THE XPS STUDY OF THE STRUC TURE OF URANIUM-CONTAINING CERAMICS

Transcription

1 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp THE XPS STUDY OF THE STRUC TURE OF URANIUM-CONTAINING CERAMICS by Anton Yu. TETERIN 1, Konstantin I. MASLAKOV 1, Yury A. TETERIN 1*, Kirill E. IVANOV 1, Tatyana S. LIVSHITS 2, Sergei V. YUDINTSEV 2, Sergei V. STEFANOVSKY 3, and Mariya I. LAPINA 2 1 Russian Research Centre Kurchatov Institute, Moscow, Russia 2 In sti tute of Ge ol ogy and Ore De po si tions of RAS, Mos cow, Rus sia 3 Mos cow NPO Ra don, Mos cow, Rus sia Sci en tific pa per UDC: : : DOI: /NTRP T The sam ples of the (Ca 0.5 GdU 0.5 )Zr 2 O 7 and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 ce ram ics with the flu o - rite and pyrochlore struc tures used as ma trixes for the long-lived high-level ra dio ac tive waste dis posal were stud ied with the X-ray pho to elec tron spec tros copy method. On the ba - sis of the X-ray pho to elec tron spec tros copy pa ram e ters of the outer and core elec trons from the bind ing en ergy range of ev the ox i da tion states of the in cluded metal ions were de ter mined, the quan ti ta tive el e men tal and ionic anal y sis was done, and the or der li ness (monophaseness) was eval u ated. The ob tained data agree with the X-ray dif frac tion and the scan ning elec tron mi cros copy re sults. Key words: X-ray pho to elec tron spec troscopy, scanning electron microscopy, outer (OVMO) and inner (IVMO) va lence mo lec u lar orbitals, pyrochlore, radioactive waste disposal IN TRO DUC TION The most dan ger ous long-lived radionuclides in the high-level ra dio ac tive waste (HLW) are actinides. Their immobilization requires the higher stability matrixes. To un der stand the chem i cal pro cesses in side these ma trixes it is nec es sary to know the phys i cal and chem i cal states of the in cluded radionuclides (el e men - tal and ionic com po si tions, ox i da tion states, num ber of un cou pled elec trons on the metal ions, close en vi ron - ment struc ture, etc.). The cor rect choice of ma te ri als is the key prob - lem of safety dur ing the HLW man age ment. Un der - stand ing of the chem i cal pro cesses in the ma trixes re - quires knowl edge of the phys i cal and chem i cal states of the in cluded radionuclides and ma trix el e ments. It will al low a pur pose ful pro duc tion of ma te ri als for the HLW and other wastes long-term stor age [1-3]. The HLW con tain ing actinides and some long-lived fis sion prod ucts ( 93 Zr, 99 Tc, 126 Sn, etc.) are pro posed to be in cluded in the firm ma trixes for the later underground disposal. To understand the chemical processes in side these ma trixes it is nec es sary to know the * Cor re spond ing au thor; teterin@ignph.kiae.ru phys i cal and chem i cal states of the in cluded ma trix el e ments and radionuclides (el e men tal and ionic com po - sitions, oxidation states, number of uncoupled electrons on the metal ions, close en vi ron ment struc ture, etc.). The pres ent work car ried out an X-ray pho to elec tron spec tral (XPS) study of the two ce ramic sam ples (Ca 0.5 GdU 0.5 )Zr 2 O 7 and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 with the flu o rite and pyrochlore struc tures as pos si ble ma trixes for the HLW dis posal. Gad o lin ium (Gd) was in tro duced for neu tron ab sorp tion. The XPS method has proven to be the most ad e quate for this pur pose. On the ba sis of the core and outer elec tron XPS pa ram e ters in the bind ing en ergy range of ev the quan ti ta tive el e men tal and ionic anal y sis of the stud ied sam ples was done, ox i da tion states of the in cluded metal ions were de ter mined, and the interatomic metal-oxygen distances were evaluated. The XPS proved to be an ef fec tive and ad e quate method for this field [4-6]. There fore, this work car ried out the qualitative elemental and ionic analysis and studied the ox i da tion states of in cluded el e ments for the two ceramic samples (Ca 0.5 GdU 0.5 )Zr 2 O 7 (1) and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 (2) with flu o rite and pyrochlore struc - tures used as ma trixes for the long-term stor age of the long-lived radionuclides from HLW. Gad o lin ium was in - tro duced in the ma trixes as a neu tron ab sorber. The ob - tained re sults were com pared with the X-ray dif frac tion and scanning electron microscopy data.

2 A. Yu. Teterin, et al.: The XPS Study of the Struc ture of Ura nium-containing Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp EXPERIMENTAL Sam ples with the cal cu lated com po si tions (Ca 0.5 GdU 0.5 )Zr 2 O 7 (1) and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 (2) were pre pared from the mix tures of CaCO 3, Gd 2 O 3, UO 2, TiO 2, and ZrO 2 ground in an ag ate mor tar to the size of 20 µm to 30 µm. The mix tures were pressed un der 200 MPa to 400 MPa into 12 mm to 30 mm di am e ter 4 mm to 5 mm high cy lin dri cal pel lets and sintered in alundum cru ci bles at 1500 C-1550 C for 6 hours to 10 hours. The struc ture of pyrochlore sam ples was stud ied with XRD on the DRON-4 (CuK a ), as well as on the scan ning (SEM/EDS: JSM-5300 with the en ergy-dis per sion spec trom e ter Link ISIS) and trans mis sion (JEM-100) elec tron mi cro scopes [3-5]. XPS spec tra of the stud ied sam ples were mea - sured with elec tro static spec trom e ters HP 5950A us ing monochromatized AlK a1,2 (hn = ev) ra di a tion and MK II VG Sci en tific us ing non-monochromatized AlK a1,2 and MgK a radiation under Pa at room temperature. The device resolutions measured as full width at the half-max i mum (FWHM) of the Au4f 7/2 peak on the stan dard rect an gu lar gold plate were 0.8 ev (HP 5950A) and 1.2 ev (MK II VG Sci en tific). Elec - tron binding energies E b (ev) were mea sured rel a tively to the bind ing en ergy of the C1s elec trons from hy dro - car bons ab sorbed on the sam ple sur face ac cepted to be equal to ev. For the gold stan dard the cal i bra tion binding energies E b (C1s) = ev and E b (Au4f 7/2 ) = = 83.7 ev (MK II VG Sci en tific) were used. The FWHM in tab. 1 are given rel a tively to that of the C1s peak of hy dro car bons ac cepted to be equal to 1.3 ev for com par i son with the data of other stud ies [4-6]. The un - certainty in determination of electron binding energies was ±0.2 ev and that of the rel a tive peak in ten si ties was less than 10%. The stud ied sam ples were pre pared as pel lets (sam ples 1 and 2) and as finely dis persed pow - ders ground in an ag ate mor tar pressed in in dium on ti - tanium substrate (standard samples). The quan ti ta tive el e men tal and ionic anal y sis was done for all the sam ples. It was based on the fact that the spec tral in ten sity is pro por tional to the num - ber of cer tain at oms in the stud ied sam ple. The fol - low ing ra tio was used: n i /n j = (S i /S j )(k j /k i ), where n i /n j is the rel a tive con cen tra tion of the stud ied at - oms, S i /S j the rel a tive core-shell spec tral in ten sity, and k j /k i the rel a tive ex per i men tal sen si tiv ity co ef - fi cient. This work used the fol low ing co ef fi cients rel a tive to car bon: 1.00 (C1s); 2.66 (O1s); 4.2 (Ca2p 3/2 ), 6.32 (Ca2p); 8.4 (Zr3d), 4.16 (Zr3p 3/2 ), 36.0 (U4f 7/2 ), 1.08 (Si2p) [7, 8]. XPS pa ram e ters of Ca, CaO, CaCO 3, UO 2, SnO 4, ZrO 4, and SrZrO 3 (tab. 1) were used for the in ter pre ta tion of the spec - tra from the stud ied sam ples. RESULTS AND DISCUSSION The XPS from the stud ied HLW ma trixes ce ram ics (Ca 0.5 GdU 0.5 )Zr 2 O 7 (sampe 1) and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 (sam ple 2) in the bind ing en ergy range of ev ex - hibit the peaks at trib uted to the in cluded el e ments (fig. 1). This bind ing en ergy range can be sub di vided into the three sub-ranges [4-6]. The first one from 0 to ~15 ev ex hib its the struc ture at trib uted mainly to the elec trons of the outer va lence mo lec u lar orbitals (OVMO) formed with elec - trons from in com pletely filled atomic va lence shells. For ex am ple, the An5f in ten sity at zero bind ing en ergy can be used for determination of actinide oxidation states [4]. The sec ond bind ing en ergy sub-range from ~15 ev to ~50 ev ex hib its the struc ture at trib uted to the elec trons of the in ner va lence mo lec u lar orbitals (IVMO) formed with elec trons from the com pletely filled atomic low-en ergy shells. Pa - rameters of this structure characterize the close environment of the con sid ered ion, in par tic u lar, for ac ti nide com - Fig ure 1. Sur vey XPS in the bind ing en ergy range of ev from sam ples: (a) (Ca 0.5 GdU 0.5 )Zr 2 O 7 ; (b) (Ca 0.5 GdU 0.5 )(ZrTi)O 7

3 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp pounds the IVMO pa ram e ters can be used for determination of the actinide-neighbour interatomic distance [6]. The third sub-range above ~50 ev shows the struc ture at trib uted to the core elec tronic shells weakly participating in the chemical binding. However, this sub-range can ex hibit the struc ture due to the spin-or bit splitting DE sl (ev), multiplet split ting DE ms (ev), many-body perturbation, dynamic effect, etc. [4, 5]. Since these structure parameters correlate with the physical and chem i cal prop er ties of com pounds, they are used to gether with the traditional XPS characteristics like electron binding energies, chemical shifts, core-valence binding energy dif fer ences, and peak in ten si ties [7, 8]. To sim plify the dis - cus sion, we are go ing to use both mo lec u lar and atomic terms. Low bind ing en ergy XPS (0 to ~50 ev). The low-bind ing en ergy XPS range from (Ca 0.5 GdU 0.5 )Zr 2 O 7 (1) and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 (2) ex hibit the two-humped OVMO struc tures at trib uted to the outer va - lence Ca4s, U5f,6d,7s, Zr4d,5s, Gd4f,5d,6s, Ti3d,4s, and O2p elec trons, as well as the IVMO struc ture due to the Ca3s,3p, U6p, Gd5p,5s, Zr4p, Ti3p, and O2s elec trons (fig. 2, tab. 1). The Zr4p, O2s, and other peaks are ob - served to be sharp. This XPS struc ture al lows only a qual i - tative elemental analysis because the considered spectra ap pear as com pli cated MO-re lated lines, not sin gle peaks. This bind ing en ergy range con sists of only the peaks at - trib uted to the in cluded el e ments. Small peaks at 9 ev and 13 ev can be ex plained by the pres ence of a CO 3 2 im pu - rity on the sam ple sur face, which was con firmed by the C1s spec tra. Core-elec tron XPS (~50 ev to 1250 ev). The XPS elemental and ionic quantitative analysis usually em ploys the most in tense peaks from the in cluded el e - ments [7, 8]. In the case of the stud ied com pounds (Ca 0.5 GdU 0.5 )Zr 2 O 7 (1) and (Ca 0.5 GdU 0.5 )(ZrTi)O 7 (2) the Ca2p, U4f, Gd3d 5/2, 4d, Zr3p,3d, Ti2p, and O1s peaks were used (tab. 1). In the case of an over lap of the peaks, other avail able sin gle peaks like, for in - stance, the Th5d and Zr3d can be used. The C1s XPS from the sam ples (1) and (2) were ob served to be sym - met ri cal with the low-in tense shoul ders of the CO 3 2 and = CO 2 groups at ev and ev (tab. 1). A small wid en ing of the C1s peak from the sam ple (2) in com par i son with that from the sam ple (1) can be ex - plained by the inhomogeneous charg ing of the sam ple sur face or by the pres ence of hy dro car bons of dif fer ent types on the sur face. The Zr3p and Ca2p peaks over lap (fig. 3, tab. 1). The Ca2p and Zr3p are ob served as typ i cal spin-or bit split (DE sl (Ca2p) = 3.7 ev, DE sl (Zr3p) = 13.6 ev) dou - blets [9]. The Zr3d XPS from the sam ples (1) and (2) ap pear as sym met ri cal dou blets. The U4f XPS are also ob served as spin-or bit split dou blets typ i cal for the U(IV) ions shake-up sat el lites (fig. 4). The peaks from the in cluded el e ments were ob served to be sin gle and sharp. It con firms the XRD re sults that the con sid ered sam ples are monophase (figs. 3 and 4). The Gd4d XPS show the fine struc ture typ i cal for the Gd(III) ions (tab. 1). But, for the stud ied sam ples (1 and 2) these spec tra ex hibit an ex tra peak at ev that must be at trib - uted to the Si2s peak from the sil i con im pu rity. The Gd3d 5/2 XPS cor re spond to Gd(III) in Gd 2 O 3 (tab. 1). These spec tra show ex tra peaks at ev which are at trib uted to the CaKLL Au ger spec tra ( ev). The Ti2p XPS ap pears as a spin-or bit split dou blet (DE sl = 5.8 ev) and shake-up sat el lites. The O1s XPS from the sam ple (1) con sists of the three peaks at 529.0, 530.5, and ev, and that from the sam ple (2) con sists of the three peaks at ev, ev, and ev (fig. 5). Tak ing into ac count eqs. (I, II) from [10] Fig ure 2. Low bind ing en ergy XPS from sam ples: E b (ev) = 2.27 R M-O 1 (nm) where from R M-O (nm) = 2.27 (E b 519.4) 1 (I) (II)

4 A. Yu. Teterin, et al.: The XPS Study of the Struc ture of Ura nium-containing Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp Table 1. Binding energies E b (ev) and FWHM (a) (ev) of the outer and core elec trons from pyrochlore ceramics Compound MO (Ca 0.5 GdU 0.5 )Zr 2 O (Ca 0.5 GdU 0.5 )(ZrTi)O UO CaZrO 3 (b) ZrO Ca (metal) CaO 0.6 (1.2) (1.8) 4.3 (2.1) 20.1 (2.6) 24.3 (2.0) 42.9 (1.9) 5.3 (2.2) 25.2 CaCO 3 (2.0) 44.1 (1.8) TiO s Gd 2 O An4f Ln3d An5d Ln4d Zr3d Sn3d (a) FWHM are given in pa ren the ses rel a tive to the FWHM of the C1s, G(C1s) = 1.3 ev; (b) O1s and C1s bind ing en er gies (531.6 and ev) for the CO 3 2 group on the sur face Zr3p Ca2p Ti2p O1s C1s (1.4) (1.6) On the ba sis of the O1s bind ing en er gies one can evaluate the metal-oxygen interatomic distances R M-O (nm) in the sam ples (1) and (2). Thus, for the sam ple (1) they are nm, nm and nm, re spec - tively, while for the sam ple (2) nm, nm, and nm, re spec tively. Since the O1s bind ing en - ergy can be mea sured with the ac cu racy to within ±0.05 ev, not ±0.2 ev as it was mea sured in this work, the accuracy of the interatomic distance evaluation can be higher. As it fol lows from eq. (I) as the in ter atomic distance R M-O grows, the O1s bind ing en ergy de - creases. There fore, one can con clude that, for ex am - ple, the value nm is too low to be ob served in ce - ram ics. Ap par ently, this dis tance can be at trib uted to a surface state. The two low-en ergy O1s com po nents in the XPS from the sam ples (1 and 2) can be at trib uted to the ox - ides of the ba sic ce ram ics, but the higher-en ergy com - ponents are, apparently, attributed to impurities like Ca(OH) 2, SiO 2, CO 3 2, Na 2 O, etc. (fig. 5, tab. 1). It has to be noted that, for ex am ple, in ZrO 2 three oxygens are lo cated from zir co nium at nm, four oxygens at nm, and the next clos est ox y gen not be long - ing to the first co-ordinating sphere at nm [11]. For this en vi ron ment the O1s XPS must con sist of two peaks at ev and ev with the in ten sity ra tio 4/3. Therefore, the interatomic distances evaluated on the ba sis of the O1s XPS are good enough for the qual - itative and partially quantitative identification of the O1s XPS peaks. Quantitative analysis. The un cer tainty in the quantitative elemental analysis of the samples 1 and 2 in creases be cause the core XPS peaks have the multiplet split ting and sec ond ary elec tronic pro cesses re lated ex tra struc ture. Since the many-body per tur ba - tion re sults in the shake-up sat el lites on the higher bind ing en ergy side from the ba sic peaks, their in ten si - ties can be taken into ac count (fig. 4). The dy namic ef -

5 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp Fig ure 3. Zr3p and Ca2p XPS from sam ples: Fig ure 4. U4f XPS from sam ples: fect is more dif fi cult to take into ac count, but its in flu - ence is low. All these ef fects lead to an en hance ment of the uncertainty in the elemental and ionic quantitative anal y sis, so the to tal un cer tainty can ex ceed 10%. In this ap prox i ma tion the sur face (~5 nm) com po si tions of the stud ied sam ples rel a tive to zir co nium at oms were found to be (Ca 0.50 Gd 1.14 U 0.42 )Zr 2.00 O I 6.18(O)O II 1.88(O)O III 9.90 (OH,.SiO 2 )Ca 2.48 [Ca(OH) 2 ]Si 1.4 (SiO 2 )C I 10.40(CH 3 ) C II 0.82(CO 3 2 ) (1) (Ca 0.50 Gd 1.01 U 0.25 )(Zr 1.00 Ti 1.37 ) O I 6.56(O)O II 5.39(O)O III 7.70 (OH,.SiO 2 )Ca 0.84 [Ca(OH) 2 ]Si 2.42 (SiO 2 )Na 0.34 (Na 2 O) C I 13.52(CH 3 )C II 1.76(-CO 2- ) (2) where O I (O), O II 1.88(O), and O III (OH 1, SiO 2 ) are oxygens of ox ides and hydroxyl groups (sil i con di ox - ide). In the stud ied sam ples the CO 3 2 impurities from cal cium car bon ate are pres ent on the sur face. The ob tained data dif fers slightly from the XRD re sults mea sured for the sam ple bulk (Ca 0.50 Gd 1.14 U 0.42 )Zr 2.00 O I (1), and (Ca 0.5 Gd 1.01 U 0.25 )(Zr 1.00 Ti 1.37 )O I (2) XPS data for the sur face; (Ca 0.5 GdU 0.5 )Zr 2 O 7 (1), and (Ca 0.62 Gd 0.97 U 0.23 )(Zr 0.84 Ti 1.34 )O 6.9 (2) XRD data for the bulk. It can be ex plained by the fact that the XPS re - flects the 5 nm to 10 nm sur face com po si tion, while the XRD re flects the bulk. The XPS shows that cal cium on the sur face of the stud ied sam ples (1) and (2) is pres ent par tially in form of hy drox ide, and it gathers more pref er a bly on the sur face rather than in the bulk. The rel a tive sur face and bulk ti ta nium, zir co nium, and ura - nium con tents do not dif fer sig nif i cantly. Dur ing the study of the Bi-Ca-Cu-O-based metal-ox ide ce ram ics [12] it was found that cal cium hy drox ides and car bon - ates are formed on the sam ple sur face un der the en vi - ron ment in flu ence. In other words, the in sta bil ity of the ce ramic sur face is associated with the presence of calcium oxides.

6 A. Yu. Teterin, et al.: The XPS Study of the Struc ture of Ura nium-containing Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp REFERENCES Fig ure 5. O1s XPS from sam ples: CON CLU SIONS On the ba sis of the core and outer elec trons XPS parameters of the studied ceramics (Ca 0.5 GdU 0.5 )Zr 2 O 7 and (Ca 0.5 GdU 0.5 ) (ZrTi)O 7 in the bind ing en ergy range of ev the ox i da tion states of the in cluded met als were determined, quantitative elemental and ionic analy sis was car ried out and a con clu sion on the monophaseness (or der li ness) of the stud ied sam ples was drawn. The ob tained data agree with the X-ray dif - frac tion and scan ning elec tron mi cros copy re sults. It is shown that the XPS method can be ef fec tively ap plied for the study of the el e men tal and ionic com po si tion of ce ramic ma trixes for the HLW dis posal. [1] Yudintsev, S. V., Stefanovsky, S. V., Ew ing, R. C., Ac - ti nide Host Phases as Ra dio ac tive Waste Forms, Structural Chemistry of Inorganic Actinide Com - pounds (Eds. S. Krivovichev, P. Burns, I. Tananaev, Elsevier B.V., Am ster dam, 2007, pp [2] Laverov, N. P., Velichkin, V. I., Omelyanenko, B. I., Yudintsev, S. V., Petrov, V. A., Bychkov, A.V., Iso la - tion of Spent Nu clear Ma te ri als, Geo log i cal and Chem i cal Ba sis, IGEM RAN, 2008, p. 280 [3] Yudintsev, S. V., Com plex Ox ides of Pyrochlore, Gar - net and Murataite Struc tural Types as Ma trixes for Im mo bi li za tion of the Nu clear En ergy Ac ti nide Wastes, Ph. D. the sis of Geo log i cal Sci ences Dis ser ta - tion, IGEM RAN, Mos cow, 2009, p. 44 [4] Teterin, Yu. A., Stefanovsky, S. V., Yudintsev, S. V., Bek-Uzarov, G. N., Teterin, A. Yu., Maslakov, K. I., Utkin, I. O., XPS In ves ti ga tion of Ce ramic Ma trixes for Dis posal of Long-Liv ing Ra dio ac tive Waste Prod - ucts, Nuclear Technology & Radiation Protection, 19 (2004), 1, pp [5] Prusakov, V. N., Teterin, Yu. A., Trotsenko, N. M., Maslakov, K. I., Teterin, A. Yu., Ivanov, K. E., Bochagin, F. S., Utrobin, D. V., An X-Ray Pho to elec - tron Spec tros copy Study of the Prod ucts of the In ter - ac tion of Gas eous IrF 6 with Fine UO 2 F 2, Nuclear Technology & Radiation Protection, 22 (2007), 1, pp [6] Veal, B. W., Lam, D. J., X-Ray Pho to elec tron Stud ies of Tho rium, Ura nium and their Di ox ides, Phys. Rev. B., 10 (1974),12, pp [7] ***, Prac ti cal Sur face Anal y sis by Au ger and X-Ray Pho to elec tron Spec tros copy (Eds. D. Briggs, M. P. Sich), Mir, Mos cow, 1987, p. 598 [8] Nefedov, V. I., Ap pli ca tion of X-Ray Pho to elec tron Spec tros copy in Chem is try, in: Over all Results of Sci - ence and Tech nol ogy, Struc ture of Mol e cules and Chem i cal Bond, VINITI, Mos cow, 1973, V. 1, pp [9] Fuggle, J. C., Burr, A. F., Lang, W., Wat son, L. M., Fa - bian, D. Y., X-Ray Pho to elec tron Stud ies of Tho rium and Ura nium, J. Phys. F: Metal. Phys., 4 (1974), 2, pp [10] Sosulnikov, M. I., Teterin, Yu. A., X-Ray Pho to elec - tron Stud ies of Ca, Sr, Ba and Their Ox ides and Car - bonates, Jour nal of Elec tron Spec tros copy and Re - lated Phenomena, 59 (1992), 2, pp [11] Wells, A., Struc tural In or ganic Chem is try, Mir, Mos - cow, 2, 1987, p. 695 [12] Teterin, Yu. A, Sosulnikov, M. I., X-Ray Pho to elec - tron Study of Ca, Sr, and Ba Ion Chem i cal States in High Tc Superconductors, Physica C., 212 (1993), 3-4, pp Re ceived on Feb ru ary 25, 2010 Ac cepted on June 30, 2010 ACKNOWLEDGEMENT This work was sup ported by the RFBR grant

7 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2010, Vol. 25, No. 2, pp Anton J. TETERIN, Konstantin I. MASLAKOV, Jurij A. TETERIN, Kiril E. IVANOV, Tatjana S. LIF[IC, Sergej V. JUDINCEV, Sergej V. STEFANOVSKI, Marija I. LAPINA PROU^AVAWE STRUKTURE KERAMIKA SA SADR@AJEM URANIJUMA RENDGEN-INDUKOVANOM SPEKTROSKOPIJOM Uzorci keramike fluoritne i pirohlorne strukture, (Ca 0.5 GdU 0.5 )Zr 2 O 7 i (Ca 0.5 GdU 0.5 )(ZrTi)O 7, koji su kori{}eni kao matriksi za radioaktivni otpad sa dugo`ive}im radionuklidima visokog nivoa aktivnosti, prou~avani su metodom rendgen-indukovane fotoelektronske spektroskopije. Na osnovu spektroskopskih parametara elektrona u jezgru i u elektronskom omota~u, u opsegu energije veza od 0 ev do 1250 ev, odre ena su oksidaciona stawa prisutnih metalnih jona, ura ena je kvantitativna analiza elemenata i jona i procewena je monofaznost. Postignuti rezultati su u saglasnosti sa rezultatima dobijenim pomo}u rendgenske difrakcije i skeniraju}e elektronske mikroskopije. Kqu~ne re~i: rendgen-indukovana spektroskopija, skeniraju}a elektronska mikroskopija,...molekularne valentne orbite, pirohlor, odlagawe radioaktivnog otpada