Biocompatible ferroelectric (Na,K)NbO3 nanofibers

Abstract

"Dense homogeneous textile composed from continuous bead-free sodium potassium niobate (NKN) nanofibers 100 mu m long and 50-200 nm in diameter was sintered by sol-gel calcination assisted electrospinning. High resolution electron microscopy and x-ray diffraction revealed preferential cube-oncube growth of fibers in [001] direction. Raman spectrum of NKN fibers contains all the features characteristic to electrically poled orthorhombic phase. In contrast to polycrystalline ceramics, it shows relative enhancement of the Raman cross section of isotropic A(1g)(nu(1)) mode compared with polar axis defined F(2g)(nu(5)) and E(g)(nu(2)) vibrations. We interpret this as an evidence for superparaelectric state of NKN nanofibers. Spontaneous polarization inside highly crystalline nanofiber exists at room temperature though big distance between fibers prevents the settling of a net macroscopic polarization.

Broadband luminescent ferroelectric biocompatible Er:(Na,K)NbO3 nanofibers

“…The relative intensity ratios of NKN Bragg reflections I hkl indicate noticeable preferential NKN(001) orientation: I 001 / I 011 = 0.90 in Er:NKN fibers compared to 0.58 in “ideal” Na 0.35 K 0.65 NbO 3 powder . This observation conforms to [001]‐directional cube‐on‐cube growth of nanocrystals in NKN fibers observed earlier in scanning and transmission electron microscope images. Full width at half maximum (FWHM) δ2Θ = 0.34° at 2Θ = 22.6° and δ2Θ = 0.40° at 2Θ = 32.1°, respectively, of (001) and (011) peaks being substituted to Debye‐Scherrer formula yield crystallites’ size of 47.5 and 41.1 nm.…”

“…Dense homogeneous NKN nanofiber mat was sintered by sol‐gel calcination assisted electrospinning technique. The process requiring neither catalysts nor templates yields continuous bead‐free NKN nanofibers . Raman spectroscopy and hysteresis P‐E polarization tests ascertained all features characteristic to electrically spontaneously poled (ferroelectric) orthorhombic phase.…”

(K,Na)NbO3 Nanofiber-based Self-Powered Sensors for Accurate Detection of Dynamic Strain

“…23 Furthermore, KNN-based materials have already been proven to be biocompatible by Nilsson and co-workers, which are friendly to environment and human bodies for long-term applications. 24,25 The impact of frequency (strain rate) on sensing behaviour is another key issue for piezoelectric active strain sensors. As the electromechanical energy conversion by piezoelectric nanowires is based on the generation of polarization charges under the induced strain, the output voltage/current exhibits switching behaviour to the applied force.…”

Electronic Properties of Lead-Free (Ba0.95Ca0.05)(Ti0.92Sn0.08)O3 Piezoceramic Nanofibers by Electrospinning

“…23 Jalanian et al explained the formation of dense homogeneous sodium potassium niobate (NKN) nanofibers. 24 In this study, (Ba 0.95 Ca 0.05 ) (Ti 0.92 Sn 0.08 )O 3 , (BCTS) nanofibers of high dielectric and piezo properties were electrospun using acetate precursors of its constituents. nium-isopropoxide, polyvinyl pyrrolidone (PVP, Mw = 40,000), ethyl alcohol (99.5%) and glacial acetic acid from M/s.…”