Hydrothermal synthesis of perovskite nanotubes

• US 7,147,834 B2
• Filed: 08/11/2004
• Issued: 12/12/2006
• Est. Priority Date: 08/11/2003
• Status: Active Grant

• Current Assignee: The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: The Research Foundation for The State University of New York (State University of New York)
• Inventors: Wong, Stanislaus, Mao, Yuanbing
• Primary Examiner(s): Vanoy, Timothy C.
• Application Number:
  US10/916,048
• Publication Number:
  US 20050036939A1
• Time in Patent Office: 853 Days
• Field of Search: 423/593.1, 423/598, 423/594.12, 423/594.8, 423/595, 423/599, 423/594.1, 423/594.3, 423/594.5, 423/594.14, 423/594.15, 423/596, 423/594.2, 423/594.4, 423/594.6, 423/594.16, 423/263, 423/594.9, 977/812, 977/963, 204/157.42
• US Class Current: 423/593.1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/13 Nanotubes
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 2213/18 Memory cell being a nanowire having RADIAL composition
• CPC Class Codes: G11C 2213/81 Array wherein the array conductors, e.g. word lines, bit lines, are made of nanowires
• CPC Class Codes: Y10S 977/812 Perovskites and superconducting composition, e.g. BaxSr1-xTiO3
• CPC Class Codes: Y10S 977/963 Miscellaneous

Abstract

A low-temperature hydrothermal reaction is provided to generate crystalline perovskite nanotubes such as barium titanate (BaTiO₃) and strontium titanate (SrTiO₃) that have an outer diameter from about 1 nm to about 500 nm and a length from about 10 nm to about 10 micron. The low-temperature hydrothermal reaction includes the use of a metal oxide nanotube structural template, i.e., precursor. These titanate nanotubes have been characterized by means of X-ray diffraction and transmission electron microscopy, coupled with energy dispersive X-ray analysis and selected area electron diffraction (SAED).

Claims

1. A monophasic perovskite nanotube having an outer diameter from about 1 nm to about 500 nm and a length from about 10 nm to about 10 μ

m.

2. The monophasic perovskite nanotube of claim 1 wherein the nanotube has a cubic crystalline structure, a rhombohedral crystalline structure, an orthorhombic crystalline structure or a tetragonal crystalline structure.

3. The monophasic perovskite nanotube of claim 1 wherein the perovskite nanotube has the formula ABO₃ wherein B is at least one metal selected from Group IVB, VB, VIB, VIIB, VIIIB, IB, or IIB of the Periodic Table of Elements, and A is at least one additional cation having a positive formula charge of from 1 to 3.

4. The monophasic perovskite nanotube of claim 3 wherein A is selected from the group consisting of K, Na, Rb, Cs, Li, Ba, Sr, La, Pb, Zn, Ca, Mg, Sc, Y, and mixtures thereof.

5. The monophasic perovskite nanotube of claim 3 wherein A is selected from the group consisting of Ba, Sr and mixtures thereof.

6. The monophasic perovskite nanotube of claim 3 wherein A is Ba and B is Ti.

7. The monophasic perovskite nanotube of claim 3 wherein A is Sr and B is Ti.

8. The monophasic perovskite nanotube of claim 1 wherein the outer diameter is from about 8 nm to about 100 nm.

9. The monophasic perovskite nanotube of claim 1 further comprising an inner diameter from about 0.5 nm to about 500 nm.

10. The monophasic perovskite nanotube of claim 1 wherein the nanotube has an aspect ratio of about 2 or greater.

11. A monophasic nanotube comprising a perovskite having the formula ATiO₃ wherein A is Sr, Ba or a mixture thereof, said nanotube having an outer diameter from about 1 nm to about 500 nm and a length from about 10 nm to about 10 μ

m.

12. A method of fabricating a perovskite nanotube comprising the steps of:

providing a metal oxide nanotube structural template comprising a metal selected from Group IVB, VB, VIB, VIIB, VIIIB, IB or IIB of the Periodic Table of Elements;

adding, in the absence of air, and CO₂, at least one precursor compound comprising a cation having a positive formula charge of from 1 to 3 to said nanotube structural template to provide a reaction mixture;

refluxing the reaction mixture in an inert atmosphere at a temperature of about 150°

C. or less to provide a suspension of perovskite nanotubes; and

recovering the perovskite nanotubes from the suspension.

13. The method of claim 12 wherein the perovskite nanotubes have the structural formula ABO₃ wherein B is at least one metal selected from Group IVB, VB, VIB, VIIB, VIIIB, IB or IIB of the Periodic Table of Elements, and A is at least one additional cation having a positive formula charge of from 1 to 3.

14. The method of claim 13 wherein A is selected from the group consisting of K, Na, Rb, Cs, Li, Ba, Sr, La, Pb, Zn, Ca, Mg, Sc, Y, and mixtures thereof.

15. The method of claim 14 wherein A is selected from the group consisting of Ba, Sr and mixtures thereof.

16. The method of claim 13 wherein A is Ba and B is Ti.

17. The method of claim 13 wherein A is Sr and B is Ti.

18. The method of claim 12 wherein the nanotube structural template is prepared by dissolving a powder of a metal oxide in a base solution, treating the dissolved metal oxide with an acid, sonicating the acid treated dissolved metal oxide to provide metal oxide nanotubes and recovering the metal oxide nanotubes.

19. The method of claim 12 wherein the nanotube structural template comprises TiO₂ nanotubes.