Mitsui Mining & Smelting Co. Ltd. plans to invest about ¥2.3 billion to boost the production capacity of its high-purity tantalum pentoxide by 2.3 times the current capacity, given the increase in demand for lithium tantalate, or LT, single crystals.

Tantalum pentoxide is the main raw material in an LT single crystal, which is, in turn, used in Surface Acoustic Wave, or SAW, filters. SAW filters are installed in mobile devices for high-speed and large-capacity data communication.

The investment will go toward expanding the capacity of its Miike rare metals plant in Japan's Fukuoka prefecture, with completion slated for August 2017, according to a Dec. 15 release.

As of Dec. 16, US$1 was equivalent to ¥118.32.