In the second step, we obtained Li2Nb2O6-H2O nanowires using the ion-exchange method. LiCl (20 M) was dissolved in 20 mL of distilled water. Na2Nb2O6-H2O nanowires were added to the LiCl solution. After stirring for 20 h, the stirred solution was filtered, washed with distilled water, and dried at 80°C for 12 h. In the third step, LiNbO3 nanowires were obtained after heating the ion-exchanged Li2Nb2O6-H2O nanowires at 500°C for 2 h. The crystalline structure of the nanowires was characterized by high-resolution X-ray diffraction (HR-XRD), field-emission scanning
electron microscopy (FE-SEM), and field-emission transmission electron microscopy (FE-TEM) measurements. https://www.selleckchem.com/products/MG132.html To characterize the detailed crystal structure and symmetry, we performed neutron diffraction measurements and a Rietveld analysis. We used piezoresponse
force microscopy (PFM) to investigate the piezoelectricity and piezoelectric/ferroelectric domains of the LiNbO3 nanowires. The PFM measurements were performed using an VX-770 concentration atomic force microscope at 1 V and 73 kHz. To scan the surface, we used Pt/Ir-coated tips and a force constant of 3 Nm-1. Before scanning, we thoroughly dispersed and tightly attached the nanowires to the Pt-coated Si substrate using a polymer (5 wt.% poly(vinylpyrrolidone) dissolved in ethanol). The LiNbO3 nanowires were then coated with 10-nm-thick Pt to obtain find more a uniform electric field and to minimize electrostatic effects. To fabricate the nanocomposite nanogenerator, the LiNbO3 nanowires were thoroughly mixed with PDMS at a volume ratio of 1:100. (We noted that LiNbO3 nanowires were not mixed well with PDMS for an increased volume ratio of 2:100.) Small amounts of the mixture were spin-coated onto an Au/Cr-coated Kapton polyimide film at 500 rpm for 10 s. The very 25-nm-thick Au and 10-nm-thick Cr films were deposited onto the Kapton film by thermal evaporation. Another Au/Cr-coated Kapton film was attached to the top surface of the spin-coated LiNbO3-PDMS composite for the electrode. Finally, polyester (PS) film was attached to the bottom Kapton film. The thicknesses of the Kapton
and PS films were 125 and 500 μm, respectively. We applied an electric field of approximately 100 kV · cm-1 for electric poling at room temperature . To measure the Young’s modulus of the LiNbO3-PDMS composite, we used a nanoindenter with a Berkovich tip, and applied the continuous stiffness measurement option. A linear motor was used to periodically apply and release compressive force at a frequency of 0.8 Hz. The pushing and bending amplitudes were varied over the course of the measurement. The output signal of the piezoelectric device was recorded by low-noise voltage and current preamplifiers. Results and discussion Microporous Na2Nb2O6-H2O nanowires seem to be an excellent template for ion exchange .