Crystallization of mixed rare earth (didymium) molybdates in silica gel

Experiments on the growth of mixed rare earth (didymium—a combination of La, Nd, Pr and Sm) molybdates in silica gel medium are reported. The optimum conditions conducive for the growth of these crystals are described and discussed. Concentration programming is reported to enhance the size of crysta...

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Bibliographic Details
Published inBulletin of materials science Vol. 24; no. 5; pp. 435 - 440
Main Authors Pandita, Sanjay, Tickoo, Ravender, Bamzai, K. K., Kotru, P. N., Sahni, Neera
Format Journal Article
LanguageEnglish
Published Bangalore Springer Nature B.V 01.10.2001
Subjects
Concentration (composition)
Crystal growth
Crystallization
Crystals
Didymium
Materials science
Molybdates
Morphology
Rare earth metals
Silica gel
Spherulites
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Summary:Experiments on the growth of mixed rare earth (didymium—a combination of La, Nd, Pr and Sm) molybdates in silica gel medium are reported. The optimum conditions conducive for the growth of these crystals are described and discussed. Concentration programming is reported to enhance the size of crystals by two-fold; the maximum size obtained being about 1 mm3. EDAX results suggest the crystals to be heptamolybdates of type R2Mo7O24, bearing composition La1.23Nd0.43Pr0.29 Sm0.05Mo7024. The didymium molybdate crystals assume morphologies corresponding to those of spherulites, platelets, cuboids and coalesced crystals. Twinned structure in didymium molybdate crystals are also reported. It is explained that spherulitic morphologies result from aggregates of crystals joining in a spherical envelope. It is suggested that the crystals of didymium molybdates grow by two-dimensional spreading and piling up of layers.
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ISSN:0250-4707
0973-7669
DOI:10.1007/BF02706712