Search

In recent years, micro-light-emitting diode (micro-LED) displays have attracted much attention due to their high brightness, low power consumption, long lifetime, and fast response. It is considered to have the potential to revolutionize the development direction of next-generation visual display technology. However, the development of micro-LED displays faces numerous issues, primarily due to etching processes for pixel array manufacturing, which cause sidewall damage and decreased photoelectric efficiency. Specifically, these issues are particularly serious when preparing small-sized high-resolution displays. In this work, we effectively overcame the above-mentioned problems by only etching the electron barrier during the preparation process of pixel arrays. The prepared micro-LED display exhibits excellent optoelectronic properties, with the highest brightness and current efficiency reaching 1.66 × 106 nits and 104 cd/A, respectively. The method provides a feasible idea for preparing high-performance micro-LED displays. [ABSTRACT FROM AUTHOR]

The strip casting technique was first used in this work to prepare the Sm2Fe17 parent alloys. Next, the Sm2Fe17N3 powders were synthesized using a gas–solid reaction of Sm2Fe17 powders with N2. Then, the anisotropic Sm2Fe17N3 powders with high performance were prepared by a surfactant-assisted grinding method in gasoline solvent. It was found that the coercivity (iHc) of ground powders increases with decreasing the average particle size (Dm), while the saturation magnetization (Ms) decreases. The maximum value of iHc of 17.5 kOe was obtained at the Dm = 1.3 µm. The ground powders with Dm of 3.1 µm show a remanence ratio (Mr/Ms) over 95% and a maximum energy product [(BH)max] of 35 MGOe. The Sm2Fe17N3 powder exhibited a very high iHc of 36.1 kOe at 10 K. Above 300 K, Sm2Fe17N3 powders mixed with epoxy resin showed a low remanence temperature coefficient of α(RT-100°C) = −0.077% °C−1. [ABSTRACT FROM AUTHOR]

Microwave absorbers are increasingly being used to enhance shielding performance at higher frequencies. Great effort has been made to develop materials with superior reflection loss (RL), thin thickness, wide bandwidth, and low density to improve their performance in electromagnetic microwave absorption. In this work, the rare-earth intermetallics La2Fe4Co10B fine powders with planar magnetocrystalline anisotropy and high magnetization were prepared using the hydrogenation desorption (HD) technique. By heating the obtained magnetic powders in the air to slowly form an oxide layer on their surfaces, its complex permittivity can be tuned without changing its complex permeability, and its microwave absorption performance can be dramatically enhanced due to the improved impedance matching condition. For the La2Fe4Co10B/paraffin composite, the real part of the complex permittivity at 10 GHz can be reduced from 20.1 to 12.8, decreasing 36.3%. Before the oxidation, the RL of La2Fe4Co10B/paraffin composite is only −14.8 dB at 3.3 GHz under 3.4 mm thickness with an effective absorption bandwidth (EAB) of 0.9 GHz. However, after the 10-hour oxidation, the RL changes to −15.6 dB at 13.4 GHz under 1.4 mm thickness with an EAB of 6.2 GHz. As an efficient and lightweight absorber, La2Fe4Co10B/paraffin composite has potential application value in constructing a new microwave absorber. [ABSTRACT FROM AUTHOR]

Rare-earth transition-metal (R-T) intermetallic compounds are emerging as competitive candidates for novel microwave absorption materials (MAMs) since they show high magnetization and tunable easy magnetization directions (EMDs). In this work, Y 2 ( Co 1 − x Fe x ) 17 (0 ≤ x ≤ 0.3) compounds with the Th2Ni17 hexagonal structure were prepared with the purpose of tuning the EMDs. As x increases, the EMDs of the Y 2 ( Co 1 − x Fe x ) 17 compounds change from the ab-plane (0 ≤ x < 0.0329) to the cone (0.0329 ≤ x ≤ 0.038) and then to the c-axis direction (0.038 < x ≤ 0.3). Furthermore, it was found that the extremely high cutoff frequencies of the uniaxial anisotropy materials give them considerably potential for microwave absorption applications above 10 GHz, despite their relatively low initial permeability compared to the planar anisotropic materials. By studying the high-frequency properties of Y 2 ( Co 1 − x Fe x ) 17 /paraffin composites, it is noted that uniaxial anisotropy compounds with x = 0.1 and x = 0.3 can possess higher permeability above 10 GHz as compared to both planar anisotropy and conical anisotropy compounds (x < 0.1) due to their high cutoff frequencies arising from large magnetocrystalline anisotropy fields. This can improve the impedance matching and thus lead to a better microwave absorption performance in the range of 10 to 40 GHz for materials with uniaxial anisotropy. Among all the compositions, the Y 2 ( Co 0.9 Fe 0.1 ) 17 /paraffin composite exhibits a minimum reflection loss (RL) of −50 dB at 6 GHz with a thickness of 2.5 mm and a wide qualified bandwidth (QB, RL < −10 dB) of 9.6 GHz at a center frequency of 30.3 GHz with a thickness of 0.6 mm, thus making it a promising candidate for MAMs above 10 GHz. [ABSTRACT FROM AUTHOR]

The site preference of N atom for R2Fe14BNx (R= Pr, Nd) and the interstitial nitrogen effect on the magnetic properties have been studied by the first-principles method. It was found that the nitrogen is more likely to occupy the 4e site for Pr2Fe14BNx compound, while 4f site for Nd2Fe14BNx. When N atoms entering some specific crystal sites (such as 2a and 4f), the total magnetic moments of these compounds are not reduced, but slightly increased. Although the doping of N may reduce the total magnetic moments of some R2Fe14B compounds in the cases of optimal occupancy, the volumetric effect caused by N doping can still change the electron density distributions of Fe near the Fermi level, improving the magnetic ordering temperature of such compounds. [ABSTRACT FROM AUTHOR]