scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) were performed to identify the reaction products. The obtained data indicated that negligible amounts of sulfates or oxysulfates were formed, but significant decomposition of pyrochlore Sm2Zr2O7 to the fluorite phase was detected. These phenomena were also observed in a much higher temperature range during pure oxidation tests, but the lowest decomposition temperature (920 degC) was observed in the sodium sulfate assisted process. The described observations were confirmed during similar tests and realized using model powder mixtures. Microstructural analysis of thermal barrier coatings (TBC) cross sections revealed a complex decomposition process that was localized to areas near the Sm2Zr2O7 splats. The decomposition of the observed pyrochlore phase was mainly related to interactions between Sm2Zr2O7 and 8YSZ in accordance with the fluxing mechanism typical for the hot corrosion process of Ni based superalloys. Additionally, the effect of eutectic Na Sm O was determined.
author_names: Grzegorz Moskal

Sebastian Jucha

Marta Mikuskiewicz

Damian Migas

Anna Jasik
title: Atypical decomposition processes of Sm2Zr2O7 8YSZ dual phase TBCs during hot corrosion
year: 2020

abstract: Abstract Rare earth zirconates are considered as one class of the ideal candidate high temperature structural materials. In this paper, a series of Y3Al5O12 doped Sm2Zr2O7 (1 x)Sm2Zr2O7 xY3Al5O12, x 0, 0.05, 0.1, 0.2, 0.3, mol. composite ceramics were prepared at 1600 degC. The influence of Y3Al5O12 doping on microstructure, mechanical properties and thermal conductivity of Y3Al5O12 doped Sm2Zr2O7 were investigated. The results showed that the composite ceramics were mainly composed of Sm2Zr2O7, Y3Al5O12 and a small amount of SmAlO3 phases. The grain size of Sm2Zr2O7 in composite ceramics obviously decreased with the increase of Y3Al5O12 doping concentration. The fracture toughness of 0.8Sm2Zr2O7 0.2Y3Al5O12 composite ceramic was (2.50 0.14) MPa*m1/2, which was the highest among the investigated ceramic materials, and was about twice as high as that of pure Sm2Zr2O7 ceramic. The thermal conductivity of composite ceramics increased with the rise of Y3Al5O12 doping concentration at above 600 degC. 0.8Sm2Zr2O7 0.2Y3Al5O12 composite ceramic had almost no change in grain size and phase composition before and after sintering at 1400 degC for 100 h, suggesting that 0.8Sm2Zr2O7 0.2Y3Al5O12 composite ceramic had good sintering resistance at 1400 degC.
author_names: Shuqin Wu

Zhao Xue

Xiaojuan Ji

Eung-sun Byon

Shihong Zhang
title: Influence of Y3Al5O12 doping on mechanical properties and thermal conductivity of Sm2Zr2O7 Y3Al5O12 composite ceramics
year: 2020

abstract: Abstract The determination of thermal resistance related to splat boundaries in composite TBC (thermal barrier coating) systems and expressed as splat to splat heat transfer coefficient was analyzed. Sm2Zr2O7 and conventional 8YSZ powders were used for coatings deposition by atmospheric plasma spraying. Two types of internal morphology were deposited: monolayered type (Sm2Zr2O7, 8YSZ) and composite TBCs (Sm2Zr2O7 8YSZ with weight ratios of 75/25, 50/50 and 25/75) The primary investigation was related to microstructural characterization of ceramic layers (pores and cracks architecture description) thermal diffusivity and conductivity characterization by laser flash analysis and theoretical models. The thermal conductivity was initially calculated on the basis of thermal diffusivity, heat capacity and density measurement as a function of temperature. Those values were corrected due to the presence of pores (microstructural analysis) and effective vales of thermal conductivity were calculated. These values were used as the basis for additional calculations based on the Hasselman Johnson model of thermal conductivity for composite materials. Based on quantitative data from image analysis and porosity corrected thermal conductivity for monolayered and composite TBC systems, the thermal boundary conductivity (splat to splat heat transfer coefficient) was calculated as a function of temperature for Sm2Zr2O7 8YSZ composite systems.
author_names: Grzegorz Moskal

Anna Jasik

Marta Mikuskiewicz

Sebastian Jucha
title: Thermal resistance determination of Sm2Zr2O7 8YSZ composite type of TBC
year: 2020

abstract: Abstract The present work demonstrated the heterovalent ions incorporated pyrochlore Sm2Zr2O7 ceramic with high NO2 sensitivity through molecular insights into the bond of [BO6] unit and the sensing mechanism. An effective B site strategy was developed to prepare a series of defective Sm2Zr1.95X0.05O7+d (SZX, X= Mn2+ Ga3+ Sn4+ Nb5+ W6+ ceramics to create oxygen vacancies or interstitial oxygen induced which enhances the NO2 sensing performances. The structural analyses carried out by XRD, SEM, XPS, Raman and the NO2 adsorption on a cold surface of the sensor clarified the potential sensing mechanism. The electrochemical results clearly indicate that NO2 sensing properties are closely related to the valence of doped cations. The sensor of Sm2Zr2O7 with Nb5+ arranged at B sites indicates high sensitivity, quick response/recovery speed, excellent selectivity and stability compared with others, exhibiting great application prospects for the automotive equipment.
author_names: Yong-Chao Zheng

Pei Duan

Zhiyu Li

Guo-hui Cai

Fulan Zhong

Yi-hong Xiao
title: Heterovalent ions incorporated pyrochlore Sm2Zr2O7 ceramic for enhanced NO2 sensing
year: 2020

abstract: A series of Sm2Zr2O7 SiC composites doped with different volume fraction and particle size of SiC were prepared by hot pressing at 1300 degC. The phase of the composites prepared is P Sm2Zr2O7 and C SiC, and no other diffraction peaks exist, which indicates that Sm2Zr2O7 has great chemical compatibility with SiC. The thermal conductivity and phonon thermal conductivity of the Sm2Zr2O7 SiC composites are measured by the laser pulse method. The photon thermal conductivity of the composites is obtained by subtracting the phonon thermal conductivity from the total thermal conductivity. The results show that the photon thermal conductivity of Sm2Zr2O7 SiC composites is lower than that of pure Sm2Zr2O7. The photon thermal conductivity of Sm2Zr2O7 SiC composites decreases first and then increases with the increase of SiC particle size. Sm2Zr2O7 (5 vol% 10 um)SiC composite has the lowest photon thermal conductivity.
author_names: Zhuang Ma

Qi Zhang

Ling Liu

Yanbo Liu
title: Preparation and heat insulating capacity of Sm2Zr2O7 SiC composites based on photon thermal transport
venue: Journal of Advanced Ceramics
year: 2020

abstract: Sm2Zr2O7 (SZO) and Y2O3 partially stabilized ZrO2 (YSZ) composite powders were prepared by agglomeration granulation after ball milling. The size, morphology and phase structure of granulated aggregates were characterized. The SZO/YSZ composite coating was prepared by atmospheric plasma. The effects of heat treatment and plasma spraying on the phase structure of composite powders and its phase stability were studied. The microstructures and phase structures of YSZ/SZO composite powders and coatings were studied by scanning electron microscopy (SEM) and X ray diffraction (XRD) The stability of YSZ/SZO composite powders was investigated by differential scanning calorimetry (DSC) The results indicate that spherical agglomerated SZO and YSZ composite powders are relatively smooth and the structure is compact with a mixed phase structure at room temperature. No phase transformation occuring in the range of room temperature to 1200 degC reveals that the YSZ/SZO powders have suitability in the service temperature. The YSZ/SZO coating has a typical layered structure, and the composition and structure distribution of the coating are relatively uniform. Compared with the single SZO coating, the bonding strength of the YSZ/SZO coating is significantly improved. During plasma spraying, the stability of the powder decreases due to ions diffuse. The ordered phase in SZO transformed to disordered phase and the composite coating only presents a single fluorite structure.
title: Preparation and Properties of YSZ/Sm2Zr2O7 Composite Powders
year: 2020

abstract: Cytotoxicity is a crucial problem in biomedical implant applications which could be overcome by enhancing the corrosion resistance through surface coating technique.Studies on biological properties and bio corrosion and a supported study on microstructureof plasma sprayed Gd2Zr2O7 hydroxyapatite and Sm2Zr2O7 hydroxyapatite coatings on type titanium (Ti 6Al 4V) of grade 5 samples are carried out in this research work. The samples are tested for Bio corrosion behaviour in Artificial Blood Plasma (ABP) as medium to study the corrosion behaviour of ceramic coated titanium (Ti 6Al 4V) The results indicated that the thick and non porous oxide passive layers formed over the ceramic coated samples augmented the corrosion resistance than bare titanium (Ti 6Al 4V) substrates. The tribology test was performed for the coated samples.
author_names: Gobi Saravanan Kaliaraj

Anderson Arul Gnana Dhas

Karthik Alagarsamy

A M Kamalan Kirubaharan

Shaik Sarwath Hussain

Kezia Sasitharan
title: Mechanical and corrosion behaviour of Gd2Zr2O7 HAp and Sm2Zr2O7 HAp composite coated Ti 6Al 4V alloy for biomedical applications
year: 2020

abstract: Abstract It is shown that Sm2Zr2O7 possessing significant coexistence of covalent and ionic features demonstrates very promising stiffness features. The corresponding analysis has been performed using density functional theory (DFT) From the chemical bonding nature, it is observed that the crystal shows significant coexistence of covalent, ionic and semiconducting features in UV VIS spectral range. This crystal is brittle, exhibits higher stiffness. The elastic anisotropy of the crystal is discussed and visualized. It is shown a possibility to use them as highly optical anisotropic materials which are promising for different optoelectronic and photoelastic devices. The origin of the anisotropy and possible changes of the content to improve the optoelectronics and mechanical features are discussed. The performed studies have been based on the full potential linearized augmented plane wave (FP LAPW) method with generalized gradient plus Hubbard parameter (GGA U) method. It was discovered a direct type of band energy gap situated at G point of Brillouin zone of Sm2Zr2O7 for spin up and down polarizations. The detailed analysis of the origin of optical functions like absorption coefficient, dielectric constant, energy loss function; refractive index, reflectivity, extinction coefficient and optical conductivity are explored. The possible ways of change of optical functions are in desirable directions.
author_names: Muhammad Irfan

Sikander Azam

Madiha Makhdoom

Banat Gul

Iwan V Kityk

Shabbir Muhammad

Saifeldin M Siddeeg
title: DFT simulations of optoelectronic and elastic features of cubic samarium zirconate (Sm2Zr2O7)
year: 2019

abstract: Abstract Fluorite and pyrochlore type compounds (Pr2Zr2O7, Sm2Zr2O7 and PrSmZr2O7) powders were prepared by glycine nitrate process (GNP) starting from metal (Sm, Pr) nitrate, zirconium chloride and glycine as a fuel. The GNP process at room temperature initially yielded amorphous powders, which crystallized after subsequent calcination to form crystalline ceramics. The formation of well crystalline compounds took place at temperature as low as 950degC. The phase evolution with thermal treatment as well as powder properties such as crystallite size, lattice strain and lattice parameter were studied by X ray powder diffraction (XRPD) at room temperature. High density ceramic pellets free of any additives were obtained after compaction of the obtained powders and subsequent sintering at 1600degC for 4 h in air. Sintering behaviour of the synthesized pyrochlore phases was followed with a scanning electron microscope. Hardness of the sintered samples was found to be in range of 8.9 to 9.9 GPa depending of chemical composition.
author_names: Branko Matovic

Jelena Maletaskic

Katsumi Yoshida

Toyohiko Yano
title: Synthesis, characterization and sintering of fluorite and pyrochlore type compounds: Pr2Zr2O7, Sm2Zr2O7 and PrSmZr2O7
year: 2019