Structures and electromagnetic properties of the A-site disordered Ba-based manganites; R0.5Ba0.5MnO3 (R = Y and rare earth elements)

2004 ◽  
Vol 383 (1-2) ◽  
pp. 135-139 ◽  
Author(s):  
Tomohiko Nakajima ◽  
Yutaka Ueda
Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 129
Author(s):  
Zhen Teng ◽  
Yongqiang Tan ◽  
Haibin Zhang

A novel class of high-entropy pyrochlore ceramics (HEPCs) with multiple heavy and light rare-earth elements at the A site were successfully synthesized via solid-state reaction. Both the XRD patterns and Raman spectroscopy demonstrated the single pyrochlore structure feature of seven kinds of HEPCs. Electron microscopic images revealed the typical morphology and the homogeneous distribution of all rare-earth elements. It can be concluded that the significance of configuration entropy in the HEPC system has promoted the tervalent lanthanide nuclides to form a single pyrochlore structure. This work is expected to provide guidance for the further design of high-entropy pyrochlore/fluorite ceramics.


2018 ◽  
Vol 106 (6) ◽  
pp. 515-524 ◽  
Author(s):  
Rahat Khan ◽  
Md. Shohel Parvez ◽  
Umma Tamim ◽  
Sopan Das ◽  
Mohammad Amirul Islam ◽  
...  

Abstract To study the compositional trends of rare earth elements (REEs: La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Lu), Th and U in soil samples collected from a site for a potential coal based power plant as well as to conduct a preliminary assessment of environmental impact of the proposed power plant in terms of REEs, Th and U, we have analyzed nine soil samples by instrumental neutron activation analysis. Evaluation of data quality by repeated analysis of IAEA-Soil-7 and IAEA-SL-1 ensures a proper data base-line for the REEs, Th and U abundances of the sampling site. Chondrite-normalized abundance patterns demonstrate the heavy REEs–light rare earth elements and Th–U fractionations in our sample suite along with significant negative Eu anomaly. Thorium/U ratio in our study area ranges from 4.55 to 6.07 which is higher than that of upper continental crust. Preliminary assessment of environmental impact of the proposed power plant is evaluated by taking NIST-SRM-1633b (coal-fly-ash) as contaminant as coal-fly-ash will be the major byproduct of the power plant. Previous literature studies and our prevailing data invoke that proposed power plant will have no severe impact on soil originated biota and on human health in terms of REEs, Th and U abundances. However, the long term effect of excessive REEs, Th and U as well as the other elemental abundances originating from coal-fly-ash should also be taken into an account.


2002 ◽  
Vol 71 (12) ◽  
pp. 2843-2846 ◽  
Author(s):  
Tomohiko Nakajima ◽  
Hiroshi Kageyama ◽  
Hideki Yoshizawa ◽  
Yutaka Ueda

2019 ◽  
Vol 88 (10) ◽  
pp. 104706
Author(s):  
Norihisa Tanikawa ◽  
Hiroki Takada ◽  
Miyuki Hori ◽  
Masaya Uchida ◽  
Daisuke Akahoshi ◽  
...  

Author(s):  
V. V. Cherepov ◽  
A. N. Kropachev ◽  
O. N. Budin

The paper presents an overview of methods for obtaining perovskite structure titanates and doping them with rare-earth elements. The results of scientific research conducted by authors from different countries related to the study of the effect of doping perovskite structure titanates with rare-earth elements on their electromagnetic properties are discussed. The paper also comprises information on the use of perovskite structure titanates in various industries. As exemplified by barium titanate (BaTiO3), a comparative analysis of some morphological properties (particle size, structure) and electromagnetic characteristics (dielectric constant, Curie temperature, modulus of longitudinal oscillations (d33)) of powders obtained (and doped) by different methods is carried out. Techniques for various BaTiO3 preparation methods such as solvothermic, hydrothermal, sol-gel, chemical deposition, and solid-phase sintering are described. The paper provides the results of studies on the effect of changes in process parameters (temperature, pH, composition of the initial mixture of materials and concentration of reagents) on the phase, morphology and BaTiO3particle formation rate in hydrothermal synthesis (using BaCl2, TiCl4and NaOH as initial materials). In addition, experiments were conducted to study the effect of microwave radiation power in ВаСОз and ТЮ2 solid-phase sintering on the dielectric and ferroelectric properties of ВаТЮз ceramics. The analysis of methods for obtaining BaTiO3 and doping it with rare-earth elements found that at present the hydrothermal method and the method of solid-phase sintering (including with microwave radiation) can be regarded as advanced technologies for obtaining perovskite structure materials with predetermined properties.


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