Patent ID: 8734666

Claim:
A method for preparing nanotubes comprising: forming nanorods comprising a piezoelectric material having an asymmetric crystal structure by a vapor phase process, a vapor-liquid process or a template process; and providing hydroxide ions to the nanorods to etch at least a portion of an inner part of the nanorods to form the nanotubes, wherein the vapor phase process comprises providing a first substrate having a catalyst disposed thereon, heating the substrate to about 700° C. to about 1200° C., and contacting the heated substrate with a precursor of the piezoelectric material to form the nanorods, wherein the vapor-liquid process comprises providing a solution comprising a precursor of the piezoelectric material, and contacting a second substrate with the solution under an oxygen atmosphere at about 400° C. or more to form the nanorods, and wherein the template process comprises providing an anodic aluminum oxide template, contacting the anodic aluminum oxide template with the solution comprising a precursor of the piezoelectric material, electroplating the piezoelectric material in pores of the anodic aluminum oxide template, and removing the anodic aluminum oxide template to form the nanorods.