Novel Method for Growth of Metal Oxide Single Crystals
The present invention outlines a process application for the growth of new, and difficult-to-synthesize, metal oxide single crystals from a molten metal flux. This new method of growth applies a chemical pressure in the form of a molten metal solvent that is capable of dissolving and subsequently crystallizing metal oxides. The chemical pressure accomplishes the creation of highly reducing conditions in the growth media which force equilibration of crystal lattice energies with kinetic energy losses from cooling of the reactions. This allows for the growth of phases below their melting points and can also be used to access incongruently melting phases. More precisely, batches of individual reactions are heat-treated to synthesize single crystals comprised of oxygen with one or more transition, alkaline-earth and/or lanthanide metals. Stoichiometries are calculated, weighed out then loaded into metal crucibles which are welded under -1atm Argon gas then jacketed in quartz ampoules under vacuum. The entire reaction vessel is heated appropriately then the furnace is opened, the ampoule is removed, inverted and briefly centrifuged to mechanically separate the flux and product crystals.
Metal fluxes are new to the growth of metal oxide single crystals and our preliminary reactions have yielded both new phases, and phases that normally require costly, extreme conditions to grow. Contrarily to current state of the art technology for the growth of metal oxide single crystal, this method of this invention utilizes temperatures below 1,000°C and no applied pressure. Since currently known metal oxides have such expansive applications, growth of these materials from synthesis routes that are less expensive or faster will have significant value to industry and government. Traditional methods of metal oxide single crystal growth do not possess the exploratory edge of this new method, which is not limited by the oxidative and thermodynamic constraints of current state of the art "open crucible" stoichiometric growth techniques.