The order–disorder transition in ion-irradiated pyrochlore

Lian, Jie; Wang, L.; Chen, J.; Sun, Kai; Ewing, Rodney C.; Farmer, J. Matt; Boatner, L. A.

doi:10.1016/s1359-6454(02)00544-x

Cited by 227 publications

(163 citation statements)

References 29 publications

Supporting

Mentioning

153

Contrasting

Order By: Relevance

“…Critical amorphization doses are reported in the order of 10 18 -10 20 α-decay events per gram [16]. Ion irradiation studies on synthetic rare earth titanates have been carried out by Lian et al [34], who also described several steps of increased disorder prior to amorphization detected by high-resolution transmission electron microscopy (HRTEM). The pyrochlores also showed an increase of their ionic conductivity.…”

Section: Hementioning

confidence: 99%

See 1 more Smart Citation

Thermal annealing of natural, radiation-damaged pyrochlore

Zietlow

Beirau

Mihailova

et al. 2016

Zeitschrift Für Kristallographie - Crystalline Materials

View full text Add to dashboard Cite

Radiation damage in minerals is caused by the α-decay of incorporated radionuclides, such as U and Th and their decay products. The effect of thermal annealing (400-1000 K) on radiation-damaged pyrochlores has been investigated by Raman scattering, X-ray powder diffraction (XRD), and combined differential scanning calorimetry/thermogravimetry (DSC/TG). The analysis of three natural radiation-damaged pyrochlore samples from Miass/Russia [6.4 wt% Th, 23.1 · 10 18 α-decay events per gram (dpg)], Panda Hill/Tanzania (1.6 wt% Th, 1.6 · 10 18 dpg), and Blue River/Canada (10.5 wt% U, 115.4 · 10 18 dpg), are compared with a crystalline reference pyrochlore from Schelingen (Germany). The type of structural recovery depends on the initial degree of radiation damage (Panda Hill 28 %, Blue River 85 % and Miass 100 % according to XRD), as the recrystallization temperature increases with increasing degree of amorphization. Raman spectra indicate reordering on the local scale during annealing-induced recrystallization. As Raman modes around 800 cm −1 are sensitive to radiation damage . The most radiation damaged pyrochlore (Miass) shows an abrupt recovery of both, its short-(Raman) and long-range order (X-ray) between 800 and 850 K, while the weakly damaged pyrochlore (Panda Hill) begins to recover at considerably lower temperatures (near 500 K), extending over a temperature range of ca. 300 K, up to 800 K (Raman). The pyrochlore from Blue River shows in its initial state an amorphous X-ray diffraction pattern superimposed by weak Bragg-maxima that indicates the existence of ordered regions in a damaged matrix. In contrast to the other studied pyrochlores, Raman spectra of the Blue River sample show the appearance of local modes above 560 K between 700 and 800 cm −1 resulting from its high content of U and Ta impurities. DSC measurements confirmed the observed structural recovery upon annealing. While the annealing-induced ordering of Panda Hill begins at a lower temperature (ca. 500 K) the recovery of the highly-damaged pyrochlore from Miass occurs at 800 K. The Blue-River pyrochlore shows a multi-step recovery which is similarly seen by XRD. Thermogravimetry showed a continuous mass loss on heating for all radiation-damaged pyrochlores (Panda Hill ca. 1 %, Blue River ca. 1.5 %, Miass ca. 2.9 %).

show abstract

Section: Hementioning

confidence: 99%

“…Synthetic and to a smaller extent natural pyrochlores with a broad range of different cation substitutes have been thoroughly investigated [16,[34][35][36][37][38][39][40][41]. Gregg et al [42] observed additional Raman modes between 700 and 800 cm −1 related to U-impurities in the pyrochlore structure.…”

Section: Hementioning

confidence: 99%

Thermal annealing of natural, radiation-damaged pyrochlore

Zietlow

Beirau

Mihailova

et al. 2016

Zeitschrift Für Kristallographie - Crystalline Materials

View full text Add to dashboard Cite

show abstract

“…However, it is difficult to ascertain, only from Raman results, whether the ordering is driven by cations, anions, or both at the same time. There is a long standing discussion of which one determines the other, i.e., whether cations or anions order first, and different techniques seem to provide contradictory results regarding this issue, 28,[34][35][36][37] although the most accepted model is that cation and anionic disorder go together. A different question arises as which is the best description of atomic distribution in disordered pyrochlores and whether disorder is due to point defect concentration or to size effects.…”

Section: A Raman Spectroscopymentioning

confidence: 99%

Raman and x-ray absorption spectroscopy study of the phase evolution induced by mechanical milling and thermal treatments inR2Ti2O
Sanjuán
¹
,
Guglieri
²
,
Díaz‐Moreno
³

et al. 2011
Phys. Rev. B
75
1
45
0
View full text Add to dashboard Cite

We report here a study of the local order in R 2 Ti 2 O 7 , (R = Y, Gd, and Dy) pyrochlores obtained by mechanical milling (MM) performed by combining both Raman and x-ray absorption (XAS) spectroscopies. In addition to both as-milled and annealed MM samples, measurements have been also recorded by performing an in situ thermal treatment of the MM pyrochlores in the range from ambient to 1300• C. The analysis of both Raman and XAS data yields a disentangled view of the evolution of the different degree of structural disorder at the Ti and rare-earth sites of the MM samples with the thermal treatment. Moreover, this study allowed us to follow the structural transformation of the MM samples through the region where exothermic processes have been previously observed. Our experiments show that an average fluorite-like structure is never formed in these pyrochlores. As milled-samples are better described as if formed by nanometer-sized pyrochlore domains embedded in a fluorite-like matrix. Thermal annealing induces domain growth, so that the event observed by differential thermal analysis can be attributed to an evolution from medium to long-range pyrochlore ordering, typically from tens to hundreds of nanometers.

show abstract

“…On the basis of best agreement between the observed (obs) and the calculated (cal) dspacing (i.e.,∑ Δd = d obs − d cal = minimum), all the PSZT compounds were found to be in tetragonal crystal system with their refined lattice parameters given in Table 1. In the XRD patterns, there is an additional peak (for x ≥ 0.08) usually referred as secondary or pyrochlore phase [17,18]. Though these peaks are undesirable, it is some time essential for formation of the perovskites [19].…”

Section: Structural Analysismentioning

confidence: 99%

Effect of Rare Earth (Sm) ion Substitution on Structural, Dielectric, and Transport Properties of PZT Ceramics

2015

IJSR

View full text Add to dashboard Cite

(PSZT) (x = 0.00, 0.04, 0.08 and 0.12) were synthesized by mixed oxide method at high temperature. The formation of single -phase compounds were confirmed by X-ray diffraction studies which were found to be in tetragonal phase at room temperature. The temperature dependence of dielectric response of the samples at selected frequencies has exhibit their phase transition well above the room temperature. The variation of ac conductivity with temperature reveals that their conduction process is of mixed type.

show abstract

The order–disorder transition in ion-irradiated pyrochlore

Cited by 227 publications

References 29 publications

Thermal annealing of natural, radiation-damaged pyrochlore

Thermal annealing of natural, radiation-damaged pyrochlore

Raman and x-ray absorption spectroscopy study of the phase evolution induced by mechanical milling and thermal treatments inR2Ti2O
Sanjuán
¹
,
Guglieri
²
,
Díaz‐Moreno
³

et al. 2011
Phys. Rev. B
75
1
45
0
View full text Add to dashboard Cite

Effect of Rare Earth (Sm) ion Substitution on Structural, Dielectric, and Transport Properties of PZT Ceramics

Contact Info

Product

Resources

About

The order–disorder transition in ion-irradiated pyrochlore

Cited by 227 publications

References 29 publications

Thermal annealing of natural, radiation-damaged pyrochlore

Thermal annealing of natural, radiation-damaged pyrochlore

Raman and x-ray absorption spectroscopy study of the phase evolution induced by mechanical milling and thermal treatments inR2Ti2OSanjuán1, Guglieri2, Díaz‐Moreno3 et al. 2011Phys. Rev. B751450View full textAdd to dashboardCite

Effect of Rare Earth (Sm) ion Substitution on Structural, Dielectric, and Transport Properties of PZT Ceramics

Contact Info

Product

Resources

About

Raman and x-ray absorption spectroscopy study of the phase evolution induced by mechanical milling and thermal treatments inR2Ti2O
Sanjuán
¹
,
Guglieri
²
,
Díaz‐Moreno
³

et al. 2011
Phys. Rev. B
75
1
45
0
View full text Add to dashboard Cite