Method for the bottom-seeded growth of potassium lead chloride crystals from polycrystalline seeds

A method of growing a single crystal KPb2Cl5 material in a growth furnace comprising an upper zone set at 480° C., said method comprising:

• providing a device comprising an axis, the device comprising a conical plug comprising a first portion defining a first conical hole about the axis, the first conical hole having a first angle, the conical plug comprising a second portion contiguous with the first portion and defining a second conical hole about the axis, the second conical hole having a second angle having the same sign as the first angle and being greater than the first angle, the conical plug comprising a third portion contiguous with the second portion and defining a cylindrical hole;
• the device comprising an upper tube comprising the conical plug fused therein;
• the device comprising a seeding well plug defining a cylindrical bole about the axis;
• the device comprising a lower tube comprising the seeding well plug fused therein, the lower tube being operable to mate with the upper tube such that the conical plug abuts the seeding well plug;
• placing an oriented single crystal KPb2Cl5 seed in the seeding well plug;
• fitting the upper tube over the lower tube;
• filling the upper tube at least part way with KPb2Cl5 powder;
• placing the upper tube and the lower tube in an ampoule;
• melting the KPb2Cl5 powder to generate a melt that wets the single crystal KPb2Cl5 seed;
• freezing the melt;
• and
• growing a single crystal KPb2Cl5 material from the oriented single crystal KPb2Cl5 seed through the first conical hole and then the second conical hole and continuing growth in the upper tube.