Materials Today Physics最新文献_第2页

Generalized rattling and thermal conductivity: Cubic LaRhTe 广义嘎嘎声和热导率：立方LaRhTe

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-12 DOI: 10.1016/j.mtphys.2026.102015

Zhen Wang , Yazhu Xu , Gaofeng Zhao , Zhenzhen Feng , David J. Singh

Thermal conductivity is a key materials parameter that is important in combination with other properties for important applications including electronics, thermal barriers and a variety of energy technologies. There are established trends that are useful in finding materials with desirable thermal conductivity. For example, stable stiff lattices typically yield high thermal conductivity, while materials near instabilities have low thermal conductivity. Rattling is widely applied approach for lowering thermal conductivity and is understood as the incorporation of loosely bound ions in a semiconducting framework. It is manifested in low frequency flat optical phonon branches that cross the acoustic branches. We investigate LaRhTe using global optimization crystal structure determination, anharmonic lattice dynamics, and first principles based characterization of bonding. There are two low energy phases, a hexagonal metallic phase and a cubic semiconducting phase. This cubic phase is predicted to be a low thermal conductivity (1.61 W m⁻¹K⁻¹ at 300 K) semiconductor. We elucidate the origins of its low thermal conductivity finding that strong anharmonic phonon scattering, induced by weak bonding of Rh within the cage-like LaTe network, is important. The Rh atoms contribute to low-frequency phonons, while the La-Te system dominates the high-frequency optical phonon branches. This is unexpected based on the chemical characteristics of Rh chalcogenides and the known thermoelectric behavior of La-Te binary phases. It arises due to the structural constraints in the cubic half-Heusler phase leading to a generalized rattling behavior involving Rh. These results show that the rattling concept is more general than usually assumed and can be operative even without the characteristic rattler induced flat optical branches anticrossing the acoustic branches that are often discussed in the context of low thermal conductivity thermoelectrics.

导热系数是一个关键的材料参数，它与电子、热障和各种能源技术等重要应用的其他性能结合在一起很重要。在寻找具有理想导热性的材料时，有一些既定的趋势是有用的。例如，稳定的刚性晶格通常产生高导热系数，而接近不稳定的材料具有低导热系数。嘎嘎是广泛应用于降低热导率的方法，被理解为在半导体框架中结合松散结合的离子。它表现为低频平面光学声子分支与声学分支交叉。我们使用全局优化晶体结构确定、非调和晶格动力学和基于第一性原理的键合表征来研究LaRhTe。有两种低能相，六方金属相和立方半导体相。该立方相预测为低导热系数（在300 K时为1.61 W m−1K−1）的半导体。我们阐明了其低热导率的起源，发现由笼状LaTe网络中Rh的弱键引起的强非谐波声子散射是重要的。Rh原子对低频声子有贡献，而La-Te系统主导高频光学声子分支。基于Rh硫族化合物的化学特性和已知的La-Te二元相的热电行为，这是出乎意料的。它的产生是由于立方半赫斯勒相的结构约束导致涉及Rh的广义咔嗒行为。这些结果表明，嘎嘎声的概念比通常假设的更普遍，即使没有响尾声诱发的平坦光学分支的特征也可以运作，而声学分支通常在低热导率的热电环境中讨论。

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引用次数: 0

Designing a hybrid α/β-Ga2O3 polymorph heterostructure from strain-relaxed phase transition for high-voltage power diodes 基于应变松弛相变的高压功率二极管α/β-Ga2O3杂化异质结构设计

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-07 DOI: 10.1016/j.mtphys.2026.102010

Kaisen Liu , Songhao Wu , Shulin Hu , Dongyang Han , Li Chen , Gaofeng Deng , Shen Hu , Li Ji , Ping Cui , Jichun Ye , Wenrui Zhang

Ultrawide bandgap (UWBG) gallium oxide (Ga₂O₃) featuring several polymorphs holds great potential for high-power electronics and solar-blind optoelectronics. Designing electronic devices based on hybrid Ga₂O₃ polymorph structures appears highly attractive, but it meets persistent obstacles from epitaxy challenges and dopant activation problems. This study reports a 3 kV-class lateral Schottky barrier diode (SBD) based on a unique heteroepitaxial α/β-Ga₂O₃ heterostructure composed of conductive β-Ga₂O₃ domains embedded in an insulating α-Ga₂O₃ matrix. The α/β-Ga₂O₃ heterostructure is constructed from a strain-relaxed α-to-β Ga₂O₃ phase transition that strongly depends on the substrate orientation and film thickness. The formation of the β-Ga₂O₃ phase presents a minor impact on the crystallinity of the α-Ga₂O₃ matrix and exhibits more readily dopant activation during the sputtering growth. The lateral SBD based on this hybrid α/β-Ga₂O₃ heterostructure combines the benefits of efficient carrier transport in β-Ga₂O₃ and the superior breakdown field in α-Ga₂O₃, thus enabling a decent rectifying behavior and a 3 kV breakdown voltage two times larger than the single-phase β-Ga₂O₃ diode. This study provides critical insights into the phase-design strategy for developing advanced UWBG electronic devices.

超宽带隙（UWBG）氧化镓（Ga2O3）具有多种多晶型，在大功率电子和太阳盲光电子领域具有巨大的潜力。设计基于杂化Ga2O3多晶结构的电子器件具有很高的吸引力，但它遇到了外延挑战和掺杂剂激活问题的持续障碍。本研究报道了一种基于α/β-Ga2O3异质结构的3 kv级横向肖特基势垒二极管（SBD），该异质结构由导电β-Ga2O3畴嵌入绝缘α- ga2o3基体组成。α/β-Ga2O3异质结构是由应变松弛的α -β Ga2O3相变形成的，该相变强烈依赖于衬底取向和薄膜厚度。β-Ga2O3相的形成对α-Ga2O3基体的结晶度影响较小，在溅射生长过程中更容易发生掺杂活化。基于α/β-Ga2O3杂化异质结构的横向SBD结合了β-Ga2O3高效载流子输运和α- ga2o3优越击穿场的优点，从而实现了良好的整流行为和3 kV击穿电压，击穿电压是单相β-Ga2O3二极管的两倍。该研究为开发先进的UWBG电子器件的相位设计策略提供了重要的见解。

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引用次数: 0

Expanding the trilayer Ruddlesden-Popper nickelate family: Synthesis and characterization of Sm4Ni3O10-δ single crystals 扩展三层Ruddlesden-Popper镍酸盐家族：Sm4Ni3O10-δ单晶的合成与表征

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.102005

Yuhang Zhang, Tian-Yi Li, Xiyu Zhu, Ying-Jie Zhang, Shengtai Fan, Qing Li, Hai-Hu Wen

The discovery of high-temperature superconductivity in Ruddlesden-Popper (RP) nickelates has attracted significant attention. Bulk superconductivity emerges under pressure in trilayer nickelates La₄Ni₃O_10-δ (T_c ≈ 30 K) and Pr₄Ni₃O_10-δ (T_c ≈ 40.5 K), where the reduced ionic radius of Pr³⁺ may generate internal chemical pressure and enhance T_c. However, synthesizing trilayer RP phases with smaller rare-earth elements (Ln) is extremely challenging. So far, only the La, Pr, and Nd analogues have been synthesized with stable phases in the single rare-earth form. Here we report the first successful high-pressure and high-temperature (HPHT) synthesis of samarium-based compound Sm₄Ni₃O_10-δ. Magnetization and transport measurements consistently confirm a density wave (DW) transition at ∼180 K at ambient pressure. Through a careful fitting to the structural data of Sm₄Ni₃O_10-δ, it is found that the bond angle of (Ni−O−Ni) associating with the interlayer apical oxygen is much smaller than 180°, which was assumed to be the key factor for the occurrence of superconductivity. By applying pressures up to 80 GPa, despite partial suppression of insulating behavior and the DW order, but superconductivity is not observed in our present study. Density functional theory calculations suggest that the

3 d_{z^{2}}

and

3 d_{x^{2} - y^{2}}

are separated from other t_2g orbitals and make a primary contribution to the density of states at the Fermi energy. The newly synthesized trilayer nickelate Sm₄Ni₃O_10-δ offers a unique platform for probing the fundamental physics of RP nickelates.

Ruddlesden-Popper （RP）镍酸盐中高温超导性的发现引起了人们的广泛关注。三层镍酸盐La4Ni3O10-δ (Tc≈30 K)和Pr4Ni3O10-δ (Tc≈40.5 K)在压力下呈现大块超导性，其中Pr3+离子半径的减小可能产生内部化学压力，提高Tc。然而，用较小的稀土元素（Ln）合成三层RP相是极具挑战性的。到目前为止，只有La， Pr和Nd类似物以单一稀土形式合成了稳定相。在这里，我们报道了首次成功的高压高温（HPHT）合成钐基化合物Sm4Ni3O10-δ。磁化和输运测量一致地证实了在环境压力下~ 180 K的密度波（DW）跃迁。通过对Sm4Ni3O10-δ结构数据的仔细拟合，发现（Ni−O−Ni）与层间顶端氧缔合的键角远小于180°，这被认为是超导现象发生的关键因素。通过施加高达80gpa的压力，尽管部分抑制了绝缘行为和DW顺序，但在我们的研究中没有观察到超导性。密度泛函理论计算表明，3dz2和3dx2−y2轨道与其他t2g轨道分离，并对费米能量的态密度做出了主要贡献。新合成的三层镍酸盐Sm4Ni3O10-δ为探索RP镍酸盐的基本物理特性提供了一个独特的平台。

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引用次数: 0

Design and analysis of an ultra-thin metamaterial absorber for C, X, Ku and K band applications C， X， Ku和K波段超薄超材料吸收体的设计和分析

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.102008

Baoqin Lin, Wenzhun Huang, Zuliang Wang, Kaibo Si, Xiaohua Zhou, Fei Xu

Metamaterial absorbers (MMAs) are a class of artificially engineered materials designed to achieve highly efficient electromagnetic (EM) wave absorption, and a large number of MMAs have been proposed in recent years. However, various existing MMAs often suffer from a trade-off between absorption bandwidth and structural thickness, those capable of achieving ultra-wideband absorption with ultra-thin profiles remain very scarce. To address this bottleneck, this study proposes a dual-layer ultra-thin MMA comprising two layers of periodically patterned resistive films integrated into a grounded dual-layer dielectric substrate. Numerical simulations and experimental verifications demonstrate that the MMA can achieve over 90 % absorption across an ultra-wide frequency range covering C, X, Ku, and K bands under normal incidence of arbitrarily polarized waves, but its total thickness is merely 0.075λ_L (where λ_L denotes the wavelength at the lowest absorption frequency), thus yielding an exceptional bandwidth-to-thickness ratio (BTR) of 11.43—surpassing numerous previous designs reported in recent literature. In addition, the MMA can maintain over 95 % absorption for transverse-magnetic (TM) waves even at incident angles up to 60°. The absorption mechanism of the MMA is theoretically elucidated via interference theory, with results basically consistent with simulations and measurements. The combination of ultra-wideband, ultra-thin profile, polarization insensitivity, and wide-angle stability makes the MMA highly promising for applications in radar stealth and electromagnetic interference suppression.

超材料吸波器是一类为实现高效电磁波吸收而设计的人工工程材料，近年来被大量提出。然而，现有的各种mma往往受到吸收带宽和结构厚度之间的权衡的影响，那些能够以超薄轮廓实现超宽带吸收的mma仍然非常稀缺。为了解决这一瓶颈，本研究提出了一种双层超薄MMA，该MMA由两层周期性图案电阻膜集成到接地的双层介电衬底中。数值模拟和实验验证表明，在任意极化波的正常入射下，MMA可以在覆盖C、X、Ku和K波段的超宽频率范围内实现90%以上的吸收，但其总厚度仅为0.075λL （λL表示最低吸收频率的波长），因此产生了11.43的特殊带宽/厚度比（BTR），超过了最近文献中报道的许多先前设计。此外，即使在入射角度高达60°的情况下，MMA对横磁（TM）波也能保持95%以上的吸收率。通过干涉理论对MMA的吸收机理进行了理论解释，结果与模拟和实测结果基本一致。超宽带、超薄外形、偏振不敏感和广角稳定性的结合使MMA在雷达隐身和电磁干扰抑制方面具有很大的应用前景。

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引用次数: 0

Stable memristive switching mechanism in CeO2/a-Ga2O3 heterostructure toward synaptic plasticity and logical operations CeO2/a-Ga2O3异质结构中突触可塑性和逻辑运算的稳定忆阻开关机制

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2026.102014

Zhihao Yu, Zhenyang Wang, Fengmin Wu, Chao Wu, Daoyou Guo

Ga₂O₃ has emerged as a highly promising candidate for next-generation memristive materials, owing to its ultra-wide bandgap, exceptional chemical stability, and tunable defect energy states. However, single-layer Ga₂O₃ memristors often suffer from unstable switching voltages caused by the random formation and rupture of conductive filaments, hindering their practical application. In this work, a CeO₂/amorphous-Ga₂O₃ (a-Ga₂O₃) heterostructure memristor with a high oxygen-vacancy gradient was fabricated by employing oxygen-vacancy-rich CeO₂ as an oxygen-vacancy reservoir. The conductance change arises from reversible vacancy migration rather than filament formation in this device, ensuring stable and uniform switching. The device exhibits excellent switching uniformity, with the coefficient of variation for V_set and V_reset as low as 0.18 and 0.15, respectively, which are significantly improved compared with those of the single-layer a-Ga₂O₃ device (0.40 and 0.53, respectively). Moreover, both the HRS and LRS states remain highly stable for up to 10⁴ s under dark conditions. This work provides an effective approach to achieve stable, uniform, and non-filamentary resistive switching in wide-bandgap oxide memristors, paving the way for reliable neuromorphic and logic device applications.

由于其超宽的带隙、优异的化学稳定性和可调的缺陷能态，Ga2O3已成为下一代记忆材料的极有前途的候选者。然而，单层Ga2O3忆阻器由于导电丝的随机形成和断裂，导致开关电压不稳定，阻碍了其实际应用。本文以富氧空位的CeO2为氧空位储层，制备了具有高氧空位梯度的CeO2/非晶ga2o3异质结构忆阻器。在该器件中，电导变化是由可逆空位迁移而不是灯丝形成引起的，从而保证了开关的稳定和均匀。该器件具有优异的开关均匀性，Vset和Vreset的变化系数分别低至0.18和0.15，与单层a-Ga2O3器件（分别为0.40和0.53）相比有显著提高。此外，在黑暗条件下，HRS和LRS状态在长达104 s的时间内保持高度稳定。这项工作为实现宽带隙氧化物忆阻器的稳定、均匀和非丝状电阻开关提供了一种有效的方法，为可靠的神经形态和逻辑器件应用铺平了道路。

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引用次数: 0

Defect engineering enables ultra-stable radiation-resistant optical transparency in polycrystalline Gd2Zr2O7 ceramics 缺陷工程使多晶Gd2Zr2O7陶瓷具有超稳定的抗辐射光学透明度

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.102009

Lexing Liang , Cong Zhang , Mao Deng , Junjing Duan , Xiaolan Zhou , Zaixin Wei , Kailei Lu , Yanli Shi , Zhangyi Huang , Jianqi Qi , Tiecheng Lu

Highly transparent polycrystalline gadolinium zirconate (Gd₂Zr₂O₇, GZO) ceramics are excellent candidates for mixed gamma (γ) and neutron radiation shielding, but suffer from γ-induced color centers. To address this, we introduce a Ce-doping–mediated defect-engineering strategy, demonstrating that the Ce valence state is the critical switch. We show that Ce⁴⁺-rich (air-annealed) samples exhibit exceptional radiation-hardening, whereas Ce³⁺-rich (vacuum-sintered) samples show catastrophic sensitization. It is confirmed that Ce⁴⁺ acts as a preferential electron trap, competitively suppressing color center formation. As a result, the optimized Ce⁴⁺-rich samples exhibit a γ-induced transmittance loss of less than 4 % (at 100 kGy) and maintain excellent transparency (71.8 % at 450 nm), vastly outperforming commercial ZF6 lead glass (which suffers a 52.6 % loss). Furthermore, GZO:Ce demonstrates 20 % higher γ attenuation (0.373 cm⁻¹ for ⁶⁰Co) and exceptional thermal neutron shielding (cross-section of 688.22 cm⁻¹), combined with excellent mechanical hardness (∼11.5 GPa) and superior corrosion resistance in both acidic and alkaline media. This work establishes Ce-doped GZO as a scalable and durable ceramic platform for γ/n shielding windows, and highlights valence-state and defect engineering as a powerful strategy for the rational design of radiation-tolerant transparent materials.

高透明多晶锆酸钆（Gd2Zr2O7， GZO）陶瓷是混合γ (γ)和中子辐射屏蔽的优秀候选人，但受到γ诱导色心的影响。为了解决这个问题，我们引入了Ce掺杂介导的缺陷工程策略，证明Ce价态是关键开关。我们发现富Ce4+（空气退火）样品表现出异常的辐射硬化，而富Ce3+（真空烧结）样品表现出灾难性的敏化。证实了Ce4+作为优先电子陷阱，竞争性地抑制了色心的形成。结果，优化后的富Ce4+样品显示出γ诱导的透射率损失小于4%（在100 kGy时），并保持良好的透明度（在450 nm时为71.8%），大大优于商用ZF6铅玻璃（其损失为52.6%）。此外，GZO:Ce在酸性和碱性介质中表现出高20%的γ衰减（60Co为0.373 cm−1）和出色的热中子屏蔽（横截面为688.22 cm−1），结合优异的机械硬度（~ 11.5 GPa）和优异的耐腐蚀性。这项工作建立了ce掺杂GZO作为γ/n屏蔽窗口的可扩展和耐用陶瓷平台，并强调了价态和缺陷工程作为合理设计耐辐射透明材料的有力策略。

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引用次数: 0

Magnetic, transport, and Raman properties of the layered charge density wave antiferromagnet EuTe4 under ambient and high pressures 层状电荷密度波反铁磁体EuTe4在环境和高压下的磁性、输运和拉曼特性

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2026.102011

Jin Jiang , Shuyang Wang , Chao An , Zhitao Zhang , Langsheng Ling , Yuqiang Liu , Xiaoping Yang , Yonghui Zhou , Xuliang Chen , Zhaorong Yang

We present a comprehensive study of EuTe₄ single crystals using axis-resolved magnetization, electrical transport, electron spin resonance, and Raman spectroscopy at ambient pressure, complemented by high-pressure measurements up to 47.3 GPa. At ambient pressure, EuTe₄ is determined as an A-type antiferromagnet (T_N∼7.1 K) with localized Eu²⁺ spins pointing along the a axis and aligning ferromagnetically within the basal plane and antiferromagnetically along the c axis. A spin-flop transition occurs below T_N at approximately 3/8 of the saturation magnetization when the magnetic field is applied along the a axis, the easy magnetization direction. Pronounced negative magnetoresistance accompanies this field-driven spin reorientation, reminiscent of the giant magnetoresistance effect in artificial magnetic superlattices. The pressure–temperature phase diagram reveals a semiconductor-to-metal transition with the suppression of CDW-related resistivity hysteresis near 4 GPa, a change in the T_N evolution at ∼11 GPa, and an antiferromagnetic-to-nonmagnetic transition near 22 GPa, likely associated with pressure-induced lattice modulations. These results provide crucial insight into the interplay among charge, spin, and lattice degrees of freedom in layered EuTe₄.

我们在环境压力下利用轴分辨磁化、电输运、电子自旋共振和拉曼光谱对EuTe4单晶进行了全面的研究，并通过高达47.3 GPa的高压测量进行了补充。在环境压力下，EuTe4被确定为a型反铁磁体（TN ~ 7.1 K），其局域化Eu2+自旋指向a轴，在基面上呈铁磁排列，并沿c轴呈反铁磁排列。当磁场沿易磁化方向A轴施加时，在饱和磁化强度约为3/8时，在TN以下发生自旋触发器跃迁。明显的负磁阻伴随着磁场驱动的自旋重定向，让人联想到人工磁超晶格中的巨磁阻效应。压力-温度相图揭示了半导体到金属的转变，cdw相关的电阻率滞后在4 GPa附近受到抑制，TN在~ 11 GPa时发生变化，在22 GPa附近发生反铁磁性到非磁性的转变，可能与压力诱导的晶格调制有关。这些结果为层状EuTe4中电荷、自旋和晶格自由度之间的相互作用提供了重要的见解。

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引用次数: 0

Structuring and patterning approaches for diamond – Toward the third dimension 菱形的结构和图案方法-朝向第三维度

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.101995

Stephan Handschuh-Wang , Zhicheng Xing , Tao Wang

Single crystal diamonds and diamond films are attractive materials for a broad variety of applications due to the intriguing properties of diamond and the ability to tailor the electrical conductivity and surface functionalization. Many applications require a specific roughness, high surface area, a specific 3-dimensional shape, a specific pattern, or a mixture thereof. However, machining, sculpting, and patterning of diamond is challenging due to diamond's growth mechanism, high hardness, wear resistance, and brittleness, rendering machining of diamond arduous. In the last decades, a variety of bottom-up and top-down methods to synthesize diamond with controlled roughness and structures has been established. This review summarizes methods to obtain diamond patterns and diamond films with controlled roughness, microstructures, nanostructures, and porous diamond. Indeed, controlled diamond structures synthesis via both bottom-up and top-down approaches have advanced considerably. The methods themselves are introduced in combination with their merits, detriments, and their capabilities, hinting towards applications of such structures. The discussion is supplemented by recent developments and advances of the controlled synthesis methods. The review is divided into methods for obtaining patterns and structures as well as methods to control the micro- and nanostructure, to control roughness of diamond films, or to obtain ultra-smooth diamond films. This review serves as a timely summary of experimental techniques and recent developments for researchers planning to generate structured or patterned diamond.

单晶金刚石和金刚石薄膜是一种具有广泛应用前景的材料，因为金刚石具有独特的特性和可定制电导率和表面功能化的能力。许多应用需要特定的粗糙度、高表面积、特定的三维形状、特定的图案或其混合物。然而，由于金刚石的生长机制、高硬度、高耐磨性和脆性，使金刚石的加工、雕刻和图案加工具有挑战性。在过去的几十年里，已经建立了各种自下而上和自上而下的方法来合成具有可控粗糙度和结构的金刚石。本文综述了获得金刚石图案、控制粗糙度的金刚石薄膜、微观结构、一维纳米结构和多孔金刚石的方法。事实上，通过自下而上和自上而下的方法合成的可控金刚石结构已经取得了相当大的进展。结合方法本身的优缺点和能力进行了介绍，并对这种结构的应用进行了提示。讨论还补充了控制合成方法的最新发展和进展。本文分为获得模式和结构的方法、控制微纳米结构的方法、控制金刚石膜粗糙度的方法和获得超光滑金刚石膜的方法。这篇综述是对实验技术和最新发展的及时总结，为研究人员计划产生结构或图案钻石。

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引用次数: 0

Integrated micromagnetics-domain-magnetization analysis unveils the characteristic pinning behavior in hot-deformed Nd-Fe-B magnets 集成微磁-域磁化分析揭示了热变形钕铁硼磁体的特征钉钉行为

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.101999

Yuqing Li , Yan Pan , Hanfei Liu , Lingqi Liu , Mengying Bian , Weiqiang Liu , Weixing Xia , Ming Yue

Hot-deformed (HD) Nd-Fe-B magnets achieve high coercivity by grain boundary pinning the domain wall motion due to the fine grain size. A thorough understanding of this pinning behavior can guide the leveraging of this advantage to achieve high-coercivity magnets without heavy rare earths. This work investigated the pinning behavior during magnetization and demagnetization of a typical HD Nd-Fe-B magnet by combining micromagnetic simulations, dynamic domain observation, and macroscopic technical magnetization analysis. Micromagnetic simulations reveal a variety of heterogeneous pinning sites. Combined with domain wall energy analysis, this provides a new perspective on the straight, trans-granular domain walls observed at the thermal demagnetization state. Domain evolution and the macroscopic magnetization analysis describe how the reversible portion transforms into the irreversible portion in the magnetization process in a low magnetic field, and further demonstrate the coexistence of asymmetric, weak, and strong pinning. Based on these findings, we argue that both the positive δm peaks and the open recoil loops in HD Nd-Fe-B magnets stem from their characteristic pinning behavior. The former arises because the initial states for magnetization and demagnetization differ. Hence, domain walls enter strong pinning sites at different stages, whereas the latter occurs because weak pinning sites impede reversible domain wall motion. Our findings enrich the coercivity theory of permanent magnetic materials by elucidating domain-wall pinning mechanisms at the sub-micrometer scale and provide a reliable reference for developing high-coercivity magnets.

热变形钕铁硼磁体由于晶粒尺寸细小，通过晶界钉住畴壁运动而获得高矫顽力。对这种钉住行为的透彻理解可以指导利用这一优势来实现不含重稀土的高矫顽力磁体。本文采用微磁模拟、动态畴观测和宏观技术磁化分析相结合的方法，研究了典型HD Nd-Fe-B磁体在磁化和退磁过程中的钉钉行为。微磁模拟显示了多种异质钉钉位点。结合畴壁能量分析，为热退磁状态下观察到的直晶畴壁提供了新的视角。畴演化和宏观磁化分析描述了在低磁场下磁化过程中可逆部分向不可逆部分转变的过程，进一步证明了不对称、弱、强钉钉的共存。基于这些发现，我们认为HD Nd-Fe-B磁体的正δm峰和开放反冲回路都源于其特有的钉钉行为。前者的产生是因为磁化和退磁的初始状态不同。因此，结构域壁在不同阶段进入强钉钉位点，而后者的发生是因为弱钉钉位点阻碍了可逆的结构域壁运动。我们的发现丰富了永磁材料的矫顽力理论，在亚微米尺度上阐明了畴壁钉钉机理，为开发高矫顽力磁体提供了可靠的参考。

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引用次数: 0

Ultrafast self-powered solar blind UV photodetectors based on amorphous Ga2O3 thin films in crossbar geometry 基于横杆非晶Ga2O3薄膜的超快自供电太阳盲紫外光电探测器

IF 9.7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2026-01-01 DOI: 10.1016/j.mtphys.2025.102007

Amit K. Das , Vikas Kumar Sahu , R.S. Ajimsha , Sunil Verma , Pankaj Misra

Amorphous gallium oxide (a-Ga₂O₃) based UV photodetectors combine the benefits of low growth temperature, large-area processibility and use of flexible, inexpensive substrates with performance comparable to their crystalline counterparts. Despite these advantages, their photoresponse time is notably slower. To mitigate this, ultrafast vertical Schottky type Au/a-Ga₂O₃/ITO solar blind ultraviolet photodetectors have been developed in crossbar geometry, wherein the a-Ga₂O₃ thin film, deposited by RF magnetron sputtering, is sandwiched between the bottom ITO and orthogonal top semi-transparent Au Schottky electrodes. The device sizes vary from ∼8 to 12 mm². The temporal UV photoresponse measurement of the devices at zero bias shows ultrafast response with both rise and fall times of ∼2 μs, which is the fastest reported till date for a-Ga₂O₃ based UV photodetectors. The zero bias spectral responsivity measurement reveals that the responsivity peaks at 250 nm with the cut-off at 273 nm. The maximum self-powered spectral responsivity of ∼14 mA/W obtained in these crossbar devices is comparable to that of a-Ga₂O₃ based devices reported in literature. These crossbar Au/a-Ga₂O₃/ITO devices showing ultrafast self-powered solar blind UV photoresponse are promising for applications requiring fast solar blind UV detectors such as UV communication, imaging, missile plume detection etc.

基于非晶氧化镓（a-Ga2O3）的紫外光电探测器结合了低生长温度、大面积可加工性和使用柔性、廉价衬底的优点，其性能可与晶体相媲美。尽管有这些优点，它们的光响应时间明显较慢。为了减轻这一问题，在横杆几何结构中开发了超快垂直肖特基型Au/a-Ga2O3/ITO太阳盲紫外光电探测器，其中，通过射频磁控溅射沉积的a-Ga2O3薄膜夹在底部ITO和正交顶部半透明Au - Schottky电极之间。器件尺寸从~ 8到12mm2不等。器件在零偏置下的时间紫外光响应测量显示出超快的响应，上升和下降时间均为~ 2 μs，这是迄今为止报道的基于a-Ga2O3的紫外光电探测器中最快的。零偏光谱响应率测量表明，响应率在250 nm处达到峰值，截止点为273 nm。在这些交叉棒器件中获得的最大自供电光谱响应率为~ 14 mA/W，与文献中报道的基于a-Ga2O3的器件相当。这些横条Au/a-Ga2O3/ITO器件显示了超快的自供电太阳盲紫外光响应，对于需要快速太阳盲紫外探测器的应用，如紫外通信、成像、导弹羽流探测等，具有很大的前景。

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