Process for producing ferrite single crystals
AssigneeFuji Electrochemical Co., Ltd.
InventorsMichihiro Torii, Utsuo Kihara, Hirohito Goto, Isamu Sasaki
Life of this patent
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Abstract
A new method for preparation of Mn-Zn or Ni-Zn type ferrite single crystals. The ferrite materials are provided in a lower portion of a crucible and completely dissolved. The crucible is moved within a predetermined atmosphere of temperature gradient. A solid which is equilibrium in composition to the ferrite materials is supplied into the crucible while the dissolved ferrite materials are crystallizing from the lower extremity while a liquid-phase zone is maintained constant in depth. Ferrite single crystals of at least about 800 mm in length are grown which are homogeneous in composition throughout their length.
Claims8
A process for producing ferrite single crystals comprising the steps of placing ferrite materials in a lower portion of a crucible, melting the ferrite material completely in a heating zone of a furnace maintained above the solidification temperature of the ferrite to produce a liquid-phase zone of 4 to 15 cm in length, moving said lower portion of the crucible out of the heating zone of the furnace to cause the melted ferrite materials to crystallize progressively from a bottom of said crucible, simultaneously and continuously supplying a rod shaped ferrite solid having a diameter substantially equal to one third the diameter of the crucible into said crucible while the melted ferrite materials are crystallizing with the depth of the liquid-phase zone of melted ferrite being maintained constant, said ferrite solid being substantially in equilibrium in composition to the liquid-phase zone.
Process for producing ferrite single crystals comprising:
- a. supplying a ferrite material into a lower portion of a crucible to be dissolved thereby forming a liquid-phase zone,
- said ferrite material consisting of 52.0 mol percent of Fe.sub.2 O.sub.3, 29.0 mol percent of MnO and 19.0 mol percent of ZnO,
- b. lowering said crucible gradually at a speed of 3 mm/h, below a portion of solidification temperature,
- c. dipping a ferrite rod into said liquid-phase zone immediately after the liquid-phase zone becomes about 40 mm in thickness and a crystalization grows to the length of about 50 mm,
- said ferrite rod consisting of 53.0 mol percent of Fe.sub.2 O.sub.3, 29.0 mol percent of MnO and 18.0 mol percent of ZnO,
- d. lowering continuously and gradually said ferrite rod at a speed corresponding to a speed of the crystallization thereby maintaining the depth of said liquid-phase zone constant.
Dependencies are inferred from the claim text.