Journal Home > Volume 7 , issue 1

In this research, Zr-doped Gd2Ti2O7 pyrochlores, with the composition of Gd2(Ti1-xZrx)2O7, were firstly synthesized by self-propagating high-temperature synthesis plus quick pressing (SHS/QP) using CuO as the oxidant and Ti as the reductant. To improve the radiation resistance of titanate–pyrochlore, up to 35 at% Zr was incorporated to substitute the Ti site of Gd2Ti2O7 pyrochlore (Gd2(Ti0.75Zr0.35)2O7). XRD and SEM microstructural characterizations showed the formation of a composite ceramic with the major pyrochlore phase and the minor Cu phase. The generated temperature of samples decreased from 1702 to 1011 ℃ with increasing Zr content. The effects of sintering temperature and pressure time on phase composition and microstructure were systematically studied. Besides, the influence of thermal transmission on the whole combustion process was also explored. The pyrochlore-based waste form possessed high bulk density of 6.25 g/cm3 and Vickers hardness of 10.81 GPa. The MCC-1 leaching test showed the normalized elemental leaching rates (42 d) of Cu, Gd, and Zr are 1.27×10-2, 1.33×10-3, and 8.44×10-7 g·m-2·d-1, respectively.


menu
Abstract
Full text
Outline
About this article

Self-propagating high-temperature synthesis of ZrO2 incorporated Gd2Ti2O7 pyrochlore

Show Author's information Le PENGa,bKuibao ZHANGa( )Zongsheng HEaDan YINaJiali XUEaChen XUbHaibin ZHANGc
State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China
Science and Technology on Surface Physics and Chemistry Laboratory, China Academy of Engineering Physics, Mianyang, Sichuan 621907, China
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China

Abstract

In this research, Zr-doped Gd2Ti2O7 pyrochlores, with the composition of Gd2(Ti1-xZrx)2O7, were firstly synthesized by self-propagating high-temperature synthesis plus quick pressing (SHS/QP) using CuO as the oxidant and Ti as the reductant. To improve the radiation resistance of titanate–pyrochlore, up to 35 at% Zr was incorporated to substitute the Ti site of Gd2Ti2O7 pyrochlore (Gd2(Ti0.75Zr0.35)2O7). XRD and SEM microstructural characterizations showed the formation of a composite ceramic with the major pyrochlore phase and the minor Cu phase. The generated temperature of samples decreased from 1702 to 1011 ℃ with increasing Zr content. The effects of sintering temperature and pressure time on phase composition and microstructure were systematically studied. Besides, the influence of thermal transmission on the whole combustion process was also explored. The pyrochlore-based waste form possessed high bulk density of 6.25 g/cm3 and Vickers hardness of 10.81 GPa. The MCC-1 leaching test showed the normalized elemental leaching rates (42 d) of Cu, Gd, and Zr are 1.27×10-2, 1.33×10-3, and 8.44×10-7 g·m-2·d-1, respectively.

Keywords:

self-propagating high-temperature synthesis plus quick pressing (SHS/QP), pyrochlore, thermal transmission, waste form, aqueous leachability
Received: 22 August 2017 Revised: 09 October 2017 Accepted: 27 October 2017 Published: 28 December 2017 Issue date: March 2018
References(39)
[1]
JQ Jing, HW Luan. On the history of world nuclear development and the road for China nuclear development. Northeast Electric Power Technology 2008, 29: 48-52. (in Chinese)
[2]
Q-Z Ye. Studies on the development strategy of China’s nuclear power. Power System and Clean Energy 2010, 26: 3-6. (in Chinese)
[3]
International Atomic Energy Agency. Design and Operation of High Level Waste Vitrification and Storage Facility. Technical Reports Series No. 339, 1992.
[4]
MI Ojovan, WE Lee. An Introduction to Nuclear Waste Immobilization. Elsevier, 2005.
[5]
TV Barinova, KB Podbolotov, IP Borovinskaya, et al. Self-propagating high-temperature synthesis of ceramic matrices for immobilization of actinide-containing wastes. Radiochemistry 2014, 56: 554-559.
[6]
L Kong, Y Zhang, I Karatchevtseva. Preparation of Y2Ti2O7 pyrochlore glass-ceramics as potential waste forms for actinides: The effects of processing conditions. J Nucl Mater 2017, 494: 29-36.
[7]
WJ Weber, RC Ewing, CRA Catlow, et al. Radiation effects in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium. J Mater Res 1998, 13: 1434-1484.
[8]
K Zhang, G Wen, H Zhang, et al. Self-propagating high-temperature synthesis of Y2Ti2O7 pyrochlore and its aqueous durability. J Nucl Mater 2015, 465: 1-5.
[9]
L Peng, K Zhang, D Yin, et al. Self-propagating synthesis, mechanical property and aqueous durability of Gd2Ti2O7 pyrochlore. Ceram Int 2016, 42: 18907-18913.
[10]
L Fan, X Shu, X Lu, et al. Phase structure and aqueous stability of TRPO waste incorporation into Gd2Zr2O7 pyrochlore. Ceram Int 2015, 41: 11741-11747.
[11]
FX Zhang, JW Wang, J Lian, et al. Phase stability and pressure dependence of defect formation in Gd2Ti2O7 and Gd2Zr2O7 pyrochlores. Phys Rev Lett 2008, 100: 045503.
[12]
M Jafar, P Sengupta, SN Achary, et al. Phase evolution and microstructural studies in CaZrTi2O7 (zirconolite)–Sm2Ti2O7 (pyrochlore) system. J Eur Ceram Soc 2014, 34: 4373-4381.
[13]
RC Ewing, WJ Weber, J Lian. Nuclear waste disposal— pyrochlore (A2B2O7): Nuclear waste form for the immobilization of plutonium and “minor” actinides. J Appl Phys 2004, 95: 5949-5971.
[14]
C Wan, Z Qu, A Du, et al. Influence of B site substituent Ti on the structure and thermophysical properties of A2B2O7-type pyrochlore Gd2Zr2O7. Acta Mater 2009, 57: 4782-4789.
[15]
L Fan, X Shu, Y Ding, et al. Fabrication and phase transition of Gd2Zr2O7 ceramics immobilized various simulated radionuclides. J Nucl Mater 2015, 456: 467-470.
[16]
EM Glagovskii, SV Yudintsev, AV Kuprin, et al. Crystalline host phases for actinides, obtained by self-propagating high-temperature synthesis. Radiochemistry 2001, 43: 632-638.
[17]
NK Kulkarni, S Sampath, V Venugopal. Preparation and characterization of Pu-pyrochlore: (La1-xPux)2Zr2O7 ( x = 0–1). J Nucl Mater 2000, 281: 248-250.
[18]
KQ Zhang, CG Liu, FZ Li, et al. Study on the crystal structure of (Gd2-xCex)Ti2O7 (0 ≤ x ≤ 0.8) pyrochlore. Adv Appl Ceram 2016, 115: 411-416.
[19]
KE Sickafus, L Minervini, RW Grimes, et al. Radiation tolerance of complex oxides. Science 2000, 289: 748-751.
[20]
BD Begg, NJ Hess, WJ Weber, . et al. Heavy-ion irradiation effects on structures and acid dissolution of pyrochlores. J Nucl Mater 2001, 288: 208-216.
[21]
RJ Finch, DB Bullen. Scientific Basis for Nuclear Waste Management XXVI: Symposium Held December 2–5, 2002, Boston, Massachusetts, USA. Warrendale, PA, USA: Materials Research Society, 2003.
[22]
J Tang, X Chen, S Pan, et al. Synthesis of Gd2Zr2O7 pyrochlore with cubic structure at high pressure and high temperature conditions. Atomic Energy Science and Technology 2010, 44: 394-399. (in Chinese)
[23]
X Lu, Y Ding, H Dan, et al. Rapid synthesis of single phase Gd2Zr2O7 pyrochlore waste forms by microwave sintering. Ceram Int 2014, 40: 13191-13194.
[24]
Q Xu, W Pan. J Wang, et al. Preparation and characterization of Gd2Zr2O7 ceramic by spark plasma sintering. Key Eng Mater 2005, 280–283: 1507-1510.
[25]
M Muthuraman, NA Dhas, KC Patil. Combustion synthesis of oxide materials for nuclear waste immobilization. Bull Mater Sci 1994, 17: 977-987.
[26]
AG Merzhanov. History and recent developments in SHS. Ceram Int 1995, 21: 371-379.
[27]
SV Yudintsev, TS Ioudintseva, AV Mokhov, et al. Study of pyrochlore and garnet-based matrices for actinide waste produced by a self-propagating high-temperature synthesis. MRS Proceedings 2003, 807, .
[28]
SV Yudintsev, SV Stefanovskii, OI Kir’Yanova, et al. Radiation resistance of fused titanium ceramic for actinide immobilization. Atomic Energy 2001, 90: 487-494.
[29]
NP Laverov, SV Yudintsev, SV Stefanovsky, et al. Radiation stability of actiniae matrices. Dokl Earth Sci 2001, 377: 175-177.
[30]
K Zhang, D Yin, L Peng, et al. Self-propagating synthesis of Nd2O3-incorporated zirconolite/Mo composites and their aqueous durability. J Nucl Mater 2017, 491: 177-182.
[31]
N Laverov, S Yudintsev, M Lapina, et al. Phases formation rate at synthesis of actinide waste forms. MRS Proceedings 2002 ,757, .
[32]
W Wong-Ng, HF McMurdie, CR Hubbard, et al. JCPDS-ICDD research associateship (cooperative program with NBS/NIST). J Res Natl Inst Stand Technol 2001, 106: 1013-1028.
[33]
KL Smith, GR Lumpkin, MG Blackford, et al. The durability of synroc. J Nucl Mater 1992, 190: 287-294.
[34]
ASTM C1220-98. Standard test method for static leaching of monolithic waste forms for disposal of radioactive waste. ASTM International, West Conshohocken, PA, USA, 1998.
[35]
K Helean, B Begg, A Navrotsky, et al. Enthalpies of formation of Gd2(Ti2-xZrx)O7 pyrochlores. MRS Proceedings 2000, 663, .
[36]
G Wen, K Zhang, H Zhang, et al. Immobilization and aqueous durability of Nd2O3 and CeO2 incorporation into rutile TiO2. Ceram Int 2015, 41: 6869-6875.
[37]
P McGlinn, T Advocat, G Leturcq, et al. Leaching behaviour of zirconolite in 0.001M citric acid at 90 °C under various flow regimes. MRS Proceedings 2006, 932, .
[38]
H Yokoi, Y Arita, T Matsui, et al. EXAFS study of (La1-xMx)2Zr2O7 (M = Nd and Ce). J Nucl Mater 1996, 238: 163-168.
[39]
WD Kingery, HK Bowen, DR Uhlmann. Introduction to Ceramics, 2nd edn. New York: John Wiley and Sons Incorporated, 1976.
Publication history
Copyright
Rights and permissions

Publication history

Received: 22 August 2017
Revised: 09 October 2017
Accepted: 27 October 2017
Published: 28 December 2017
Issue date: March 2018

Copyright

© The author(s) 2017

Rights and permissions

Open Access The articles published in this journal are distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permission requests may be sought directly from editorial office.

Return