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Crystal Growth of Mg 2 SiO 4 and MgSiO 3 Single Crystals by the Flux Method
Author(s) -
Ushio Masumi,
Kobayashi Nobuo,
Suzuki Miyoko,
Sumiyoshi Yoshihiro
Publication year - 1991
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1991.tb07155.x
Subject(s) - forsterite , tridymite , flux (metallurgy) , analytical chemistry (journal) , crystal (programming language) , materials science , flux method , crystallite , mineralogy , alkali metal , tungstate , crystal growth , crystallography , single crystal , cristobalite , chemistry , metallurgy , quartz , organic chemistry , chromatography , computer science , programming language
Single crystals of Mg 2 SiO 4 and MgSiO 3 have been synthesized by the evaporation‐aided slow‐cooling flux method. Acidic oxides such as V 2 O 5 , MoO 3 , and WO 3 were used as the flux, and alkali metallic oxides or calcium oxides were added to the MoO 3 and WO 3 as flux modifiers. The starting mixture was first held at 1400°C and then slow cooled to 1000°C at a rate of 10 C/h. The temperature difference between the upper and lower limits of the melt was ∼25°C. Using an Li 2 O─MoO 3 system flux with an Li 2 O:MoO 3 ratio of 1:2 produces a polycrystalline clinoenstatite with a 9‐mm crystal size; a 1:1 ratio, however, results in forsterite crystals of 90‐μm size. The metallic oxides (Na 2 O and K 2 O) as flux modifiers produce forsterite with a crystal size of 65 and 40 μm, respectively. Similar results are observed when a Li 2 O─WO 3 flux is used. Enstatite (10‐mm size) and forsterite (1.6‐mm size) are produced when the Li 2 O:WO 3 ratios are 1:2 and 1:1, respectively. A V 2 O 5 or CaO·WO 3 flux produces no forsterite. The V 2 O 5 flux results in tridymite as a primary phase, whereas calcium and magnesium tungstate were grown from a CaO·WO 3 flux. The forsterite single crystals are tabular in form, generally bounded by the planes (001), (100), (010), (110), and (021), and are transparent. The enstatite consists of an aggregation of individual single crystals. The refractive indexes of the forsterite are α= 1.636 ± 0.001, β= 1.653 ± 0.001, and γ= 1.671 ± 0.001 (20°C).