| 1. |
- Grishin, Alexander M., et al.
(författare)
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Gadolinia nanofibers as a multimodal bioimaging and potential radiation therapy agent
- 2015
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- Continuous bead-free C-type cubic gadolinium oxide (Gd2O3) nanofibers 20-30 mu m long and 40-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning technique. Dipole-dipole interaction of neighboring Gd3+ ions in nanofibers with large length-to-diameter aspect ratio results in some kind of superparamagnetic behavior: fibers are magnetized twice stronger than Gd2O3 powder. Being compared with commercial Gd-DTPA/Magnevist (R), Gd2O3 diethyleneglycol-coated (Gd2O3-DEG) fibers show high 1/T-1 and 1/T-2 proton relaxivities. Intense room temperature photoluminescence, high NMR relaxivity and high neutron scattering cross-section of Gd-157 nucleus promise to integrate Gd2O3 fibers for multimodal bioimaging and neutron capture therapy.
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| 2. |
- Grishin, Alexander M., et al.
(författare)
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Nb2O5 nanofiber memristor
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:5, s. 053111-
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Tidskriftsartikel (refereegranskat)abstract
- Non-woven bead-free 100 mu m long and 80-200 nm in diameter highly crystalline orthorhombic T-Nb2O5 nanofibers were sintered by sol-gel assisted electrospinning technique. Electrical and dielectric spectroscopy tests of individual fibers clamped onto Pt coated Si substrate were performed using a spreading resistance mode of atomic force microscope. Reproducible resistive switching with ON-OFF resistance ratio as high as 2 x 10(4) has a bipolar character, starts with a threshold voltage of 0.8-1.7 V, and follows by continuous growth of conductivity. Resistive memory effect is associated with a voltage-driven accumulation/depletion of oxygen vacancies at Nb2O5/Pt cathode interface. Poole-Frenkel emission from the electronic states trapped at reduced NbOx complexes determines a shape of Nb2O5/Pt diode I-V characteristics. Simple thermodynamic model explains a threshold character of switching, relates experimentally observed characteristics in low and high resistive states, and gives a reasonable estimate of the concentration of oxygen vacancies.
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| 3. |
- Jalalian, Abolfazl, et al.
(författare)
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Biocompatible ferroelectric (Na,K)NbO(3) nanofibers
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:1, s. 012904-
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Tidskriftsartikel (refereegranskat)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-on-cube 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.
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| 4. |
- Jalalian, Abolfazl, et al.
(författare)
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Fabrication of Ca, Zr doped BaTiO 3 ferroelectric nanofibers by electrospinning
- 2012
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; 9:7, s. 1574-1576
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Tidskriftsartikel (refereegranskat)abstract
- As first time, (Ba0.85Ca0.15)(Ti0.9Zr0.1)O-3 (BCTZ) nanofibers are synthesized by sol-gel assisted electrospining technique. Non-woven and bead-free BCTZ nanofibers mat was formed and a single chemical phase was achieved after calcination of the nanofibers at 700 degrees C in air. XRD and Raman spectroscopy show that BCTZ nanofibers crystallized in the morphotropic phase boundary (MPB) region.
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| 5. |
- Jalalian, Abolfazl, et al.
(författare)
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Ferroelectric and Ferromagnetic Nanofibers : Synthesis, Properties and Applications
- 2012
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Ingår i: ASIA-PACIFIC INTERDISCIPLINARY RESEARCH CONFERENCE 2011 (AP-IRC 2011). - : IOP Publishing. ; , s. 012006-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As first time, ferroelectric (Ba0.85Ca0.15)(Ti0.9Zr0.1)O-3 (BCTZ), biocompatible (Na0.5K0.5)NbO3 (NKN), and ferromagnetic Y3Fe5O12 (YIG) nanofibers were synthesized by sol-gel assisted electrospining technique. Non-woven, bead-free 100 mu m long fiber mat was formed from close-packed nanocrystals after calcination in air at 800 degrees C (BCTZ and NKN) and 1100 degrees C (YIG). BCTZ fibers are 200 nm in width whereas NKN and YIG fibers have smaller 50-100 nm diameter. X-ray diffraction and Raman spectroscopy show that BCTZ and NKN crystallized in tetragonal and rhombohedral polar phases in the vicinity of morphotropic phase boundary. Room temperature ferromagnetism in YIG fibers is indicated by a well formed M-H hysteresis loop with about 70% of remnant magnetization to the saturated value reached at 150 Oe. Broad band microwave spectroscopy revealed strong asymmetry of the shape of ferromagnetic resonance lines that conforms to a three orders of magnitude shape aspect ratio of YIG nanofibers.
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| 6. |
- Jalalian, Abolfazl, et al.
(författare)
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Ferromagnetic resonance in Y(3)Fe(5)O(12) nanofibers
- 2011
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:10, s. 102501-
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Tidskriftsartikel (refereegranskat)abstract
- Continuous bead-free polycrystalline yttrium iron garnet (YIG) nanofibers 100 mu m long and 50-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning. Room temperature ferromagnetism in YIG fibers is indicated by a well formed M-H hysteresis loop with about 70% of remnant magnetization to the saturated value reached at 150 Oe. Broad band microwave spectroscopy revealed strong asymmetry of ferromagnetic resonance lines that conforms to a three orders of magnitude shape aspect ratio of YIG nanofibers.
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| 7. |
- Jalalian, Abolfazl, et al.
(författare)
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Large piezoelectric coefficient and ferroelectric nanodomain switching in Ba(Ti0.80Zr0.20)O-3-0.5(Ba0.70Ca0.30)TiO3 nanofibers and thin
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 104:10, s. 103112-
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Tidskriftsartikel (refereegranskat)abstract
- Currently available low-dimensional piezoelectric materials show a low piezoelectric coefficient d(33) of merely 100pm V-1 with Pb(Zr, Ti)O-3-based materials at the high end. Here, we report very large piezoelectricity in Ba(Ti0.80Zr0.20)O-3-0.5(Ba0.70Ca0.30)TiO3 (BTZ-0.5BCT) lead-free nanostructures sintered as thin films (d(33) = 140pm V-1) and nanofibers (d(33) = 180pm V-1). The influences of lateral size, geometry, and the clamping effect on the piezoelectric performance were investigated for both thin films and nanofibers. Combining a high piezoelectric coefficient with environmental benefits, the BTZ-0.5BCT nanostructures provide the superior functions sought for highly efficient piezoelectric devices and electromechanical systems.
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| 8. |
- Jalalian, Abolfazl, et al.
(författare)
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Piezoelectricity and electrostriction in biocompatible (Na,K)NbO3 nanofiber scaffolds
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 104:24, s. 243701-
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Tidskriftsartikel (refereegranskat)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 d(33) 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 E-c = 31 kV/cm, remnant P-r = 6.2 mu C/cm(2), and the maximum achieved polarization P-max = 21.2 mu C/cm(2). Enhanced piezoelectric effect and strong electrostriction promise NKN fibers as electrically polarizable scaffolds for tissue engineering and for energy harvesting biocompatible nanogenerators.
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