Tokuyama Corporation

Shinshu University

Teruhiko Nawata

Hiroyuki Yanagi

Tsuguo Fukuda

Yukihiro Kanechika

Katsuya Teshima

Kikuo Yamamoto

Shota Daiki

Kyoichi Fujinami

Hidetaka Miyazaki

Akimasa Kuramoto

Ken Yasumura

Mou Ou

Saiko Fujii

Eiichi Nishijima

Nobuyuki Kuramoto

Shinichi Nitta

Harumasa Ito

Isao Yamaga

Yuichi Ikeda

Tetsuya Yamada

It is an object to achieve a resin sheet having high thermal conductance and high dielectric strength. Hexagonal boron nitride powder in accordance with an aspect of the present invention includes hexagonal boron nitride agglomerate particles each including agglomerated hexagonal boron nitride primary particles, and has a specific surface area of not less than 0.5 m/g and not more than 5.0 m/g. The hexagonal boron nitride primary particles each have a long diameter of not less than 0.6 μm and not more than 4.0 μm and an aspect ratio of not less than 1.5 and not more than 5.0.

Hexagonal boron nitride powder, resin composition, resin sheet, and method for producing hexagonal boron nitride powder

To provide an aluminum nitride particle having a hexagonal columnar barrel part and bowl-like projection parts at both ends of the columnar part, wherein the long diameter (D) of the barrel part is 10 to 250 &#x3bc;m, the ratio (L/D) of the distance (L) between the apexes of the two projection pars to the long diameter (D) of the barrel part is 0.7 to 1.3, and the percentage of the length or thickness (L) of the barrel part to the distance (L) between the apexes of the two projection parts is 10 to 60%. The aluminum nitride particle can provide high heat conductivity and excellent electric insulation to a resin when it is filled into the resin.

Nitride aluminum particle

A metal fluoride single crystal pulling apparatus that upward pulling initiation through termination, in the state of shallow melt capable of highly effective inhibition of scatterer formation, can perform stable growth of single crystal and can suppress any mixing of air bubbles and occurrence of crystal break during crystal growth, etc; and a process for producing a metal fluoride single crystal therewith. As a crucible for accommodating a melt of raw metal fluoride, use is made of a double structured crucible composed of an outer crucible and an inner crucible. In the upward pulling of single crystal, the accommodation depth of inner crucible relative to the outer crucible is increased in accordance with any decrease of melt accommodated in the inner crucible according to the growth of single crystal, so that the melt accommodated in the outer crucible is fed into the inner crucible to thereby maintain the amount of melt accommodated in the inner crucible within a given range. Further, at the position of an opening that upward opens any gap space between an external surface of outer crucible and an internal surface of inner crucible, or an interstice, situated below the opening, between a side wall internal surface of outer crucible and a side wall external surface of inner crucible, there is disposed a cutoff member that cuts off at least part of the position.

Process for producing metal fluoride single crystal

A single crystal of alkaline earth metal fluoride is produced by a single crystal pulling method, has a straight barrel part diameter of not less than 17 cm, preferably has a straight barrel part length of not less than 5 cm, and has a light transmittance, as measured at a wavelength of 632.8 nm, of not less than 80%, preferably 90 to 98%. Further, the main crystal growth plane of the single crystal is the {111} plane or the {100} plane. The single crystal of alkaline earth metal fluoride has a large diameter as described above, and in spite that it is in an as-grown state, the peripheral surface is not opaque and the visible light transmittance is high. Therefore, evaluation of bubbles or inclusions in the crystal becomes feasible without performing complicated machining of the crystal, and from the single crystal, a large-sized optical material having advantageous properties such as high quality and high uniformity can be cut out.

As-grown single crystal of alkaline earth metal fluoride

A single crystal pulling apparatus for a metal fluoride comprising a crucible provided in a chamber for filling with a molten solution of a single crystal material, a melting heater provided to surround the crucible, a vertically movable single crystal pulling bar for attaching a seed crystal on a tip thereof for coming in contact with the molten solution of the single crystal material in the crucible, a heat insulating wall provided in the chamber to surround at least a peripheral side portion of a single crystal pulling region in an upper part of the crucible, a ceiling board for closing an opening portion of an upper end in an upper part of the heat insulating wall, and a single crystal pulling chamber surrounded by the heat insulating wall and the ceiling board, wherein the ceiling board is provided with at least an inserting hole for inserting the single crystal pulling bar, and wherein a coefficient of thermal conductivity in a direction of a thickness of the ceiling board is 1000 to 50000 W/m&#xb7;K.

Single crystal pulling apparatus for a metal fluoride

Growing community of inventors

Shunan, Japan

Teruhiko Nawata