Extreme synthesis of crystalline aerogel materials from amorphous aerogel precursors

Abstract

In one embodiment, a system includes a pressure cell adapted for enclosing a porous structure; an inert pressure medium within the pressure cell; and a heat source for heating the porous structure. In another embodiment, a composition of matter includes a crystalline porous structure having a density of about 30 to about 50 mg/cm 3 . A method according to one embodiment includes positioning an amorphous porous structure in a pressure cell; injecting an inert pressure medium within the pressure cell; and pressurizing the pressure cell to a pressure that thermodynamically favors a crystalline phase of the porous structure over an amorphous phase of the porous structure to transition the amorphous porous structure into a crystalline porous structure. Additional embodiments are also presented.

1 . A system, comprising:
 a pressure cell adapted for enclosing a porous structure;   an inert pressure medium within the pressure cell; and   a heat source for heating the porous structure.   
     
     
         2 . The system as recited in  claim 1 , wherein the pressure cell is a diamond anvil cell, the diamond anvil cell comprising:
 a gasket having a front side and a back side;   a first diamond having at least one flat, smooth face; and   a second diamond having at least one flat, smooth face,   wherein the at least one flat, smooth face of the first diamond has a surface area greater than a surface area of the front side of the gasket and is capable of completely covering a perimeter of the front side of the gasket,   wherein the at least one flat, smooth face of the second diamond has a surface area greater than the surface area of the front side of the gasket and is capable of completely covering a perimeter of the back side of the gasket,   wherein the flat, smooth face of the first diamond is in contact with the front side of the gasket, and   wherein the flat, smooth face of the second diamond is in contact with the back side of the gasket.   
     
     
         3 . The system as recited in  claim 2 , wherein the first diamond and the second diamond are ultralow fluorescence diamonds. 
     
     
         4 . The system as recited in  claim 1 , wherein the heat source is a laser. 
     
     
         5 . The system as recited in  claim 4 , wherein the inert pressure medium has a low photon absorption cross section at an operational wavelength and intensity of the laser and low chemical reactivity with the porous structure such that chemical reactions and background absorption are reduced during heating of the porous structure at high pressure. 
     
     
         6 . The system as recited in  claim 1 , wherein the inert pressure medium comprises supercritical neon gas. 
     
     
         7 . The system as recited in  claim 1 , wherein the inert pressure medium comprises at least one of: neon gas, argon gas, helium gas, krypton gas, xenon gas, and carbon dioxide gas. 
     
     
         8 . The system as recited in  claim 1 , wherein the porous structure comprises a carbonized resorcinol-formaldehyde aerogel that has a specific density of about 30 to 50 mg/cm 3 . 
     
     
         9 . The system as recited in  claim 1 , wherein the porous structure comprises one of: amorphous silica aerogel, amorphous alumina aerogel, and amorphous titania aerogel. 
     
     
         10 . A composition of matter, comprising:
 a crystalline porous structure having a density of about 30 to about 50 mg/cm 3 .   
     
     
         11 . The composition of matter as recited in  claim 10 , wherein the porous structure comprises carbonized resorcinol-formaldehyde aerogel that has a specific density of about 40 mg/cm 3 . 
     
     
         12 . The composition of matter as recited in  claim 10 , wherein the crystalline porous structure comprises one of: silica aerogel, alumina aerogel, and titania aerogel. 
     
     
         13 . The composition of matter as recited in  claim 10 , wherein the crystalline porous structure has characteristics of being phase-transitioned from an amorphous porous structure. 
     
     
         14 . The composition of matter as recited in  claim 10 , further comprising one or more dopant elements. 
     
     
         15 . The composition of matter as recited in  claim 10 , wherein the one or more dopant elements comprise dopant elements that impart at least one of: optical and electrical properties to the porous structure. 
     
     
         16 . A method, comprising:
 positioning an amorphous porous structure in a pressure cell;   injecting an inert pressure medium within the pressure cell; and   pressurizing the pressure cell to a pressure that thermodynamically favors a crystalline phase of the porous structure over an amorphous phase of the porous structure to transition the amorphous porous structure into a crystalline porous structure.   
     
     
         17 . The method as recited in  claim 16 , further comprising heating the amorphous porous structure to accelerate transition to the crystalline phase and to overcome a corresponding phase change barrier. 
     
     
         18 . The method as recited in  claim 17 , wherein a laser is selectively applied according to a user-defined pattern to heat one or more selected regions of the amorphous porous structure. 
     
     
         19 . The method as recited in  claim 17 , wherein the amorphous porous structure is heated to a temperature of greater than about 500° C. 
     
     
         20 . The method as recited in  claim 16 , further comprising returning the pressure and temperature in the pressure cell to ambient conditions. 
     
     
         21 . The method as recited in  claim 16 , wherein the amorphous porous structure comprises one of silica aerogel, alumina aerogel, and titania aerogel. 
     
     
         22 . The method as recited in  claim 16 , wherein the amorphous porous structure is an aerogel of carbonized resorcinol-formaldehyde that has a specific density of about 30 to 50 mg/cm 3 . 
     
     
         23 . The method as recited in  claim 16 , wherein the amorphous porous structure comprises carbon aerogel and has a specific density of about 40 mg/cm 3 . 
     
     
         24 . The method as recited in  claim 16 , wherein the inert pressure medium conformally and homogeneously occupies a void volume of the pressure cell and a void volume of pores of the amorphous porous structure without disturbing pore morphology of the amorphous porous structure. 
     
     
         25 . The method as recited in  claim 16 , wherein the pressure cell is pressurized to a pressure of about 21×10 9  Pa, wherein the amorphous porous structure comprises an amorphous-phase carbonized resorcinol-formaldehyde aerogel. 
     
     
         26 . The method as recited in  claim 16 , wherein the inert pressure medium comprises at least one of: neon gas, argon gas, helium gas, krypton gas, xenon gas, and carbon dioxide gas.