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US-12624439-B2 - λ-Ti3O5 film forming substrate and method for producing λ-Ti3O5 film forming substrate

US12624439B2US 12624439 B2US12624439 B2US 12624439B2US-12624439-B2

Abstract

A λ-Ti 3 O 5 film forming substrate includes a support substrate and a λ-Ti 3 O 5 film formed directly on the support substrate.

Inventors

  • Kohei YOSHIMATSU

Assignees

  • TOHOKU UNIVERSITY

Dates

Publication Date
20260512
Application Date
20220906
Priority Date
20210906

Claims (4)

  1. 1 . A λ-Ti 3 O 5 film forming substrate, comprising: a support substrate; and a λ-Ti 3 O 5 film provided directly on the support substrate, wherein the support substrate consists of a (110) plane LaAlO 3 .
  2. 2 . The λ-Ti 3 O 5 film forming substrate according to claim 1 , wherein in thin film X-ray diffraction, when performing measurement at a position where a diffraction intensity A 203 of a (203) plane of the λ-Ti 3 O 5 film becomes maximum, an intensity ratio A 203 /A 20-3 between the diffraction intensity A 203 and a diffraction intensity A 20-3 of a (20-3) plane is 10 or more.
  3. 3 . The λ-Ti 3 O 5 film forming substrate according to claim 2 , wherein in the thin film X-ray diffraction, when performing measurement at a position after the λ-Ti 3 O 5 film forming substrate is rotated by 180° from the position where the diffraction intensity A 203 becomes maximum, an intensity ratio A 20-3 /A 203 between the diffraction intensity A 20-3 and the diffraction intensity A 203 is 10 or more.
  4. 4 . The λ-Ti 3 O 5 film forming substrate according to claim 1 , wherein when a position spaced apart from an interface between the support substrate and the λ-Ti 3 O 5 film toward a surface of the λ-Ti 3 O 5 film by 10 nm in a plate thickness direction is set as a position A, and a position of a surface of the λ-Ti 3 O 5 film is set as a position B, in a region from the position A to the position B in the plate thickness direction, an element X contained in the support substrate is 0.1 atomic % or less with respect to all elements in the λ-Ti 3 O 5 film.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Stage entry of International Application No. PCT/JP2022/033363, filed on Sep. 6, 2022, which, in turn, claims priority to Japanese Patent Application No. 2021-144696, filed on Sep. 6, 2021, both of which are hereby incorporated herein by reference in their entireties for all purposes. TECHNICAL FIELD The present disclosure relates to a λ-Ti3O5 film forming substrate and a method for producing the λ-Ti3O5 film forming substrate. BACKGROUND ART Trititanium pentoxide (hereinafter, may be referred to as Ti3O5) is an oxide material having many crystal polymorphisms such as an α-phase, a β-phase, a γ-phase, a δ-phase, and a λ-phase. λ-type Ti3O5 (hereinafter, may be referred to as λ-Ti3O5) consisting of the λ-phase undergoes a phase transition into the α-phase or the β-phase by heat, light, or pressure. Particularly, the λ-Ti3O5 undergoes a reversible transition between the λ-phase and the β-phase by a nanosecond pulsed laser, and exhibits a photo-induced phase transition under visible light. Therefore, the λ-Ti3O5 is expected to be applied to an optical recording medium. As a method for producing λ-Ti3O5, NPL 1 discloses a method for producing reduction-sintered SiO2-coated λ-Ti3O5 nanoparticles by using a reverse micelle method and a sol-gel method. Since the λ-Ti3O5 is a metastable phase, the size of a crystal is limited to a nanometer order. In a large crystal, the β-phase is most stable, and it is difficult to obtain λ-Ti3O5. In the method described in NPL 1, enlarging of crystals is suppressed by coating with SiO2. However, in the method described in NPL 1, a process such as chemical etching with SiO2 is necessary. As a method for producing the λ-Ti3O5 in which the chemical etching with SiO2 is not necessary, NPL 2 discloses a technology of forming MgTi2O5 as a seed layer on LaAlO3, and forming the λ-Ti3O5 film on the seed layer. CITATION LIST Non Patent Literature NPL 1: S. Ohkoshi et al., Nature Chem. 2, 539 (2010)NPL 2: H. Chen et al., Appl. Phys. Lett. 116, 201904 (2020)NPL 3: A. Ould-Hamouda et al., Chem. Phys. Lett. 608, 106-112 (2014) SUMMARY OF INVENTION Technical Problem When the seed layer exists between the λ-Ti3O5 film and the substrate as in NPL 2, a component of the seed layer diffuses into the λ-Ti3O5 film, and the λ-phase is stabilized, and thus a phase transition into the β-phase is not exhibited. This has a problem when considering application to the optical recording medium. The present invention has been made in consideration of such circumstances, and an object thereof is to provide a λ-Ti3O5 film forming substrate including a λ-Ti3O5 film that is formed directly on the substrate and is capable of stably transitioning from λ-Ti3O5 into another phase, and a method for producing the λ-Ti3O5 film forming substrate. Solution to Problem To solve the problem, the invention suggests the following means. <1> A λ-Ti3O5 film forming substrate according to an aspect of the invention includes a support substrate; and a λ-Ti3O5 film provided directly on the support substrate.<2> In the λ-Ti3O5 film forming substrate according to <1>, in thin film X-ray diffraction, when performing measurement at a position where a diffraction intensity A203 of a (203) plane of the λ-Ti3O5 film becomes maximum, an intensity ratio A203/A20-3 between the diffraction intensity A203 and a diffraction intensity A20-3 of a (20-3) plane may be 10 or more.<3> In the λ-Ti3O5 film forming substrate according to <2>, in the thin film X-ray diffraction, when performing measurement at a position after the λ-Ti3O5 film forming substrate is rotated by 180° from the position where the diffraction intensity A203 becomes maximum, an intensity ratio A20-3/A203 between the diffraction intensity A20-3 and the diffraction intensity A203 may be 10 or more.<4> In the λ-Ti3O5 film forming substrate according to any one of <1> to <3>, the support substrate may be a (110) plane LaAlO3.<5> In the λ-Ti3O5 film forming substrate according to any one of <1> to <4>, a component of the support substrate may substantially not diffuse to the λ-Ti3O5 film.<6> In the λ-Ti3O5 film forming substrate according to any one of <1> to <5>, when a position spaced apart from an interface between the support substrate and the λ-Ti3O5 film toward a surface of the λ-Ti3O5 film by 10 nm in a plate thickness direction is set as a position A, and a position of a surface of the λ-Ti3O5 film is set as a position B, in a region from the position A to the position B in a plate thickness direction, an element X contained in the support substrate may be 0.1 atomic % or less with respect to all elements in the λ-Ti3O5 film.<7> A method for producing a λ-Ti3O5 film forming substrate according to another aspect of the invention may include forming a λ-Ti3O5 film on a support substrate heated to a temperature region higher than 1000° C. and lower than 1200° C. by a physical vapor deposition method.<8>