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Alkaline earth metal titanate crystal laminate

外国特許コード F210010323
整理番号 J1023-03WO
掲載日 2021年2月1日
出願国 アメリカ合衆国
出願番号 201816647333
公報番号 20200346941
出願日 平成30年9月14日(2018.9.14)
公報発行日 令和2年11月5日(2020.11.5)
国際出願番号 JP2018034156
国際公開番号 WO2019054474
国際出願日 平成30年9月14日(2018.9.14)
国際公開日 平成31年3月21日(2019.3.21)
優先権データ
  • 特願2017-177321 (2017.9.15) JP
  • 2018JP34156 (2018.9.14) WO
発明の名称 (英語) Alkaline earth metal titanate crystal laminate
発明の概要(英語) There are provided a new type of crystal laminate of an alkaline earth metal titanate having improved catalytic activity, and a method for producing the same. The crystal laminate is provided having a crystal of the alkaline earth metal titanate as a constitutional unit, wherein the crystal being the constitutional unit is a cubic crystal, a tetragonal crystal or an orthorhombic crystal; the crystal being the constitutional unit has a primary particle diameter of 500 nm or less; and the crystal is layered with an orientation in a {100} plane direction thereof.
従来技術、競合技術の概要(英語) BACKGROUND ART
Alkaline earth metal titanates such as strontium titanate and barium titanate have photocatalytic activity and high dielectricity, and are used for photohydrolysis, ceramic capacitors, piezoelectric elements and the like. Nanoparticles of metal titanates, however, are liable to randomly aggregate, and the decrease in surface area, the interfacial mismatch and the like caused thereby pose the following problem: the decrease in photocatalytic activity and light energy conversion efficiency.
As means for solving the above problem, with regard to metal oxide nanoparticles, reported were means in which metal oxide nanoparticles are made into a metal oxide mesocrystal, which is a superstructure made by self-organization of the metal oxide nanoparticles (Non Patent Literatures 1 and 2). The present inventor has further studied in order to conveniently obtain a mesocrystal of a metal oxide represented by titanium oxide, and has then found that by calcining using an aqueous solution containing a metal oxide precursor, an ammonia salt and water, or a metal oxide precursor, an ammonia salt, a surfactant and water, a metal oxide mesocrystal having a large size and a large specific surface area can be obtained (Patent Literatures 1 and 2). It has also been found that a mesocrystal of a composite oxide containing two or more metal species can also be obtained (Patent Literature 2).
特許請求の範囲(英語) [claim1]
1. A crystal laminate, comprising:
a crystal of an alkaline earth metal titanate as a constitutional unit, wherein:
the crystal is a cubic crystal, a tetragonal crystal or an orthorhombic crystal;
the crystal has a primary particle diameter of 500 nm or less; and
the crystal is layered with an orientation in a {100} plane direction thereof.

[claim2]
2. The crystal laminate according to claim 1, wherein the crystal laminate has an average width of 1 μm or more.

[claim3]
3. The crystal laminate according to claim 1, wherein the crystal laminate has an average thickness of 50 nm or more.

[claim4]
4. The crystal laminate according to claim 1, wherein the crystal present on a surface of the crystal laminate has a primary particle diameter more than a primary particle diameter of the crystal present in an interior of the crystal laminate.

[claim5]
5. The crystal laminate according to claim 1, wherein the crystal laminate has a specific surface area of 10 m2/g or more.

[claim6]
6. A structure having an alkaline earth metal titanate crystal nanoparticle on a surface of the crystal laminate according to claim 1, wherein
a crystal orientation of the alkaline earth metal titanate crystal nanoparticle is in the same direction as that of the crystal laminate.

[claim7]
7. The structure according to claim 6, wherein the alkaline earth metal titanate crystal nanoparticle has a primary particle diameter of twice or more a primary particle diameter of the crystal present on the surface of the crystal laminate.

[claim8]
8. The structure according to claim 6, wherein the alkaline earth metal titanate crystal nanoparticle has a primary particle diameter of 50 nm or more.

[claim9]
9. A method for producing a crystal laminate of an alkaline earth metal titanate, the method comprising:
subjecting a titanium oxide mesocrystal having a titanium oxide nanoparticle orderly layered therein and an alkaline earth metal atom source to a hydrothermal reaction.
  • 発明者/出願人(英語)
  • TACHIKAWA TAKASHI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
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