Japan Aerospace Exploration Agency

Takehiko Ishikawa

Shinichi Yoda

Kentei Yono

Yasutomo Arai

Atsunobu Masuno

Paul-Francois Paradis

Disclosed is a method of producing a barium-titanium-based ferroelectric glass using a containerless solidification process, such as an electrostatic levitation process or a gas levitation process, which comprises the steps of levitating a sampleof a barium-titanium-based compound by a levitating force of compressed air, heating the sample up to a temperature greater than its melting point (1330&#xb0; C.) by about 100&#xb0; C. to allow the sample to be molten, and, after maintaining the molten state for a given time period (at least several second), quenching the sample from a given temperature range (1400 to 1000&#xb0; C.) at a cooling rate of about 10K/sec, so as to allow the sample to be solidified while inhibiting nucleation and mixing of impurities from a container. The present invention makes it possible to provide a glass exhibiting an unprecedented, extremely large permittivity.

Method of producing barium-titanium-based oxide glass using containerless solidification process

A titanium-containing oxide glass having a bulky form and substantially having a chemical composition represented by the formula: (M1)(M2)(Ti(M3))O[wherein M1 represents an element selected from Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na and Ca; M2 represents at least one element selected from Mg, Ba, Ca, Sr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Sc, Y, Hf, Bi and Ag; M3 represents at least one element selected from V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Al, Si, P, Ga, Ge, In, Sn, Sb and Te; and x, y1, y2 and z satisfy the following requirements: 0&#x2266;x&#x2266;0.5, 0&#x2266;y1&#x3c;0.31, 1.4&#x3c;y2&#x3c;3.3, and 3.9&#x3c;z&#x3c;8.0, provided that x+y1&#x2260;0 when M1 represents Ba, and y1&#x2260;0 when both M1 and M2 represent Ba].

Titanium-containing oxide glass and method for production thereof

Disclosed is a method for producing a barium titanium oxide single crystal piece with a given structure using a containerless solidification process, which comprises the steps of preparing a material made of a barium titanium oxide, controlling the material to be in a levitated state within a levitation furnace, melting the levitated material using a laser, and solidifying the molten material while maintaining the levitated state. In a specific embodiment, a spherical sample having a composition of BaTiOand a weight of about 20 mg is subjected to a rapid solidification and melting process (temperature gradient: about 700 K/sec) 3 times while levitating the sample in 4.5 atm of air atmosphere using an electrostatic levitation furnace. Then, the re-molten sample is maintained at a temperature just below the melting point of the sample for a given time, and then rapidly cooled at a cooling rate of 300 K/sec to obtain a transparent blue barium titanium oxide single crystal. The single crystal exhibits innovative dielectric characteristics having a large relative permittivity (100,000 or more at room temperature) and a low dielectric loss. In addition, the single crystal has excellent temperature stability allowing the relative permittivity to be gently reduced in the range of room temperature to 70 K.

Growing community of inventors

Tsukuba, Japan

Takehiko Ishikawa