•Three-dimensional porous bismuth is fabricated by dealloying Sn–Bi alloys.•The resulting Bi microstructures are affected by the amount of Bi in the Sn–Bi alloys.•Single-crystal Bi nanowires growing in the [110] direction are fabricated by dealloying Sn–Bi alloys with a low Bi content.The fabrication of three-dimensional (3D) porous bismuth by electrochemical dealloying of two-phase Sn–Bi alloys was investigated. The results show that the resulting porous bismuth changes from a microporous structure composed of bismuth microparticles to an aligned nanowire matrix composite as the Bi content in the Sn–Bi master alloy decreases. Single-crystal bismuth nanowires growing in the [110] direction were fabricated by the selective dissolution of the Sn phase from an alloy with ultralow Bi content. The influence of the two states of elemental Bi existing in smelted Sn–Bi alloys during dealloying was systematically analyzed and discussed. This report presents a novel strategy for direct fabrication of bismuth nanowires by electrochemical dealloying.Download high-res image (209KB)Download full-size image

Ce-doping NiFe2O4 spinel ferrite thin films were prepared on Pt / Ti / SiO2 / Si substrates using a chemical solution deposition method. It has been observed that Ce-doping induced enhancement of unipolar resistive switching properties, such as uniform switching voltages, enlarged ON / OFF ratio, and long retention in Pt / NiFe2O4 / Pt memory devices. The dominant conduction mechanisms in the thin film devices were Ohmic conduction at low resistance state and lower voltage region of high resistance state, while Schottky emission dominated at higher voltage region in high resistance state. The physical mechanism of resistive switching is related to the formation and rupture of conducting filament. The improved stability of the switching parameters for the devices can be attributed to Ce-doping minimizing random formation and rupture of conductive filament. This study indicates that doping rare earth ions in ferrite thin films would be an effective approach for obtaining stable resistance switching memory devices.

Pr-doped ZnO hexagonal structure thin films with c-axis preferred orientation were deposited on Pt/Ti/SiO2/Si substrates by chemical solution deposition technique. The effects of Pr doping amount on the resistive switching behavior of Pt/Zn1−xPrxO/Pt (x = 0, 0.01, 0.03, and 0.05) memory cells were investigated. The results showed that Pr-doping lowered the c-axis orientation degree of the ZnO thin films, but improved the resistive switching properties of Pt/Zn1−xPrxO/Pt devices. The resistive switching devices exhibited good endurance, long retention, and uniform switching voltages. I-V characteristics and their temperature dependence analysis indicated that the conduction mechanism of LRS was Ohmic behavior, and that of HRS at relatively higher voltage is trap-controlled space charge limited current. The physical origin of the resistive switching can be referred to the formation and rupture of the oxygen vacancies related filaments.

Pr3+/Cd2+ co-doped ZnO hexagonal structure thin films with c-axis preferred orientation were deposited on Pt/Ti/SiO2/Si substrates using a chemical solution deposition method, and the effect of Cd-ion doping on the resistive switching properties of Zn0.97−xPr0.03CdxO thin films (x = 0, 0.02, 0.04, and 0.06) has been investigated. The results showed that Cd-doping improved the resistive switching properties of the Pt/Zn0.97−xPr0.03CdxO/Pt devices. The resistive switching devices exhibited good endurance, long retention, and uniform switching voltages. The resistive switching characteristics also show a good temperature stability beneficial for further device applications. The I–V characteristics and their temperature dependence analysis indicated that the conduction mechanism was ohmic conduction behavior for the low resistance state and at low voltage region for the high resistance state, whereas the conduction mechanism at relatively higher voltage for the high resistance state is trap-controlled space charge limited current. The resistive switching process has been explained using a conductive filament-related formation/rupture mechanism considering the thermal effects and the migration of oxygen vacancies. The reasons for the improvement of resistive switching performance through Cd ion doping, were attributed to the decrease of the band gap and the control of oxygen vacancies.

Ag-NPs doped NiFe2O4 (NFO) thin films have been synthesized by the chemical solution deposition method. The effect of Ag-NPs incorporation on the resistive switching (RS) properties of NFO films with different doping concentrations in the range of 0 to 1.0% Ag was investigated. Results show that Ag-NPs doped NFO based memory devices perform resistive switching with much better uniformity and repeatability in switching cycles, and have excellent reliability at an appropriate Ag-NPs doping concentration (i.e. 0.5%) instead of very low and high doping concentrations (i.e. un-doped NFO film, 0.2% and 1.0% Ag). On the basis of analyses performed on current–voltage characteristics and their temperature dependence, it was found that the carrier transport occurred through the conducting filaments in the low resistance state with ohmic conduction, and in the high resistance state with Schottky emission. In addition, the temperature dependence of the resistance and magnetic behavior at HRS and LRS revealed that the physical origin of the RS mechanism, which involves the formation and rupture of the conducting paths, consists of oxygen vacancies and Ag atoms. Ag-NPs doping-induced changes in the saturation magnetization, associated with resistive switching, have been ascribed to variations in the oxygen vacancy concentration. The excellent endurance properties (>103 cycles), data retention (of >105 s at 298 and 358 K), and good cycle-to-cycle uniformity are observed in 0.5% Ag-NPs doped NFO-based memory devices.

•Pt/Ta2O5/TiN structures were fabricated and investigated for resistive switching application.•Pt/Ta2O5/TiN devices exhibited high speed and multi-level bipolar resistive switching properties.•Electrical pulse induced multi-level storage capability showed good endurance and long retention.•Multi-level switching capability has been explained by the conducting filament model.Bipolar resistive switching performance has been demonstrated in the sandwiched Pt/Ta2O5/TiN structures, including uniform set and reset voltages distributions, good endurance, long retention, and high operation speed. In addition, multi-level storage capability has been achieved through controlling different reset stop voltages and different compliance currents in direct current voltage sweeping modes and by means of different pulse erasing voltages in pulse programming/erasing modes. High speed electrical pulse induced multi-level storage capability shows good endurance and long retention of the four level resistance states. On the basis of the conducting filament model, the multi-level switching capability has been explained. This study suggests that the Pt/Ta2O5/TiN devices have potential application in nonvolatile high speed and multi-level resistive switching memory.

•(Bi1.90Eu0.10)(V1−zMoz)O5.5 (z = 0, 0.05, 0.10, 0.15 and 0.20) thin films with c-axis oriented were prepared.•Eu3+ion can be used as an effective luminescent probe in the above thin films.•Dielectric properties of the thin films can be improved by Mo6+ doping.(Bi1.90Eu0.10)(V1−zMoz)O5.5 (z = 0, 0.05, 0.10, 0.15 and 0.20) thin films with c-axis oriented were prepared on Pt(111)/Ti/SiO2/Si substrates by using chemical solution deposition method. The effect of Mo6+ concentration on the structure, luminescence properties and dielectric properties of the thin films were characterized systematically. X-ray diffraction data indicates that the thin films with low Mo6+-doping content can remain Bi2VO5.5 structure. When the Mo6+-doping content z reaches to 0.15, the thin films are a mixture of diphase with the main phase Bi2VO5.5 and secondary phase Bi2MoO6. Under UV irradiation, all the thin films emit a bright red or orange emission which origin from Eu3+. With increasing Mo6+-doping content z, the relative intensity of the Red and Orange emissions show obviously change. The value of Red/Orange ratio first decrease, and it reached minimum when z is 0.15, then it recover to the initial value. The variation trend of the Red/Orange ratio reflects the change of the lattice symmetry. Dielectric constant of the thin films increased with the increasing of the Mo6+ concentration while dielectric loss decreased. The decrease of the quantities of oxygen vacancies and the generation of Bi2MoO6 phase are responsible for the improvement of electric properties. These results explain that Eu3+ion can be used as an effective luminescent probe in (Bi1.90Eu0.10)(V1−zMoz)O5.5 (z = 0, 0.05, 0.10, 0.15 and 0.20) thin films, and the electric properties of the thin films can be improved by Mo6+ doping.

Eu-doped Ba1−xSrxTiO3 (x = 0, 0.2, 0.3, and 0.4) thin films with Eu-doping content of 1 mol% have been prepared on fused silica substrates by a chemical solution deposition method and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), optical and photoluminescence measurements. XRD analysis showed that the films were well crystallized with a pure perovskite structure in the annealing temperature range from 650 to 750 °C. AFM observation indicated that the films were dense and smooth. The band-gap energies of the thin films were also investigated. The more the Sr content in the thin films, the narrower the energy gap of the thin films. Photoluminescence spectra of the thin films showed two prominent transitions of Eu3+ ions at 594 nm (5D0 → 7F1) and 618 nm (5D0 → 7F2) upon excitation at 395 nm (7F0 → 5L6). The observed changes of luminescence spectra by the decrease of the intensity ratio R, which was defined as the ratio of the integrated emission intensity of 5D0 → 7F2 transition to that of 5D0 → 7F1 transition, were associated with the increase of the inversion symmetry of Eu3+ sites when Sr content increased. Lifetime study of photoluminescence indicated that the average lifetime of the thin films was approximately 0.7 ms.

We report that CoNi2S4 nanosheet arrays exhibit ultrahigh specific capacitance of 2906 F g–1 and areal capacitance of 6.39 F cm–2 at a current density of 5 mA cm–2, as well as good rate capability and cycling stability, and superior electrochemical performances with an energy density of 33.9 Wh kg–1 at a power density of 409 W kg–1 have been achieved in an assembled aqueous asymmetric supercapacitor. The CoNi2S4 nanosheet arrays were in situ grown on nickel foams by a facile two-step hydrothermal method. The formation mechanism of the CoNi2S4 nanosheet arrays was based on an anion-exchange reaction involving the pseudo Kirkendall effect. The two aqueous asymmetric supercapacitors in series using the CoNi2S4 nanosheet arrays as the positive electrodes can power four 3-mm-diameter red-light-emitting diodes. The outstanding supercapacitive performance of CoNi2S4 nanosheet arrays can be attributed to ravine-like nanosheet architectures with good mechanical and electrical contact, low crystallinity and good wettability without an annealing process, rich redox reactions, as well as high conductivity and transport rate for both electrolyte ions and electrons. Our results demonstrate that CoNi2S4 nanosheet arrays are promising electrode materials for supercapacitor applications.Keywords: anion-exchange reaction; CoNi2S4; energy storage; nanosheet arrays; supercapacitor

We report on highly uniform resistive switching properties of amorphous InGaZnO (a-IGZO) thin films. The thin films were fabricated by a low temperature photochemical solution deposition method, a simple process combining chemical solution deposition and ultraviolet (UV) irradiation treatment. The a-IGZO based resistive switching devices exhibit long retention, good endurance, uniform switching voltages, and stable distribution of low and high resistance states. Electrical conduction mechanisms were also discussed on the basis of the current–voltage characteristics and their temperature dependence. The excellent resistive switching properties can be attributed to the reduction of organic- and hydrogen-based elements and the formation of enhanced metal-oxide bonding and metal-hydroxide bonding networks by hydrogen bonding due to UV irradiation, based on Fourier-transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and Field emission scanning electron microscopy analysis of the thin films. This study suggests that a-IGZO thin films have potential applications in resistive random access memory and the low temperature photochemical solution deposition method can find the opportunity for further achieving system on panel applications if the a-IGZO resistive switching cells were integrated with a-IGZO thin film transistors.Keywords: InGaZnO; photochemical solution deposition; resistive switching; RRAM; thin film;

•Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 films were prepared by chemical solution deposition.•Intense blue and near-infrared (NIR) emission can be detected under 980 nm excitation.•Blue emission is a three-photon process while NIR emission a two-photon process.•The thin films have a relatively high dielectric constant and a low loss.•The thin films exhibit temperature and frequency dependent dielectric relaxation.The blue emission and near-infrared (NIR) up-conversion photoluminescence and dielectric relaxation of Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 pyrochlore thin films prepared by a chemical solution deposition method have been investigated. The pyrochlore phase has been maintained for all compositions. Intense blue and NIR emission can be detected on the thin films on fused silica substrates excited by a 980 nm diode laser. Three UC emission bands centered at 480 nm, 665 nm, and 800 nm in the spectra can be assigned to 1G4→3H6, 1G4→3F4 and 3H4→3H6 transitions of Tm3+ ions, respectively. The dependence of UC emission intensity on pumping power indicates that the blue emission of the thin films follows a three-photon process while the NIR emission is a two-photon process. The thin films also exhibit a relatively high dielectric constant and a low loss as well as good bias voltage stability. Temperature and frequency dependent dielectric relaxation has been investigated. This study suggests that Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 thin films can be applied to new multifunctional photoluminescence dielectric thin-film devices.

We report the reproducible complementary switching based on the exceptional TiN/MgZnO/ZnO/Pt bipolar resistive memory devices. The uniform complementary switching with good endurance was observed after the second electroforming process. The resultant complementary switching of TiN/MgZnO/ZnO/Pt devices were interpreted in view of rupture and recovery of conductive filaments inside MgZnO layer and ZnO layer resulted from the redistribution of oxygen vacancies. The TiN/MgZnO/ZnO/Pt devices with complementary switching characteristics ensure the capability to suppress the sneak current paths of cross-point memories, and have great potential applications for future 3D crossbar memory architecture.

•c-axis oriented Bi2−xEuxVO5.5 films were prepared by chemical solution deposition.•The thin films show bright red emission.•Eu3+-doping leads to weakened dielectric dispersion and decreased dielectric loss.•The thin films have potential applications in luminescent ferroelectric devices.Highly c-axis oriented Bi2−xEuxVO5.5 (x = 0, 0.05, 0.10, 0.15, and 0.20) thin films were prepared on Pt(111)/Ti/SiO2/Si and fused silica substrates by using chemical solution deposition method, and characterized by X-ray diffraction, scanning electron microscopy, and optical and electrical measurements. Under 356 nm UV irradiation, a bright red photoluminescence can be observed in the thin films with x = 0.10, 0.15, and 0.20. The emission spectra included two strong peaks which originated from 5D0 → 7F1 (595 nm) and 5D0 → 7F2 (619 nm) transitions of Eu3+ ions. With increasing Eu3+-doping content x, the dielectric dispersion weakened, and dielectric loss decreased. Eu3+ doping can also decrease the leakage current of the thin films. These results demonstrate that Bi2−xEuxVO5.5 thin films are a kind of multifunctional material with potential applications in luminescent ferroelectric devices.

•Ce1 − xEuxO2 thin films were prepared by chemical solution deposition.•The thin films show strong red-orange emission.•There is concentration quenching effect of photoluminescence.•Eu-doping leads to structure distortion of the thin films.•The thin films have potential applications in optoelectronic devices.(200)-oriented Eu-doped cerium oxide thin films were fabricated, on fused silica substrates by a chemical solution deposition method. The thin films obtained were characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence measurements. Ce with valence state 4 + is confirmed to be predominant in Eu-doped CeO2 thin films. All the thin films were dense and crack-free, and showed bright orange-red emissions under ultraviolet light excitation, originated from the 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3 + ions. Structure distortions induced by Eu-doping affected the light emission of electric dipole transition 5D0 → 7F2. The strongest photoluminescent intensity was observed in the thin films with a Eu-doping content x of 0.08, indicating the existence of concentration quenching effect of photoluminescence. Lifetime study of photoluminescence indicated that the decrease of lifetime was originated from augmented pathway for deactivating excited Eu3 + ions. Our study suggests that Eu3 +-doped CeO2 thin films have potential applications in optoelectronic devices.

Pr-doped PbZrO3 antiferroelectric thin films have been fabricated on Pt/Ti/SiO2/Si substrates by a chemical solution deposition method. All the thin films with different Pr doping contents crystallized in perovskite phase with strong (111)-preferred orientation. When Pr doping amount was 1 mol%, the thin film exhibited a large saturation polarization of 59.4 μC cm−2, a high energy storage density of 14.2 J cm−3 at about 600 kV cm−1, and a dielectric constant of about 354 at 1 kHz. The high (111) orientation and occupying site of Pr ions were suggested to be responsible for the improved electrical properties of the thin films.Highlights► Pr-doped PbZrO3 antiferroelectric films prepared by chemical solution deposition. ► The Pr-doped thin films exhibit strong (111) orientation. ► Pr-doping results in large polarization and high energy storage density. ► Occupying site of Pr ions and high orientation play an important role.

The opportunity of spinel ferrites in nonvolatile memory device applications has been demonstrated by the resistive switching performance characteristics of a Pt/NiFe2O4/Pt structure, such as low operating voltage, high device yield, long retention time (up to 105 s), and good endurance (up to 2.2 × 104 cycles). The dominant conduction mechanisms are Ohmic conduction in the low-resistance state and in the lower-voltage region of the high-resistance state and Schottky emission in the higher-voltage region of the high-resistance state. On the basis of measurements of the temperature dependence of the resistances and magnetic properties in different resistance states, we explain the physical mechanism of resistive switching of Pt/NiFe2O4/Pt devices using the model of formation and rupture of conducting filaments by considering the thermal effect of oxygen vacancies and changes in the valences of cations due to the redox effect.

We reported the effects of Mn doping on the structure and dielectric properties of (Ba0.835Ca0.165)(Zr0.09Ti0.91)O3 (BCZT) thin films prepared by sol–gel method. The (Ba0.835Ca0.165)Mnx(Zr0.09Ti0.91)1 − xO3 (x = 0, 0.002, 0.005, and 0.01) thin films exhibited a pure pseudo-cubic perovskite structure with random orientation. Scanning electron microscopy and atomic force microscopy observation showed that increasing Mn-doping amount caused a decrease in particle size and a cluster of the particles, while the film surface remained smooth and crack-free. Compared with the undoped film, Mn doped BCZT thin films exhibited smaller dielectric constant and lower dielectric loss. The figure of merit reached the maximum value of 16.7 with a tunability of 53.6% for the film with 0.5 mol % Mn doping, when a bias electric field of 400 kV/cm was applied at 100 kHz. The results indicated that the Mn doped BCZT thin films are suitable for tunable microwave device applications.Highlights► Mn doped (Ba,Ca)(Zr,Ti)O3 (BCZT) films were prepared by sol–gel method. ► Mn doping effects on structure and dielectric properties of BCZT films. ► The Mn doped BCZT films show high dielectric tunability. ► The films have moderate dielectric constant and low dielectric loss. ► The films are suitable for tunable microwave device applications.

We report high dielectric tunabilities of (1 − x)Ba(Zr0.2Ti0.8)O3 − x(Ba0.7Ca0.3)TiO3 (BZT–xBCT) (x = 0.15, 0.30, 0.40, 0.45, 0.50, and 0.55) thin films prepared by a sol–gel method. The films show a pure perovskite structure with random orientation. They have moderate dielectric constant ranging from 350 to 500 and low dielectric loss near 3.0% at 1 kHz with 0 V bias at room temperature. The dielectric tunability of the BZT–0.55BCT thin films is up to 65% at 400 kV/cm and 100 kHz. The films exhibit a high optical transmission in the range of 420 nm–1500 nm. Their optical band gap energies are about 3.90 eV.Highlights► BZT-xBCT films with perovskite structure prepared by sol–gel method. ► High dielectric tunability and moderate dielectric constant for BZT-xBCT films. ► Band gap energy of about 3.90 eV for highly transparent BZT-xBCT films.

Bi4-xEuxTi3O12 (BEuT) ferroelectric thin films were prepared on fused silica substrates by using chemical solution deposition technique. The attained samples had a polycrystalline bismuth-layered perovskite structure, and their optical properties were composition dependent. The thin film samples had good optical transmittance above 500 nm wavelength. A blue shift of the optical absorption edge was observed in the BEuT thin films with increasing Eu3+ concentration. The optical band gaps of BEuT thin films were estimated to be about 3.57, 3.60, 3.61, 3.63, and 3.69 eV for the samples with x = 0.25, 0.40, 0.55, 0.70, and 0.85, respectively. Photoluminescence measurements showed that two emission peaks of BEuT thin films originated from two transitions of 5D0 → 7  F1 (594 nm) and 5D0 → 7  F2 (617 nm) had maximum intensities when Eu3+ concentration was x = 0.40. The relatively high quenching concentration of Eu3+ content was thought to be related to the layered structure of BEuT thin films. These results suggested that multifunctional BEuT thin film materials could have promising applications in optoelectronic devices.

Highly c-axis oriented \( {\text{M}}{{\text{g}}_{\text{x}}}{\text{Z}}{{\text{n}}_{{1 - {\text{x}}}}}{\text{O}}\left( {x = 0 \sim 0.2} \right) \) thin films with pure hexagonal phase were prepared on Pt/TiO2/SiO2/Si substrates by chemical solution deposition method, and their structure, photoluminescence, and lattice vibrational properties were studied. For the thin films with Mg contents ranging 0 ≤ x ≤ 0.20, the room-temperature near-band-edge emission exhibited blueshift up to about 0.35 eV, indicating that the band-gaps of thin films could be tailored by Mg incorporation, meanwhile, the green emission of the thin films enhanced with increasing Mg content. Raman spectra analysis indicated that the decreasing high frequency E2 Raman modes showed composition-dependent asymmetrically broadening. The difference of electronegativity between Mg2+ for Zn2+ as well as the potential fluctuation were discussed. Furthermore, longtitudial optical modes exhibited one-mode behavior with observed ~25.8 cm−1 blueshift. X-ray photoelectron spectroscopy measurements clearly confirmed the Mg incorporation.

We have developed a hybrid chemical solution method for preparing nanocomposite thin films composed of a ferroelectric Bi3.6Eu0.4Ti3O12 (BEuT) matrix and highly c-axis-oriented ZnO nanorods on Si substrates. First, a seed-layer solution growth approach was used to prepare the highly c-axis-oriented ZnO nanorods, and then a chemical solution deposition method was employed to fabricate the BEuT matrix by coating the ZnO nanorods using a spin-coating technique. The nanocomposite thin films obtained exhibited significantly enhanced red photoluminescence (PL) properties. The PL enhancement can be attributed to very efficient radiation energy transfer from the ZnO nanorods to Eu3+ ions in the BEuT matrix due to two spectral overlaps between the emission spectra of the ZnO nanorods and the excitation bands of Eu3+ ions in the BEuT matrix: the spectral overlap between the sharp UV emission of ZnO centered at 380 nm and the excitation spectrum of the 7F0 → 5L6 transition of Eu3+ ions at 395 nm and that between the defect-related deep-level green emission band of ZnO centered at 525 nm and the excitation spectrum of the 7F0 → 5D2 transition of Eu3+ ions at 465 nm. Our study opens possibility of realizing highly efficient photoluminescent ferroelectric multifunctional integrated thin-film devices. In addition, the hybrid chemical solution method also provides a useful route for the synthesis of some new nanocomposite thin films consisting of other inorganic matrix and c-axis-oriented ZnO nanorods.

Neodymium-doped lanthanum nickelate (La1 − xNdxNiO3, LNNO) thin films have been prepared on Si substrates by chemical solution deposition method. The effects of annealing temperature and the neodymium concentration on the structural and electrical properties of the thin films have been investigated. X-ray diffraction analysis showed that the LNNO thin films exhibited perovskite structure with (100) preferential orientation. The (100) orientation degree of the thin films changed with neodymium content; however, the resistivity of the thin films was not related to the degree of orientation. Field emission scanning electron microscopy observations confirmed that the films had a smooth surface and uniform thickness. The resistivity of the thin films annealed at 700 °C increased from 1.97 mΩ·cm to 5.35 mΩ·cm, with increasing neodymium doping amount from LaNiO3 to La0.6Nd0.4NiO3.

Epitaxial (Bi,La)4Ti3O12 (BLT) thin films, epitaxial Pb(Zr,Ti)O3 (PZT) thin films, and epitaxial multilayered BLT/PZT ferroelectric thin films with different orientations were prepared on SrTiO3 (STO) single crystal substrates by pulsed laser deposition. From X-ray pole-figures and electron diffraction patterns, the epitaxial orientation relationships between BLT layers, PZT layers, and STO substrates were identified to be (1) BLT(001)//PZT(001)//STO(001), and BLT[110]//PZT[100]//STO[100] for the multilayered thin films on (001)-oriented STO substrates, and (2) BLT(118)//PZT(011)//STO(011), and \( {\text{BLT}}{\left[ {\overline{1} \overline{1} 0} \right]}//{\text{PZT}}{\left[ {100} \right]}//{\text{SrTiO}}_{3} {\left[ {100} \right]} \) for the multilayered films on (011)-oriented STO substrates. Tri-layered films of the same compositions showed well-defined hysteresis loops as well as a high fatigue resistance up to 1 × 1010 switching cycles.

(Bi3.2La0.4Nd0.4)Ti3O12 (BLNT) thin films were prepared on Pt/Ti/SiO2/Si substrates by using chemical solution deposition technique, and the effects of annealing temperatures in the range of 550–750 °C on structure and electrical properties of the thin films were investigated. X-ray diffraction analysis shows that the thin films have a bismuth-layered perovskite structure with preferred (117) orientation. The surface morphology observation by field-emission scanning electron microscopy confirms that films are dense and smooth with uniformly distributed grains. The grain size of the thin films increases with increasing annealing temperature; meanwhile, the structural distortion of the thin films also increases. It was demonstrated that the thin films show good electrical properties. The dielectric constant and dielectric loss are 191 and 0.028, respectively, at 10 kHz for the thin film annealed at 600 °C, and the 2Pr value of the thin film annealed at 700 °C is 20.5 μC/cm2 at an electric field of 500 kV/cm.

•Flower-like Ni-Zn-Co oxide nanowire arrays were grown on nickel foam.•The Ni-Zn-Co oxide electrodes exhibited high supercapacitor performance.•Flower-like structure offered facile electron transport paths and rich reaction sites.The flower-like nickel-zinc-cobalt (Ni-Zn-Co) mixed metal oxide nanowire arrays have been directly synthesized on nickel foam by using a simple hydrothermal method and subsequent thermal treatment. According to the electrochemical characterization, it is demonstrated that the flower-like Ni-Zn-Co oxide nanowire arrays manifest high specific capacitance (776 F g−1) and areal capacitance (1.16 F cm−2) at a current density of 2 A g−1. It should also be noted that the Ni-Zn-Co oxide nanowire arrays exhibit long cycle stability (88.9% of the maximum value after 10000 cycles) and good rate capability (retention of 73.8% at 32 A g−1). The assembled aqueous asymmetric supercapacitor shows an energy density of 44.5 Wh kg−1 at a power density of 880 W kg−1. Furthermore, in terms of the analysis results of material characterization and electrochemical performance, the excellent pseudocapacitive performance could be ascribed to the unique flower-like nanowire architecture with high surface areas, rich redox reaction sites, good mechanical and electrical contacts, as well as high conductivities and transport rates for both electrolyte ions and electrons. This study indicates that the flower-like Ni-Zn-Co oxide nanowire arrays could find opportunities in supercapacitor applications.