Shengli An

Composition-dependent dielectric and energy-storage properties of (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric thick films

1.8 -μm-(Pb0.97La0.02)(Zr0.95−xSnxTi0.05)O3 antiferroelectric thick films with orthorhombic (x = 0.05 and 0.25) and tetragonal (x = 0.40) structure were deposited on platinum-buffered silicon substrates by using a chemical solution way. All the films had a uniform microstructure with pure perovskite phase. With increasing x value, dielectric constant and critical electric breakdown field of the thick films were gradually increased, while their saturated polarizations were decreased. As a result, their maximum recoverable energy-storage density was increased for the thick films with larger x values. A huge recoverable energy-storage density of 56 J/cm3 was obtained in antiferroelectric thick films with x = 0.40. Moreover, a good temperature-dependent stability of the energy storage was obtained in the all films from 20 to 120 °C.

Large enhancement of energy-storage properties of compositional graded (Pb1−xLax)(Zr0.65Ti0.35)O3 relaxor ferroelectric thick films

In this letter, the compositionally graded multilayer (Pb1-xLax)(Zr0.65Ti0.35)O3 (PLZT) relaxor ferroelectric thick films were fabricated on LaNiO3/Si(100) substrates via a sol-gel method. The effects of composition-gradient sequence on the microstructure, dielectric properties, and energy-storage behaviors were investigated in detail. As compared to PLZT films with single composition, the compositionally graded PLZT films displayed significant enhancement in dielectric properties and energy-storage performance. The largest dielectric constant of 2170 at 100 kHz and the largest discharged energy-storage density of 12.4 J/cm3 at 800 kV/cm were achieved in the up-graded multilayer PLZT thick films.

Significant enhancement of energy-storage performance of (Pb0.91La0.09)(Zr0.65Ti0.35)O3 relaxor ferroelectric thin films by Mn doping

1.5-μm-thick (Pb0.91La0.09)(Zr0.65Ti0.35)O3 (PLZT) relaxor ferroelectric (RFE) films doped by Mn from 0 to 5 mol. % were deposited on LaNiO3/Si(100) substrates via a sol-gel method. The microstructure, dielectric properties, and energy-storage performance of PLZT thin films were investigated as a function of Mn content. X-ray diffraction patterns and scanning electron microscopy indicated that all the films possessed a similar microstructure with pure perovskite phase. However, the dielectric constant, average breakdown fields, and the difference between maximum polarization and remnant polarization of the films were improved by Mn doping. A giant recoverable energy-storage density of 30.8 J/cm3 was obtained in 1 mol. % Mn-doped films. Moreover, good temperature-dependent energy-storage stability was also observed in the films. These results indicated that Mn-doping was an efficient way to optimize the energy-storage behaviors of PLZT RFE films.

Nondestructive up-conversion readout in Er/Yb co-doped Na0.5Bi2.5Nb2O9-based optical storage materials for optical data storage device applications

Luminescence modulation based on photochromic reactions is always considered to be a promising method to achieve nondestructive readout in photochromic materials. Generally speaking, two conventional strategies have been widely used to achieve this target: tuning the absorption bands and adjusting luminescent quenching mechanisms. In this paper, we found a new strategy to improve effectively luminescence readout capability in Er/Yb codoped NBN-based solid-state inorganic photochromics by using a two-photon absorption mode of luminescent centers. Upon alternating visible light irradiation (407 nm) and the thermal stimulus, the materials exhibited a high luminescence switching contrast ratio (ΔRt = 86%), excellent reversibility, and significantly improved luminescent efficiency (22 times). Most importantly, the photochromic reaction process can be efficiently read out using the two-photon absorption (or up-conversion) mode without inducing any new reactions, showing extremely low destruction on information recording (destruction degree <11%), which is superior to other luminescence emission modes (down-shifting or down-conversion). These results could be used as a guide to tailor the luminescence modulation properties of photochromic materials to realize non-destructive readout in 3D optical data storage device applications.

Luminescence photoswitching of Ho-doped Na0.5Bi2.5Nb2O9 ferroelectrics: the luminescence readout process

Luminescent switching materials upon photochromic reactions have potential applications in optical switching and high-density optical data storage in optoelectronic devices. To avoid interference and destruction of information in practical data storage applications, a nondestructive luminescence readout is essential. However, it is still unclear how to select the optimized excitation and emission bands to avoid the photochromic reaction during the “reading” process while maintaining high luminescence contrast and stability in inorganic photochromic materials. On the basis of the nonradiative energy transfer mechanism, Ho3+ ions were introduced into the Na0.5Bi2.5Nb2O9 host to obtain efficient luminescence switching due to their special excitation (451 nm) and emission (547 nm) characteristics. Under 407 nm irradiation (“writing”), the photochromic phenomenon can be effectively read out by measuring the changes in the luminescence emission intensity. The luminescence switching contrast increased up to 94%. Importantly, the excitation and emission energies did not significantly induce new photochromic reactions, causing less destruction to the material and the luminescence readout process. This outcome is superior to our previously reported results. Furthermore, the luminescence switching properties exhibit hardly any degradation after undergoing several cycles of the “writing”, “reading” and “erasing” processes, indicating excellent reversibility.

(K,Na)NbO3 ferroelectrics: a new class of solid-state photochromic materials with reversible luminescence switching behavior

In this paper, we reported a new photosensitive material, Sm doped K0.5Na0.5NbO3 (KNN) ceramics, fabricated using a solid-sate reaction method, which exhibits both photochromism and luminescence switching properties. By alternating visible light irradiation (λ > 407 nm) and thermal stimulus, the samples show a reversible color change from the initial green to pale gray. Interestingly, luminescence emission intensity can be effectively tuned using photochromic reactions. Furthermore, the luminescence switching degree strongly depends on the firing temperature. These results suggest that KNN-based perovskite oxides with photochromism, luminescence switching and ferroelectric energy storage properties are particularly attractive for optical data storage applications as multi-functional materials.

High energy-storage performance of 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3} relaxor ferroelectric thin films prepared by RF magnetron sputtering

Highlights: • High-quality PMN-PT 90/10 RFE thin films were prepared by RF magnetron sputtering. • The maximum discharged density of 31.3 J/cm{sup 3} was obtained in the 750-nm-thick film. • PMN-PT RFE films might be a promising material for energy-storage application. - Abstract: 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3} (PMN-PT 90/10) relaxor ferroelectric thin films with different thicknesses were deposited on the LaNiO{sub 3}/Si (100) by the radio-frequency (RF) magnetron sputtering technique. The effects of thickness and deposition temperature on the microstructure, dielectric properties and the energy-storage performance of the thin films were investigated in detail. X-ray diffraction spectra indicated that the thin films had crystallized into a pure perovskite phase with a (100)-preferred orientation after annealed at 700 °C. Moreover, all the PMN-PT 90/10 thin films showed the uniform and crack-free surface microstructure. As a result, a larger recoverable energy density of 31.3 J/cm{sup 3} was achieved in the 750-nm-thick film under 2640 kV/cm at room temperature. Thus, PMN-PT 90/10 relaxor thin films are the promising candidate for energy-storage capacitor application.