Crystal growth system and method for lead-contained compositions using batch auto-feeding
This invention includes a system and a method for growing crystals including a batch auto-feeding mechanism. The proposed system and method provide a minimization of compositional segregation effect during crystal growth by controlling growth rate involving a high-temperature flow control system operable in an open and a closed loop crystal growth process. The ability to control the growth rate without corresponding loss of volatilize-able elements enables significantly improvement in compositional homogeneity and a consequent increase in crystal yield. This growth system and method can be operated in production scale, simultaneously for a plurality of growth crucibles to further the reduction of manufacturing costs, particularly for the crystal materials of binary or ternary systems with volatile components, such as Lead (Pb) and Indium (In).
1. A method of operating a crystal growth system, for growing a crystalline material, comprising the steps of:
providing a furnace system containing at least a high-temperature melting zone and a sub-high temperature crystal growth zone;
said high-temperature zone having a temperature growth gradient transition range including a liquidus/solidus temperature transition of said crystalline material;
said crystalline material including a PMN-PT-based material;
providing a melting crucible in said high-temperature melting zone containing a melted batch of said crystalline material;
providing a crystal growth crucible in said sub-high temperature zone;
providing a melt conduit extending from said melting crucible to said crystal growth crucible for transferring said melted batch melt;
providing control means for controlling a growth rate of said crystalline material in said crystal growth crucible;
providing positioning means in said control means for moving at least said crystal growth crucible relative to said sub-high temperature zone to maintain said growth rate and said temperature growth gradient transition range relative to a growth of said crystalline material during a use of said system; and
providing at least one of a thermal valve means in said control means for thermally controlling said transfer of said melted batch along said melt conduit and a fluid control means in said control means for fluidly controlling said transfer of said melted batch along said melt conduit, whereby said at least one of said thermal valve means and said fluid control means enables an improved composition control by said growth rate.
2. The method, according to claim 1 , wherein:
said PMN-PT based material includes a composition selected from at least one of the following formulas:
Pb(Mg 1/3 Nb 2/3 ) 1-x Ti x O 3 (VII)
wherein x is defined as molar % 0.00 to 0.50,
and,
(1- y )Pb(Mg 1/3 Nb 2/3 ) 1-x Ti x O 3 +yPb(R 1/2 Nb 1/2 )O 3 (VIII)
wherein x is defined as molar % 0.00 to 0.50,
y is defined as molar % 0.00 to 0.35, and R is selected from at least one element of Bi, Fe, Sc, Yb, In, Co, and Zr, and a combination of the of the above elements.
3. The method, according to claim 2 , further comprising:
at least one crystal seed in said crystal growth crucible; and
said at least one crystal seed has an orientation including at least one of a <001>, <110>, and a <111> orientation.
4. The method, according to claim 3 , wherein:
said crystalline material produced according to said method has a depoling temperature of greater than 90° C. in use.