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Preparation and characterization of Laication

Journal of Alloys and Compounds 509 (2011) 3172–3176

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Journal of Alloys and

Compounds

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j a l l c o

Preparation and characterization of La 9.33Si 6O 26powders by molten salt method for solid electrolyte application

Buyin Li,Jia Liu,Yunxiang Hu ?,Zhaoxiang Huang

Department of Electronic Science &Technology,Huazhong University of Science &Technology,Wuhan,430074,PR China

a r t i c l e i n f o Article history:

Received 18August 2010

Received in revised form 12October 2010Accepted 27October 2010

Available online 13 December 2010Keywords:

Lanthanum silicate Molten salt method Electrical conductivity Powder synthesis

a b s t r a c t

Lanthanum silicate La 9.33Si 6O 26(LSO)powders with more uniform particle and less agglomeration were obtained at a much lower synthesis temperature by the molten salt method than by the solid-state method.LSO ceramic electrolytes were prepared with these powders and characterized as well.The optimal molten salt synthesis conditions are mass ratio of reactants to NaCl of 1:3and synthesis temper-ature of 900?C.XRD results showed that when the mass ratio of reactants to NaCl was no more than 1:3,pure LSO phase powder was obtained at 900?C.XRD and XRF results showed that when synthesis tem-perature was higher than 900?C,a solid solution type LSO powder with Na replacement for La formed at a ?xed mass ratio of reactants to NaCl of 1:3.The involvement of Na in LSO lattice might lead to the lattice contraction in powders and deteriorate the conductance of ceramic electrolytes.The ceramic electrolytes prepared from the pure LSO powder via molten salt process exhibited better electrical properties than those from the powder via solid-state method.

1.Introduction

Solid oxide fuel cells (SOFCs)draw much attention in recent years,because of their high ef?ciency and environmentally friendly nature.A basic SOFC consists of three main ceramic components:an anode and a cathode separated by a solid electrolyte.Currently,yttria-stabilized zirconia (YSZ)with ?uorite structure is the most common electrolyte material for SOFCs due to its excellent ionic conductivity and negligible electronic conduction at elevated tem-peratures (850–1000?C),and good chemical stability.Nevertheless,this high operating temperature causes problems in terms of mate-rials selection and lifetime [1–4].So people search for alternative functional materials with higher ionic conductivity at relatively lower temperature [2,5].The apatite structure materials as a new class of oxide-ion conductors for SOFCs,?rst found by Nakayama et al.[6,7],have high ionic conductivity at intermediate temper-atures (700–800?C),suitable thermal expansion matching with the electrode material,and other bene?ts [3–5,8].The conduction mechanism of apatite structure materials is based on interstitial conduction and completely different from the oxygen vacancy conduction mechanism in the traditional materials with ?uorite or perovskite related structures [5,9–11].These apatite structure materials have a common chemical formula Ln 10?x (MO 4)6O 2±y (Ln is a metal such as rare earth or alkaline earth and M is a p-block

?Corresponding author.Tel.:+862787558482;fax:+862787545167.E-mail address:hyx@https://www.wendangku.net/doc/d96850971.html, (Y.Hu).element such as P,As,Si,or Ge),and La 9.33SiO 6O 26(LSO)is a typical compound in this series [5,9,10,12–14].Ln site ions can be partly replaced by other ion dopants with lower valance,and the conduc-tivity of the resultant materials decreases with increasing dopant concentration if the ion radius of the dopants is smaller [15–20].

So far the preparation methods of LSO powders mainly include solid-state,sol–gel,and hydrothermal methods [9,12,13,21–24],while little study refers to the molten salt synthesis of them.In the molten salt process,the salt plays a role as ?ux.The reactants in the molten salt have a high reactivity and mobility,and react easily and completely,which can greatly reduce the synthesis tem-perature.Moreover the product powders have a better uniformity and fewer agglomerates [25].These advantages are expected to be also embodied if molten salt method is applied to the synthesis of LSO powders.

The aim of the present paper is to explore the feasibility of the molten salt synthesis of LSO powders.The originality of this work is to decrease the synthesis temperature of LSO powders via the molten salt method and to obtain ultra-?ne powders with nar-row size distribution and dense ceramics with these powders.The effects of the mass ratio of reactants to the salt and the synthesis temperature on crystalline structure of the synthesized powders are investigated in detail.

2.Experimental procedures

Starting reactant powders of silicon dioxide (SiO 2,98%)and lanthanum oxide (La 2O 3,99%)were weighed in the nominal composition of La 9.33Si 6O 26.Sodium chloride (NaCl,99%)was taken as the molten salt and weighed.The mass ratios of

B.Li et al./Journal of Alloys and Compounds509 (2011) 3172–3176

3173

Fig.1.XRD patterns of powders calcined at900?C for4h with different mass ratios of reactants to salt.

reactants to NaCl were?xed to be1:1,1:3,and1:5respectively.Then the mixtures of reactants and the salt were ball milled in ethanol medium for4h,dried,ground and sifted to avoid agglomerated powders.The sifted powders were calcined at 900–1100?C for4h.Next,the as-synthesized powders were washed repeatedly with de-ionized water and?ltered to remove free NaCl until there was no appearance of white precipitate in the?ltrate by adding AgNO3solution.Finally LSO powders were obtained through drying the products at105?C for6h.In addition,for comparison a LSO powder was prepared by the solid-state reaction for4h at1300?C which is the lowest required temperature to synthesize the powder via traditional solid-state method.

The LSO powders were pelleted and pressed at200MPa for25s into disks (15mm in diameter,2mm in thickness).The green disks were then heated to1500?C with a heating rate of300?C/h in air,soaked for4h,and then furnace-cooled.

X-ray diffraction(XRD)analyses at room temperature were carried out on a diffractometer(X’Pert PRO,PANalytical B.V.)using a Cu K?radiation source (K?1=1.54060?A and K?2=1.54443?A).This method has been performed on each powder sample in order to reveal the crystallographic structures and cell param-eters.

X-ray?uorescence(XRF)probe analyses(EAGLE III)were adopted to analyze qualitatively and semi-quantitatively the elemental composition of ceramic sam-ples.

Scanning electron micrograph(SEM)analyses(Quanta200,Philips)was used to observe the micromorphology of the synthesized powders and ceramics.

A.C.conductivity measurement of the ceramics was performed with an accurate impedance analyzer(Agilent4294A)at frequencies of40Hz–20MHz at tempera-tures of300–800?C.

3.Results and discussion

3.1.Synthesis and characterization of LSO powders

The effect of mass ratio of reactants to salt on the phase com-position of synthesized powders was investigated.Fig.1shows the XRD patterns of powders calcined at900?C for4h with dif-ferent mass ratios.It is apparent that no NaCl,La2O3,and SiO2 peaks were detected in all synthesized powders,indicating that the presence of NaCl in the reactant mixture is helpful for the reac-tion between the reactants at relatively lower temperature(900?C) and free NaCl can be completely removed from the product pow-ders by washing repeatedly.Further,at lower salt concentration (reactants:salt=1:1)apatite structure LSO phase(JCPDS49-0443) formed with the companion of other impurity phases La2SiO5 (JCPDS40-0234)and La4.67(SiO4)3O(JCPDS75-1145).However, only did single LSO apatite phase exist at higher salt concentration (1:3and1:5).The XRD results indicate that there is a threshold salt concentration for the preparation of pure LSO powders which lies between1:1and1:3.It seems that excess salt concentration(1:5) has no further help to the synthesis of pure LSO powders.Therefore the mass ratio of1:3was taken for the succeeding

experiments.Fig.2.(a)XRD patterns and(b)(211)peak magni?cation patterns of powders obtained at different synthesis temperatures by different methods.

In order to explore the effect of the synthesis temperature on the microstructure of LSO powders,powders were synthesized using molten salt method at900,1000,and1100?C for4h respectively with a?xed reactants to salt ratio of1:3.For comparison,a powder was synthesized by the solid-state method at1300?C for4h.For simpli?cation these four powders were named MS9,MS10,MS11, and SS13respectively.

XRD patterns of these four powders are displayed in Fig.2(a). They all had the same pure apatite structure characteristic peaks (JCPDS49-0443),and no signi?cant impure peaks appeared,indi-cating that pure apatite structure phase could be formed when reactant mixture was calcined at temperatures of900–1100?C for molten salt method while at1300?C for solid-state method.More-over,it is apparent that MS9had larger peak intensity than SS13 though MS9was synthesized at a much lower temperature than SS13.This observation shows that the molten salt method allows the synthesis of LSO powders with better crystal growth at a rela-tively low temperature.

Furthermore,it is observed that the strongest(211)peak moved slightly to the right side in turn from MS9to MS11 (Fig.2(b)).According to Bragg’s diffraction law,the(211)inter-planar spacing in the synthesized powders decreased from MS9 to MS11.In order to prove this inference,the Philips X’pert Highscore software was used to calculate the cell parameters, and the results are shown in Table1.For comparison parame-ters of SS13,and the standard LSO and NaLa9(SiO4)6O2(JCPDS 32-1109)are also listed.It can be seen that cell parameters a, b,and c and cell volume V all decreased from MS9to MS11. For SS13and MS9these parameters approached to those of

3174 B.Li et al./Journal of Alloys and Compounds509 (2011) 3172–3176

Table1

Cell parameter comparison between the synthesized powders and standard LSO and NaLa9(SiO4)6O2.

Standard LSO SS13MS9MS10MS11Standard NaLa9(SiO4)6O2

Cell parameters a,b(?A)9.71289.7108±0.00329.7134±0.00489.7022±0.00289.6943±0.00129.6920

Cell parameter c(?A)7.18587.1906±0.00417.1842±0.00227.1824±0.00157.1823±0.00097.1820

Cell volume,V(?A3)587.08587.22587.02585.51584.56584.26

Table2

Conductance data,elemental composition,and average grain size for different ceramic samples.

SS13MS9MS10MS11

@800?C(S/cm)8.78×10?4 1.09×10?3 2.25×10?4 1.58×10?4

E a(eV)0.810.77 1.03 1.05

Na:La:Si(atom%)0:57.83:42.170:56.23:43.77 6.52:47.68:45.813.83:49.01:37.16 Grain size(?m) 2.3 5.0 2.8 3.2

the standard LSO,while for MS11to those of the standard NaLa9(SiO4)6O2.

The changes in(211)peak position and cell parameters from MS9to MS11might result from the involvement of Na ions in the reaction.Na+probably occupied in part the sites and the vacancy of La3+and entered the LSO lattice at high temperatures,which led to the formation of a solid solution of Na x La9.33?x/3(SiO4)6O2. Since Na+has a slightly smaller radius(0.97?A)than La3+(1.06?A), the replacement of Na+for La3+led to decreased crystal parame-ters(https://www.wendangku.net/doc/d96850971.html,ttice contraction).The presence of elemental Na in the synthesized powders via molten method was con?rmed by the composition analysis on ceramics made from powders MS10and MS11through XRF(See Table2).Notice that XRD results show absence of free NaCl in these powders.It can be concluded that Na existed in the form of solid solution in these powders.Further-more no elemental Na was detected in SS13and MS9powders. Notice that the synthesis temperature increased from900?C for MS9to1100?C for MS11.Therefore there was a synthesis tempera-ture threshold for Na+replacing La3+in the molten salt process,and when synthesis temperature exceeded this threshold the replace-ment amount increased with the increasing temperature.

Fig.3shows the SEM morphology of SS13and MS9powders. Both powders consisted of spherical shape particles.The mean par-ticle size for MS9was250±20nm while600±100nm for SS13.In addition MS9had less agglomeration than SS13.The contrastive pictures directly con?rm that molten salt method allows the syn-thesis of homogeneous LSO powders with smaller crystallites at a much lower temperature compared with solid-state method.These particles can be used to prepare dense ceramics.

3.2.Preparation and characterization of LSO ceramics

LSO ceramics were sintered at1500?C in air for4h using SS13, MS9,MS10,and MS11powders respectively.The bulk densities

of Fig.4.SEM images of SS13,MS9,MS10,and MS11ceramics sintered at1500?C in air for4h.

SS13,MS9,MS10,and MS11ceramic samples were4.91,5.04,4.93, and4.89g cm?3,respectively.Fig.4shows the SEM images of the four obtained ceramic samples.It can be seen that all these sam-ples were very dense and could satisfy the application in SOFCs [12].Furthermore,the three ceramic samples from molten salt method powders had a bigger average grain size than the one from solid-state method powder under the same sintering condi-tion.The average grain sizes of these four ceramics were2.3?m (SS13),5.0?m(MS9),2.8?m(MS10),and3.2?m(MS11).Finally, the grains of the SS13ceramic only developed3.5times than

its Fig.3.SEM images of LSO powders prepared by solid-state method(SS13)and molten salt method(MS9).

B.Li et al./Journal of Alloys and Compounds509 (2011) 3172–3176

3175

Fig.5.Arrhenius plots of the overall electrical conductivity of LSO ceramics sintered from different powders.

staring powder(Fig.3),while the growth multiple was about20 times for the MS9ceramic.This result indicated that the powders prepared by molten salt method had a higher growth activity than the powder by solid-state method.

The elemental composition results were listed in Table2for the four ceramic samples.The Na atomic ratio varied from zero in MS9 and SS13,6.59%in MS10,to13.83%in MS11.It is worth to stress that the Na atomic ratio increased from MS9,MS10,to MS11ceram-ics,i.e.it increased with the increasing synthesis temperature of precursor powders by the molten salt method.This observation supports the conclusion that the replacement of Na+to La3+took place in MS10and MS11powders while did not do in MS9powder due to lower synthesis temperature.

In order to investigate the conductivity of these LSO ceramic electrolytes,silver paste as electrodes was applied to opposite faces of sintered pellets and then heated at850?C for10min for metallization.A.C.impedance measurement was performed on pellets at frequencies of40Hz–20MHz at300–800?C.The obtained impedance spectrum showed substantial overlapping of the impedance arcs,and it is dif?cult to separate the grain bulk and grain boundary contribution from the impedance curve.Therefore, the total impedance is taken to calculate the conductivities of sam-ples herein.These result data are parameterized by the Arrhenius equation:

= 0

T exp

E a

(1)

where , 0,E a,k,and T are,respectively,the conductivity,pre-exponential factor,activation energy,Boltzmann constant,and absolute temperature.Arrhenius plots of the four LSO ceramic sam-ples are shown in Fig.5.

First of all,for each ceramic sample,the conductivity increased when the temperature increased.Secondly,it can be seen that among the four samples the MS9ceramics showed the most excel-lent conductance in the range of300–800?C,including the highest conductivity at every?xed temperature point and the lowest acti-vation energy E a(Table2).The SS13ceramics took the second best place while MS10and MS11ceramics exhibited the worst conduc-tance.Finally,the conductivity discrepancy among samples became smaller with the increasing temperature.These phenomena will be explained in details as follows.

From MS9,MS10,to MS11ceramic,the conductance became worse and worse,although their precursor powders all were pre-pared by the same way—molten salt method.This might originate from the differences in the average grain size and the amount of Na element in the ceramic samples.The density factor which was often considered elsewhere may be neglected here because all ceramic samples in this work were dense.As we know,the sum of grain bulk and grain boundary contributions was considered to determine the conductivity values for apatite materials[12].MS9had larger grains and therefore less grain boundaries in unit volume than MS10and MS11(Fig.4),which led to MS9having a better conductance than other two.

What is more important is that from MS9,MS10,to MS11 ceramic,the amount of Na element increased,and the involvement of Na deteriorated the conductance of electrolytes.It is well known that oxygen ions in the apatite silicates are con?rmed to migrate via an interstitial conduction mechanism:excess oxide ions can be introduced in the structure and facilitate oxide-ion migration in the conduction channel by a complex sinusoidal pathway along the c-axis.Moreover,the pathway is strongly dependent on the ability of the silicate substructure to relax towards the La sites that contain the cation vacancies in the apatite structure[5,9–11]. The involvement of Na in LSO lattice could change the micro-conduction mechanism of samples by two ways.Firstly,the lattice contraction(see Table1)and conduction channel narrowing caused by the incorporation of Na+ions might limit the oxide ions diffusion. Secondly,to maintain total charge balance in the composition,the replacement of lower valence ion Na+for La3+certainly resulted in the reduction in the number of cation vacancies,which had a directly harmful in?uence on oxide ions migration to the interstitial site[15].

The reason for MS9ceramic exhibited a better conductance than SS13ceramic may be explained as follows.Notice that there was no Na element in both MS9and SS13ceramics.Furthermore,MS9 had a larger average grain size and therefore less grain boundaries than SS13ceramic,which led to MS9having a higher conductivity. However,although MS10and MS11ceramics had a slightly big-ger grain size than SS13ceramic,a much worse conductivity was observed for the former.This might be due to the adverse effects of Na in MS10and MS11on their conductance.

4.Conclusions

In summary,LSO powders with pure apatite phase were suc-cessfully synthesized at relatively low temperature via molten salt method.The optimal synthesis conditions are mass ratio of reac-tants to NaCl of1:3and synthesis temperature of900?C.When the mass ratio of reactants to NaCl was greater than1:3,impurity phases existed in the powder synthesized at900?C.When synthe-sis temperature was higher than900?C,a solid solution type LSO powder with Na replacement for La formed at a?xed mass ratio of reactants to NaCl of1:3.The involvement of Na in LSO lattice may be responsible for the lattice contraction in MS10and MS11 powders and for the conductance deterioration in MS10and MS11 ceramic electrolytes.Ceramic electrolytes prepared from the pure LSO molten salt powder(MS9)exhibited better electrical properties than those from the solid-state powder(SS13).

References

[1]G.J.Offer,J.Mermelstein,E.Brightman,N.P.Brandon,J.Am.Ceram.Soc.92

(2009)763–780.

[2]A.Orera,P.R.Slater,Chem.Mater.22(2010)675–690.

[3]K.Huang,J.Wan,J.B.Goodenough,J.Mater.Sci.36(2001)1093–1098.

[4]Y.Higuchi,M.Sugawara,K.Onishi,M.Sakamoto,S.Nakayama,Ceram.Int.36

(2010)955–959.

[5]T.Kharlamova,S.Pavlova,V.Sadykov,T.Krieger,L.Batuev,V.Muzykantov,N.

Uvarov,C.Argirusis,Solid State Ionics180(2009)796–799.

[6]S.Nakayama,H.Aono,Y.Sadaoka,Chem.Lett.6(1995)431–432.

[7]S.Nakayama,M.Sakamoto,J.Eur.Ceram.Soc.18(1998)1413–1418.

[8]D.Marrero-López,M.C.Martín-Sedeno,J.Pena-Martínez,J.C.Ruiz-Morales,

P.Núnez,M.A.G.Aranda,J.R.Ramos-Barrado,J.Power Sources195(2010) 2496–2506.

3176 B.Li et al./Journal of Alloys and Compounds509 (2011) 3172–3176

[9]L.León-Reina,J.M.Porras-Vázquez,E.R.Losilla,M.A.G.Aranda,Solid State Ionics

177(2006)1307–1315.

[10]T.Iwata,E.Bechade,K.Fukuda,O.Masson,I.Julien,E.Champion,P.Thomas,J.

Am.Ceram.Soc.91(2008)3714–3720.

[11]L.Leon-Reina, E.R.Losilla,M.Mart?nez-Lara,S.Bruque, A.Llobet,

D.V.Sheptyakovc,M.A.G.Aranda,J.Mater.Chem.15(2005)2489–

2498.

[12]P.J.Panteix,I.Julien,D.Bernache-Assollant,P.Abelard,Mater.Chem.Phys.95

(2006)313–320.

[13]T.Nakajima,K.Nishio,T.Ishigaki,T.Tsuchiya,J.Sol–Gel Sci.Technol.33(2005)

107–111.

[14]P.J.Panteix,I.Julien,P.Abelard,D.Bernache-Assollant,Ceram.Int.34(2008)

1579–1586.

[15]P.J.Panteix,E.Bechade,I.Julien,P.Abelard,D.Bernache-Assollant,Mater.Res.

Bull.43(2008)1223–1231.[16]P.J.Panteix,I.Julien,P.Abelard,D.Bernache-Assollant,J.Eur.Ceram.Soc.28

(2008)821–828.

[17]E.Kendrick,K.S.Knight,P.R.Slater,Mater.Res.Bull.44(2009)1806–1809.

[18]E.Kendrick,P.R.Slater,Solid State Ionics179(2008)981–984.

[19]E.Kendrick,A.Orerac,P.R.Slater,J.Mater.Chem.19(2009)7955–7958.

[20]J.R.Tolchard,P.R.Slater,M.S.Islam,Adv.Funct.Mater.17(2007)2564–2571.

[21]S.Kato,T.Yoshizawa,N.Kakuta,S.Akiyama,M.Ogasawara,T.Wakabayashi,Y.

Nakahara,S.Nakata,Res.Chem.Intermed.34(2008)703–708.

[22]A.Chesnaud,G.Dezanneau,C.Estournès,C.Bogicevic,F.Karolak,S.Geiger,G.

Geneste,Solid State Ionics179(2008)1929–1939.

[23]S.Zec,J.Dukic,M.Puˇs evac,S.Boˇs kovic,R.Petrovic,Mater.Manuf.Process.24

(2009)1104–1108.

[24]S.H.Jo,P.Muralidharan,D.K.Kim,Electrochim.Acta54(2009)7495–7501.

[25]P.Afanasiev,C.Geantet,Coord,Chem.Rev.178(1998)1725–1752.

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雅思口语素材

U s e f u l E x p r e s s i o n s: Words and phrases Friends and communication: mutual understanding solidify/ strengthen/ enhance/ promote communication / connection with relationship network/circle of friends cultivate/develop friendship with sb. keep steady relationship with sb. establish interpersonal networksac build up the social circle spur message transmission Knowledge and experience widen one’s outlook broaden one’s vision/horizon acquire knowledge and skills comprehensive/overall quality expand/enlarge one’s scope of knowledge knowledge reserve/base/storage theoretical knowledge practical skills social experience broaden one’s knowledge base promote one’s overall/ comprehensive accumulate experiences competence learn lessons from past experiences Work and experience the scarcity of employment opportunities lay the foundations for career prosperity immerse oneself in endless job tasks boost/augment/enhance efficiency be adept in boost one’s c ompetitiveness Health and pressure diminish individuals' leisure time drive away lassitude lighten one’s burden homework/workforce overload

近期雅思口语卡片新题素材汇总

近期雅思口语卡片新题素材汇总人物Describe a classmate of yours Describe a good friend Describe a happy person Describe a colleague Describe a neighbor Describe your own personality Describe a family member Describe a child you know Describe an old person Describe an old person who has influenced you the most Describe a successful person Describe a singer Describe a sportsman Describe a movie star Describe a character in TV or movie Describe a teacher of yours Describe a famous person that you want to spend a day with.地点Describe a building at schools Describe a historical place

Describe a monument Describe an interesting building Describe a lake, river or sea. Describe a peaceful place Describe a leisure place Describe a park Describe a place of interest Describe a natural beauty Describe a city you want to live in Describe a place you have visited Describe a place you always go for shopping

Simon考官范文-雅思口语素材2(Cook整理)

一.雅思P2相关话题一日假期和外国朋友一起吃饺子的建议 1.The best way to eat a dumpling is in one bite. “Dumplings are designed to be consumed in one mouthful, as it’s the best way to enjoy the combination of the meat filling and the very thin and springy flour wrapper,” If you can’t use chopsticks, eat your dumplings with your fingers. Avoid using a fork at all costs, as piercing the dumpling will compromise the flavour. 3.Mix two parts vinegar with one part soy sauce for the perfect dumpling sauce. Add young ginger slices too， Chili oil is also a great addition when available. 4.Dumplings are just one element of dim sum. “Dim sum doesn’t just include dumplings. It’s also braised dishes like pork ribs, chicken feet, and beef balls. It’s actually small tapas-style dishes that are eaten in Cantonese restaurants at lunchtime,” 5.Xiao long bao dumplings are different from others as they contain broth. They originated in the Jiangnan region of China and are prepared in bamboo steaming baskets called xiao long, hence the name. 6.When eating xiao long bao or a dumpling with a ~soupy~ interior, opt for chopsticks and a spoon. “As soon as the dumplings arrive at your table, lift one from the steamer basket onto a soup spoon. Next, tear the skin of the dumpling by pressing the chopsticks from the side of the dumpling onto the spoon. The broth will ooze out onto the spoon. Sip the soup then enjoy the dumpling in one mouthful.” 7.You can tell whether your dumpling was cooked fresh or frozen by looking at the skin. “The skin of a freshly made dumpling is springy and light. “Frozen ones tend to be soggy.” 8.When makingdumplingsat home, try to keep your packages small.

(完整word版)雅思口语素材整理汇总

雅思口语素材训练 by Tina Li Do you like music??A—肯定:Definitely yes, everyone enjoys music, and I am no exception! I love... 否定 :Well, honestly speaking, music is really not my cup of tea, simply because... ( 给出直接原因) What—pop, techno ( 电音音乐), hip-hop, rock, meditation ( 冥想乐) and especially light music.( 罗列名词) Where—Normally speaking, I would like to listen to music with my earphones when I take a ride on public transportation. ( 给出一个具体的场景) When—As long as I couldn’t go to sleep, I’d like to listen to some light music to calm myself down. ( 给出一个条件 :As long as I..., I would...)

Who—My most favourite singers include Adele, James Blunt, Avril Lavigne, and so forth. ( 喜欢的歌手) Why—I am fond of music mainly because it can cheer me up greatly when I feel down/low/ blue/bored/tired/depressed. ( 心情不好的时候让我高兴起来)?Besides, I also believe that music is an indispensable part of culture and tradition, through which I could have a better understanding of different cultures around the world, including cowboy culture, African-American street culture, the three main reli- gions and so on. ( 有助于理解不同的文化) Do you like watching movies?? A—Speaking of movies, yes, I am a big fan of all types of movies, such as...?What—comedy, action, romance, sci-fi, manga, vampire, zombie, animation...

雅思口语part 2 素材分类整理

做有偿工作的人 Describe a person you know who is doing a paid job. You should say: Who this person is What job it is; How long the job lasted; And explain why you or this person chose to do this job. 让你笑的小孩 Describe a time that a child did something that made you laugh. You should say: When this happened Who the child was What the child did And explain why it was funny 特殊的旅行 Describe an educational trip you went on when you were in school. You should say: When and where you went; Who you went with; What you did; And explain what you learned on this trip.

Describe an electronic machine you want to buy. You should say: What it is When you know this machine What specific And explain why you want this machine 难忘的广告 Describe an unforgettable advertisement (that you saw or heard liked) You should say: Where you saw or heard it What kind of advertisement it was What the contents of the advertisement were (or, what product or service was advertised) And explain how you felt when you saw or heard this advertisement/why you like it

【2019-2020】雅思口语话题素材-精选word文档 (1页)

【2019-2020】雅思口语话题素材-精选word文档本文部分内容来自网络整理，本司不为其真实性负责，如有异议或侵权请及时联系，本司将立即删除！ == 本文为word格式，下载后可方便编辑和修改！ == 雅思口语话题素材雅思口语素材总结雅思口语要求学生平时多多的积累素材，在口语方面要不断的加强练习。烤鸭们要多模拟不同的场景，多用丰富的口语短语，这样你的雅思口语水平才能越来越高。下面是常用的一些口语短语，供大家参考！ 1、 a change of pace 改变步调;换口味 You cant do these chemistry experiments all day long . You certainly need a change of pace . 2、 a far cry from 相距甚远 The published book is a far cry from the early manuscript . 3、 and how 的确 A ： Shes a good dancer . B ： And how . 4、 a matter of time 时间问题 It is only a matter of time . 5、 a phone call away 一个电话之远，即愿意过来帮忙 If you need my help , do let me know . Just remember I am a phone call away . 6、 a while back 不久以前 Well , I listened to that CD you lent me a while back . 7、 all along 一直 I knew it all along . 8、 anything but 绝对不 I was anything but happy about going . 9、 account for 解释 How do you account for it ? 10、 after all 毕竟;终究 A ： Ive just seen the X - rays and your teeth look just fine . B ： I see . Then there is nothing to worry about after all . 11、allergic to 对过敏 Oh man ! Something in this room is making my eyes itch . I must be allergic to something . 12、 at sbs service 愿为某人服务 I am at your service at any time . 13、 around the clock 24小时不停 Martha studied around the clock for management exam . 14、 as far as I know 就我所知 But as far as I know , he once won the world champion at the Olympic Games . 15、 at home with 对很熟悉 She is at home with problems like this . 16、 back out 退出 A ： Wasnt Bert supposed to sing tonight ? B ： Yes , but he backed out at last minute . 17、be cut out for 适合于，有做某事物的天赋 She is cut out for a dancer . 18、 be absorbed in 全神贯注于某事物 She has been absorbed in a horrorfiction . I cant tear her away . 19、 be addicted to 对某事物上瘾 She has been addicted to drugs for years . 20、 be attached to 对某事物有感情 A ： Im amazed that you are still driving that old car of yours . I thought you would have gotten rid of it years ago . B ： It runs well and Ive actually been quite attached to it .

雅思口语话题素材积累：Hometown

雅思口语雅思托福技巧雅思口语-美联国际教育雅思口语话题素材积累：Hometown 2014-02-18 17:00 类别：雅思口语来源：enguo 责编：meten 考生们在练习备考雅思口语过程中，可以多从身边的生活中取材，锻炼自己的口语表达能力。下面小编就为大家整理了雅思口语话题素材：Hometown，希望对大家备考有所帮助。 1、Where do you come from? 2、What tourist attractions are there in your hometown? Would a foreign visitor enjoy them? 3、Did you learn much about the history of your hometown in school? 4、What do you think needs to change in your hometown? 5、What place(s) in your hometown do you go to in your spare time? 6、Why did you choose to live here/there? 7、What do you like about your hometown? 8、What do you think needs to be done to make your hometown a better place to live in? 9、For you, what benefits are there to living in a big city? 10、What facilities does your hometown have? 11、What sorts of buildings are there in your hometown? 12、What's the most attractive part of your hometown? 13、What forms of transport do visitors use to come to your hometown? 14、How could your hometown attract more visitors? 15、Has the weather in your hometown changed much in recent years? Important: At the moment (2012) in China, there are about 30 different topics being used in Part 1. These topics and questions are in the examiner's question book(topic pool), the examiner is not allowed to make his or her own questions in Part 1 test. 众所周知，雅思口语考试是非常重视临场发挥的，虽然这些雅思口语考试试题看上去都很平常，但是还是要求大家在自己熟悉的题目和熟悉的事物中发挥自己的真实水平，所以大家一定不能掉以轻心，平时就要多加训练，在考场上正常甚至超常发挥出来。

雅思口语高分模板汇总

雅思口语高分模板汇总多看一些雅思口语高分模板，有助于提升英语说话的逻辑，还能增强我们遣词造句的能力。下面就和大家分享，来欣赏一下吧。雅思口语高分模板：描述兴趣爱好的话题雅思口语高分模板一： From a middle class family, I was born in Hsin Ying, Tainan on October 10th, 1965. My father is a civil official at Tainan City Government. My mother is a house wife good at . Although I am the only child of my parents, I am by no mans a spoiled one. On the contrary, I have been expected to be . I study hard at school. Besides texts knowledge, journalism is my favorite; whenever reading, my heart is filled with great joy and interesting. 从中产阶级家庭，我出生在Hsin Ying，台南1965年10月10日。我父亲是台南市政府的一名公务员。我母亲是一位善于烹饪的家庭主妇。虽然我是我父母的独生子女，但我决不是一个被宠坏的孩子。相反，我被认为是一个成功的受过高等教育的人。我在学校努力学习。除了文字知识，新闻是我的最爱;每当阅读，我心中充满了极大的乐趣和乐趣。

雅思口语考试素材

雅思口语试题参考素材 1.被污染的地方 Last vacation, I went to Hainan with my family.Hainan is such a wonderful place that I will never forget it. It's really a good place where gave me a rather good impression. I feel so wonderful during the journey, as I have experienced a lot of things for the first time. The sky is also brighter and clearer than that I had ever seen. It was my first time to experience the sea and the beach in the sunshine. When sitting on the cruise, I could clearly see the ocean waves pushing the windows of the cruise. But last week, I went to Hainan again. I went to the beach the second time, but this trip changed my idea about its scenery. There were a lot of rubbish. The water was full of flotsam and refuse.When I walked along the sea, terrible smell went into my nose.The beach had been affected by pollution.Due to poor management, people who visited there damaged the environment. It is to be regretted that a beautiful place has gone.

雅思口语素材汇编

描述一个未来你想安家的地方。 This place is a coastal mountain in Hong Kong, I have been there followed a tour group last winter vacation.The mountain is not high, but it is arborous.And when you walk in the mountain,you will find the air is particularly fresh. The sky way stretching from the foot of the mountain to the peak , and there are many apartment buildings and villas in there. Down from the mountain is the ocean, it has soft beach as well as clear seawater,sea birds flying overhead time to time. The inhabitants of the mountain exercise along the highway by running or cycling every morning. I am aspire to live in that place because it isvery comfortable. In addition to the good environment , another reason I choose to make a home there is that, Hong Kong is an international metropolis, and there are a lot of employment opportunities, I think I can find a nice job there. And Hong Kong are referred to as the shopping paradise, the stuff is superior in quality and the price is relatively cheap. But in Hong Kong, people have a rapid pace of life, I think I can’t adapt to the fast pace of life. So living in the mountain far away from the downtown is a good choice for me because I can go to work in downtown during the day, and go back to the mountain to release the pressure of a day at night. In addition,the traffic is very developed in Hong Kong, so there is no need to worry about the traffic, I can arrive quickly at the downtown if i want. 我喜欢的一个喜剧演员是马特·勒布朗，他在情景喜剧《老友记》中饰演乔伊·崔比安尼。剧中乔伊与钱德勒为共租公寓的室友，是一位没什么天分但很执着的龙套演员，他从没有拍过什么很重要的角色，但是对于每一个上镜机会他都非常珍惜，非常认真。在拍戏方面的每一点进步都会让他非常兴奋。我觉得他是《六人行》里最单纯最可爱的一个人，他四肢发达、头脑简单，他的很多台词都非常搞笑，动作也很滑稽。另外乔伊是一个非常善良，富有爱心的人，他非常关心他的五个朋友，总能给人带去温暖。马特真的把这个演员演活了。从乔伊身上我们能看到自己的影子，虽然我们都是平凡的普通人，但是为了自己的梦想一直在努力，就算遇到很多挫折依然很乐观。我觉得这是马特塑造的这个角色最成功的地方，它能给人带去希望。 One of my favorite comedian is Matt Leblanc, he played in the situation come dy Friends,which i watched a couple years ago,he played in friends as the cha racter,Joey Tribbiani . In Friends ,joey is an actor, an utility man.Although he had never took a chance to play a big role,he cherish every chance he got.An d with one hundred percent of the effort.Every bit of progress in performance would make him very excited. I think he is a simple person as well as the most lovely one in Friends.he is limbs developed but simple-minded, and many of his lines are very funny, actionsare also very funny, Matt just make the ch