We are developing new ceramics and improve existing products in order to provide better ceramics and expand the possibilities of ceramics for meeting any needs of our customers.
This is also the mission of our company, which has the only densification and transparent ceramics technology in the world.
TGG, which is currently used as an isolator crystal, has a small Verdet constant in visible region and uses expensive Ga, so it is difficult to cope with the miniaturization of visible light lasers, and it cannot be fabricated inexpensively.
Therefore, TAG (Tb3Al5O12) is attracting attention as a crystal that solves this problem.
TAG has better physical properties such as thermal conductivity and Verdet constant than TGG.
In addition, TAG ceramics is superior than TGG in terms of price, since it uses inexpensive Al instead of expensive Ga.
In the future, TAG is expected to become a key part in short-wavelength high-power lasers and blue lasers for optical recording.
However, since TAG single crystals are fabricated by a special method, they can only be made in small size and have not been put into practical use yet.
Therefore, we are developing TAG ceramics using our technology of transparent ceramics.
Since TAG has a higher thermal conductivity than TGG, it is easy for processing and growing in size on TAG.
At present, we are able to produce TAG ceramics that are equivalent to single crystals in terms of appearance and transmittance.
Now, we are working on research and development for realization of large-sized TAG ceramics.
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Our transparent ceramics are only those that take crystals, which are isotropic crystal structures.
However, crystal structures other than cubic crystals, such as tetragonal crystals and orthorhombic crystals, are also used as laser medium or/and piezoelectric crystals.
We are challenging to fabricate highly oriented transparent ceramics with an anisotropic crystal structure, by applying magnetic oriented technology under strong magnetic field.
Since conventional bonded ceramics are bonded by heating, thermal stress remains inside, which may cause defects such as warping and cracking of the material.
Another problem is difficult to bond materials having coefficients of different thermal expansion.
Room temperature bonding can solve these problems. Room temperature bonding is a method in which a high-velocity atomic beam (FAB: Fast Atomic Beam) irradiated on the bonding surface, and activated by removing hydroxy groups and impurities, and the surface layer is formed with an amorphous layer.
Since room temperature bonding can be bonded without heating, it is possible to bond materials with different thermal stresses.
In addition, the bonding process is shorter than the conventional bonding method, so it is possible to prevent the occurrence of defects due to heating.
Currently, we are researching for the purpose of establishing a room temperature bonding method for ceramics.
In the future, we are developing not only for bonding YAG ceramics to each other, but also for bonding different materials such as YAG ceramics/sapphire.