- Email: [email protected]
The growth of LaAlO3 crystals enriched in isotope 17O
Journal of Crystal Growth 47 (1979) 315—316 © North-Holland Publishing Company
LETTER TO THE EDITORS THE GROWTH OF LaAIO3 CRYSTALS ENRICHED IN ISOTOPE’ ~O S.H. SMITH and P.J. WALKER Clarendon Laboratory, Oxford University, Oxford, England Received 19 April 1979 170-enriched, were obtained g melt. PbO enriched in isotope 170 was prepared andfrom used,a 23 with PbF2, for the flux growth of Cr~doped LaA1O3. Crystals up to 5 mm in width, 5.1%
LaA1O 3 crystals enriched in the oxygen isotope
Miles—Yeda Ltd. The method had to be modified 7O-enriched PbO. Finely-divided slightly to obtain 1 lead, freshly reduced with hydrogen, was found to react very slowly with oxygen, and the metal particles became covered with a surface layer of oxide which prevented further reaction. This problem was over-
170 are of interest for EPR studies [1], and the flux growth of small crystals, together with details of the apparatus, has been described [2]. The 70-enrichment in the crystals was, however, appreciably less than that in the constituent oxides because the PbO PbF 2 flux was not enriched 70-enriched in 1 ~O. This PbOletter and describes 1 the growththeof preparation more highly ofenriched LaA1O 3 crystals from a different flux composition which yields larger crystals. 70-enriched oxides by direct The production of ‘ oxygen and the metals has reaction between enriched been reported previously [3]. La 203 was prepared
come by using pyrophoric which was prepared from lead tartrate (obtainedlead, from aqueous solutions of lead nitrate and potassium tartrate) by decomposition in vacuum at 200°C.The pyrophoric lead, which was a veryoxygen finely-divided form, reacted heating rapidly with in enriched at 200—300°C.Further to 800°Censured complete reaction. 7O-enriched PbO, 8.9 g BDH A mixture of 12.1 g ‘
$~
using this method, but Al
203 was obtained from
Optran grade PbF2, 1.7 g La203 and 0.6 g Al203,
~mm
3~doped crystals of LaAIO
Fig. 1. Cr
3 enriched in
315
~
~oisotope from a 23
g melt.
316
S.H. Smith, P.J. Walker! Growth of LaA1
both enriched ‘~O were placed in a Johnson 3 in“electropure” platinum crucible.MatAs they 10 cm dopant 9 mg Specpure Cr 203 was added and the crucible was covered by a tightly-fitting lid. The crucible was inserted into a platinum tube which formed part of a gas-tight enclosure, as described previously oxy[2], 170-enriched and was an atmosphere nitrogen and tube was heated in gen introduced.ofThe platinum a tube furnace until the crucible reached 1270°Cand, after a soak period of 7 h, was cooled to 1050°Cat I Kh’. It was then cooled at 200 Kh~ to room temperature. Tabular Cr3~doped LaA1O 3 crystals up to 5 mm in width were produced (as shown in fig. 1) and vacuum fusion analysis [3] showed that these contamed 5.1% 170 The crystals obtained from a flux containing a higher proportion of PbO than reported earlier [2], were considerably larger than those was ob70-enrichment tamed previously and the ‘
3 crystals enriched in isotope
1
increased yield of 100% wasItobtamed as by the 89%. flux A hadcrystal completely evaporated. is proposed to increase the enrichment further in future work by using more highly enriched oxides. Measurements on the crystals will be reported elsewhere. The authors wish to thank Mrs. B.M. Wanklyn for helpful discussions and Mr. R. Ward for vacuum fusion analysis. P.J.W. thanks the S.R.C. for continuing support.
References [1] J. Owen and T. Thornley, Rept. Progr. Phys. 29 (1966) 675. [2] G. Garton,B.F. Hann,B.M.Wanklyn and S.H. Smith, J. [3] G. 545.Garton and P.J. Walker, Mater. Res. Bull. 11(1976)
LETTER TO THE EDITORS THE GROWTH OF LaAIO3 CRYSTALS ENRICHED IN ISOTOPE’ ~O S.H. SMITH and P.J. WALKER Clarendon Laboratory, Oxford University, Oxford, England Received 19 April 1979 170-enriched, were obtained g melt. PbO enriched in isotope 170 was prepared andfrom used,a 23 with PbF2, for the flux growth of Cr~doped LaA1O3. Crystals up to 5 mm in width, 5.1%
LaA1O 3 crystals enriched in the oxygen isotope
Miles—Yeda Ltd. The method had to be modified 7O-enriched PbO. Finely-divided slightly to obtain 1 lead, freshly reduced with hydrogen, was found to react very slowly with oxygen, and the metal particles became covered with a surface layer of oxide which prevented further reaction. This problem was over-
170 are of interest for EPR studies [1], and the flux growth of small crystals, together with details of the apparatus, has been described [2]. The 70-enrichment in the crystals was, however, appreciably less than that in the constituent oxides because the PbO PbF 2 flux was not enriched 70-enriched in 1 ~O. This PbOletter and describes 1 the growththeof preparation more highly ofenriched LaA1O 3 crystals from a different flux composition which yields larger crystals. 70-enriched oxides by direct The production of ‘ oxygen and the metals has reaction between enriched been reported previously [3]. La 203 was prepared
come by using pyrophoric which was prepared from lead tartrate (obtainedlead, from aqueous solutions of lead nitrate and potassium tartrate) by decomposition in vacuum at 200°C.The pyrophoric lead, which was a veryoxygen finely-divided form, reacted heating rapidly with in enriched at 200—300°C.Further to 800°Censured complete reaction. 7O-enriched PbO, 8.9 g BDH A mixture of 12.1 g ‘
$~
using this method, but Al
203 was obtained from
Optran grade PbF2, 1.7 g La203 and 0.6 g Al203,
~mm
3~doped crystals of LaAIO
Fig. 1. Cr
3 enriched in
315
~
~oisotope from a 23
g melt.
316
S.H. Smith, P.J. Walker! Growth of LaA1
both enriched ‘~O were placed in a Johnson 3 in“electropure” platinum crucible.MatAs they 10 cm dopant 9 mg Specpure Cr 203 was added and the crucible was covered by a tightly-fitting lid. The crucible was inserted into a platinum tube which formed part of a gas-tight enclosure, as described previously oxy[2], 170-enriched and was an atmosphere nitrogen and tube was heated in gen introduced.ofThe platinum a tube furnace until the crucible reached 1270°Cand, after a soak period of 7 h, was cooled to 1050°Cat I Kh’. It was then cooled at 200 Kh~ to room temperature. Tabular Cr3~doped LaA1O 3 crystals up to 5 mm in width were produced (as shown in fig. 1) and vacuum fusion analysis [3] showed that these contamed 5.1% 170 The crystals obtained from a flux containing a higher proportion of PbO than reported earlier [2], were considerably larger than those was ob70-enrichment tamed previously and the ‘
3 crystals enriched in isotope
1
increased yield of 100% wasItobtamed as by the 89%. flux A hadcrystal completely evaporated. is proposed to increase the enrichment further in future work by using more highly enriched oxides. Measurements on the crystals will be reported elsewhere. The authors wish to thank Mrs. B.M. Wanklyn for helpful discussions and Mr. R. Ward for vacuum fusion analysis. P.J.W. thanks the S.R.C. for continuing support.
References [1] J. Owen and T. Thornley, Rept. Progr. Phys. 29 (1966) 675. [2] G. Garton,B.F. Hann,B.M.Wanklyn and S.H. Smith, J. [3] G. 545.Garton and P.J. Walker, Mater. Res. Bull. 11(1976)