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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 9
BKCSDE 19(9)
September 20, 1998 

The Synthesis of Vanadium-Doped Forsterite by the H2O2-Assisted Son-Gel Method, and the Growth of Single Crystals of Vanadium-Doped Forsterite by the Floating Zone Method
Dong Gon Park, Mikio Higuchi, Rudiger Dieckmann, James M. Burlitch
Polycrystalline powder of vanadium-doped forsterite (Vδ Mg2SiO4) was synthesized by the H2O2-assisted sol-gel method. The vanadium dopant, which was added as VO(OMe)3 in methanol, went through several redox reactions as the sol-gel reaction proceeded. Upon adding VO(OMe)3 to a mixture of Mg(OMe)2 and Si(OEt)4 in methanol, V(V) reduced to V(IV). As hydrolysis reaction proceeded, the V(IV) oxidized all back to V(V). Apparently, some of the V(V) reduced to V(IV) during subsequent gelation by condensation reaction. The V(IV) remained even after heat treatment of the gel in highly oxidizing atmosphere. The crystallization of the xerogel around 880 ℃ readily produced single phase forsterite without any minor phase. Using the polycrystalline powder as feeding stock, single crystals of vanadium-doped forsterite were grown by the floating zone method in oxidizing or reducing atmosphere. The doping was limited in low level because of the high partitioning of the vanadium in liquid phase during melting. The greenish single crystal absorbed visible light of 700∼1100 nm. But, no emission was obtained in near infrared range.
927 - 933
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