• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Carrier and magnetism engineering for monolayer SnS2 by high throughput first-principles calculations*

    2021-11-23 07:30:36QingZhan詹慶XiaoguangLuo羅小光HaoZhang張皓ZhenxiaoZhang張振霄DongdongLiu劉冬冬andYingchunCheng程迎春
    Chinese Physics B 2021年11期
    關(guān)鍵詞:張皓迎春

    Qing Zhan(詹慶) Xiaoguang Luo(羅小光) Hao Zhang(張皓) Zhenxiao Zhang(張振霄)Dongdong Liu(劉冬冬) and Yingchun Cheng(程迎春)

    1Key Laboratory of Flexible Electronics&Institute of Advanced Materials,Jiangsu National Synergetic Innovation Center for Advanced Materials,Nanjing Tech University,Nanjing 211816,China

    2Frontiers Science Center for Flexible Electronics(FSCFE),Shaanxi Institute of Flexible Electronics(SIFE)&Shaanxi Institute of Biomedical Materials and Engineering(SIBME),Northwestern Polytechnical University(NPU),Xi’an 710129,China

    Keywords: SnS2,high throughput first-principles calculations,carrier,magnetism

    1. Introduction

    Tin disulfide(SnS2)is van der Waals semiconductor with an indirect band gap of 1.58 eV.[1]Free-standing SnS2monolayer can be prepared by mechanical exfoliation,[2]liquid exfoliation,[3]as well as chemical vapor deposition. SnS2has been demonstrated for various applications such as solar cells,[4]field-effect transistors,[5]lithium-ion batteries,[6]photothermal therapeutics,[7]catalysis and sensors.[8,9]To extend its application,chemical doping has been proposed experimentally and theoretically as an effective strategy.[10-14]For example,SnS2monolayer doped with Fe has been verified as a two-dimensional(2D)dilute magnetic semiconductor.[15-17]Till now various chemical doping, such as Li, B, C, N,O, F,Na, Mg, Al, P, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn,Ga, As, Se , Br, Sr, Y, Zr, Nb, Mo, Tc, Ru ,Rh, Pd, Ag, Cd,In, Sn, Te, I, W, Re, Os, Ir, Pt, Au and Hg have been investigated by first-principles calculations.[1,18-23]However,there are some other elements doping absent,such as Be,Si,S,Sc,Ge, Rb, Sb, Ba, Lu, Hf, Ta, Tl, Pb, Bi, Po, At, Fr and Ra. In addition,debates remain. For example,Li and Na doped SnS2is predicted to be magnetic,[24]which is different from nonmagnetic results.[18]Therefore,a comprehensive investigation of chemical doping in SnS2is necessary.[25]

    In this paper, we systematically investigate the stability,electronic structure and magnetic properties of monolayers SnS2doped with foreign elements,based on high-throughput first-principles calculations. We firstly screen out the elements which can be effectively doped in SnS2with high stability.Then the effect of dopants on carrier in SnS2is discussed.More importantly,we find that monolayer SnS2systems doped with elements in VIB,VIIB,VIIIB8,and VIIIB9 groups show large binding energies with non-zero magnetic moment,indicating high possibility of fabrication experimentally and application in spintronics.Our present work provides a comprehensive view regarding chemical doping in SnS2and that predicts chemical doping is an effective strategy to functionalize SnS2for various applications, such as field effect transistor, optoelectronic device and spintronic technology.

    2. Computational details

    First-principles calculations are carried out by using the projector-augmented wave method implemented in the Viennaab initiosimulation package (VASP) based on density functional theory.[26]The Perdew-Burke-Ernzerhof(PBE) functional of the generalized gradient approximation(GGA) is adopted for electron exchange and correlation interactions.[27,28]The van der Waals interactions between layers are corrected using the DFT-D3 functional.The kinetic energy cut-off of the wave function is set to 500 eV.To mimic the defects in monolayer SnS2, a 4×4×1 supercell is used and a 4×4×1k-mesh sampling is applied. The ions relaxation is achieved until the force for per atom is less than 0.01 eV/?A and the total energy converges to 10?5eV.A vacuum spacing of 20 ?A is used to prevent interaction between adjacent slabs.

    3. Results and discussion

    3.1. Structural properties and binding energies

    Pristine monolayer SnS2is hexagonal with space groupD3d(Pˉ3m1). The optimized lattice constants of the 4×4×1 supercell area=b=14.80 ?A.When removing one Sn/S atom from the monolayer SnS2supercell,a VSn/VSwill be created with corresponding vacancy concentration of 6.25%/3.125%.Figure 1 shows the structure of a 4×4×1 SnS2supercell doped byXSnandXS.

    Fig. 1. Top view of the relaxed structures for (a) pristine, (b) Sn-vacant monolayer SnS2, (c) single XSn doped monolayer SnS2, (d) S-vacant monolayer SnS2, (e) single XS doped monolayer SnS2 (XSn and XS indicate Sn and S substitutions). The purple, yellow, green and orange balls denote the Sn,S,XSn and XS atoms,respectively.

    3.2. Binding energy

    To check the stability of different dopants,we calculated the binding energies for various doping systems, as summarized in Fig. 2. The binding energyEbis defined asEb=Ev+μ?Ed,whereEvis the energy of a relaxed SnS2monolayer with one Sn/S vacancy,μis the energy of the doped atom,andEdis the energy of a relaxed SnS2monolayer with one Sn/S atom replaced by aXSn/XSatom.

    Figure 2(a)shows the binding energy of main group metal doped in SnS2. Only the binding energy of Al and Si is higher than that of Sn, indicating Al and Si are energetically favorable doped in SnS2. The binding energies of Be, Ca, Sr, Ba,Ga, Ge, Pb, In, and Sb are close to that of Sn, suggesting the high possibility of doping those different elements in SnS2. It has been reported that Al and Sr can be doped in SnS2by a simple soft chemical route.[29,30]Therefore,it is expected that Si, Be, Ca, Ba, Ga, Ge Pb, In and Sb can be verified experimentally in future.

    Figure 2(b) shows the binding energies for non-metal doped SnS2. Taking the binding energy of S doping as a reference,we can claim that B,C,O and F are easy to be doped in SnS2. The C doped SnS2has been fabricated by using hydrothermal method and demonstrated as a high-efficient solar fuel catalyst under visible light.[31]Because Se and Te can also replace S in SnS2,[23]we can estimate that N, Se, and Cl are possible to be doped in SnS2from the binding energy shown in Fig.2(c). However,there are few reports regarding B,O,N,and Cl doping in SnS2.

    Figure 2(c)shows the binding energy of transition metal doped in SnS2. Take the binding energy of Sn as a reference, we can find that Sc, Y, Lu, Ti, Zr, Hf, V, Nb, Ta,Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni and Pt can be doped in SnS2. Ni, Co and Mn doped SnS2have been synthesized by solvothermal method and can be applied for supercapacitors.[32]Fe, Cr and Y doped SnS2have also been successfully prepared by thermolysis method.[31,33]V and W doped SnS2have been demonstrated by spray pyrolysis technique.[34]Therefore,our prediction is consistent with previous experimental work.

    Figure 3(a) shows the spin polarized DOS of pristine monolayer SnS2. The band gap is 1.487 eV according to DFT calculation. Si has same valence electrons as Sn, and therefore, SiSnis isovalent doping, which will induce band gap change without defect states.The DOS shown in Fig.3(b)confirms this assumption and SiSnwill induce the change of band gap(1.367 eV).Because Al atom has one less electron than Sn atom,it is expected a p-type doping for Al substitution. From the DOS shown in Fig.3(b),we can clearly observe the Fermi level cross the band edge states of the valence band,which is the signature of p-type doping. We expect SbSndefect will induce n-type doping because Sb has one more valence electron than Sn. However,the defect states locate in the middle of the band gap and the Fermi level is far from the conduction band or valence band edge as shown in Fig. 3(d). Therefore, SbSndefect will introduce trap states in SnS2, which is consistent with previous experimental and theoretical results.[35,36]

    Fig.2. Binding energies and magnetic moments of monolayer SnS2 doped by(a)group A metal atoms from the period IA to VIA,(b)nonmetal from IIIA to VIIA,(c)group B metal atoms from IB to VIIIB.

    Fig.3. Spin polarized density of states of(a)pristine,(b)SiSn,(c)AlSn,and(d)SbSn doped monolayer SnS2.

    Fig.4. Spin polarized density of states of(a)CS,(b)FS,and(c)OS doped monolayer SnS2.

    Figure 4(a) shows the DOS for SnS2with CSdefect.There is an occupied defect state above the valence band edge,indicating the p-type doping of CS.In contrast,FSdefect leads to a defect state close to the conduction band edge,indicating a n-type doping scenario,as shown in Fig.4(b).As a typical isovalent doping,OSleads to the change of band gap(1.454 eV)without defect states in the band gap as shown in Fig. 4(c).Similarly, SeSand TeSalso induce change of band gap without defect states.

    The valence state of transition metal ranges from +2 to+5. Therefore, it is also expecting p-type and n-type doping by transition metals substitution. Figure 5(a) shows the band structure of Hf doped SnS2,which evidently shows there is no defect state in the band gap. The absence of defect state can be attributed to the same valent state of Hf as that of Sn in SnS2. In addition, both HfS2and monolayer SnS2are in the same space group and the in-plane lattice parameters for each compound are similar. Because of the band gap of monolayer HfS2is smaller than that of SnS2, the doping of Hf in SnS2will reduce the band gap of SnS2. The band gap of Hf doped SnS2with doping concentration of 6.25%is 1.228 eV,which is smaller than that of pristine SnS2. We also can find that Zr,Pt,Pd,and Ni have the similar effect to Hf. The DOS for ScSnin Fig.5(b)shows that the Fermi level is on the valence band edge, indicating a p-type doping nature. YSnand LuSnhave the same scenario.

    Fig. 5. Spin polarized density of states of (a) HfSn, and (b) ScSn, doped monolayer SnS2.

    For non-metal doping, the dopant with high binding energy is absent of magnetic moment. There are some dopants with non-zero magnetic moment, such as NS, PSand AsS.However, the binding energies for those dopants are low, indicating difficulty of formation. For dopant from IA group,the binding energy is low though magnetism is introduced by Li,Na,K doping. The introduction of magnetism by elements in IA group is consistent with previous calculation.[24]For dopant in IIA group,the formation energies are larger than that in IA group. The magnetic moments for those dopants range from 1.0μBto 2.0μB. Figure 6(a)shows the DOS of monolayer SnS2with CaSndefect. The spin up and spin down DOS are unsymmetrical, indicating that Ca doping possibly leads to magnetism in SnS2. Moreover, the Fermi level crosses the valence band edge,suggesting p-type doping.

    For transition metal doping,the dopant from VIB,VIIB,VIIIB8 or VIIIB9 groups is with local magnetic moment and has high binding energies. The magnetic moments are around 2.0μB,3.0μB,2.0μBand 1.0μBfor single dopant from VIB,VIIB,VIIIB8 and VIIIB9 groups,respectively.Magnetism has been predicted/observed in 2D transition metal doped monolayer 2D semiconductors, such as Mn doped MoS2,[37]Fe doped SnS2.[16]Figure 6(b)shows the spin polarized DOS of Mn doped SnS2. Though Re and Mn are in the same group and magnetic moments both are~3.0μB, the spin polarized DOS of Re doped SnS2shown in Fig. 6(c) is quite different from that of Mn doped SnS2. There are two more gap states in the spin up channel for Re doped SnS2. V and Nb in VB group also introduce magnetism in SnS2,while the magnetism is absent in Ta doped SnS2. Therefore, the doping scenarios are different from elements in the same group.

    Fig.6. Spin polarized density of states of(a)CaSn,(b)MnSn,and(c)ReSn doped monolayer SnS2.

    Due to valence state of each element is different from each other, the doping scenarios, including binding energy,electronic and magnetic properties, are different. Doping a specific element in SnS2depends on various factors, such as growth temperature, type of reactant, and abundance of reactant. In our present work, the calculated binding energy is applied to check the possibility of doping foreign element. To further verify the possibility of doping, the formation energy for doping on chemical potential should be investigated.However, it has been proven efficient and validity of evaluating the doping possibility by using the binding energy.[18,22,24,37]Some predictions by using such method have been experimentally verified,such as Fe,Co,and Mn doping in MoS2.[38-40]By evaluating the binding energy shown in Fig.2 and the carrier type for different element doping shown in Figs. 3 and 4, and Figs. S1-S6 in supporting information, we conclude that CS, AlSn, ScSn, LuSn, and YSnare promising experimentally realized for p-type doping, as well as FS, SbSnand TaSnfor n-type doping without magnetism. In addition, we screen out some foreign elements doping that may introduce magnetism in SnS2.Under doping concentration of 6.25%,the ferromagnetic state is 0.60 meV,2598.95 meV,637.75 meV,and 906.58 meV lower than non-magentic or antimagnetic state for Ca,Mn,Re,and Fe substitutional doping,respectively,see Table S1 in supporting information. The Curie temperature(TC)is an important parameter of a ferromagnetic semiconductor.Based on the mean-field theory and Heisenberg model we estimateTCusing the relationkBTC=(2/3)?E,[41,42]wherekBand ?Eare the Boltzmann constant and the energy difference of ferromagnetic and non-magnetic/antiferromagnetic states,respectively. The estimated values ofTCare listed in Table S1,together with magnetic moments. TheTCof ReSnis around 30 K,while others are lower than 10 K.It is well known that doping concentration also affect magnetic coupling and the value ofTC. We take Re and Fe doped SnS2as two representatives. The two Re ions are antiferromagnetic coupled,while Fe ions remains ferromagnetic coupled for doping concentration of 12.5%. The detailed magnetic ground state and further exploration of highTCof a certain doping should be investigated in future.

    4. Conclusion

    By using high throughput first-principles calculation,we comprehensively investigate the substitutional doping in monolayer SnS2. Metal dopants from group A can induce ptype doping(AlSn),deep states in the gap(SbSn),or band gap change without defect states (SiSn). However, metal dopants from group A can not introduce n-type doping from our calculations. Nonmetal dopants from group A not only can introduce n-type doping(FS),p-type doping(CS),and band gap variation (OS). Transition metal dopants from VB to VIIIB9 can introduce magnetism in SnS2and high binding energy for each dopant indicates high possibility of growth transition metal doped SnS2. Our present work provides a comprehensive view of chemical doping effect on carrier and magnetism of SnS2, which is important for field effect transistor, optoelectronic device and spintronics.

    猜你喜歡
    張皓迎春
    Quantum algorithm for minimum dominating set problem with circuit design
    大白鵝
    迎春
    保健與生活(2022年8期)2022-04-08 21:55:54
    迎春
    中國機(jī)長
    我最喜歡的翻花繩
    何迎春
    寶藏(2018年6期)2018-07-10 02:26:40
    讓我們攜手迎春
    歡樂過中秋
    誰是王者
    成人午夜高清在线视频| 国产精品美女特级片免费视频播放器| 亚洲av五月六月丁香网| 一二三四社区在线视频社区8| 日本三级黄在线观看| 无遮挡黄片免费观看| 中文字幕精品亚洲无线码一区| 日本黄大片高清| 夜夜爽天天搞| 成年版毛片免费区| 久久久久久久精品吃奶| 国产熟女xx| 综合色av麻豆| 日韩欧美在线乱码| 有码 亚洲区| 日韩大尺度精品在线看网址| 美女黄网站色视频| 国产aⅴ精品一区二区三区波| 亚洲片人在线观看| 精品久久久久久成人av| 国产一区在线观看成人免费| 日本撒尿小便嘘嘘汇集6| 久久欧美精品欧美久久欧美| 午夜激情欧美在线| 男人舔奶头视频| 日本黄色片子视频| 亚洲成人精品中文字幕电影| www国产在线视频色| 美女免费视频网站| 一卡2卡三卡四卡精品乱码亚洲| 在线视频色国产色| 中出人妻视频一区二区| av国产免费在线观看| 亚洲av电影不卡..在线观看| 日本 av在线| 黄色丝袜av网址大全| 国产蜜桃级精品一区二区三区| 黄色丝袜av网址大全| 久久久久久久久久黄片| 脱女人内裤的视频| 国产精品三级大全| 在线播放无遮挡| 国内毛片毛片毛片毛片毛片| 国产免费男女视频| 一个人免费在线观看电影| 免费无遮挡裸体视频| 中亚洲国语对白在线视频| 午夜两性在线视频| 最近在线观看免费完整版| 日韩人妻高清精品专区| 狂野欧美白嫩少妇大欣赏| 人人妻,人人澡人人爽秒播| 欧美丝袜亚洲另类 | 搡老岳熟女国产| 亚洲国产精品久久男人天堂| 国产私拍福利视频在线观看| 国产色婷婷99| 亚洲av免费高清在线观看| 国内精品久久久久久久电影| 国产精品久久视频播放| 成人特级av手机在线观看| 日韩 欧美 亚洲 中文字幕| 日本黄大片高清| 免费av不卡在线播放| 一本综合久久免费| 最近最新免费中文字幕在线| 免费在线观看影片大全网站| 最新在线观看一区二区三区| 亚洲片人在线观看| 成人一区二区视频在线观看| 18禁在线播放成人免费| 一个人看的www免费观看视频| 真人一进一出gif抽搐免费| 啪啪无遮挡十八禁网站| 国产精品久久久久久人妻精品电影| 久久精品影院6| 最新中文字幕久久久久| 好男人电影高清在线观看| 老司机在亚洲福利影院| 91九色精品人成在线观看| 一区二区三区免费毛片| 此物有八面人人有两片| 黄色丝袜av网址大全| 最近视频中文字幕2019在线8| 国产精品99久久99久久久不卡| 欧美日韩福利视频一区二区| www日本黄色视频网| 夜夜躁狠狠躁天天躁| 精品免费久久久久久久清纯| 在线天堂最新版资源| bbb黄色大片| 午夜两性在线视频| 久久久久性生活片| 国产91精品成人一区二区三区| 亚洲无线观看免费| 性色avwww在线观看| 日韩欧美精品v在线| 怎么达到女性高潮| 99国产精品一区二区蜜桃av| 久久久久久人人人人人| 丰满人妻熟妇乱又伦精品不卡| 最近最新中文字幕大全免费视频| 麻豆成人午夜福利视频| 国内揄拍国产精品人妻在线| 午夜视频国产福利| 最后的刺客免费高清国语| 免费看a级黄色片| 亚洲人成网站高清观看| 亚洲七黄色美女视频| 国产精品综合久久久久久久免费| 人妻久久中文字幕网| a级毛片a级免费在线| 亚洲国产高清在线一区二区三| 国产成人欧美在线观看| 九色成人免费人妻av| 在线观看免费视频日本深夜| aaaaa片日本免费| 国产欧美日韩精品亚洲av| 国语自产精品视频在线第100页| 欧美色欧美亚洲另类二区| АⅤ资源中文在线天堂| 在线a可以看的网站| 婷婷丁香在线五月| 欧美性猛交黑人性爽| 三级国产精品欧美在线观看| 日本三级黄在线观看| 性色av乱码一区二区三区2| 久久精品人妻少妇| 99热这里只有是精品50| 老鸭窝网址在线观看| 国产午夜精品久久久久久一区二区三区 | 成年免费大片在线观看| 亚洲精品国产精品久久久不卡| 欧美日韩综合久久久久久 | 人妻久久中文字幕网| 欧美性感艳星| 国产极品精品免费视频能看的| 亚洲第一电影网av| 精品免费久久久久久久清纯| av天堂在线播放| 美女被艹到高潮喷水动态| 一本一本综合久久| 一进一出好大好爽视频| 成人高潮视频无遮挡免费网站| 久久久久性生活片| 色综合站精品国产| 精品一区二区三区人妻视频| 中文在线观看免费www的网站| 亚洲欧美日韩卡通动漫| 亚洲欧美日韩无卡精品| 亚洲无线观看免费| 欧美色欧美亚洲另类二区| 成人特级av手机在线观看| 一区二区三区高清视频在线| 观看免费一级毛片| 黄片大片在线免费观看| 国产蜜桃级精品一区二区三区| 国内精品一区二区在线观看| 亚洲成a人片在线一区二区| 色综合站精品国产| 亚洲精品成人久久久久久| 国产三级黄色录像| 少妇的逼好多水| 亚洲国产欧洲综合997久久,| 婷婷六月久久综合丁香| 久久精品夜夜夜夜夜久久蜜豆| 国产男靠女视频免费网站| 一本综合久久免费| 欧美极品一区二区三区四区| 色播亚洲综合网| av国产免费在线观看| 白带黄色成豆腐渣| 在线播放国产精品三级| 男人的好看免费观看在线视频| 精品乱码久久久久久99久播| 一区二区三区激情视频| 国产色婷婷99| 欧美中文综合在线视频| 免费一级毛片在线播放高清视频| 黄色成人免费大全| 村上凉子中文字幕在线| 国产三级中文精品| 午夜福利在线在线| 人人妻人人澡欧美一区二区| 亚洲真实伦在线观看| 午夜福利18| av国产免费在线观看| 久久精品91蜜桃| 天堂av国产一区二区熟女人妻| 国产亚洲欧美98| 亚洲aⅴ乱码一区二区在线播放| 欧美bdsm另类| 亚洲电影在线观看av| a级一级毛片免费在线观看| 成年免费大片在线观看| 女人十人毛片免费观看3o分钟| 搡女人真爽免费视频火全软件 | 欧美zozozo另类| 国产精品,欧美在线| 免费在线观看影片大全网站| 午夜日韩欧美国产| 少妇的丰满在线观看| 亚洲精华国产精华精| 亚洲熟妇中文字幕五十中出| 欧美又色又爽又黄视频| 国产精品乱码一区二三区的特点| 亚洲不卡免费看| 亚洲av免费高清在线观看| 亚洲狠狠婷婷综合久久图片| 亚洲国产精品999在线| 在线a可以看的网站| 免费人成在线观看视频色| 桃色一区二区三区在线观看| 久久亚洲真实| 变态另类丝袜制服| 亚洲国产精品sss在线观看| av福利片在线观看| 欧美最黄视频在线播放免费| 欧美3d第一页| 国产成人影院久久av| 无人区码免费观看不卡| 亚洲自拍偷在线| 淫秽高清视频在线观看| 日本黄色片子视频| 韩国av一区二区三区四区| 久久精品人妻少妇| 中文字幕熟女人妻在线| 男人舔女人下体高潮全视频| 我的老师免费观看完整版| 搞女人的毛片| 国产成人av激情在线播放| 欧美3d第一页| 毛片女人毛片| 日本免费a在线| 亚洲国产欧洲综合997久久,| 国产真实伦视频高清在线观看 | 岛国视频午夜一区免费看| 免费看a级黄色片| 全区人妻精品视频| 搡老熟女国产l中国老女人| 一本精品99久久精品77| 99热6这里只有精品| 最后的刺客免费高清国语| av在线天堂中文字幕| 美女黄网站色视频| 日韩欧美精品v在线| 中文亚洲av片在线观看爽| 国产亚洲精品一区二区www| 国产 一区 欧美 日韩| 在线看三级毛片| 日本一二三区视频观看| 超碰av人人做人人爽久久 | 黄色视频,在线免费观看| 91麻豆精品激情在线观看国产| 神马国产精品三级电影在线观看| av天堂中文字幕网| 老司机深夜福利视频在线观看| 国产探花在线观看一区二区| 欧美日韩亚洲国产一区二区在线观看| 99精品久久久久人妻精品| 久久久久久久精品吃奶| 噜噜噜噜噜久久久久久91| 免费人成在线观看视频色| 美女 人体艺术 gogo| 女人十人毛片免费观看3o分钟| 成年女人永久免费观看视频| 禁无遮挡网站| 级片在线观看| 国产亚洲精品一区二区www| 国产视频一区二区在线看| 99国产极品粉嫩在线观看| 国产精品久久久久久精品电影| 亚洲无线在线观看| 嫁个100分男人电影在线观看| 中文在线观看免费www的网站| aaaaa片日本免费| 亚洲人与动物交配视频| 99在线视频只有这里精品首页| 久久天躁狠狠躁夜夜2o2o| 精品久久久久久久毛片微露脸| 97超视频在线观看视频| 国产精品av视频在线免费观看| 免费看a级黄色片| 日韩人妻高清精品专区| 日韩中文字幕欧美一区二区| 婷婷亚洲欧美| 99国产精品一区二区三区| 久久久久久久久中文| 成人一区二区视频在线观看| 最近最新中文字幕大全电影3| 国产精品久久电影中文字幕| 欧美丝袜亚洲另类 | 欧美大码av| 亚洲久久久久久中文字幕| 三级毛片av免费| 男人和女人高潮做爰伦理| 日韩欧美精品免费久久 | 天堂动漫精品| 精品乱码久久久久久99久播| 黄色女人牲交| 久久精品国产亚洲av香蕉五月| 五月伊人婷婷丁香| 91av网一区二区| 国产三级在线视频| 嫩草影视91久久| 又粗又爽又猛毛片免费看| 国产精品综合久久久久久久免费| 国产午夜福利久久久久久| 在线a可以看的网站| 亚洲精品一卡2卡三卡4卡5卡| 99国产精品一区二区三区| 国产免费男女视频| 国产免费男女视频| 欧美乱色亚洲激情| 搡老熟女国产l中国老女人| 在线观看舔阴道视频| 色综合婷婷激情| 波多野结衣巨乳人妻| 天堂av国产一区二区熟女人妻| 美女被艹到高潮喷水动态| 国产精品电影一区二区三区| 免费观看精品视频网站| 亚洲欧美日韩高清在线视频| 天堂网av新在线| 日韩大尺度精品在线看网址| 国内精品久久久久精免费| 人妻丰满熟妇av一区二区三区| xxx96com| 国产精品电影一区二区三区| 99久久精品一区二区三区| 中文字幕高清在线视频| 午夜视频国产福利| 18+在线观看网站| 久久精品亚洲精品国产色婷小说| 国产精品亚洲美女久久久| 国产精品99久久久久久久久| 日本熟妇午夜| 成年版毛片免费区| 老司机在亚洲福利影院| 国产老妇女一区| 成年女人看的毛片在线观看| 老汉色∧v一级毛片| 日韩人妻高清精品专区| 亚洲真实伦在线观看| 美女免费视频网站| 婷婷六月久久综合丁香| 亚洲av美国av| 国产黄a三级三级三级人| 亚洲av电影在线进入| 18禁在线播放成人免费| 亚洲欧美日韩卡通动漫| 久久精品91无色码中文字幕| 一本久久中文字幕| 99在线视频只有这里精品首页| 黄色片一级片一级黄色片| 欧美3d第一页| 亚洲不卡免费看| 亚洲在线观看片| 成人精品一区二区免费| 特级一级黄色大片| 亚洲色图av天堂| 国产一级毛片七仙女欲春2| 悠悠久久av| 日韩成人在线观看一区二区三区| 日本 av在线| 免费高清视频大片| 欧美性猛交╳xxx乱大交人| 狠狠狠狠99中文字幕| www.www免费av| 18禁黄网站禁片午夜丰满| 最新在线观看一区二区三区| 精品久久久久久成人av| 久久久久久久亚洲中文字幕 | 国产亚洲欧美98| 宅男免费午夜| 国产一区在线观看成人免费| 国产野战对白在线观看| 久久精品夜夜夜夜夜久久蜜豆| 国产高清视频在线观看网站| 俄罗斯特黄特色一大片| 国模一区二区三区四区视频| 少妇的逼水好多| 美女大奶头视频| 欧美在线一区亚洲| 色尼玛亚洲综合影院| 女同久久另类99精品国产91| 国产欧美日韩一区二区三| 在线观看午夜福利视频| 亚洲av成人精品一区久久| 亚洲va日本ⅴa欧美va伊人久久| 国内精品美女久久久久久| 亚洲国产精品sss在线观看| 一二三四社区在线视频社区8| 18禁美女被吸乳视频| 欧美色视频一区免费| 91麻豆av在线| 国产av麻豆久久久久久久| 亚洲av二区三区四区| 午夜福利在线在线| 久久中文看片网| 我要搜黄色片| 99精品久久久久人妻精品| 蜜桃久久精品国产亚洲av| 中文字幕av在线有码专区| 欧美+亚洲+日韩+国产| 俺也久久电影网| 高潮久久久久久久久久久不卡| 好男人电影高清在线观看| 叶爱在线成人免费视频播放| 亚洲欧美精品综合久久99| 激情在线观看视频在线高清| 色综合亚洲欧美另类图片| 男人和女人高潮做爰伦理| 国产亚洲精品综合一区在线观看| 午夜两性在线视频| 最新中文字幕久久久久| 综合色av麻豆| 国产亚洲精品久久久com| 亚洲人成网站在线播| 亚洲午夜理论影院| 不卡一级毛片| 国产蜜桃级精品一区二区三区| 香蕉丝袜av| 国产淫片久久久久久久久 | 国产免费av片在线观看野外av| or卡值多少钱| 一本一本综合久久| 精品久久久久久成人av| 国产熟女xx| 国产高潮美女av| 18禁裸乳无遮挡免费网站照片| 在线播放无遮挡| 一二三四社区在线视频社区8| 老师上课跳d突然被开到最大视频 久久午夜综合久久蜜桃 | 亚洲人成网站高清观看| 中文字幕人成人乱码亚洲影| 国产成人av教育| 欧美日韩黄片免| 免费搜索国产男女视频| 脱女人内裤的视频| 99视频精品全部免费 在线| 男人舔女人下体高潮全视频| 国产精品爽爽va在线观看网站| 午夜福利视频1000在线观看| 国产69精品久久久久777片| 国产精品电影一区二区三区| 女同久久另类99精品国产91| 国产一区二区在线观看日韩 | 国产精品久久久久久人妻精品电影| 亚洲专区国产一区二区| 每晚都被弄得嗷嗷叫到高潮| 91麻豆精品激情在线观看国产| 69人妻影院| 性欧美人与动物交配| netflix在线观看网站| 91字幕亚洲| 亚洲熟妇中文字幕五十中出| 桃红色精品国产亚洲av| 内地一区二区视频在线| 国产精品国产高清国产av| 丁香欧美五月| 精品免费久久久久久久清纯| 欧美3d第一页| 一本综合久久免费| 日本与韩国留学比较| 90打野战视频偷拍视频| 狂野欧美白嫩少妇大欣赏| 看免费av毛片| 一区二区三区激情视频| 在线免费观看的www视频| 男人的好看免费观看在线视频| 久久久久精品国产欧美久久久| 亚洲av二区三区四区| 久久精品国产自在天天线| 亚洲欧美日韩卡通动漫| 亚洲av电影不卡..在线观看| 欧美激情久久久久久爽电影| 亚洲国产精品999在线| 狠狠狠狠99中文字幕| 一卡2卡三卡四卡精品乱码亚洲| 岛国在线观看网站| 日韩 欧美 亚洲 中文字幕| 欧美三级亚洲精品| 黄片小视频在线播放| 桃红色精品国产亚洲av| 亚洲人成网站高清观看| 1000部很黄的大片| 亚洲精品粉嫩美女一区| bbb黄色大片| 亚洲无线观看免费| 一级a爱片免费观看的视频| 欧美成人性av电影在线观看| 久久草成人影院| 日韩精品中文字幕看吧| 草草在线视频免费看| 国产成人影院久久av| 久久国产精品人妻蜜桃| av在线蜜桃| 国产三级黄色录像| 狂野欧美白嫩少妇大欣赏| 在线观看舔阴道视频| 亚洲精品日韩av片在线观看 | 男插女下体视频免费在线播放| 夜夜躁狠狠躁天天躁| 国产乱人视频| 久久久国产精品麻豆| 一本一本综合久久| 看黄色毛片网站| 亚洲精品一区av在线观看| 亚洲av第一区精品v没综合| 亚洲国产精品久久男人天堂| 精品国产亚洲在线| 欧美一区二区国产精品久久精品| 最新在线观看一区二区三区| 老熟妇乱子伦视频在线观看| 丰满人妻一区二区三区视频av | 少妇的丰满在线观看| 国产精品1区2区在线观看.| 欧美黑人欧美精品刺激| 女警被强在线播放| 欧美绝顶高潮抽搐喷水| 色综合亚洲欧美另类图片| 麻豆国产av国片精品| 欧美日本视频| 精华霜和精华液先用哪个| www.www免费av| 小蜜桃在线观看免费完整版高清| 精品久久久久久,| 午夜老司机福利剧场| 国产精品电影一区二区三区| 欧美av亚洲av综合av国产av| 亚洲五月天丁香| 国产欧美日韩精品一区二区| 日韩成人在线观看一区二区三区| 嫩草影院入口| 麻豆一二三区av精品| 欧美bdsm另类| av女优亚洲男人天堂| 两性午夜刺激爽爽歪歪视频在线观看| 一进一出好大好爽视频| 三级毛片av免费| 网址你懂的国产日韩在线| 国产高清视频在线观看网站| 日本黄色片子视频| 中文亚洲av片在线观看爽| 最近视频中文字幕2019在线8| 国产久久久一区二区三区| 国产一区二区在线观看日韩 | 国内精品一区二区在线观看| 免费大片18禁| 9191精品国产免费久久| 19禁男女啪啪无遮挡网站| 亚洲人成网站高清观看| 九九久久精品国产亚洲av麻豆| 国产v大片淫在线免费观看| 3wmmmm亚洲av在线观看| 日韩欧美在线二视频| 男女做爰动态图高潮gif福利片| 两个人看的免费小视频| 国产精品一区二区三区四区久久| 日本一本二区三区精品| 黄片小视频在线播放| 亚洲在线观看片| 久久精品国产亚洲av香蕉五月| x7x7x7水蜜桃| 999久久久精品免费观看国产| 狠狠狠狠99中文字幕| 亚洲av中文字字幕乱码综合| 国产精品久久久人人做人人爽| 国内精品久久久久久久电影| 亚洲中文字幕日韩| 午夜亚洲福利在线播放| 欧美最黄视频在线播放免费| 一区福利在线观看| 日本撒尿小便嘘嘘汇集6| 精品国产超薄肉色丝袜足j| 国产高清有码在线观看视频| 小蜜桃在线观看免费完整版高清| 香蕉av资源在线| 91麻豆av在线| 亚洲av成人不卡在线观看播放网| 午夜福利在线观看吧| 欧美+日韩+精品| 国产国拍精品亚洲av在线观看 | 国产亚洲精品综合一区在线观看| 俄罗斯特黄特色一大片| 岛国在线观看网站| 夜夜爽天天搞| 三级男女做爰猛烈吃奶摸视频| 一区二区三区免费毛片| 又紧又爽又黄一区二区| 性色avwww在线观看| 亚洲中文字幕日韩| 禁无遮挡网站| 日本黄大片高清| av女优亚洲男人天堂| 大型黄色视频在线免费观看| 黄色片一级片一级黄色片| 亚洲美女黄片视频| svipshipincom国产片| 亚洲激情在线av| 欧洲精品卡2卡3卡4卡5卡区| 五月伊人婷婷丁香| 美女高潮的动态| av天堂在线播放| 女警被强在线播放| 麻豆久久精品国产亚洲av| 午夜免费激情av| 日本成人三级电影网站| 老鸭窝网址在线观看| 岛国在线观看网站| 日本免费a在线| 国产亚洲精品一区二区www| 色综合站精品国产| 免费一级毛片在线播放高清视频|