Crystal Growth Atmosphere For Oxyorthosilicate Materials Production

Abstract

A method of growing a rare-earth oxyorthosilicate crystal, and crystals grown using the method are disclosed. The method includes preparing a melt by melting a first substance including at least one first rare-earth element and providing an atmosphere that includes an inert gas and a gas including oxygen.

1 . A method of growing a rare-earth oxyorthosilicate crystal, comprising: preparing a melt by:
 melting a first substance comprising at least one first rare-earth element;   melting at least one of: a substance comprising a group 2 element, a substance comprising a group 3 element, a substance comprising a group 6 element, or a substance comprising a group 7 element;   providing an atmosphere comprising an inert gas and a gas including oxygen, the atmosphere being in contact with a surface of the melt;   providing a seed crystal;   contacting the surface of the melt with the seed crystal; and   withdrawing the seed crystal from the melt.   
     
     
         2 . The method of  claim 1 , wherein the gas including oxygen comprises an oxygen-containing compound that disassociates to oxygen. 
     
     
         3 . The method of  claim 1 , wherein the inert gas has a thermal conductivity less than or equal to 150 mW/m−° K at the temperature used during crystal growth. 
     
     
         4 . The method of  claim 1 , wherein the gas including oxygen comprises carbon dioxide. 
     
     
         5 . The method of  claim 1 , wherein the gas including oxygen comprises at least one of carbon monoxide, oxygen, sulfur trioxide, phosphorous pentoxide or an oxide of nitrogen. 
     
     
         6 . The method of  claim 1 , wherein the oxide of nitrogen comprises at least one of NO 2 , N 2 O, NO, N 2 O 3 , or N 2 O 5 . 
     
     
         7 . The method of  claim 1 , wherein the atmosphere comprises 0.01-10 percent oxygen by volume, inclusive. 
     
     
         8 . The method of  claim 1 , wherein the atmosphere comprises less than 300 parts per million of oxygen. 
     
     
         9 . The method of  claim 1 , wherein the atmosphere comprises less than 200 parts per million of oxygen. 
     
     
         10 . The method of  claim 9 , wherein the inert gas comprises at least one of helium, argon, krypton, or xenon. 
     
     
         11 . The method of  claim 9 , wherein the inert gas comprises nitrogen. 
     
     
         12 . The method of  claim 1 , further comprising melting a second substance comprising a second rare-earth element, the second rare-earth element being incorporated into the rare-earth oxyorthosilicate crystal as a dopant. 
     
     
         13 . The method of  claim 12 , wherein the second rare-earth element is cerium. 
     
     
         14 . The method of  claim 1 , wherein the growing of the oxyorthosilicate crystal comprises growing a lutetium oxyorthosilicate crystal. 
     
     
         15 . A method of decreasing oxygen vacancies incorporated in a rare-earth oxyorthosilicate crystal, the method comprising:
 preparing a melt by melting a first substance comprising at least one first rare-earth element;   providing an atmosphere comprising an inert gas and a gas including oxygen, the atmosphere including less than 300 ppm oxygen, the atmosphere being in contact with a surface of the melt;   providing a seed crystal;   contacting the surface of the melt with the seed crystal; and   withdrawing the seed crystal from the melt.   
     
     
         16 . The method of  claim 15 , wherein the gas including oxygen comprises an oxygen-containing compound that disassociates to oxygen. 
     
     
         17 . The method of  claim 15 , wherein the inert gas has a thermal conductivity less than or equal to 150 mW/m−° K at the temperature used during crystal growth. 
     
     
         18 . The method of  claim 15 , wherein the gaseous substance comprising oxygen comprises carbon dioxide. 
     
     
         19 . The method of  claim 15 , wherein the gaseous substance comprising oxygen comprises least one of carbon monoxide, oxygen, sulfur trioxide, phosphorous pentoxide or an oxide of nitrogen. 
     
     
         20 . The method of  claim 15 , wherein the oxide of nitrogen comprises at least one of NO 2 , N 2 O, NO, N 2 O 3 , or N 2 O 5 . 
     
     
         21 . An oxyorthosilicate scintillator crystal, the crystal comprising an oxyorthosilicate of at least one first rare-earth element and further comprising at least one of: a group 2 element, a group 3 element, a group 6 element, or a group 7 element;
 the crystal grown from a melt in an atmosphere comprising an inert gas and a gas including oxygen.   
     
     
         22 . The scintillator crystal of  claim 21 , wherein the inert gas has a thermal conductivity less than or equal to 150 mW/m−° K at the temperature used during crystal growth. 
     
     
         23 . The scintillator crystal of  claim 21  wherein the gas including oxygen comprises at least one of carbon dioxide, carbon monoxide, or oxygen. 
     
     
         24 . The scintillator crystal of  claim 21  wherein the atmosphere comprises 0.01-10 percent oxygen by volume, inclusive. 
     
     
         25 . The scintillator crystal of  claim 21  wherein the atmosphere comprises less than 300 parts per million of oxygen. 
     
     
         26 . The scintillator crystal of  claim 21  wherein the atmosphere comprises less than 200 parts per million of oxygen. 
     
     
         27 . The scintillator crystal of  claim 21 , wherein the inert gas comprises at least one of helium, argon, krypton, or xenon. 
     
     
         28 . The scintillator crystal of  claim 21 , wherein the inert gas comprises nitrogen. 
     
     
         29 . The scintillator crystal of  claim 21  further comprising a second rare earth element incorporated as a dopant. 
     
     
         30 . The scintillator crystal of  claim 29 , wherein the second rare-earth element is cerium. 
     
     
         31 . The oxyorthosilicate scintillator crystal of  claim 21  wherein the first rare-earth element is lutetium. 
     
     
         32 . A scintillator crystal, the crystal comprising an oxyorthosilicate of at least one first rare-earth element;
 the crystal grown from a melt in an atmosphere, the atmosphere comprising an inert gas and less than less than 300 ppm oxygen.   
     
     
         33 . The scintillator crystal of  claim 32 , wherein the inert gas has a thermal conductivity less than or equal to 150 mW/m−° K at the temperature used during crystal growth. 
     
     
         34 . The scintillator crystal of  claim 32  further comprising a second rare earth element incorporated as a dopant. 
     
     
         35 . The scintillator crystal of  claim 34 , wherein the second rare-earth element is cerium. 
     
     
         36 . The oxyorthosilicate scintillator crystal of  claim 32  wherein the first rare-earth element is lutetium.