《厦门大学学报（自然科学版）》

采用标准固相反应烧结法制备烧绿石结构的Lu2Ti2O7.在室温下,用800 keV Kr2+和200 keV He+进行辐照.辐照后的样品采用掠入式X射线衍射(GIXRD)表征.结果表明:用800 keV Kr2+辐照样品时,辐照剂量达到2×1014cm-2(相应dpa(displacement per atom)为0.4)时,样品出现非晶化转变,并且随着辐照剂量的增加,非晶化转变量不断增加,增加至一定值后不再变化,未出现完全的非晶化转变; 用200 keV He+进行辐照时,即使辐照剂量增加至2×1017cm-2(dpa为1.25),样品也没有出现非晶化转变.通过分子动力学模拟对结果进行分析后发现:重离子辐照时,样品在较小范围内产生较多的缺陷,且电子能损较低,样品温度增幅较小,缺陷复合率低,易导致非晶化转变; 而轻离子辐照时结果相反.

The pyrochlore structure of Lu2Ti2O7 was prepared by standard solid-state reaction sintering method.Pyrochlore pellets of Lu2Ti2O7 were irradiated with 800 keV heavy Kr2+ and 200 keV light He+ at room temperature.The microstructural evolution induced by different ion irradiation was observed using grazing incidence X-ray diffraction(GIXRD).The results showed that the phase transition of pyrochlore from ordered to partial amorphous was achieved under 800 keV Kr2+ irradiation with the fluence of 2×1014cm-2(the corresponding dpa(displacement per atom)was 0.4).The percent of amorphization kept increasing with the increasing of the fluence,until it reached a certain value,but no complete amorphous transition was observed.However,a defected fluorite phase transformation was observed in the pyrochlore Lu2Ti2O7 under 200 keV He+ irradiation.No amorphous transition was observed even under 200 keV He+ with a higher fluence of 2.0×1017 cm-2(dpa was 1.25).Then molecular dynamics simulation was performed to interpret the above observation.The simulation results showed that when the sample was irradiated by heavy ions,more defects ge-nerated in a smaller range,the electron energy loss was lower,the temperature of the sample increased less,the recombination rate of defect was lower and the amorphous transitions occured more easily,while for the light ion irradiation,the results exhibited conversely.

引言
1 实验
2 结果和讨论
3 结论

表1 烧绿石Lu2Ti2O7的短程Buckingham势参数[12]<br/>Tab.1 Short-range Buckingham potential parameters for pyrochlore Lu2Ti2O7[12]

表1 烧绿石Lu2Ti2O7的短程Buckingham势参数[12]
Tab.1 Short-range Buckingham potential parameters for pyrochlore Lu2Ti2O7[12]

图1 样品的XRD谱图<br/>Fig.1 XRD pattern of the sample

图1 样品的XRD谱图
Fig.1 XRD pattern of the sample

图2 Lu2Ti2O7辐照前后的GIXRD谱图<br/>Fig.2 GIXRD patterns of pristine Lu2Ti2O7 pellets and Lu2Ti2O7 after irradiation

图2 Lu2Ti2O7辐照前后的GIXRD谱图
Fig.2 GIXRD patterns of pristine Lu2Ti2O7 pellets and Lu2Ti2O7 after irradiation

图3 Lu2Ti2O7体系的原子平均能量(a)和密度(b)与引入的弗伦克尔缺陷对含量的关系<br/>Fig.3 The energy per atom(a)and density(b)of Lu2Ti2O7 system as a function of content of introduced Frenkel defect pairs

图3 Lu2Ti2O7体系的原子平均能量(a)和密度(b)与引入的弗伦克尔缺陷对含量的关系
Fig.3 The energy per atom(a)and density(b)of Lu2Ti2O7 system as a function of content of introduced Frenkel defect pairs

图4 不同离子辐照烧绿石Lu2Ti2O7产生的电子能损、核能损和RENSP的计算结果<br/>Fig.4 Ionization and nuclear stopping power, andthe corresponding RENSP results for different ions irradiation in pyrochlore Lu2Ti2O7

图4 不同离子辐照烧绿石Lu2Ti2O7产生的电子能损、核能损和RENSP的计算结果
Fig.4 Ionization and nuclear stopping power, andthe corresponding RENSP results for different ions irradiation in pyrochlore Lu2Ti2O7

图5 Lu2Ti2O7体系内保留下来的空位个数与弛豫温度之间的关系<br/>Fig.5 The relationship between the retained number of vacancy and the relaxing temperature in Lu2Ti2O7 system

图5 Lu2Ti2O7体系内保留下来的空位个数与弛豫温度之间的关系
Fig.5 The relationship between the retained number of vacancy and the relaxing temperature in Lu2Ti2O7 system

[1] HERBST A M,HOPLEY G W.Nuclear energy now:why the time has come for the world's most misunderstood energy source[M].Toronto:John Wiley & Sons,2007:35-61.
[2] 董晓囡,张建,郭奇勋,等.Kr离子辐照磷灰石陶瓷材料Ca10(PO4)6FxCl2-x(x=0,0.5,1.0,1.5和2.0)导致的非晶相变[J].厦门大学学报(自然科学版),2018,57(1):38-43.
[3] HART K P.Retention of actinides in natural pyrochlores and zirconolites[J].Radiochimica Acta,1994,66/67(S1):469-474.
[4] SICKAFUS K E,MINERVINI L,GRIMES R W,et al.Radiation tolerance of complex oxides[J].Science,2000,289(5480):748-751.
[5] CHAKOUMAKOS B C.Systematics of the pyrochlore structure type,ideal A2B2X6Y[J].Journal of Solid State Chemistry,1984,53(1):120-129.
[6] LIAN J,CHEN J,WANG L M,et al.Radiation-induced amorphization of rare-earth titanate pyrochlores[J].Physical Review B,2003,68(13):134107.
[7] LUMPKIN G R,EWING R C.Alpha-decay damage in minerals of the pyrochlore group[J].Physics & Chemistry of Minerals,1988,16(1):2-20.
[8] XIE Q R,ZHANG J,DONG X N,et al.Heavy ion irradiation-induced microstructural evolution in pyrochlore Lu2Ti2O7 at room temperature and 723 K[J].Journal of Solid State Chemistry,2015,231:159-162.
[9] ZHANG J,WANG Y Q,TANG M,et al.Helium irradi-ation induced micro-swelling and phase separation in pyrochlore Lu2Ti2O7[J].Nuclear Instruments and Methods in Physics Research Section B:Beam Interactions with Materials and Atoms,2015,342:179-183.
[10] LI Y H,UBERUAGA B P,JIANG C,et al.Role of antisite disorder on preamorphization swelling in titanate pyrochlores[J].Phys Rev Lett,2012,108(19):195504.
[11] XIE Q R,ZHANG J,YIN D M,et al.Krypton ion irra-diation-induced amorphization and nano-crystal formation in pyrochlore Lu2Ti2O7 at room temperature[J].Chinese Physics B,2015,24(12):126103.
[12] MINERVINI L,GRIMES R W,SICKAFUS K E.Disorder in pyrochlore oxides[J].Journal of the American Ceramic Society,2000,83(8):1873-1878.
[13] SOULIE A,MENUT D,CROCOMBETTE J P,et al.X-ray diffraction study of the Y2Ti2O7 pyrochlore disordering sequence under irradiation[J].Journal of Nuclear Materials,2016,480:314-322.
[14] DEVANATHAN R,WEBER W J,GALE J D.Radiation tolerance of ceramics:insights from atomistic simulation of damage accumulation in pyrochlores[J].Energy & Environmental Science,2010,3(10):1551-1559.
[15] WEN J,SUN C,DHOLABHAI P P,et al.Temperature dependence of the radiation tolerance of nanocrystalline pyrochlores A2Ti2O7(A=Gd,Ho and Lu)[J].Acta Materialia,2016,110:175-184.
[16] 谢秋荣,张建,董晓囡,等.正交结构Gd2TiO5陶瓷材料的轻重离子辐照效应比较[J].厦门大学学报(自然科学版),2017,56(1):53-58.

备注

引言

1 实验

2 结果和讨论

3 结论

学报简介

备注

引言

1 实 验

2 结果和讨论

3 结 论

学报简介

1 实验

3 结论