This paper proposes a scheme based on the Potts and Ising models for simulating polarization switching of polycrystalline ferroelectrics using the Monte Carlo method. The polycrystalline texture with different average...This paper proposes a scheme based on the Potts and Ising models for simulating polarization switching of polycrystalline ferroelectrics using the Monte Carlo method. The polycrystalline texture with different average grain size is produced from the Potts model. Then Ising model is implemented in the polycrystalline texture to produce the domain pattern and hysteresis loop. The domain patterns and hysteresis loops have been obtained for polycrystalline texture with different average grain size. From the results of domain pattern evolution process under an applied electric field using this scheme, an extended domain, which covers more than one grain with polarization aligned roughly in the same direction, has been observed during the polarization reversal. This scheme can well reproduce the basic properties of polycrystalline ferroelectrics and is a valuable tool for exploring the physical properties of polycrystalline ferroelectrics.展开更多
A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1-3x/2^NdxZr0.52Ti0.48O3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The resu...A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1-3x/2^NdxZr0.52Ti0.48O3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. Piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate (PZT). Especially, the supreme values of piezoelectric constant (d33) and dielectric constant (ε) for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization (Pr) also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions.展开更多
Neodymium-doped strontium bismuth titanate (SrBi4-xNdxTi4O15) ferroelectric thin films were fabricated using the sol-gel method on Pt/Ti/SiO2/Si substrates. The influence of Nd content on the microstructure and ferr...Neodymium-doped strontium bismuth titanate (SrBi4-xNdxTi4O15) ferroelectric thin films were fabricated using the sol-gel method on Pt/Ti/SiO2/Si substrates. The influence of Nd content on the microstructure and ferroelectric properties of SrBi4-xNdxTi4O15 thin films were systematically studied. The results indicated that the SrBi3.88Nd0.12Ti4O15 (SBNT0.12) thin films had better ferroelectric properties, with a remanent polarization of (2Pr) of 34.3 μC/cm^2 and a coercive field (2Ec) of 220 kV/cm. This could be attributed to the fact that SBNT0.12 ferroelectric thin films consisted of more and larger ball-like grains, approximately 150-200 nm, with structure distortion, which greatly contributed to the improvement of the ferroelectric properties of the films. Furthermore, the film exhibited a good fatigue resistant property. The value of 2Pr after 10^10 switching cycles did not change significantly. The SrBi3.88Nd0.12Ti4O15 films were promising candidates for the application of FeRAMs.展开更多
Ho doping 0.825K_(0.5)Na_(0.5)NbO_(3)-0.175Sr(Yb_(0.5)Nb_(0.5))_(O3)(KNN-SYbN-x%Ho)transparent ceramics were prepared by solid-state sintering method.The structure,ferroelectric,energy storage,and optical properties o...Ho doping 0.825K_(0.5)Na_(0.5)NbO_(3)-0.175Sr(Yb_(0.5)Nb_(0.5))_(O3)(KNN-SYbN-x%Ho)transparent ceramics were prepared by solid-state sintering method.The structure,ferroelectric,energy storage,and optical properties of KNN-SYbN-x%Ho were explored.With the addition of Ho,under the excitation of a 980 nm laser,the ceramics exhibit up-conversion luminescence properties with wavelengths of 550 nm and 670 nm,however,the ceramics change from pseudo-cubic phase to triphase-orthorhombic phase and the light transmittance decreases.The addition of Ho significantly enhances the ferroelectric properties and the energy storage performance of KNN-SYbN-x%Ho ceramics.When x=0.15,the residual polarization P_(r)=9.11μC/cm^(2),while x=0.20,the maximum energy storage density W_(rec) reaches 0.26 J/cm^(3),and the energy storage efficiencyηreaches 87.1%.展开更多
Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb^2+ substituted for Ba^2+ ceramics (Ba0.7-xPbx)Sr0.3TiO3 (x=0.1-0.4, BPST) were prepared by using conventional solid-reaction method. XRD analysis shows that t...Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb^2+ substituted for Ba^2+ ceramics (Ba0.7-xPbx)Sr0.3TiO3 (x=0.1-0.4, BPST) were prepared by using conventional solid-reaction method. XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb^2+ content increasing. ESEM analysis shows that the Pb^2+ substituted samples have a denser and more uniform surface morphology than that of pure BST. Measured electrical properties suggest that the Pb^2+ substitution for Ba^2+ in the BST system enhances the ferroelectric performance obviously when x=0.2. In addition, the substitution increases the samples Curie temperature (To) r (Ba0.5Pb0.2)Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature. The corresponding saturated polarization (Ps), remnant polarization (Pr) and coercive field (Ec) is respectively 15.687 μC/cm^2, 8.100 μ C/cm^2 and 6.611 kV/cm. The measured Tc of (Ba0.5Pb0.2)Sr0.3TiO3 is 117 ℃.展开更多
Multiferroic properties and exchange bias (EB) in Bi1-xSrxFeO3 (x = 0-0.6) ceramics synthesized by a modified Pechini method are investigated. Sr concentration dependence of structure distorting, ferroelectric pro...Multiferroic properties and exchange bias (EB) in Bi1-xSrxFeO3 (x = 0-0.6) ceramics synthesized by a modified Pechini method are investigated. Sr concentration dependence of structure distorting, ferroelectric properties, and dielectric properties were studied at room temperature. Appropriate Sr doping (x = 0.05-0.2) has been found to decrease the conductivity, enhance ferroelectric properties and give rise to high dielectric constant. Compared with antiferromagnetic BiFeO3 compound, BSFO-x (O≤x ≤0.4) ceramics show weak ferromagnetism at room temperature, and their exchange bias field and vertical magnetization shift are observed and exhibit a strong dependence on the content of Sr. This observed EB effect which keeps stable in BSFO ceramics at 10 K tend to vanish at room temperature with Sr concentration over 0.4.展开更多
The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were...The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 μC/cm^2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.2eLa0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed.展开更多
A new three-phase PZT C/PVC composite comprising PZT(50 vol%),nanocrystalline PVC (50 vol%) and a small volume fraction f of black(C0was prepared by the hot-pressing technique.The dielectric property of the comp...A new three-phase PZT C/PVC composite comprising PZT(50 vol%),nanocrystalline PVC (50 vol%) and a small volume fraction f of black(C0was prepared by the hot-pressing technique.The dielectric property of the composite as α function of the frequency and the dielectric and piezoelectric properties as α function of the volume fraction f of C were studied.The measured dielectric property demonstrates that α percolation transition occurs in the three-phase composites as in normal two-phase metal-insulator continuum media.The dielectric constant varies slightly with f at f〈0.1 and increases rapidly when f is close to the percolation threshold at 1kHz.The optimum properties were obtained for f=0.5 before the percolation threshold in the PZT/C/PVC(50/f/(50-f)vol%)composite with its d33(20pC/N) being 50% higher than that of the PZT/PVC(50/50vol%),and its g33(47.23×10^-3Vm/N)and Kp(0.25) much higher than the earlier reported values,XRD patterns and P-E hysteresis loops were used to interpret the experimental results.展开更多
(Ba0.4Pb0.3)Sr0.3TiO3 thin films were fabricated via pulsed laser deposition (PLD) technique on Pt/TiO2/SiO2/Si substrate. The crystallization of the films was characterized by XRD and FSEM, and the experimental r...(Ba0.4Pb0.3)Sr0.3TiO3 thin films were fabricated via pulsed laser deposition (PLD) technique on Pt/TiO2/SiO2/Si substrate. The crystallization of the films was characterized by XRD and FSEM, and the experimental results suggested deposition parameters, especially the deposition temperature was the key factor in forming the perovskite structure. The dielectric properties of the film deposited with optimized parameters were studied by an Agilent 4294A impedance analyzer at 1 MHz. The dielectric constant was 772, and the loss tangent was 0.006. In addition, the well-shaped hysteresis loop also showed that the film had a well performance in ferroelectric. The saturated polarization P, remnant polarization Pr and coercive field E were about 4.6 μC/cm2, 2.5 μC/cm2 and 23 kV/cm (the coercive voltage is 0.7 V), respectively. It is suggested the film should be a promising candidate for microwave applications and nonvolatile ferroelectric random access memories (NvFeRAMs).展开更多
Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 (C0.4S0.6BNT) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. Effect of annealing process (time and temperature) on structures and ferroelectric p...Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 (C0.4S0.6BNT) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. Effect of annealing process (time and temperature) on structures and ferroelectric properties of C0.4S0.6BNT thin film was investigated. The relative intensity of (200) peak increased first then decreased with annealing temperature and became predominant at 800 ℃. In contrast, no evident change could be observed in the (001) peak. The remnant polarization (Pr) and coercive field (Ec) for C0.4S0.6BNT film annealed at 800℃ for 5 min were 21.6μC/cm2 and 68.3 kV/cm, respectively.展开更多
Bi0.9Ba0.lFeO3 (BBFO)/La2/3Srl/3MnO3 (LSMO) heterostructures are fabricated on LaA103 (100) substrates by pulsed laser deposition. Giant remnant polarization value (~ 85 μC/cm2) and large saturated magnetizat...Bi0.9Ba0.lFeO3 (BBFO)/La2/3Srl/3MnO3 (LSMO) heterostructures are fabricated on LaA103 (100) substrates by pulsed laser deposition. Giant remnant polarization value (~ 85 μC/cm2) and large saturated magnetization value (~ 12.4 emu/cm3) for BBFO/LSMO heterostructures are demonstrated at room temperature. Mixed ferroelectric domain structures and low leakage current are observed and in favor of enhanced ferroelectrie properties in the BBFO/LSMO het- erostructures. The magnetic field-dependent magnetization measurements reveal the enhancement in the magnetic moment and improved magnetic hysteresis loop originating from the BBFO/LSMO interface. The heterostructure is proved to be effective in enhancing the ferroelectric and ferromagnetic performances in multiferroic BFO films at room temperature.展开更多
The structure and properties of Mg-doped SrBi4Ti4O15(SBT) were dicussed. Mg substitution into SBT had two possibilities states with the dopant amount variety. Mg cation substituted mostly into Sr^2+ and the amount ...The structure and properties of Mg-doped SrBi4Ti4O15(SBT) were dicussed. Mg substitution into SBT had two possibilities states with the dopant amount variety. Mg cation substituted mostly into Sr^2+ and the amount proportion was 68.11%.Mg ion will substitute into Ti ion site in perovskite layer when the doping amount increases. Polarization increases sharply when x=0.1 and then decreases becauses of the domain pinning. The Curie temperature of Mg-doped SBT is about 300 ℃ and there is a broad diffuse phase transition near Tc with a flat peak near the Ta of SBT.展开更多
Most widely used piezoelectric ceramics are based on Pb(Zr,Ti)O3(PZT)composition which has adverse environmental and health effects due to its high lead content.Environmental and safety concerns with respect to the ut...Most widely used piezoelectric ceramics are based on Pb(Zr,Ti)O3(PZT)composition which has adverse environmental and health effects due to its high lead content.Environmental and safety concerns with respect to the utilization,recycling,and disposal of lead-based piezoelectric ceramics have induced a new surge in developing lead-free piezoelectric ceramics.Among all the lead-free ceramics,(K,Na)NbO3(KNN)has drawn increasing attention because of its well-balanced piezoelectric properties and better environmental compatibility.On basis of the author’s work,this review summarizes the progress that has been made in recent years on development of KNN-based piezoelectric ceramics,including crystallographic structure and phase transition analysis,pressurized solid-state sintering as well as liquid-phase-assisted sintering process,and poling treatment for property enhancement.All in all,KNN is a promising lead-free system,but more research is still required both from academic and industrial interests.展开更多
Bi_(3.25)La_(0.75)Ti_(3)O_(12)(BLT)thin films are promising materials used in non-volatile memories.In this work,BLT films were deposited on Pt(111)/Ti/SiO_(2)/Si substrates by rf-magnetron sputtering method followed ...Bi_(3.25)La_(0.75)Ti_(3)O_(12)(BLT)thin films are promising materials used in non-volatile memories.In this work,BLT films were deposited on Pt(111)/Ti/SiO_(2)/Si substrates by rf-magnetron sputtering method followed by annealing treatments.The microstructures of BLT thin films were investigated via X-ray diffraction(XRD),scanning electron microscopy(SEM)and atomic force microscopy(AFM).With the increase in annealing temperature,the grain size increased significantly and the preferred crystalline orientation changed.A well-saturated hysteresis loop with a superior remnant polarization of 15.4μC/cm^(2) was obtained for BLT thin films annealed at 700°C.The results show that the dielectric constant decreased with the increase in grain sizes.展开更多
Electronic devices that are transparent and flexible have a wide range of applications in the domains of vital sign parameter monitoring,health management,and so on.Ferroelectric memory is a revolutionary nonvolatile ...Electronic devices that are transparent and flexible have a wide range of applications in the domains of vital sign parameter monitoring,health management,and so on.Ferroelectric memory is a revolutionary nonvolatile memory that is ideal for data storage and processing in transparent flexible electronic systems.In this study,Ce-doped hafnium oxide ferroelectric thin film is manufactured on mica substrate by the chemical solution deposition with transparent indium tin oxide(ITO)thin films as the bottom electrodes.The transmittance of mica/ITO/Hf_(0.85)Ce_(0.15)O_(2)thin film is over 80%.The 2Pr of the transparent flexible Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film is increased by about 22.4%and the Ec is reduced by 26.7%compared with those of Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film grown on p+-Si substrate.The transparent flexible Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film can remain keeping good quality when being bent under±2.5 mm bending radius.Additionally,degradation of polarization,retention,and endurance performance was not obvious even at a bending radius of 5.0 mm after 104 bending cycles.This research provides a new strategy and an important experimental basis for the development and implementation of transparent flexible ferroelectric memories.展开更多
Na_(0.5)Bi_(0.5)TiO_(3)(NBT)-based ceramics have been widely used as dielectric materials for energy storage capacitors because of their environmental friendliness and excellent ferroelectric properties.However,their ...Na_(0.5)Bi_(0.5)TiO_(3)(NBT)-based ceramics have been widely used as dielectric materials for energy storage capacitors because of their environmental friendliness and excellent ferroelectric properties.However,their energy storage performance still needs to be further improved to satisfy the increasing demand.Herein,we report a novel 0.90(Na_(0.5)Bi_(0.5))0.7Sr_(0.3)TiO_(3-0.10)Bi(Ni_(0.5)Sn_(0.5))O_(3)(0.90NBST-0.10BNS)ceramic with significantly improved energy density(5.0 J cm3),enhanced recoverable energy density(4.18 J cm^(3))and high energy efficiency(83.64%)through the incorporation of Bi(Ni0.5Sn0.5)O3(BNS),due to the increased breakdown strength and the relaxation ferroelectric(RFE)properties.The first-order reversal curve(FORC)measurements confirm that the addition of BNS improves RFE properties by breaking the order of long-range ferroelectricity.The 0.90NBST-0.10BNS ceramic also possesses an outstanding temperature and frequency stability of energy storage properties in the range of 20C e140C and 1 Hze100 Hz,respectively.More importantly,the discharge properties characterized by a preeminent power density(36.19 MW cm^(3)),transient energy release times(144.2 ns),and high discharge energy density(1.16 J cm3)also synchronously observed in 0.90NBST-0.10BNS ceramic.These results show that the 0.90NBST-0.10BNS ceramic with outstanding comprehensive performances is a promising energy storage ceramic candidate for capacitors in high power systems.展开更多
The Ba(0.96)Ca(0.04)Ti(0.90)Sn(0.10)O3-xNd2 O3(x = 0-0.08%) ceramics were prepared via traditional solid-state sintering method. The influences of Nd3+ substitution on the phase structure, dielectric proper...The Ba(0.96)Ca(0.04)Ti(0.90)Sn(0.10)O3-xNd2 O3(x = 0-0.08%) ceramics were prepared via traditional solid-state sintering method. The influences of Nd3+ substitution on the phase structure, dielectric properties,piezoelectric and ferroelectric properties of the ceramics were investigated. All the samples possess pure BaTiO3-type perovskite structure. MPB with orthorhombic and tetragonal phase coexist at around x = 0.03-0.04. Nd^(3+) doping decreases both Tc and T(O-T) to lower temperature. All the samples exhibit an intermediate state with the coexistence of ferroelectric and diffuse relaxor ferroelectric behavior with the addition of Nd^(3+). The electric properties of the ceramics were optimized at x = 0.03 with d33, Kp, εr and Pr values of 545 pC/N, 51.9%, 24,412 and 10.74 μC/cm^2.展开更多
Bil_xTbxFe03 thin films were prepared on Sn02 (fluorine doped tin oxide) substrates by a sol-gel method. The structural and electrical properties of the BiFe03 thin films were characterized and tested. The results i...Bil_xTbxFe03 thin films were prepared on Sn02 (fluorine doped tin oxide) substrates by a sol-gel method. The structural and electrical properties of the BiFe03 thin films were characterized and tested. The results indicated that the diffraction peak of the Tb-doped BiFe03 films was shifted towards right as the doping amounts were increased. The structure was transformed from the rhombohedral to tetragonal/orthorhombic phase. The Bio.sgTbo.11Fe03 thin film showed the well-developed P-E loops, which enhanced remnant polarization (Pr = 88.05 μC/cm2) at room temperature. The dielectric constant and dielectric loss of Bio.sgTbo.llFe03 thin film at 100 kHz were 185 and 0.018, respectively. Furthermore, the Bio.seTbo.llFe03 thin film showed a relatively low leakage current density of 2.07×10-5 A/cm2 at an applied electric field of 150 kV/cm. The X- ray photoelectron spectroscopy (XPS) spectra indicated that the presence of Fe2+ ions in the Bio.egTbo.11Fe03 thin film was less than that in the pure BiFe03.展开更多
As one of the representatives of lead-free NBT ceramics,Na_(0.5)Bi_(4.5)Ti_(4)O_(15) has still attracted much attention due to its excellent dielectric properties and has become the focus of research.However,its piezo...As one of the representatives of lead-free NBT ceramics,Na_(0.5)Bi_(4.5)Ti_(4)O_(15) has still attracted much attention due to its excellent dielectric properties and has become the focus of research.However,its piezoelectric properties are far from satisfactory.In order to improve the piezoelectric properties of Na_(0.5)Bi_(4.5)Ti_(4)O_(15),Na_(0.5)Bi_(4.5)Ti_(4-x)Mg_(x)O_(y)–BaTiO_(3)(NBTM–BT)composite ceramics were synthesized by a conventional mixed oxide route and sintered at 1040℃ through two-step method.We optimized the electrical properties of NBTM–BT by changing the stoichiometric ratio of Mg content and studied its microscopic mechanism.The piezoelectric coefficient(d33)is stable at about 20 pC/N.Moreover,the maximum remanent polarization(2Pr)of the ceramic is 3.08C/cm^(2) with the coercive field of 18.01 kV/cm.The dielectric constant and dielectric loss for Na_(0.5)Bi_(4.5)Ti_(3.96)Mg_(0.04)–BT composite ceramic were found to be 486 and 0.17 at 10 kHz,respectively.The characteristic peaks of BT and Na_(0.5)Bi_(4.5)Ti_(4)O_(15) can be observed clearly from the X-ray diffraction analysis.SEM analysis showed that all samples were well crystallized.Consequently,the piezoelectric and ferroelectric properties of Na_(0.5)Bi_(4.5)Ti_(4)O_(15)–BT composite ceramic will be enhanced much by Mg doping,which means it has a wider range of applications in electronic devices such as piezoelectric devices.展开更多
Na_(0.5)(Bi_(3/4)RE_(1/4))_(0.5)TiO_(3)(RENBT,RE=Nd,Gd,Dy,and Ho)compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave(FP-LAPW)method ba...Na_(0.5)(Bi_(3/4)RE_(1/4))_(0.5)TiO_(3)(RENBT,RE=Nd,Gd,Dy,and Ho)compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave(FP-LAPW)method based on the spin-polarized density functional theory implemented in the WIEN2k code.Combined charge density distribution and Ti K-edge X-ray absorption spectra reveal that the RENBT compositions with high polarization values are accompanied by a higher TiO_(6)distortion,DyNBT,and NdNBT compounds.The effect of the rare-earth elements on the polarization is confirmed experimentally with the collection of the hysteresis loops.The investigation of the electronic properties of the compounds highlights the emergence of a magnetization owing to the 4f orbital effect of the rare-earth elements.Besides,the investigation of the chemical ordering shows a short-range chemical ordering for the pure composition and an increased A-site disorder for dysprosium doped NBT system.The increased disorder may speak for increased relaxor properties in the RE doped compositions.展开更多
基金Project supported by National Natural Science Foundation of China (Grant No 10474057)
文摘This paper proposes a scheme based on the Potts and Ising models for simulating polarization switching of polycrystalline ferroelectrics using the Monte Carlo method. The polycrystalline texture with different average grain size is produced from the Potts model. Then Ising model is implemented in the polycrystalline texture to produce the domain pattern and hysteresis loop. The domain patterns and hysteresis loops have been obtained for polycrystalline texture with different average grain size. From the results of domain pattern evolution process under an applied electric field using this scheme, an extended domain, which covers more than one grain with polarization aligned roughly in the same direction, has been observed during the polarization reversal. This scheme can well reproduce the basic properties of polycrystalline ferroelectrics and is a valuable tool for exploring the physical properties of polycrystalline ferroelectrics.
基金Project supported by the National Natural Science Foundation of China (Grant No 50742007)the National High Technology Research and Development Program of China (Grant No 2007AA03Z103)+2 种基金the National Defence Foundation of China (GrantNo 401050301)the Key Laboratory Foundation of Sonar Technology of China (Grant No 9140C24KF0901)the Scientific Project of Heilongjiang Province,China (Grant No E2007-31)
文摘A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1-3x/2^NdxZr0.52Ti0.48O3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. Piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate (PZT). Especially, the supreme values of piezoelectric constant (d33) and dielectric constant (ε) for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization (Pr) also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions.
基金the National Natural Science Foundation of China (60471042)the Natural Science Foundation of Shandong Province (Y2007F36)
文摘Neodymium-doped strontium bismuth titanate (SrBi4-xNdxTi4O15) ferroelectric thin films were fabricated using the sol-gel method on Pt/Ti/SiO2/Si substrates. The influence of Nd content on the microstructure and ferroelectric properties of SrBi4-xNdxTi4O15 thin films were systematically studied. The results indicated that the SrBi3.88Nd0.12Ti4O15 (SBNT0.12) thin films had better ferroelectric properties, with a remanent polarization of (2Pr) of 34.3 μC/cm^2 and a coercive field (2Ec) of 220 kV/cm. This could be attributed to the fact that SBNT0.12 ferroelectric thin films consisted of more and larger ball-like grains, approximately 150-200 nm, with structure distortion, which greatly contributed to the improvement of the ferroelectric properties of the films. Furthermore, the film exhibited a good fatigue resistant property. The value of 2Pr after 10^10 switching cycles did not change significantly. The SrBi3.88Nd0.12Ti4O15 films were promising candidates for the application of FeRAMs.
基金Funded by the National Nature Science Foundation of China(No.61965007)the Guangxi Nature Science Foundation,China(No.2018GXNSFDA281042)the Guangxi Key Laboratory of Information Materials(Guilin University of Electronic Technology),China(No.201007-Z)。
文摘Ho doping 0.825K_(0.5)Na_(0.5)NbO_(3)-0.175Sr(Yb_(0.5)Nb_(0.5))_(O3)(KNN-SYbN-x%Ho)transparent ceramics were prepared by solid-state sintering method.The structure,ferroelectric,energy storage,and optical properties of KNN-SYbN-x%Ho were explored.With the addition of Ho,under the excitation of a 980 nm laser,the ceramics exhibit up-conversion luminescence properties with wavelengths of 550 nm and 670 nm,however,the ceramics change from pseudo-cubic phase to triphase-orthorhombic phase and the light transmittance decreases.The addition of Ho significantly enhances the ferroelectric properties and the energy storage performance of KNN-SYbN-x%Ho ceramics.When x=0.15,the residual polarization P_(r)=9.11μC/cm^(2),while x=0.20,the maximum energy storage density W_(rec) reaches 0.26 J/cm^(3),and the energy storage efficiencyηreaches 87.1%.
基金Funded by the National Natural Science Foundation of China (No. 60571009)
文摘Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb^2+ substituted for Ba^2+ ceramics (Ba0.7-xPbx)Sr0.3TiO3 (x=0.1-0.4, BPST) were prepared by using conventional solid-reaction method. XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb^2+ content increasing. ESEM analysis shows that the Pb^2+ substituted samples have a denser and more uniform surface morphology than that of pure BST. Measured electrical properties suggest that the Pb^2+ substitution for Ba^2+ in the BST system enhances the ferroelectric performance obviously when x=0.2. In addition, the substitution increases the samples Curie temperature (To) r (Ba0.5Pb0.2)Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature. The corresponding saturated polarization (Ps), remnant polarization (Pr) and coercive field (Ec) is respectively 15.687 μC/cm^2, 8.100 μ C/cm^2 and 6.611 kV/cm. The measured Tc of (Ba0.5Pb0.2)Sr0.3TiO3 is 117 ℃.
基金supported by the Program for New Century Excellent Talents in Universities of China(Grant No.41322028)the Fundamental Research Funds for the Central University of China(Grant No.WUT 2014-Ia-018)the National Science Fund for Excellent Young Scholars of China(Grant No.41074056)
文摘Multiferroic properties and exchange bias (EB) in Bi1-xSrxFeO3 (x = 0-0.6) ceramics synthesized by a modified Pechini method are investigated. Sr concentration dependence of structure distorting, ferroelectric properties, and dielectric properties were studied at room temperature. Appropriate Sr doping (x = 0.05-0.2) has been found to decrease the conductivity, enhance ferroelectric properties and give rise to high dielectric constant. Compared with antiferromagnetic BiFeO3 compound, BSFO-x (O≤x ≤0.4) ceramics show weak ferromagnetism at room temperature, and their exchange bias field and vertical magnetization shift are observed and exhibit a strong dependence on the content of Sr. This observed EB effect which keeps stable in BSFO ceramics at 10 K tend to vanish at room temperature with Sr concentration over 0.4.
基金the Foundation of Wuhan University of Science and Technology
文摘The Bi4Ti3Oi2 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 μC/cm^2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.2eLa0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed.
文摘A new three-phase PZT C/PVC composite comprising PZT(50 vol%),nanocrystalline PVC (50 vol%) and a small volume fraction f of black(C0was prepared by the hot-pressing technique.The dielectric property of the composite as α function of the frequency and the dielectric and piezoelectric properties as α function of the volume fraction f of C were studied.The measured dielectric property demonstrates that α percolation transition occurs in the three-phase composites as in normal two-phase metal-insulator continuum media.The dielectric constant varies slightly with f at f〈0.1 and increases rapidly when f is close to the percolation threshold at 1kHz.The optimum properties were obtained for f=0.5 before the percolation threshold in the PZT/C/PVC(50/f/(50-f)vol%)composite with its d33(20pC/N) being 50% higher than that of the PZT/PVC(50/50vol%),and its g33(47.23×10^-3Vm/N)and Kp(0.25) much higher than the earlier reported values,XRD patterns and P-E hysteresis loops were used to interpret the experimental results.
基金the National Natural Science Foundation of China(No.60571009)
文摘(Ba0.4Pb0.3)Sr0.3TiO3 thin films were fabricated via pulsed laser deposition (PLD) technique on Pt/TiO2/SiO2/Si substrate. The crystallization of the films was characterized by XRD and FSEM, and the experimental results suggested deposition parameters, especially the deposition temperature was the key factor in forming the perovskite structure. The dielectric properties of the film deposited with optimized parameters were studied by an Agilent 4294A impedance analyzer at 1 MHz. The dielectric constant was 772, and the loss tangent was 0.006. In addition, the well-shaped hysteresis loop also showed that the film had a well performance in ferroelectric. The saturated polarization P, remnant polarization Pr and coercive field E were about 4.6 μC/cm2, 2.5 μC/cm2 and 23 kV/cm (the coercive voltage is 0.7 V), respectively. It is suggested the film should be a promising candidate for microwave applications and nonvolatile ferroelectric random access memories (NvFeRAMs).
基金supported by the Natural Science Foundation of Shandong Province (Y2007F36)the National Natural Science Foundation of China (50872075)
文摘Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 (C0.4S0.6BNT) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. Effect of annealing process (time and temperature) on structures and ferroelectric properties of C0.4S0.6BNT thin film was investigated. The relative intensity of (200) peak increased first then decreased with annealing temperature and became predominant at 800 ℃. In contrast, no evident change could be observed in the (001) peak. The remnant polarization (Pr) and coercive field (Ec) for C0.4S0.6BNT film annealed at 800℃ for 5 min were 21.6μC/cm2 and 68.3 kV/cm, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.61078057)the Natural Science Foundation of Shannxi Province,China(Grant No.2011GM6013)+2 种基金the Foundation for Fundamental Research of Northwestern Polytechnical University of China(Grant Nos.JC20110270 and 3102014JCQ01029)the Open Project of Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education,Lanzhou University,China(Grant Nos.LZUMMM2013001 and LZUMMM2014007)the Scholarship Fund of China(Grant No.201303070058)
文摘Bi0.9Ba0.lFeO3 (BBFO)/La2/3Srl/3MnO3 (LSMO) heterostructures are fabricated on LaA103 (100) substrates by pulsed laser deposition. Giant remnant polarization value (~ 85 μC/cm2) and large saturated magnetization value (~ 12.4 emu/cm3) for BBFO/LSMO heterostructures are demonstrated at room temperature. Mixed ferroelectric domain structures and low leakage current are observed and in favor of enhanced ferroelectrie properties in the BBFO/LSMO het- erostructures. The magnetic field-dependent magnetization measurements reveal the enhancement in the magnetic moment and improved magnetic hysteresis loop originating from the BBFO/LSMO interface. The heterostructure is proved to be effective in enhancing the ferroelectric and ferromagnetic performances in multiferroic BFO films at room temperature.
基金Funded by the Natural Science Foundation of China (No. 50472016, 50502027)the main project of the Ministry of Education (MOE) of China and the Chenguang Science Plan of Wuhan (No. 200750731268)
文摘The structure and properties of Mg-doped SrBi4Ti4O15(SBT) were dicussed. Mg substitution into SBT had two possibilities states with the dopant amount variety. Mg cation substituted mostly into Sr^2+ and the amount proportion was 68.11%.Mg ion will substitute into Ti ion site in perovskite layer when the doping amount increases. Polarization increases sharply when x=0.1 and then decreases becauses of the domain pinning. The Curie temperature of Mg-doped SBT is about 300 ℃ and there is a broad diffuse phase transition near Tc with a flat peak near the Ta of SBT.
基金Tsinghua University Initiative Scientific Research Program and National Nature Science Foundation of China(Grant Nos.50921061 and 51028202).
文摘Most widely used piezoelectric ceramics are based on Pb(Zr,Ti)O3(PZT)composition which has adverse environmental and health effects due to its high lead content.Environmental and safety concerns with respect to the utilization,recycling,and disposal of lead-based piezoelectric ceramics have induced a new surge in developing lead-free piezoelectric ceramics.Among all the lead-free ceramics,(K,Na)NbO3(KNN)has drawn increasing attention because of its well-balanced piezoelectric properties and better environmental compatibility.On basis of the author’s work,this review summarizes the progress that has been made in recent years on development of KNN-based piezoelectric ceramics,including crystallographic structure and phase transition analysis,pressurized solid-state sintering as well as liquid-phase-assisted sintering process,and poling treatment for property enhancement.All in all,KNN is a promising lead-free system,but more research is still required both from academic and industrial interests.
基金supported by the Research Foundation of Liaocheng University(No.318051939)Opening Project of Beijing Key Laboratory of Digital Stomatology(PKUSS20210301)+1 种基金Natural Science Foundation of Shandong Province of China(Nos.ZR2020ME031,ZR2020ME033)Innovation Team of Higher Educational Science and Technology Program in Shandong Province(No.2019KJA025).
文摘Bi_(3.25)La_(0.75)Ti_(3)O_(12)(BLT)thin films are promising materials used in non-volatile memories.In this work,BLT films were deposited on Pt(111)/Ti/SiO_(2)/Si substrates by rf-magnetron sputtering method followed by annealing treatments.The microstructures of BLT thin films were investigated via X-ray diffraction(XRD),scanning electron microscopy(SEM)and atomic force microscopy(AFM).With the increase in annealing temperature,the grain size increased significantly and the preferred crystalline orientation changed.A well-saturated hysteresis loop with a superior remnant polarization of 15.4μC/cm^(2) was obtained for BLT thin films annealed at 700°C.The results show that the dielectric constant decreased with the increase in grain sizes.
基金supported by the National Natural Science Foundation of China(Nos.11902285 and 12072307)the Department of Education Project of Hunan Province,China(Nos.21B0112 and 19A106)+2 种基金the Science and Technology Agency Project of Hunan Province,China(No.2020JJ5526)the China Postdoctoral Science Foundation(No.2019TQ0273)the Outstanding Youth Science Foundation of Hunan Province,China(No.2021JJ20041).
文摘Electronic devices that are transparent and flexible have a wide range of applications in the domains of vital sign parameter monitoring,health management,and so on.Ferroelectric memory is a revolutionary nonvolatile memory that is ideal for data storage and processing in transparent flexible electronic systems.In this study,Ce-doped hafnium oxide ferroelectric thin film is manufactured on mica substrate by the chemical solution deposition with transparent indium tin oxide(ITO)thin films as the bottom electrodes.The transmittance of mica/ITO/Hf_(0.85)Ce_(0.15)O_(2)thin film is over 80%.The 2Pr of the transparent flexible Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film is increased by about 22.4%and the Ec is reduced by 26.7%compared with those of Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film grown on p+-Si substrate.The transparent flexible Hf_(0.85)Ce_(0.15)O_(2)ferroelectric thin film can remain keeping good quality when being bent under±2.5 mm bending radius.Additionally,degradation of polarization,retention,and endurance performance was not obvious even at a bending radius of 5.0 mm after 104 bending cycles.This research provides a new strategy and an important experimental basis for the development and implementation of transparent flexible ferroelectric memories.
基金The authors sincerely thank the support from the National Natural Science Foundation of China(Grant No.51572159)the Shaanxi Science&Technology Co-ordination&Innovation Project of China(Grant No.2017TSCXL-GY-08-05)the Science Fund for Distinguished Young Scholars of Shaanxi Province(Grant No.2018JC-029).
文摘Na_(0.5)Bi_(0.5)TiO_(3)(NBT)-based ceramics have been widely used as dielectric materials for energy storage capacitors because of their environmental friendliness and excellent ferroelectric properties.However,their energy storage performance still needs to be further improved to satisfy the increasing demand.Herein,we report a novel 0.90(Na_(0.5)Bi_(0.5))0.7Sr_(0.3)TiO_(3-0.10)Bi(Ni_(0.5)Sn_(0.5))O_(3)(0.90NBST-0.10BNS)ceramic with significantly improved energy density(5.0 J cm3),enhanced recoverable energy density(4.18 J cm^(3))and high energy efficiency(83.64%)through the incorporation of Bi(Ni0.5Sn0.5)O3(BNS),due to the increased breakdown strength and the relaxation ferroelectric(RFE)properties.The first-order reversal curve(FORC)measurements confirm that the addition of BNS improves RFE properties by breaking the order of long-range ferroelectricity.The 0.90NBST-0.10BNS ceramic also possesses an outstanding temperature and frequency stability of energy storage properties in the range of 20C e140C and 1 Hze100 Hz,respectively.More importantly,the discharge properties characterized by a preeminent power density(36.19 MW cm^(3)),transient energy release times(144.2 ns),and high discharge energy density(1.16 J cm3)also synchronously observed in 0.90NBST-0.10BNS ceramic.These results show that the 0.90NBST-0.10BNS ceramic with outstanding comprehensive performances is a promising energy storage ceramic candidate for capacitors in high power systems.
基金supported by the National Natural Science Foundation of China(51702024)Sci-Tech Support Plan-Social Development of Changzhou City(CE20175041)the Priority Academic Program Development of Jiangsu Higher Education Institutions(15KJA43002)
文摘The Ba(0.96)Ca(0.04)Ti(0.90)Sn(0.10)O3-xNd2 O3(x = 0-0.08%) ceramics were prepared via traditional solid-state sintering method. The influences of Nd3+ substitution on the phase structure, dielectric properties,piezoelectric and ferroelectric properties of the ceramics were investigated. All the samples possess pure BaTiO3-type perovskite structure. MPB with orthorhombic and tetragonal phase coexist at around x = 0.03-0.04. Nd^(3+) doping decreases both Tc and T(O-T) to lower temperature. All the samples exhibit an intermediate state with the coexistence of ferroelectric and diffuse relaxor ferroelectric behavior with the addition of Nd^(3+). The electric properties of the ceramics were optimized at x = 0.03 with d33, Kp, εr and Pr values of 545 pC/N, 51.9%, 24,412 and 10.74 μC/cm^2.
基金supported by the Project of the National Natural Science Foundation of China(Grant No.51172135)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51002092)+1 种基金Research and Special Projects of the Education Department of Shaanxi Province(Grant No.12JK0445)the Graduate Innovation Fund of Shaanxi University of Science and Technology(SUST-A04)
文摘Bil_xTbxFe03 thin films were prepared on Sn02 (fluorine doped tin oxide) substrates by a sol-gel method. The structural and electrical properties of the BiFe03 thin films were characterized and tested. The results indicated that the diffraction peak of the Tb-doped BiFe03 films was shifted towards right as the doping amounts were increased. The structure was transformed from the rhombohedral to tetragonal/orthorhombic phase. The Bio.sgTbo.11Fe03 thin film showed the well-developed P-E loops, which enhanced remnant polarization (Pr = 88.05 μC/cm2) at room temperature. The dielectric constant and dielectric loss of Bio.sgTbo.llFe03 thin film at 100 kHz were 185 and 0.018, respectively. Furthermore, the Bio.seTbo.llFe03 thin film showed a relatively low leakage current density of 2.07×10-5 A/cm2 at an applied electric field of 150 kV/cm. The X- ray photoelectron spectroscopy (XPS) spectra indicated that the presence of Fe2+ ions in the Bio.egTbo.11Fe03 thin film was less than that in the pure BiFe03.
基金We wish to thank China Scholarship Council(CSC).CSC supports us as academic visitors to join Derek C.Sinclair’s Research Group at the Department of Materials Science and Engineering, University of Sheffield, UK. We thank thefunding of Natural Science Foundation of Hubei Province,China (Grant No. 2017CFB574).
文摘As one of the representatives of lead-free NBT ceramics,Na_(0.5)Bi_(4.5)Ti_(4)O_(15) has still attracted much attention due to its excellent dielectric properties and has become the focus of research.However,its piezoelectric properties are far from satisfactory.In order to improve the piezoelectric properties of Na_(0.5)Bi_(4.5)Ti_(4)O_(15),Na_(0.5)Bi_(4.5)Ti_(4-x)Mg_(x)O_(y)–BaTiO_(3)(NBTM–BT)composite ceramics were synthesized by a conventional mixed oxide route and sintered at 1040℃ through two-step method.We optimized the electrical properties of NBTM–BT by changing the stoichiometric ratio of Mg content and studied its microscopic mechanism.The piezoelectric coefficient(d33)is stable at about 20 pC/N.Moreover,the maximum remanent polarization(2Pr)of the ceramic is 3.08C/cm^(2) with the coercive field of 18.01 kV/cm.The dielectric constant and dielectric loss for Na_(0.5)Bi_(4.5)Ti_(3.96)Mg_(0.04)–BT composite ceramic were found to be 486 and 0.17 at 10 kHz,respectively.The characteristic peaks of BT and Na_(0.5)Bi_(4.5)Ti_(4)O_(15) can be observed clearly from the X-ray diffraction analysis.SEM analysis showed that all samples were well crystallized.Consequently,the piezoelectric and ferroelectric properties of Na_(0.5)Bi_(4.5)Ti_(4)O_(15)–BT composite ceramic will be enhanced much by Mg doping,which means it has a wider range of applications in electronic devices such as piezoelectric devices.
基金Project supported by the Haute France Region/FEDER(project MASEN)H2020-RISE-ENGIMA-778072 project。
文摘Na_(0.5)(Bi_(3/4)RE_(1/4))_(0.5)TiO_(3)(RENBT,RE=Nd,Gd,Dy,and Ho)compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave(FP-LAPW)method based on the spin-polarized density functional theory implemented in the WIEN2k code.Combined charge density distribution and Ti K-edge X-ray absorption spectra reveal that the RENBT compositions with high polarization values are accompanied by a higher TiO_(6)distortion,DyNBT,and NdNBT compounds.The effect of the rare-earth elements on the polarization is confirmed experimentally with the collection of the hysteresis loops.The investigation of the electronic properties of the compounds highlights the emergence of a magnetization owing to the 4f orbital effect of the rare-earth elements.Besides,the investigation of the chemical ordering shows a short-range chemical ordering for the pure composition and an increased A-site disorder for dysprosium doped NBT system.The increased disorder may speak for increased relaxor properties in the RE doped compositions.