The present disclosure relates to advanced materials, particularly single crystal grain structures including the formation of single crystal grain structures. Single crystal grain structures offer improved mechanical properties when used with individual components. Improving mechanical properties is favorable for components that are used in applications with high temperature, pressure, and stress. In these applications, mechanical failure is extremely undesirable. Individual components, such as seals, can be designed with a single crystal grain structure in a preferred direction. By selecting a preferred direction, and orienting the single crystal grain structure accordingly, the single crystal grain structure can improve the component's mechanical properties. Single crystal grain structure seals and the method of forming the seals, therefore, offer various improvements to individual components, specifically when the components are designed for high temperature, pressure, and stress applications.

The present disclosure relates to advanced materials, particularly single crystal grain structures including the formation of single crystal grain structures. Single crystal grain structures offer improved mechanical properties when used with individual components. Improving mechanical properties is favorable for components that are used in applications with high temperature, pressure, and stress. In these applications, mechanical failure is extremely undesirable. Individual components, such as seals, can be designed with a single crystal grain structure in a preferred direction. By selecting a preferred direction, and orienting the single crystal grain structure accordingly, the single crystal grain structure can improve the component's mechanical properties. Single crystal grain structure seals and the method of forming the seals, therefore, offer various improvements to individual components, specifically when the components are designed for high temperature, pressure, and stress applications.

An epitaxial growth substrate on an embodiment includes a non-oriented base material and a buffer layer including a metal chalcogenide on the base material. The metal chalcogenide has uniform crystal orientation on a surface of the buffer layer opposite to the base material side. The buffer layer has a thickness of at least 1.0 m.

A process for casting a single crystal axis-symmetric thick walled tube comprising forming a axisymmetric single crystal ring seed around a circular internal core, wherein the ring seed has an inner diameter and a taper on the inner diameter, and wherein the internal core has an outer diameter and a matching taper on the outer diameter, the matching taper matching the taper of the inner diameter of the ring seed, and the internal core being free to translate in a vertical direction relative to the ring seed; and heating the ring seed so as to expand the ring seed relative to the internal core, and allowing the circular internal core to translate relative to the ring seed in a direction of the force of gravity, thereby maintaining contact between the circular internal core and the ring seed.

A process for casting a single crystal axis-symmetric thick walled tube comprising forming a axisymmetric single crystal ring seed around a circular internal core, wherein the ring seed has an inner diameter and a taper on the inner diameter, and wherein the internal core has an outer diameter and a matching taper on the outer diameter, the matching taper matching the taper of the inner diameter of the ring seed, and the internal core being free to translate in a vertical direction relative to the ring seed; and heating the ring seed so as to expand the ring seed relative to the internal core, and allowing the circular internal core to translate relative to the ring seed in a direction of the force of gravity, thereby maintaining contact between the circular internal core and the ring seed.

An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

A method and apparatus for measuring a melt back of a seed in a boule are provided. The method includes lifting a boule once it has been produced using an actuating device onto a support table to automatically manipulate the boule from a furnace to the support table. The melt back of the seed is then automatically measured using a vision system that is installed on an imaging device disposed below the boule.

A method and apparatus for measuring a melt back of a seed in a boule are provided. The method includes lifting a boule once it has been produced using an actuating device onto a support table to automatically manipulate the boule from a furnace to the support table. The melt back of the seed is then automatically measured using a vision system that is installed on an imaging device disposed below the boule.

A casting method includes: forming a seed, the seed having a first end and a second end, the forming including bending a seed precursor; placing the seed second end in contact or spaced facing relation with a chill plate; contacting the first end with molten material; and cooling and solidifying the molten material so that a crystalline structure of the seed propagates into the solidifying material. The forming further included reducing a thickness of the seed proximate the first end relative to a thickness of the seed proximate the second end.