Piezoelectricity and electrostriction in biocompatible (Na,K)NbO3 nanofiber scaffolds

Abstract

Single phase and highly crystalline biocompatible ferroelectric (Na,K)NbO3 (NKN) nanofibers were synthesized by sol-gel assisted electrospinning technique. Low amplitude piezoelectric response as well as electrostriction effect in NKN fibers were examined using piezoelectric force microscopy technique. Piezoelectric coefficient d33 is strongly anisotropic varying from 75.8 to 18.3 pm/V for, respectively, out-of-axis and on-axis oriented ferroelectric domains in NKN fibers. Hysteresis P-E loop for individual nanofiber reconstructed from the bipolar E-field-induced butterfly strain curve yields: coercive field Ec = 31 kV/cm, remnant Pr = 6.2 μC/cm2, and the maximum achieved polarization Pmax = 21.2 μC/cm2. Enhanced piezoelectric effect and strong electrostriction promise NKN fibers as electrically polarizable scaffolds for tissue engineering and for energy harvesting biocompatible nanogenerators.

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.…”

“…Piezoelectric coefficient d 33 was found to be strongly anisotropic varying from 75.8 to 18.3 pm/V in out‐of‐axis and on‐axis oriented ferroelectric domains, correspondingly. Hysteresis P‐E loop yields: coercive field E c = 31 kV/cm, remnant P r = 6.2 μC/cm 2 , and the maximum achieved polarization P max = 21.2 μC/cm 2 …”

“…Recently, we added highly crystalline NKN nanofibers to the portfolio of lead-free biocompatible strongly ferroelectric materials. 18,19 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.…”

Advanced Synthesis on Lead‐Free KxNa(1−x)NbO3 Piezoceramics for Medical Imaging Applications

“…Interestingly, the crystalline nanofibers with a length of 100 μm and diameter 50–200 nm, at room temperature, displayed a spontaneous polarization . Further results, published in a second step, showed that the piezoelectric coefficient d 33 of these nanofibers was strongly anisotropic varying from 75.8 to 18.3 pm V −1 for out‐of‐axis and on‐axis oriented ferroelectric domains, respectively …”

Gadolinia nanofibers as a multimodal bioimaging and potential radiation therapy agent

“…Besides commonly used Gd 3+ chelates, Gd 2 O 3 agent can be encapsulated by coaxial electrospinning in biocompatible (Na,K)NbO 3 sheath to form core-shell nanofibers. 11,12 Observed intense room temperature photoluminescence and easy Gd 3+ substitutability by other rare earths (e.g. Tb…”