Application of artificial synapse based on all-inorganic perovskite memristor in neuromorphic computing

Artificial synapse inspired by the biological brain has great potential in the field of neuromorphic computing and artificial intelligence.The memristor is an ideal artificial synaptic device with fast operation and good tolerance.Here,we have prepared a memristor device with Au/CsPbBr_(3)/ITO structure.The memristor device exhibits resistance switching behavior,the high and low resistance states no obvious decline after 400 switching times.The memristor device is stimulated by voltage pulses to simulate biological synaptic plasticity,such as long-term potentiation,long-term depression,pair-pulse facilitation,short-term depression,and short-term potentiation.The transformation from short-term memory to long-term memory is achieved by changing the stimulation frequency.In addition,a convolutional neural network was constructed to train/recognize MNIST handwritten data sets;a distinguished recognition accuracy of~96.7%on the digital image was obtained in 100 epochs,which is more accurate than other memristor-based neural networks.These results show that the memristor device based on CsPbBr3 has immense potential in the neuromorphic computing system.

Emerging memristors and applications in reservoir computing

Recently, with the emergence of ChatGPT, the field of artificial intelligence has garnered widespread attention from various sectors of society. Reservoir Computing (RC) is a neuromorphic computing algorithm used to analyze time-series data. Unlike traditional artificial neural networks that require the weight values of all nodes in the trained network, RC only needs to train the readout layer. This makes the training process faster and more efficient, and it has been used in various applications, including speech recognition, image classification, and control systems. Its flexibility and efficiency make it a popular choice for processing large amounts of complex data. A recent research trend is to develop physical RC, which utilizes the nonlinear dynamic and short-term memory properties of physical systems (photonic modules, spintronic devices, memristors, etc.) to construct a fixed random neural network structure for processing input data to reduce computing time and energy. In this paper, we introduced the recent development of memristors and demonstrated the remarkable data processing capability of RC systems based on memristors. Not only do they possess excellent data processing ability comparable to digital RC systems, but they also have lower energy consumption and greater robustness. Finally, we discussed the development prospects and challenges faced by memristors-based RC systems.

Artificial synaptic simulating pain-perceptual nociceptor and brain-inspired computing based on Au/Bi_(3.2)La_(0.8)Ti_(3)O_(12)/ITO memristor

Recently, memristors have garnered widespread attention as neuromorphic devices that can simulate synaptic behavior, holding promise for future commercial applications in neuromorphic computing. In this paper, we present a memristor with an Au/Bi_(3.2)La_(0.8)Ti_(3)O_(12) (BLTO)/ITO structure, demonstrating a switching ratio of nearly 103 over a duration of 104 s. It successfully simulates a range of synaptic behaviors, including long-term potentiation and depression, paired-pulse facilitation, spike-timing-dependent plasticity, spike-rate-dependent plasticity etc. Interestingly, we also employ it to simulate pain threshold, sensitization, and desensitization behaviors of pain-perceptual nociceptor (PPN). Lastly, by introducing memristor differential pairs (1T1R-1T1R), we train a neural network, effectively simplifying the learning process, reducing training time, and achieving a handwriting digit recognition accuracy of up to 97.19 %. Overall, the proposed device holds immense potential in the field of neuromorphic computing, offering possibilities for the next generation of high-performance neuromorphic computing chips.

Excellent energy storage properties realized in novel BaTiO_(3)-based lead-free ceramics by regulating relaxation behavior

BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field severely impede the improvement of its energy storage capabilities.Here,the BaTiO_(3)e-Bi(Zn_(0.5)Hf_(0.5))O_(3)(BT-BZH)ceramics with high breakdown field strength and remarkable relaxation characteristics can be obtained by introducing the composite component BZH in BT to regulate the phase structure and grain size of the ceramics.The findings demonstrate that the improvement of energy storage performance is related to the increase of relaxation behavior.A large energy storage density(Wrec~3.62 J/cm^(3))along with superior energy storage efficiency(h~88.5%)is achieved in 0.88BT-0.12BZH relaxor ceramics only at 240 kV/cm.In addition,the sample suggests superior thermal stability and frequency stability within 25e115℃and 1e500 Hz,respectively.Furthermore,the outstanding chargedischarge properties with an ultrafast discharge time(100 ns),large discharged energy density(1.2 J/cm^(3)),impressive current density(519.4 A/cm^(2))and power density(31.1 MW/cm^(3))under the electric field of 120 kV/cm are achieved in studied ceramics.The excellent energy storage performance of BT-BZH ceramics provides a promising platform for the application of lead-free energy-storage materials.

Composition-tailor induced electrocaloric effect near room temperature in(Pb,Ba)HfO_(3)films

More and more researchers start to pay attention to the electrocaloric temperature change(DT)in polar materials,which is caused by an applied electric field.In this paper,Ba-doped PbHfO_(3)(PBH)films were prepared by sol-gel method.Their components,microstructures,dielectric polarization and electro-caloric effects(ECEs)were investigated.With the addition of Ba^(2+),PBH films went from antiferroelectric(AFE)to ferroelectric(FE).At the same time,their dielectric peaks shifted toward lower temperature.The maximum DT obtained in Pb_(0.8)Ba_(0.2)HfO_(3)FE film is 41.1 K,which is an order of magnitude larger than PbHfO_(3)film(△T<4 K at 50℃)and Pb_(0.9)Ba_(0.1)HfO_(3)film(△T<4 K at 120℃).In order to explain this phenomenon,the Landau-Devonshire theory was adopted.Our analysis shows that the rapid variation of energy barrier height near the phase transition temperature is beneficial to obtain large polarization change and high△T,which is needed in solid-state cooling devices.

Superior Energy and Power Density Realized in Pb(Hf_(1-x)Ti_(x))O_(3) System at Low Electric Field

The development of antiferroelectric materials with large energy density and fast discharge speed makes dielectric capacitors possess great prospects for applications in pulsed power technology.Here,the PbHfO_(3)-based ceramics with compositions of Pb(Hf_(1-x)Ti_(x))O_(3)(PHT,0.01≤x≤0.05)were synthesized,and their antiferroelectricity and phase transition behavior were studied.According to the tests of x-ray diffraction,dielectric spectrum,and polarization-electric field hysteresis loops,PHT ceramics gradually transition from an orthorhombic symmetric antiferroelectric phase to a hexagonal symmetric ferroelectric phase at room temperature as Ti^(4+)concentration increases.The forward phase switching field of antiferroelectric to ferroelectric phase transition can be markedly regulated by the introduction of Ti^(4+),and the optimal energy storage performance was obtained in Pb(Hf_(0.98)Ti_(0.02))O_(3) ceramics with a large recoverable energy storage density of Wrec~4.15 J/cm^(3) and efficiency ofη~65.3%only at a low electric field of 190 kV/cm.Furthermore,the outstanding charge-discharge properties with an ultrafast discharge time(71 ns),remarkable discharged energy density(2.84 J/cm^(3)),impressive current density(1,190 A/cm^(2)),and ultrahigh power density(101 MW/cm^(3))at a low electric field of 170 kV/cm were obtained in studied ceramics.The excellent energy storage performance of PHT ceramics provides a promising platform for the application of dielectric capacitors.

Oxygen-vacancy-related dielectric relaxation behaviours and impedance spectroscopy of Bi(Mg_(1/2)Ti_(1/2))O_(3) modified BaTiO_(3) ferroelectric ceramics

Lead-free ferroelectric ceramics(1-x)BaTiO_(3-x)Bi(Mg_(1/2)Ti_(1/2))O_(3)(x=0.0-0.07)were synthesized by conventional solid state reaction method and the correlation of structure,dielectric,ferroelectric and impedance properties were investigated.It was found that T_(m) andε_(m) showed decreasing trend with the increase of BMT content.The high-temperature dielectric relaxation behaviour was observed in all the samples.The activation energy calculated from impedance(E_(a))and conductivity(E_(cond)),which revealed that the relaxation behaviours were linked with the migration of OVs.The values of E_(a)were almost equivalent to Econd.It was concluded that the short-range hopping of oxygen vacancy contributed to the dielectric relaxation and long-distance movement of doubly ionized oxygen vacancies contributed to the conduction.On the other hand,with increasing BMT contents,it was found that P-E loops became slimmer and slimmer,which indicated the increase of relaxor behaviour.The temperature dependence of P-E loops for 0.98BT-0.02BMT ceramic clearly showed the transition process from ferroelectric to relaxed ferroelectrics.

Composition dependence of giant electrocaloric effect in PbxSr1-xTiO_(3) ceramics for energy-related applications

Pb_(x)Sr_(1-x)TiO_(3)(x=0.30,0.35,0.40,0.45,0.50 and 0.55)ceramics were fabricated by a solid-state reaction route.Xeray diffraction data at room temperature show PST samples shift from cubic to tetragonal phase with the increase of Pb^(2+) content.The microstructures were observed by scanning electron microscopy.Dielectric measurement was employed to investigate the ferroelectriceparaelectric phase transition behavior.Temperature dependent polarizationeelectric field hysteresis loops were conducted to study the electrocaloric effect(ECE)of the ferroelectric ceramics by indirect methods over a wide temperature range.Direct measurement of temperature change(DT)at room temperature for all samples can achieve 0.79e1.86 K.What's more,a giant ECE(△T=2.05 K,EC strength(△T/△E)=0.51×10^(-6) K m/V,under 40 kV/cm)was obtained in the sample of x=0.35 near phase transition temperature.Our results suggest that the ceramics are promising cooling materials with excellent EC properties for energy related applications.

Pulmonary embolism during pregnancy in a case of blue rubber bleb nevus syndrome

To the Editor:Blue rubber bleb nevus syndrome (BRBNS) is a rare systemic vascular disorder characterized by multiple venous malformations involving many organs.BRBNS can occur in various organs,but the most frequently involved organs are the skin and gastrointestinal tract.Gastrointestinal lesions of BRBNS can cause acute or chronic bleeding and anemia.[1] Only several case reports of pregnant women with BRBNS could be found in the current database and most of them were complicated by hemorrhage of the gastrointestinal tract.We report a case of BRBNS during pregnancy that suffered from severe pulmonary embolism (PE) and was successfully resuscitated.