The procedure of measuring the diffusion profiles of Cerium by means of a proton microprobe was developed.

These profiles in the synthetic aluminosilicate matrix synthesized on the base of kaolin and red granite were

measuredВідпрацьованo методику виміру дифузійних профілів Ce за допомогою протонного мікрозонда і

проведено вимірювання таких профілів у синтетичній алюмосилікатній матриці, синтезованої на основі

каоліну і червоного граніту.Отработана методика измерения диффузионных профилей Ce с помощью протонного микрозонда и

проведено измерение таких профилей в синтетической алюмосиликатной матрице, синтезированной на

основе каолина и красного гранит

Bondarenko, V.N.

Goncharov, A.V.

Kuz’menko, V.V.

Pistryak, V.M.

Saenko, S.Yu.

Sukhostavets, V.I.

Surkov, A.E.

Наукова електронна бібліотека періодичних видань НАН України (Vernadsky National Library of Ukraine)

APPLICATION OF A PROTON MICROPROBE TO STUDY DIFFUSION PROFILES OF Ce IN SYNTHETIC ALUMINOSILICATESV.N. Bondarenko, A.V. Goncharov, V.V. Kuz’menko, V.M. Pistryak,S.Yu. Saenko, V.I. Sukhostavets, A.E. Surkov National Science Center “Kharkov Institute of Physics and Technology”,Institute of Solid State Physics, Materials Science and Technologies, Kharkov, Ukrainee-mail: goncharov@kipt.kharkov.uaThe procedure of measuring the diffusion profiles of Cerium by means of a proton microprobe was developed. These  profiles  in  the  synthetic  aluminosilicate  matrix  synthesized  on  the  base  of  kaolin  and  red  granite  were measured.PACS: 29.27.-a, 61.72.ss1. INTRODUCTIONThe methods of nuclear physics are widely applied for  investigation  of  materials  on  accelerated  particle beams. In the present work these methods were used to study glass ceramics, which can be applied for disposal of radioactive waste (RAW).Development  of  nuclear  power  in  Ukraine  is accompanied by the RAW accumulation. According to the  forecasts  for  2025  a  total  volume of  RAW to be stored in Ukraine will be approximately 70000 m3 [1]. In  this  connection  in  Ukraine  a  conception  for construction of a geological RAW depository has been adopted.  Before  disposal  of  high-level  radioactive wastes into the underground depository it is necessary to reprocess  wastes with subsequent their  immobilization in the matrix from a material based on natural rocks.For immobilization of high-level RAW it is intended to apply synthetic aluminosilicates (glass ceramics) as a promising material. Long-term forecasting of the rate of radioactive  element  release  from  the  geological depository  with  the  use  of  such  materials  requires carring  out  studies  on  the  processes  of  radionuclide diffusion  and  migration  in  synthetic  aluminosilicates. Generally, for such investigations Cerium is used as an actinide imitator. In paper  [2] the diffusion profiles of Cerium in glass ceramics were measured by sequential removal  of  layers  from  the  material  sample  with measuring the gamma-spectra from the material of each layer after gamma-activation.There  are  available  also  other  methods  of  profile measuring deeply  in  the  depth  (tens  and  hundreds  of microns). In particular, the investigations can be carried out by means of a microprobe (see, for example, [3-8]).The  goal  of  the  present  work  is  to  develop  the procedure of measuring the diffusion profiles of Cerium by means of a proton microprobe and to measure these profiles  in  the  synthetic  aluminosilicate  matrix synthesized on the base of kaolin and red granite.2. MATERIALS AND METHODS The  procedure  of  sample  preparation  for investigations consists in the following. The samples of granite  and  kaolin  were  milled  in  the  mechanical vibratory mill to obtain a  powder with a  particle  size less  than  40 µm. The  weighted  powder  samples  were filled  into  the  press-mould.  The  press-mould  and  the movable  dies  were  made of  graphite.  To  prevent  the interaction  between  the  material  of  the  filler  and  the material  of  the  crucible  the  latter  was  lined  with  a molybdenum  foil.  After  that,  the  powder  filler  was subjected  to  vibrational  compaction  on  the  vibration-testing  machine  and  to  pressing  at  room temperature under pressure of 40 MPa. Sintering of samples under pressure was realized by direct  passing of the electric current  through  the  press-mould.  Hot  pressing  was carried out at a temperature of 1050°C under pressure of 40 MPa. The treatment duration was 15 min.The  aluminosilicate  samples  were  obtained  in  the form  of  a  pellet.  The  material  density  was  2.5…2.7 g/cm3. By the same method using the CeO2 powder we sintered a pellet of the imitator material containing Cerium,  i.e.  the  element  imitating  Uranium  and transuranium  elements  when  studying  their  mass transfer. For simulation of the processes of mass transfer two pellets  (of  aluminosilicate  and  material-imitator)  were placed  in  interior  of  the  metallic  capsule  where  they were brought into close contact with polished surfaces. The  capsules  were sealed  by the electric  welding and after  subjected  to  the  gasostatic  pressing  at  a temperature of 920°C during 30 min. After treatment in the gasostatic press these capsules with  the  pellets  of  aluminosilicate  and  cerium oxide were  annealed  in  the  temperature  range  from 600  to 750°C  in  vacuum  during  10  hours.  As  a  result  of annealing some amount of Ce from Cerium oxide pellet were migrating throught the interface into the depth of 114 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2005, № 6.Series: Nuclear Physics Investigations (45), p. 114-116.the aluminosilicate  pellet.  The  pellets were drawn out from the pressed  capsule with the  help of  a  diamond tool. Then the pellets were separated and cleaved in the direction  transversal  to  the  former  interface  of  the pellets.To  measure  the  diffusion distribution of  Cerium a proton  microprobe  based  on  the  duplet  of  magnetic quadrupole  lenses  [9,10]  and  an  X-ray  spectrometer were  used.  A 10-micron  proton  beam with energy of 1.8 MeV and a current of 2 nA was applied.Beam  monitoring  was  performed  by  counting  of protons  backscattered  from  the  target  periodically overlapping the beam of protons (interruption frequency was  of  about  1 s-1).  The  monitoring  unit  was  placed between the diaphragms of the collimator forming the beam  before  the  port  into  the  duplet  of  magnetic qudrupole  lenses.  The  X-ray  spectra  were  measured using  the  detector  made  of  high-pure  germanium of BDRG-05165  type  (product  of  the  firm  “Baltic Scientific Instruments”).The  detector  was  arranged  at  an  angle  of  135° relatively to the beam direction. The distance from the sample to the detector was 20 mm.The  spectrometric  path  was  chosen  basing  on standard  modules  “VECTOR”.  The  resolution  of  the spectrometer was 155 eV along the Mn Kα line. Spectra were  recorded  by  the  computer-added  spectrometric amplitude-digital  converter  ADC-8K-B2  produced  by the firm “Aspect”.The  profile  of  Cerium  distribution  in  the aluminosilcate  matrix  was  measured  by  moving discretely the microprobe beam in the direction of the transverse  cleavage  of  the  surface  from  the  former interface  into  the  depth  of  the  pellet  material.  After beam extraction into the given point of cleavage the X-ray  spectrum  was  measured.  A  similar  technique  of profile measurement was applied earlier in works [3,4]. In  this  case  the  Cerium  concentration  at  the corresponding  depth,  counted  from  the  separation surface, was determined along the Ce Lβ line. A pellet of compacted Cerium oxide was used as a standard. Fig. 1  demonstrates  the  cleavage  surface  of  the aluminosilicate sample and the area of measurement of local Cerium concentrations. Fig. 1.  1 - the  cleavage  surface  of  the  alumino-silicate  sample  (×5).  2 - the  area  of  measurement  of  local Cerium concentrations3. DISCUSSION OF RESULTSFig. 2  shows  the  characteristic  X-ray  spectrum obtained  from  the  cleavage  surface  of  the aluminosilicate pellets after separating it from the pellet-imitator  of  CeO2.  In  the  spectrum  observed  are  the characteristic lines of such elements as Cl, K, Ca, Ti and Fe contained in the composition of the initial matrix, and the lines of Cerium diffused into aluminosilicate from the imitator material.50 100 150 200050010001500Cl KCe LβCe Lα+Ti KβTi KαFe KβFe KαCa KαK KβK KαCountsChannel numberFig. 2. The characteristic X-ray spectrum obtained  from the aluminosilicate pelletThe  diffusion  profile  of  Cerium  in  the aluminosilicate matrix measured with help of the proton microprobe is presented in Fig. 3.0 50 100 150 200 2500,0000,0050,0100,0150,0200,0250,0300,0350,040Profile of Ce in AlSi matrixContent of Ce, %, mas.Depth, µ mFig. 3. Distribution  of  Ce  in  the  aluminosilicate  matrix  (annealing  temperature 700°C,  annealing time 300 hs). Points -experimental data, solid line - result of  smoothingFrom the distribution obtained it can be concluded that  the  maximum  content  of  Cerium  in  the aluminosilicate matrix subjected to diffusion annealing is  approximately  0.03%, mas.  The  depth  of  Cerium penetration  into  the  matrix  is  of  about  130 µm. At  a depth of 150 µm the content of Cerium decreases up to the level of 0.003%, mas. Evidently, such a content of 1115Cerium  is  characteristic  for  the  initial  material  of aluminosilicate, as this level is remained at a depth more than 200 µm. 4. CONCLUSIONSThe  investigations  have  shown  that  a  proton microprobe  can  be  a  useful  tool  for  measuring  the concentration  profiles  of  imitators  of  actinides  in materials being applied for immobilization of actinides. One  of  its  advantages  is  that  the  profiles  can  be measured practically at an unlimited depth. It is reached by the microbeam scanning over the transverse cleavage surfaces of samples under study.The developed technique also can be easily applied for  investigation  of  migration  processes  of  such elements as Strontium, Iodine, Cesium and Uranium into the depth of synthetic aluminosilicate saples.REFERENCES1. Yu.A. Shibetsky  Preliminary  estimation  of  the volume of a geological repository  for isolation  of  high-level  and  long-living  RAW  of  Ukraine. Theses  of  VI  Conference  of  International Chernobyl  Center  International  co-operation  for Chernobyl, 2003, p. 29 (in Russian).2. J.S. Azhazha,  S.V. Gabelkov,  N.P. Dikij, V.I. Zmij,  Yu.V. Lyashko,  E.P. Medvedeva, I.M. Neklyudov,  S.Yu. Saenko,  A.E. Surkov, R.V. Tarasov, V.L. Uvarov, G.A. Kholomeev.  The methods of determining the effective coefficients of  radionuclide diffusion in a glass ceramic material  for  isolation  of  high-level  radioactive  waste. Proceeding  of  XVI  International  Conference  on Radiation Physics and Radiation Materials Science, 2004, p. 230-231 (in Russian).3. V.N. Bondarenko,  A.V. Goncharov, V.Y. Kolot,  V.I. Sukhostavets.  Investigation  of  F and Ta distribution profiles in W-Ta coatings by a nuclear microprobe //  Surface Investigation. 2000, v. 15, p. 727-732.4. V.N. Bondarenko,  A.V. Goncharov, V.I. Zmij,  V.Ya. Kolot,  S.G. Rudenky, V.I. Sukhostavets. The investigation of a transition layer  of  Chromium-Graphite  by  a  nuclear microprobe  //  Surface  Investigation.  2001,  v. 16, p. 771-774.5. R.A. Brown, G.R. Johnston. Application of a microbeam to study of high-temperature oxidation of  a  comlex  multiphase  alloy  //  Nuclear Instruments  and  Methods  in  Physics  Research.  1991, v. B54, p. 264-268.6. E. Rokita,  T. Cichocki,  S. Divoux.  Proton microprobe  studies  of  mineralzation  process  in selected  organic  matrices  //  Nuclear  Instruments  and  Methods  in  Physics Research.  1990,  v. B50, p. 217-220.7. O. Decroupter,  G. Demortier.  PIXE microprobe  studies  of  gold-cadmium  alloys processed by local diffusion // Nuclear Instruments and  Methods  in  Physics  Research.  1990,  v. 191, p.379-382.8. C.J. Sofied,  L.B. Bridwell,  C.J. Wright. Microbeam analysis of hydrogen in coked catalyst pellets  //  Nuclear  Instruments  and  Methods  in  Physics Research. 1981, v. B49, p. 501-504.9. V.N. Bondarenko,  A.V. Goncharov, V.Y. Kolot, V.I. Sukhostavets Nuclear microprobe facility.  Proc  of  XII  International  Conference  on Electrostatic Accelerators, 1997, p. 86-89.10. V.N. Bondarenko,  A.V. Goncharov, V.Y. Kolot.  Development  of  NSC  KIPT  nuclear microprobe  //  Problems  of  Atomic  Science  and  Technology.  Series:  Nuclear Physics Investigations. 1999, №4(35), p. 98-101.ПРИМЕНЕНИЕ ПРОТОННОГО МИКРОЗОНДА ДЛЯ ИССЛЕДОВАНИЯ ПРОФИЛЕЙ ДИФФУЗИИ Се В СИНТЕТИЧЕСКИХ АЛЮМОСИЛИКАТАХВ.Н. Бондаренко, А.В. Гончаров, В.В. Кузьменко, В.М. Пистряк, С.Ю. Саенко, В.И. Сухоставец, А.Е. Сурков Отработана  методика  измерения  диффузионных  профилей  Ce с  помощью  протонного  микрозонда  и проведено  измерение  таких  профилей  в  синтетической  алюмосиликатной  матрице,  синтезированной  на основе каолина и красного гранита.ЗАСТОСУВАННЯ ПРОТОННОГО МІКРОЗОНДА ДО ДОСЛІДЖЕННЯ ПРОФІЛІВ ДИФУЗІЇ Се У СИНТЕТИЧНИХ АЛЮМОСИЛІКАТАХВ.М. Бондаренко, О.В. Гончаров, В.В. Кузьменко, В.М. Пістряк, С.Ю. Саєнко, В.І. Сухоставець, О.Є. Сурков Відпрацьованo методику  виміру  дифузійних  профілів  Ce за  допомогою  протонного  мікрозонда  і проведено  вимірювання  таких профілів  у синтетичній  алюмосилікатній  матриці,  синтезованої  на  основі каоліну і червоного граніту.1116

Application of a proton microprobe to study diffusion profiles of Ce in synthetic aluminosilicates

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Application of a proton microprobe to study diffusion profiles of Ce in synthetic aluminosilicates

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