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Title: In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g.while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studiedin situduring the melting and solidification processes with a temporal resolution of 5–7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ~50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (~0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging ofmore » the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging forin situdiagnostics and the optimization of crystal-growth procedures.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7] ;  [3] ;  [3]
  1. Univ. of California, Berkeley, CA (United States). Space Sciences Lab.
  2. Technical Univ. of Denmark, Lyngby (Denmark); European Spallation Source (ESS), Lund (Sweden)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. European Spallation Source (ESS), Lund (Sweden)
  7. Technical Univ. of Denmark, Lyngby (Denmark)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Crystallography (Online)
Additional Journal Information:
Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 49; Journal Issue: 3; Journal ID: ISSN 1600-5767
Publisher:
International Union of Crystallography
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; neutron imaging; non-destructive testing; crystal growth; scintillators; in situ diagnostics
OSTI Identifier:
1378976