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As a promising candidate for high-density data storage and neuromorphic computing, cross-point memory arrays provide a platform to overcome the von Neumann bottleneck and accelerate neural network computation. In order to suppress the sneak-path current problem that limits their scalability and read accuracy, a two-terminal selector can be integrated at each cross-point to form the one-selector-one-memristor (1S1R) stack. In this work, we demonstrate a CuAg alloy-based, thermally stable and electroforming-free selector device with tunable threshold voltage and over 7 orders of magnitude ON/OFF ratio. A vertically stacked 64 × 64 1S1R cross-point array is further implemented by integrating the selector with SiO2-based memristors. The 1S1R devices exhibit extremely low leakage currents and proper switching characteristics, which are suitable for both storage class memory and synaptic weight storage. Finally, a selector-based leaky integrate-and-fire neuron is designed and experimentally implemented, which expands the application prospect of CuAg alloy selectors from synapses to neurons. Designing efficient selector devices remains a challenge. Here, the authors propose a CuAg alloy-based selector with excellent ON/OFF ratio and thermal stability. It can effectively suppress the sneak-path current in 1S1R arrays, making it suitable for storage class memory and neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.1Mn0.1O2 cathodes suffer from severe bulk structural and interfacial degradation during battery operation. To address these issues, a three in one strategy using ZrB2 as the dopant is proposed for constructing a stable Ni‐rich cathode. In this strategy, Zr and B are doped into the bulk of LiNi0.8Co0.1Mn0.1O2, respectively, which is beneficial to stabilize the crystal structure and mitigate the microcracks. Meanwhile, during the high‐temperature calcination, some of the remaining Zr at the surface combined with the surface lithium source to form lithium zirconium coatings, which physically protect the surface and suppress the interfacial phase transition upon cycling. Thus, the 0.2 mol% ZrB2‐LiNi0.8Co0.1Mn0.1O2 cathode delivers a discharge capacity of 183.1 mAh g−1 after 100 cycles at 50 °C (1C, 3.0–4.3 V), with an outstanding capacity retention of 88.1%. The cycling stability improvement is more obvious when the cut‐off voltage increased to 4.4 V. Density functional theory confirms that the superior structural stability and excellent thermal stability are attributed to the higher exchange energy of Li/Ni exchange and the higher formation energy of oxygen vacancies by ZrB2 doping. The present work offers a three in one strategy to simultaneously stabilize the crystal structure and surface for the Ni‐rich cathode via a facile preparation process. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectric 0.94Na0.5Bi0.5TiO3‐0.06BaTiO3‐modified antiferroelectric Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 ceramics, (1−x)PNZST‐x(BNT‐6BT), were prepared to acquire high energy storage and thermal stability properties. X‐ray diffraction and element mapping revealed that a solid solution between PNZST and BNT‐6BT occurs, and Ti cations enter the PNZST lattice, partly extruding Sn cations and leading to the formation of isolated SnO2 particles at the grain boundaries and a 0‐3 type composite structure. Such a composite structure helps to create deviatoric stress in the solid solution component. The BNT‐6BT content significantly influences the energy storage capacity, and the x = 0.2 composition renders optimal performance. The room‐temperature‐recoverable energy density and energy efficiency are 2.23 J/cm3 and 78%, respectively, at 260 kV/cm. Both parameters vary less than 6% within a temperature range of 25°C and 125°C. The improved energy storage and temperature stability indicate that the ceramics can potentially be applied in pulse power capacitors and that this relaxor‐modified antiferroelectric ceramic preparation method is a valuable reference for further optimizing the functional properties. [ABSTRACT FROM AUTHOR]

The doping of ZnO is efficient to improve the piezoelectric property and thermal stability of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) based ceramics. However, the underlying physics, especially the local domain structures of the ZnO modified PMN–PT ceramics, which is strongly associated with the electric properties, is not clear yet. In this paper, we investigated the local domain structures and their evolution as a function of x in PMN–0.32PT:xZnO ceramics. It was found that, the domain evolution is mainly caused by the growth of grain size induced by the sintering aiding effect of ZnO at x < 0.04, and the domain evolution can be attributed to the phase transition induced by the partial replacement of Mg2+ by Zn2+ in the B‐site of PMN–PT lattice at x > 0.06. Furthermore, we also investigated the domain structure evolution as functions of temperature and local external electric field in PMN–0.32PT:0.06ZnO ceramics, which exhibited superior piezoelectric property relative to other compositions. We found that the irregular nanodomains are more stable at high‐temperature range, and the regular non‐180° domains exhibited more complex rotation behavior under local electric field, which probably leads to the thermal stability and piezoelectric property enhancement in the ZnO‐modified PMN–0.32PT ceramics. [ABSTRACT FROM AUTHOR]

Ferro‐/piezoelectric ceramics with high performances are generally found at the morphotropic phase boundary (MPB), where two or more different ferroelectric phases coexist. However, the MPB region is usually very narrow; for example, that of (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMN‐xPT) locates between x = 0.30−0.34. Herein, we report that ZnO‐modified PMN‐xPT polycrystalline ceramics have dramatically broadened MPB regions from x = 0.28, with rhombohedral and monoclinic coexisting phases, to x = 0.36, with tetragonal and monoclinic coexisting phases, as confirmed by powder X‐ray diffraction and piezoresponse force microcopy measurements. The wide MPB region is attributed to lattice distortion caused by the substitution of Zn for Mg cations. As a result, the ceramics show composition insensitive electrical properties over wide composition ranges; for example, the piezoelectric coefficient (d33) and electromechanical coupling factor (kp) remain at near constant values of 450 pC/N and 0.5, respectively, in the range from x = 0.28−0.34. This work not only provides a robust and feasible method to broaden the MPB region but also offers some novel insights into promoting fundamental research on high‐performance piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Highlights • Mesoporous CoO(OH) with high surface area was synthesized successfully via one-pot hydrothermal method. • The impedance of mesoporous CoO(OH) based humidity sensor changed nearly four orders of magnitude from 11%RH to 95%RH. • The humidity sensor is of fast response time 1.6 s. • The present sensor possessed good long term stability and cyclic stability. Abstract A humidity-responsive material of mesoporous CoO(OH) was synthesized successfully via one-pot hydrothermal method and the influence of CoO(OH) precursor concentration on humidity sensitive performance was studied. The structure and morphology of mesoprous CoO(OH) was characterized by X-ray Diffraction, Infrared spectra, Nitrogen adsorption and desorption, Scanning electron microscope, Transmission electron microscope and so on. The optimized mesoporous CoO(OH) based sensor showed the best linearity and high humidity sensitivity over a wide range of the humidity range (11–95% RH). Its impedance changed nearly four orders of magnitude and the response time was about 1.6 s. Humidity sensing mechanism was discussed in detail. [ABSTRACT FROM AUTHOR]

Amorphous Na 2 O·2SiO 2 (A-Na 2 O·2SiO 2 ) is one of the promising sodium ionic conductors for solid-state sodium-ion battery electrolytes owing to its easy preparation and low production cost. However, Na 2 O·2SiO 2 glass suffers from relatively low conductivity and poor thermal stability as a result of crystallization and other defects. Herein, we improved the ionic conductivity and thermal stability of A-Na 2 O·2SiO 2 by adding this material with metal oxides (M x O y , M = Y, Sm, and Zr) at varying loadings. The physical properties and stability of the A-Na 2 O·2SiO 2 added with different oxides were systematically investigated. The results indicated that oxide adding on A-Na 2 O·2SiO 2 resulted in larger density values that increased with the adding content. Additionally, oxide adding changed the strength of the Si O bond in A-Na 2 O·2SiO 2 , thereby affecting the overall network structure and uniformity. Among the different oxides prepared, added with 3 mol% Sm 2 O 3 , 3 mol% Y 2 O 3 , and 2 mol% ZrO 2 showed maximum hardness and elasticity modulus values. Additionally, oxide adding on A-Na 2 O·2SiO 2 resulted in significantly improved ionic conductivity values. 3 mol% Y 2 O 3 -added A-Na 2 O·2SiO 2 material showed the highest ionic conductivity value (5.2 × 10 −3 S cm −1 ) and optimum thermal stability, indicating that Y 2 O 3 -added Na 2 O·2SiO 2 has high potential to be high-performance and stable sodium ionic conductors. [ABSTRACT FROM AUTHOR]

Here we report the 0.94(BiNa)TiO-0.06Ba(ZrTi)O (0.94BNT-0.06BZT) lead-free ceramics was synthesized by two-step solid state reaction route. The structural, dielectric, ferroelectric, piezoelectric and electromechanical properties of the ceramics were studied, and showed excellent electric properties ( P = 39.9 μC/cm, P = 33.7 μC/cm, E = 2.79 kV/mm, S = 0.20%, d = 174 pC/N, k = 0.33). The depolarization temperature ( T ) of the ceramics is about 65 °C, which is determined from the first hump of relative dielectric constant. The electromechanical factor k disappears at 65 °C, is consistent with the depolarization temperature ( T ) and the ferroelectric-antiferroelectric phase transition temperature ( T ) determined from the temperature-dependent P- E and bipolar S- E curves. These results indicate the 0.94BNT-0.06BZT ceramics has a good thermal stability in range of − 60-60 °C, and meets the actual demand. [ABSTRACT FROM AUTHOR]

In the present study, Zr 50 Cu 34 Al 8 Ag 8 amorphous alloy rods with a diameter of 3 mm were prepared and the influence of the cooling capacity on the properties of cast samples was analyzed. To this end, three mold materials, including heat-resistant steel, copper, and high purity graphite were utilized. Then the amorphous structure, glass-forming ability, and thermal stability of the cast alloy were investigated using an X-ray diffractometer and differential scanning calorimeter. A universal testing machine was applied to investigate the mechanical properties of amorphous alloys with different mold materials. The fracture characteristics of the amorphous alloy were analyzed by scanning electron microscope, and the microstructures were analyzed using a high-resolution transmission electron microscope. The experimental results showed that among the studied cases, the highest glass-forming ability was achieved from the copper mold. Moreover, the glass transition and crystallization activation energies of the amorphous alloy obtained by suction casting of high-purity graphite mold were the largest, which were 525.8 kJ/mol and 334.0 kJ/mol, respectively, reflecting good thermal stability. Meanwhile, the performed analyses revealed that the fracture strength of the amorphous alloy and the corresponding strain were 1888.2 MPa and 3.55%, respectively, indicating that the cast sample has good mechanical properties. With the decrease of the cooling rate, the content of free volume in the amorphous alloy of high-purity graphite mold suction casting decreased, and the ordered structure was generated, which was the main reason for its high thermal stability and plastic deformation ability. [ABSTRACT FROM AUTHOR]

Grain-oriented Pb(Mg 1/3 Nb 2/3)O 3 -PbZrO 3 -PbTiO 3 (PMN-PZ-PT) based ceramics were synthesized through templated grain growth via using BaTiO 3 (BT) templates. Although BT templates are partially destroyed by PMN-PZ-PT matrix, CuO addition remarkably promotes [001] c -oriented grain growth behavior of the ceramics, resulting in an improvement of Lotgering factor F 001 from ~86% to 98%. Both crystallographic texture and CuO doping increase tetragonality and reduce average domain size of the ceramics dominated by rhombohedral phase. Consequently, 0.50 wt% CuO-doped ceramics (F 001 ~98%) exhibit optimum electromechanical properties: d 33 ~860 pC/N, d 33 × g 33 ~48.6 × 10−12 m2/N, k p ~0.80, E c ~7.2 kV/cm, tan δ ~0.8% and T c ~222 °C. In addition to ~3.7 times and 6.6 times higher d 33 and d 33 × g 33 , those ceramics possess about 240% enhanced piezoelectric strain and much better thermal stability (S max / E max variation ≤2% between RT and 150 °C) relative to non-textured counterpart. This work offers a good paradigm for simultaneously exploring high piezoelectric response and good temperature stability in piezoceramics, benefiting the development of next-generation advanced electromechanical devices. [ABSTRACT FROM AUTHOR]

Unquenched and quenched ceramics of 0.85Na 0.5 Bi 0.5 TiO 3 -0.11K 0.5 Bi 0.5 TiO 3 -0.04BaTiO 3 have been prepared, and their crystal structure, temperature-dependent ferro-/piezoelectric properties and domain structure have been comparatively investigated. It is shown that quenching process can significantly improve the ferroelectric-relaxor transition temperature (T F-R), which is 130 °C for unquenched ceramics and 198 °C for quenched one. As the result, the thermal stability of ferro-/piezoelectric properties is highly enhanced. These observations are mainly attributed to the quenching induced stable rhombohedral ferroelectric phase and the defect altered domain evolution. This work may deepen the understanding of the effect of quenching on crystal structure, domain structure and their contributions to thermal stability of NBT-based ceramics. [ABSTRACT FROM AUTHOR]

Highlights • A new ceramic by introducing Bi(Mn 0.5 Ti 0.5)TiO 3 into 0.8Bi 0.5 Na 0.5 TiO 3 -0.2Bi 0.5 K 0.5 TiO 3 is prepared via solid state reaction method. • The compositions within x = 0.03–0.055 exhibit large strain of 0.31% ˜0.41% and electrostrictive coefficient of 0.027–0.041 m4/C2. • At x = 0.04, the large strain and electrostrictive coefficient are nearly temperature-independent in the range of 25–100 °C. Abstract (1- x)[0.8Bi 0.5 Na 0.5 TiO 3 -0.2Bi 0.5 K 0.5 TiO 3 ]- x Bi(Mn 0.5 Ti 0.5)O 3 (x = 0–0.06, BNKMT100 x) lead-free ferroelectric ceramics were prepared via solid state reaction method. Bi(Mn 0.5 Ti 0.5)O 3 induces a structure transition from rhombohedral-tetragonal morphotropic phases to pseudo-cubic phase. Moreover, the wide range of compositions within x = 0.03–0.055 exhibit large strain of 0.31%–0.41% and electrostrictive coefficient of 0.027–0.041 m4/C2. Especially, at x = 0.04, the large strain and electrostrictive coefficient are nearly temperature-independent in the range of 25–100 °C. The impedance analysis shows the large strain and electrostrictive coefficient originate from polar nanoregions response due to the addition of Bi(Mn 0.5 Ti 0.5)O 3. [ABSTRACT FROM AUTHOR]

Further improving electromechanical properties and overcoming relatively low Curie temperature ( T c ) of (1- x )Pb(Mg 1/3 Nb 2/3 )O 3 - x PbTiO 3 (PMN-100 x PT) are still two scientific issues. Here, we demonstrate a stable coexistence of monoclinic-tetragonal (M C -T) phases in ZnO-modified PMN-32PT (PMN-32PT: x ZnO) due to the diffusion-induced substitution of Zn 2+ for Mg 2+ . The Curie temperature, saturated polarization, remnant polarization, piezoelectric coefficient ( T c , P s , P r , d 33 ) are increased from (160 °C, 22.0 μC/cm 2 , 13.3 μC/cm 2 , 350 pC/N) for x = 0 to (180 °C, 30.3 μC/cm 2 , 22.4 μC/cm 2 , 470 pC/N) for x = 0.06. Moreover, the thermal stability is improved. After annealing at 150 °C, the x = 0.06 sample shows retrained d 33 value of 209 pC/N, about 4 times larger than that of x = 0 counterpart. The improved properties are attributed to the substituting increased polar nanoregions and easy domain switching in M C phase. [ABSTRACT FROM AUTHOR]

Piezoelectric materials are considered an enabling technology generating an annual turnover of about 20 billion $. At present, lead-based materials dominate the market with the known risk to health and environment. One of the three key competitors for their replacement is the class of sodium bismuth titanate (NBT)-based relaxor ferroelectrics, the use of which is limited by thermal depolarization. An increased thermal stability has recently been experimentally demonstrated for composites of Na 1/2 Bi 1/2 TiO 3 -6BaTiO 3 with ZnO inclusions (NBT-6BT: x ZnO). However, the exact mechanism for this enhancement still remains to be clarified. In this study, piezoresponse force microscopy and 23 Na NMR spectroscopy were used to demonstrate that the incorporation of ZnO leads to a stabilization of the induced ferroelectric state at room temperature. Temperature-dependent measurements of the relative dielectric permittivity ε′(T) , the piezoelectric coefficient d 33 and the strain response revealed an increase of the working temperature by 37 °C. A simple mechanics model suggests that thermal deviatoric stresses stabilize the ferroelectric phase and increase, as well as broaden, the temperature range of depolarization. Our results reveal a generally applicable mechanism of enhancing phase stability in relaxor ferroelectric materials, which is also valid for phase diagrams of other ceramic matrix composites. [ABSTRACT FROM AUTHOR]

• The properties of die castings with different contents of remelting materials were studied. • The addition of remelting materials introduces oxygen, which has an impact on the phase formation, thermal stability and mechanical properties of amorphous castings. • The mechanism of the mechanical property change was analyzed by combining the change of atomic configuration and apparent activation energy. • Considering the cost of die casting, the castings with 33 and 66% primary remelting materials possess great application potential. Herein, different contents of remelting materials were added to the Zr 34 Ti 32 Cu 9 Fe 4 Be 21 amorphous alloy to conduct the die-casting experiment of the amorphous alloy gear. The effects on the microstructure, mechanical properties, and thermal stability of the Zr 34 Ti 32 Cu 9 Fe 4 Be 21 amorphous alloy gear castings were investigated after adding different contents of remelting materials. The results indicate that the fracture strength of the amorphous alloy gear castings increases with the increasing remelting material content, whereas the plastic deformation ability decreases. Meanwhile, the glass transition temperature and crystallization temperature of the amorphous alloy gear castings increase, and the supercooled liquid region reduce. When the primary remelting material content increases to 66%, a small amount of crystalline phase precipitates in the matrix of the amorphous alloy gear casting, and the crystalline phase increases when 66% secondary remelting material content is added. The castings with 33 and 66% primary remelting material contents exhibited excellent mechanical properties. Considering the cost of die casting, they possess great application potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • Realizing stabilized antiferroelectric phase and enhanced relaxor behavior in (Na 1-3/2 x Bi 3/2 x)(Nb 1- x Mg x)O 3 ceramics. • The large E b of 78.3 kV/mm, ultrahigh W rec of 10.9 J/cm3 and high η of 83% were achieved in × = 0.06. • x = 0.06 exhibited superior frequency, fatigue, thermal stability and ultrafast discharge rate. Lead-free ceramic-based dielectric capacitors have attracted extensive investigation due to their potential applications in pulsed power devices. However, the main drawback of dielectric ceramics is the relatively low energy storage density. Herein, Bi3+ and Mg2+ with different ionic radius and valence are introduced into antiferroelectric NaNbO 3 matrix to form (Na 1-3/2 x Bi 3/2 x)(Nb 1- x Mg x)O 3 solid solutions, where the antiferroelectric phase is stabilized and the relaxor behavior is also improved. Of particular importance is that a large breakdown strength (E b) of 78.3 kV/mm, an ultrahigh recoverable energy density (W rec) of 10.9 J/cm3 and efficiency (η) of 83% are simultaneously achieved in (Na 0.91 Bi 0.09)(Nb 0.94 Mg 0.06)O 3 ceramic. Moreover, the energy storage properties of (Na 0.91 Bi 0.09)(Nb 0.94 Mg 0.06)O 3 ceramic also reveals superior frequency (1–100 Hz), cycling (100–105) and thermal (30°C–100°C) stability, together with the ultrafast discharge rate (<25 ns). These results demonstrate the NaNbO 3 -based lead-free relaxor antiferroelectric ceramics is a promising candidate for energy storage application. [ABSTRACT FROM AUTHOR]

0.8Na 0.5 Bi 0.5 TiO 3 -(0.2- x)K 0.5 Bi 0.5 TiO 3 - x Bi(Zn 0.5 Ti 0.5)O 3 (NBT-KBT-BZT, x = 0–0.05 with interval of 0.01) lead-free piezoceramics were prepared and investigated. The addition of BZT has not led to deviation of rhombohedral-tetragonal morphotropic phase boundary, but apparently composition-dependent electrical property and monotonously improved thermal stability. The x = 0.02 has the optimal electrical property with remnant polarization, bipolar total strain, piezoelectric constant of 26.5 μC/cm2, 0.30%, 121 pC/N respectively, while the depolarization temperature is increased from 93 °C for x = 0–135 °C for x = 0.05 based on dielectric measurement. Detailed investigation reveals that the domain structure transforms from labyrinthian domain for x = 0 to coexistence of nanodomain and labyrinthian domain for x = 0.02, end up with large amount of nanodomain (x = 0.04). Such domain evolution should be responsible for the composition dependent electrical property and improved thermal stability. Our work confirms that domain engineering is an alternative method to develop high performance piezoelectric materials. • NBT-KBT-BZT lead-free piezoceramics have been prepared. • The piezoceramics show composition-dependent property and improved thermal stability. • Domain transforms from labyrinthian domain, coexisted nanodomain and labyrinthian domain, to nanodomain. [ABSTRACT FROM AUTHOR]