粉末冶金(FeNiMnAl_(x))_(50)Cu_(50)中熵合金的微观组织与力学性能EI北大核心CSCD

对物理法制备的再生铜合金粉末进一步合金化,通过机械合金化(MA)结合放电等离子烧结(SPS)的方法制备了(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50),(Fe_(38)Ni_(38)Ni_(38)Mn_(19)Al_(5))_(50)Cu_(50),(Fe_(36)Ni_(36)Mn_(18)Al_(10))50 Cu_(50)和(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)四种中熵合金块体,并研究了Al元素的含量对中熵合金微观组织与力学性能的影响。结果表明:在高能球磨60 h之后合金粉末完成合金化,四种中熵合金粉末均形成单一FCC相的过饱和固溶体且有微量WC杂质。经SPS烧结后,(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50),(Fe_(38)Ni_(38)Mn_(19)Al_(5))_(50)Cu_(50)和(Fe_(36)Ni_(36)Mn_(18)Al_(10))50 Cu_(50)形成了由富Cu的FCC1相和富Fe-Ni的FCC2相组成的双相FCC结构,并具有超细晶+微米晶的多尺度结构;而(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)由富Cu的FCC主相和少量富Fe-Mn的FCC2相及富Ni-Al的BCC相(B2)组成。随着Al含量的提高,四种中熵合金的塑性逐渐降低,而强度和硬度逐渐提高。(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50)合金的压缩屈服强度、抗压强度和维氏硬度分别为878 MPa,1257 MPa和248.5HV。与(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50)相比,(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)的压缩屈服强度和硬度分别提高了50.1%和50.4%,断裂应变由19.55%下降至8.31%。     

金属有机框架复合材料的制备及其性能研究

通过气态扩散作用,合成了MIL-101(Cr)@[Fe(HB(pz)3)2]、NH2-MIL-101(Al)@[Fe(HB(pz)3)2]和MIL-100(Al)@[Fe(HB(pz)3)2]3种MOFs材料@([Fe(HB(pz)3)2])复合物。采用红外光谱仪、原子吸收光谱仪、X射线衍射仪、物理吸附仪对3种MOFs材料@[Fe(HB(pz)3)2]复合物的组成、结构和性能进行表征测试。测试结果表明:[Fe(HB(pz)3)2]成功进入MOFs材料的孔洞中,形成了MOFs材料@[Fe(HB(pz)3)2]的复合物;MOFs材料的孔洞结构使[Fe(HB(pz)3)2]形成了一层保护外壁,从而使复合物的热稳定性和化学稳定性。经原子吸收光谱测试,可知MIL-101(Cr)@[Fe(HB(pz)3)2]、NH2-MIL-101(Al)@[Fe(HB(pz)3)2]和MIL-100(Al)@[Fe(HB(pz)3)2]中分别含有质量分数为8.11%,7.42%和1.64%的[Fe(HB(pz)3)2]。最后,对比分析了MIL-101(Cr)@[Fe(HB(pz)3)2]、NH2-MIL-101(Al)@[Fe(HB(pz)3)2]与[Fe(HB(pz)3)2]经多次转变后的颜色变化情况,实验结果表明,MOFs材料@[Fe(HB(pz)3)2]的复合物可应用到防伪包装材料之中。     

2007——2008学年高三总复习数学教学实践感悟

高三数学总复习教学反思;(一)第一轮总复习、(二)第二轮总复习、(三)第三轮总复习、(四)检查考试、(五)课堂教学、(六)作业布置(七)成绩跟踪、(八)考前指导、(九)学科协调、(十)导优辅差。     

Mg13Al14和Mg17Al12中间合金的第一性原理研究

Mg-Al合金具有密度小、刚度好、强度质量比极佳、可铸性以及延展性良好等优点,可作为一种性能优异的轻量级结构材料。Mg_(17)Al_(12)作为其中的中间合金,具有阻碍位错运动来强化晶界的重要作用。本工作采用第一性原理方法,系统研究了Mg_(13)Al_(14)和Mg_(17)Al_(12)两种中间合金的晶体结构、电子结构及力学性能。研究结果表明:Mg_(13)Al_(14)的原胞结构不具有热力学稳定性,而Mg_(13)Al_(14)初胞结构热力学稳定,且稳定性高于Mg_(17)Al_(12);通过电子结构分析发现,Mg_(13)Al_(14)和Mg_(17)Al_(12)均具有很强的金属性,且Mg_(17)Al_(12)的离子性略强于Mg_(13)Al_(14),因此Mg_(17)Al_(12)具有更高的结构稳定性;通过力学参数计算,可以得出二者的初胞均具有良好的力学稳定性,而Mg_(13)Al_(14)的原胞不具有力学稳定性。其中Mg_(13)Al_(14)表现为延性材料,Mg_(17)Al_(12)表现为脆性材料; Mg_(13)Al_(14)初胞的可塑性更好,抵抗剪切形变的能力强于Mg_(17)Al_(12); Mg_(17)Al_(12)的刚性更高,抗塑性变形能力强于Mg_(13)Al_(14); Mg_(13)Al_(14)和Mg_(17)Al_(12)均表现为弹性各向异性;对于Mg-Al合金,中间合金初胞结构的Mg_(13)Al_(14)的综合力学性能优于Mg_(17)Al_(12),但原胞的热力学稳定性较差,与Mg_(17)Al_(12)相比不利于提升Mg-Al的热稳定性。     

ISO第28届技术管理局会议概况

ISO第28届技术管理局TMB会议于2003年9月15日至16日在阿根廷召开，来自美国(ANSI)、英国(BSI)、德国(DIN)、丹麦(DS)、马来西亚(DSM)、日本(JISC)、荷兰(NFN)、中国(SAC)、新西兰(SNZ)、意大利(UNI)、澳大利亚(SAI)等国的TMB成员参加了会议，会议由TMB主席Mr．Wraight(澳大利亚标准国际有限公司)主持。     

Mg:Er:LiNbO3晶体波导基片抗光损伤的研究

以Czochralski技术生长Mg(2mol%)Er(1mol%)LN,Mg(4mol%)Er(1mol%)LN,Mg(6mol%)Er(1mol%)LN,Mg(8mol%)Er(1mol%)LN和Er(1mol%)LN晶体.测试了MgErLiNbO3晶体的红外光谱,Mg(2mol%)ErLN,Mg(4mol%)ErLN OH-吸收峰在3486cm-1附近,Mg(6mol%)ErLN和Mg(8mol%)ErLN晶体OH-吸收峰移动到3535cm-1附近,对MgErLN晶体OH-吸收峰移动机理进行研究.采用m线法测试MgErLN晶体光损伤阈值.Mg(6mol%)Er(1mol%)LN和Mg(8mol%)ErLN晶体光损伤阈值比ErLN晶体提高两个数量级以上.Mg(2mol%)ErLN和Mg(4mol%)ErLN晶体比Er(1mol%)LN晶体提高一个数量级.     

Sr、Co共掺多铁性材料BiFeO3的性能

利用溶胶-凝胶法制备了BiFeO_3、Bi_(0.95)Sr_(0.05)FeO_3、BiFe_(0.95)Co_(0.05)O_3和Bi_(0.95)Sr_(0.05)Fe_(0.95)Co_(0.05)O_3样品,并对样品的结构、形态、元素含量、铁电性和铁磁性进行了研究。结果表明,共掺杂样品Bi_(0.95)Sr_(0.05)Fe_(0.95)Co_(0.05)O_3的晶体结构发生了变化,铁电性明显增强,但漏电流变大;Bi_(0.95)Sr_(0.05)FeO_3、BiFe_(0.95)Co_(0.05)O_3样品的磁性都有所增强,但Bi_(0.95)Sr_(0.05)Fe_(0.95)Co_(0.05)O_3样品的磁性并没有随着Sr和Co的共同掺杂而进一步提高,从氧空位浓度、Fe-O共价键结构的变化和晶体尺寸三个方面对产生这种现象的原因进行了分析。     

静电纺丝法制备的Co0.6Ni0.3Cu0.1Fe2O4和Co0.6Ni0.3Zn0.1Fe2O4纳米纤维的结构及磁性能

采用静电纺丝技术制备出表面光滑、直径均匀的Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4/PVP和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4/PVP纳米纤维前驱丝,经500~900℃煅烧后得到Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维。用TG-DSC、XRD、SEM及VSM现代测试分析手段对Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的结构、形貌及磁学性能进行测试表征。结果表明:在空气气氛中经500~900℃煅烧后可得到纯尖晶石相、结晶度良好的纳米纤维或短纤维;当温度为700℃时,Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的形貌细长而光滑且直径相对均匀,大约为80nm;此时Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维则保有较高的剩磁比(M_r/M_s)及矫顽力,分别为0.56和1 088.87Oe。在500℃、600℃、700℃、800℃、900℃煅烧后,Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的饱和磁化强度分别比Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维增大了14.5%、7%、16%、10.7%、8%,而矫顽力则分别降低了38%、51%、50%、46%、46.7%。两种纳米纤维的饱和磁化强度及矫顽力存在差异,为CoNi铁氧体在电磁方面的应用提供了很好的参考。     

CoZnB添加量对稀土基储氢合金电化学性能的影响

首先采用化学还原法制备了CoZnB非晶合金,随后用机械球磨法将其引入到稀土基合金La_(0.7) Mg_(0.3)Ni_(3.5)中制备成复合物,考察了CoZnB的添加量对La_(0.7) Mg_(0.3)Ni_(3.5)合金电化学性能的影响。实验结果表明,加入CoZnB非晶合金后,复合物合金电极首次放电即可达到最大放电容量,高倍率放电性能得到了显著改善,电荷转移阻抗和极限电流密度均高于La_(0.7) Mg_(0.3)Ni_(3.5)合金电极。复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比1∶1)的最大放电容量高达487.5mAh/g,800mA/g放电电流密度下的复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比2∶1)的高倍率放电性能(HRD)可达94.8%。     

苝四羧酸二酰亚胺修饰增强g-C_(3)N_(4)光催化性能EI北大核心CSCD

以3,4,9,10-苝四甲酸二酐和L-天冬氨酸为原料,合成水溶性苝二酰亚胺衍生物N,N′-二(2-丁二酸基)-3,4,9,10-苝四羧酸二酰亚胺(PASP)。采用水热法将PASP接枝在g-C_(3)N_(4)上,制备PASP改性g-C_(3)N_(4)复合光催化剂(g-C_(3)N_(4)-PASP)。通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见光漫反射光谱(UV-Vis DRS)和固体荧光光谱等对g-C_(3)N_(4)-PASP的组成、结构、形貌和光学性质等进行表征,考察g-C_(3)N_(4)-PASP对水溶液中模型污染物亚甲基蓝(MB)的光催化降解活性。结果表明:g-C_(3)N_(4)与PASP经水热反应,可通过酰胺键共价结合;相比纯g-C_(3)N_(4),g-C_(3)N_(4)-PASP比表面积显著增大,吸收带边红移至614 nm,同时PASP修饰可促进g-C_(3)N_(4)材料表面光生电子和空穴分离,进而有效提升光催化活性。在可见光(λ>420 nm)照射下,g-C_(3)N_(4)-PASP对MB的降解率60 min内可达99.4%,降解速率常数k约为g-C_(3)N_(4)的2倍。     

Nonpolar a-plane ZnO growth and nucleation mechanism on (1 0 0) (La,Sr)(Al,Ta)O3 substrate

Nonpolar a-plane ZnO epitaxial film with [1 1 −2 0] orientation was successfully grown on a (1 0 0) (La_0.3,Sr_0.7)(Al_0.65,Ta_0.35)O₃ (LSAT) substrate by a chemical vapor deposition method. The dependence of surface morphologies and epi-film crystallinity on the growth temperature was studied by a scanning electron microscopy and X-ray diffraction. Room temperature photoluminescence spectra all exhibit a strong near-band-edge emission peak at 378.6 nm without noticeable green band. From high resolution transmission electron microscopy, we found two distinct growth configurations for our a-plane ZnO on (1 0 0) LSAT. To explain the epitaxial properties, we illustrate four possible nucleation sites on (1 0 0) LSAT for two kinds of orientational relationship, i.e. [1 0 −1 0]_ZnO//[0 1 1]_LSAT and [0 0 0 1]_ZnO//[0 1 1]_LSAT.     

A study of the loading path and crystal orientation effects on size-dependent limit strength

To better understand the loading path and crystal orientation effects on size-dependent material strength, molecular dynamics (MD) simulations are performed with the use of single crystal diamond (SCD) of various sizes under uniaxial tension and simple shear loading conditions. In the MD simulations, mechanical responses of SCD blocks with three different sizes under 〈1 0 0〉 and 〈1 1 0〉 tensions, and under {1 0 0}〈0 1 0〉, {1 0 0}〈1 1 0〉 and {1 1 0}〈0 0 1〉 shear slips at different loading rates are studied. Based on the simulation data, a power scaling law is proposed to predict the size effect on the material strength of pristine diamond under given loading conditions.     

Surface mound formation during epitaxial growth of CrN(001)

Single crystal CrN(001) layers, 10 to 160 nm thick, were grown on MgO(001) by reactive magnetron sputtering at growth temperatures T_s = 600 and 800 °C. Insitu scanning tunneling microscopy shows that all layer surfaces exhibit mounds with atomically smooth terraces that are separated by monolayer-high step edges aligned along ( 110) directions, indicating N-rich surface islands. For T_s = 600 °C, the root mean square surface roughness σ initially increases sharply from 0.7 ± 0.2 for a thickness t = 10 nm to 2.4 ± 0.5 nm for t = 20 nm, but then remains constant at σ = 2.43 ± 0.13 nm for t = 40, 80 and 160 nm. The mounds exhibit square shapes with edges along ( 110) directions for t ≤ 40 nm, but develop dendritic shapes at t = 80 nm which revert back to squares at t = 160 nm. This is associated with a lateral mound growth that is followed by coarsening, yielding a decrease in the mound density from 5700 to 700 µm⁻² and an initial increase in the lateral coherence length ξ from 7.2 ± 0.6 to 16.3 ± 0.8 to 24 ± 3 nm for t = 10, 20, and 40 nm, respectively, followed by a drop in ξ to 22 ± 2 and 16 ± 2 nm for t = 80 and 160 nm, respectively. Growth at T_s = 800 °C results in opposite trends: σ and ξ decrease by a factor of 2, from 2.0 ± 0.4 and 20 ± 4 nm for t = 10 nm to 0.92 ± 0.07 and 10.3 ± 0.4 nm for t = 20 nm, respectively, while the mound density remains approximately constant at 900 μm⁻². This unexpected trend is associated with mounds that elongate and join along ( 100) directions, yielding long chains of interconnected square mounds for t = 40 nm. However, coalescence during continued growth to t = 160 nm reduces the mound density to 100 µm⁻² and increases σ and ξ to 2.5 ± 0.1 and 40 ± 2 nm, respectively.     

Preferentially oriented thin-film growth of CuO(1 1 1) and Cu2O(0 0 1) on MgO(0 0 1) substrate by reactive dc-magnetron sputtering

Copper oxide films deposited on MgO(0 0 1) substrates by reactive magnetron sputtering under the metal-mode condition were studied by X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED) analyses for structural analysis, and X-ray-excited Auger electron spectroscopy (XAES) for chemical bonding analysis. CuO(1 1 1) thin films grew from their initial growth stage maintaining the same crystallinity on MgO(0 0 1) substrates at 400°C. When the substrate temperature was increased to 600 °C, the as-sputtered films comprise Cu(0 0 1), amorphous Cu₂O phase, and Cu₂O(0 0 1) phase. The Cu(0 0 1) phase was observed at initial growth stage. This is probably because O₂ gas molecules could not sufficiently stick to the MgO substrate at 600 °C. Single phase of Cu₂O(0 0 1) was obtained by the cooling of the as-sputtered films in O₂ atmosphere. The growth of single phase Cu₂O(0 0 1) is considered as a solid-phase heteroepitaxial growth on MgO(0 0 1) surface, which was caused by incorporating O₂ gas into the as-sputtered films.     

Ductile-brittle behavior at the (1 1 0)[0 0 1] crack in bcc iron crystals loaded in mode I

Fracture experiments performed at room temperature on four test samples made of Fe-3wt.%Si single crystals with an edge crack (1 1 0)[0 0 1] (crack plane, crack front) showed approximately 45° deflections of the crack from the initial crack plane (1 1 0). This behavior appeared to be independent on loading rate. Fractographic analysis confirmed that the cracks were deviated along {1 0 0} planes and the fracture was accompanied by dislocation slip and by twinning. 3D simulations at 300 K by molecular dynamic technique in bcc iron with edge cracks of equivalent orientation indicated that the crack itself could contribute to understanding of this behavior by three processes: twinning on oblique {1 1 2} planes, which hindered growth of the original crack, and by emission of dislocations on oblique {0 1 1} and {1 2 3} planes, which led to separation of the {1 0 0} planes and might cause decohesion and subsequent cleavage fracture along the mentioned planes.     

Regularity of nanopores in anodic alumina formed on orientated aluminium single-crystals

On aluminium single crystals with (1 1 1), (1 1 0) and (1 0 0) orientation, nanoporous alumina layers were formed in a two-step anodization process within sulphuric acid. The pore ordering within the hexagonal arrangement of the nanopores was documented by scanning electron microscopy (SEM), described on the basis of defect thermology and analyzed quantitatively by image evaluation. The best ordering was obtained in nanoporous alumina on (1 0 0) aluminium. We supposed that this is caused by the interface energy term within the driving force for the formation of the nanoporous alumina, since – in contrast to (1 1 1) and (1 1 0) aluminium as substrate – in the case of (1 0 0) aluminium the interface energy is minimised in the waved interface between aluminium and hexagonally arranged nanoporous alumina.     

Crystal orientation dependence of the out-of-plane dielectric properties for barium stannate titanate thin films

The orientation-dependent out-of-plane dielectric properties of barium stannate titanate (Ba(Sn_0.15Ti_0.85)O₃ (BTS)) thin films prepared by sol–gel method were investigated. Films with (1 0 0), (1 1 0), and (1 1 1) orientation were grown on LaNiO₃-buffered (1 0 0), (1 1 0), and (1 1 1) LaAlO₃ (LAO) single-crystal substrates, respectively. The different temperature of the dielectric constant maximum (T_m) of the BTS thin films with different orientation was believed to be attributing to stress inside the films. Films with the (1 1 1) orientation had higher relative dielectric constant and tunability than (1 0 0)- and (1 1 0)-oriented films. This difference in dielectric properties in these three kinds of oriented BTS films may be attributed to change in the direction and magnitude of electric polarization in orientation engineered BTS films and stress in the films.     

Epitaxial growth of InN on c-plane sapphire by pulsed laser deposition with r.f. nitrogen radical source

We have grown InN films on c-plane sapphire substrates by pulsed laser deposition (PLD) with a radio frequency nitrogen radical source for the first time and investigated the effect of the substrate surface nitridation on the structural and electrical properties of InN films with reflection high energy electron diffraction (RHEED), atomic force microscope, the Hall effect measurements and high-resolution X-ray diffraction (HRXRD). RHEED and HRXRD characterizations revealed that high-quality InN grows epitaxially on sapphire by PLD and its epitaxial relationship is InN (0 0 0 1)∣∣sapphire (0 0 0 1) and InN [2 -1 -1 0]∣∣sapphire [1 0 -1 0]. The InN crystalline quality and the electron mobility are improved by the substrate nitridation process. The area of the pits at the InN surface is reduced by the substrate nitridation process probably due to the reduction in the interface energy between InN and the substrate. The full width at half maximum of the -1 -1 2 4 X-ray rocking curve for InN grown by the present technique without using any buffer layers was as small as 34.8 arcmin. These results indicate that the present technique is promising for the growth of the high-quality InN films.     

Surface Preparation of Aluminum Nitride for Metallization: Effect of Temperature on Surface Reactivity

The current aqueous cleaning step in the surface preparation of aluminum nitride (AlN) prior to metallization causes performance and reliability issues for the substrates used for microelectronic packaging due to surface reactions. These issues limit the use of AlN and its replacing of BeO, an environmentally hazardous material currently used. The aim of this investigation was to determine the effects of different solutions on the surface of AlN substrates under varying conditions at times up to 2419.2 ks (28 days). Concentration of the solutions, temperature, and immersion time were varied for the AlN samples in the solutions. Both elevated temperatures (50°C and 90°C) and low temperatures (5°C) were investigated.

Four general types of behavior were observed: minor changes in average surface roughness and microstructure, linear change in average surface roughness and pitted grains, nonlinear change in average surface roughness and product formation on AlN surface, and miscellaneous change in average surface roughness with surface product formation.

The surface roughening kinetics were very complex due to changes in both the reaction product morphology and reaction mechanism with temperature, solvent, and pH for a specific solvent. Minor changes in average surface roughness and microstructure were observed for HCl pH = 5, H₂ SO₄ pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, deionized water and Alfred tap water at 5°C, HCl pH = 3 and oleic acid at 50°C and citric acid and oleic acid at 90°C. Linear changes in average surface roughness and pitted grains were observed for HCl pH = 2 and H₂SO₄ pH = 3 at 50°C and HCl pH = 2, H₂SO₄ pH = 3, and deionized water at 90°C. Non-linear change in average surface roughness and product formation on AlN surface was observed for HCl pH = 5, NaOH pH = 8 and Alfred tap water at 50°C and HCl pH = 5 and H₂SO₄ pH = 2 at 90°C. Miscellaneous changes in average surface roughness with surface product formation were observed for H₂SO₄ pH = 2, H₂SO₄ pH = 5, NaOH pH = 10, NaOH pH = 12, citric acid, Micro-90 and deionized water at 50°C and HCl pH = 3, H₂SO₄ pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, Micro-90 and Alfred tap water at 90°C.     

Study of epitaxial lateral overgrowth of semipolar (1 1 − 2 2) GaN by using different SiO2 pattern sizes

We investigated the growth mode and the crystal properties of lateral epitaxial overgrowth (LEO) semipolar (1 1 − 2 2) GaN by using the various SiO₂ pattern sizes of 6, 8, 10 and 12 μm with the window width of 4.0 μm. By using three-step growth technique, we successfully obtained the fully-coalescenced semipolar (1 1 − 2 2) LEO-GaN films regardless of the SiO₂ pattern sizes. However, the coalescence thickness of LEO-GaN film was decreased with decreasing SiO₂ pattern size, indicating that the coalescence of semipolar (1 1 − 2 2) GaN was easily formed by decreasing the pattern size of SiO₂ mask. The full width at half maximums (FWHMs) of X-ray rocking curves (XRCs) of LEO-GaN films decreased with increasing SiO₂ pattern size. In the pattern size of 4 × 10 μm, we achieved the minimum XRCs FWHM of 537 and 368 arc s with two different X-ray incident beam directions of [1 1 − 2 − 3] and [1 − 1 0 0], respectively. Moreover, the photoluminescence bandedge emission of semipolar (1 1 − 2 2) GaN was 45 times increased by LEO process. Based on these results, we concluded that the LEO pattern size of 4 × 10 μm would effectively decrease crystal defects of semipolar (1 1 − 2 2) GaN epilayer, resulting in an improvement of the optical properties.