Tanねlum Penねchlorid』E with Ammo血血the Vapor Pkase An《量properties of the Tan.Tal㎜ N’Itride Forme通
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676 DENKI KAGAKU Fomation Process of Tanね1㎜Nitri-e by the Reaction of Tanねlum Penねchlorid』e with Ammo血血the VaPor Pkase an《量Properties of the Tan.tal㎜ N’itride Forme通 Akimasa YAJIMA*,Ryoko MATsuzAKI*and Yuzo SAEKI* The reaction products of gaseous TaC15with ammonia were TaCl5・5NH3at2QO。CラTaC15・5 NH3,Ta3N5,NH4Cl at250~600℃,Ta3N5and NH4Cl at650~950。C,Ta3N5,Ta4N5・and NH4Cl at 10000C,and Ta4N5シTa2N,θ一TaN,ε一TaN,NH4Cl,and HCl at1100~1400。C.In the vapor、phase reaction of gaseous TaCl5with ammonia,the reaction of gaseous TaC15with ammonia to form TaCI5・5NH3㏄curs丘rst.Above6α.235。C,the TaC15・5NH3reacts with ammonia to form Ta3N5. Above侃.1000。C,the Ta3N5decomposes to Ta4N5.Above侃。1100。C,in addition to these reactiolls, the nitriding of tantalum,formed by the reduction of gaseous TaCI5with hydrogen resulting from the thermal dissociation of ammonia,also o㏄urs to form Ta2Nシθ一TaN,andε一TaN.On heating the Ta3N5,formed by the vapor-phase reaction,in an argon atmosphere,it changed to Ta4N5at6α・ 9000C,to Ta5N6,θ一TaN,andε一TaN at6α.1100。C,and then toθ一TaN andε一TaN at1300~1400。C. The tantalum nitrides formed above1200。C were uniform,ultra丘ne powders with the particle diametersoftheorderof1/100粋m. 11ntroduction 2 Experimental The vapor-phase reaction of transition metal 2.1Materials chlorides with ammonia has recently become The TaCl,used was prepared by the reaction important for the preparation of6ne powders of tantalum powder(Ta99.8形,Hermann C. or thin丘lms of transition metal nitrides,which Starck Berlin)with chlorine at350℃and puri一 are aquiring importance as new industrial ma- 丘ed by fractional sublimatlon.The chemical terials. analysis gave Ta50.5%1,Cl49.4%(calcd.:Ta Concerning the vapor-phase reaction of tan・ 50.51彩,Cl49.49%).Ammonia was dried by talum pentachloride(TaCl,)with ammoni且,1ittle passing it over sodium hydroxide granules and information has been available apart from the barium oxide powders. work of Hieber夏),who reports that tritantalum 2.2 Experimental proced皿es pentanitride(Ta,N,)films deposit on a fused- The experimental apparatus used for exami・ silic&substrate at900~1300℃from a gaseous ning the reaction products of gaseous TaCl, mixture of TaCl,and ammonia at a pressure wlth ammonia is schematically shown in Fig.1. of400torr.However,no information is at pre- Gaseous TaCl,was formed by heating solid sent available on the reaction process of TaC1, TaC1、(14g)at190℃ and was carried by a with ammonia in the vapor phase. stream of argon(50cm3/min)into the reaction In this paper,the reaction products of gaseous zone (28mm∫.4.,250mm length)held at a TaCI、with ammonia at200~1400。C were ex- speci且ed temperature. The TaCl、inlet tube amined in detaiL The possible reactions which consisted of two concentric tubes. Gaseous were considered to occur on the basis of the TaCl5cαrried by argon was intro(iuced through above experiments were examined.Further, the inner tube and the outer tube was utilized the thermal stability of the tantalum nitride for introducing argon(50cm3/min)as a sheath formed was examined.The tantalum nitride gas to prevent formation of the reaction prod・ formed was also examined by electron micro- uct at the chloride inlet tube.Ammonia was scopy・ simultaneously introduced at a How.rate of100 cm3 min into the reaction zone. The mean How-rate of gaseous Tac1、was6.o cm3/min,A *Research Laboratory of Resources Utilization,Tokyo quartz or alumina tube was inserted inside the Institute of Technology(4259,Nagatsuta-cho,Mido- ri・ku,Yokohama227) reaction tube to make the removal of the reac一 677 51,No.8(1983) spheric moist皿e. 1. ロ /\ 3. 4. NH5、盲 3 Results and 】Discussion A r→ ウ 3.1 Reaction products of gaseo旦1s tan・ 司 Ar→ ↑ ↑ ↑ talum pentachloride with ammonia 5. 6、 5. The products formed by heating gαseous TaC15 Fig.1 Experimental apparatus in an ammOnia Stream at VariOUS tem- 1:TaCl5,2=Electric fumace,3:Quartz or peratures were examined both by X-ray an&1・ alumina reaction tube,4=Quartz or alumina 2)~6)ys1S and chemical analysis。Reaction tem- inner tube,5=The㎝㏄ouple,6:Brick or peratures above200。C were employed,because ribbon heater gaseous TaCl,was generated at190。C. tion product easier. The reaction was allowed The product formed at200。C showed a hith- to proceed for2h, erto unknown X-ray diflraction pattern which The by-product ammonium chloride(NH、Cl) was clearly diflerent from those of ㎞own which deposited outs至de the reaction zone to- tantalum compounds.The chemical analysis of gether w三th the tantalum nitride formed was the product gave Ta40,8%,C139・9%,NH3 separated by heating the mixture in an argon 19。2%. The ratio of Ta;Cl;NH,was ca正cu・ stream at400℃for10~15h. lated to be1:4.99:5,00.This was considered 2.3 Analy・tical to indicate that tke product formed at2000C The chem孟cal analysis of the reaction product had a composition of TaCl,・5NH、(calcd,=Ta wαs performed as follows:The tantalum con- 40.81%,Cl39.98%,NH31921%)。 tent of TaCl,一NH、adduct was gravimetrically The reaction products at various temperatures determined as Ta,0、after hydrolyzing the are shown in Table1.Unreacted TaC15was sample in3M-nitric acid.The chlorine and not observed throughout the temperature range ammonia contents were determined by the gra- of this work.At500~1000℃,all the products vimetric method as AgCI and by the Kjeldah豆 were obtained outside the reaction zone in the method,respectively,from the Hltrate.In the form of powder.However,at1100~1300℃, case of a mixture of the adduct Emd tantalum in addition to Ta、N,obtained outside the reac・ nitride,the tantalum and chlorine contents were tion zone in the form of powder,Ta2N,θ一 gravimetrically deternlined after the fusion of TaN,andε一TaN were obtained inside the reac- the sampie with sodium carbonate. Thc NH3 tion zone in the form of film. At14000C, content was determined by the Kjeldahl method Ta、N,θ一TaN,andε一TaN were obtained inside from the丘ltrate after hydrolyzing the sample the reaction zone in the form of mm and small in3M-nitric acid. amomts of Ta4N,,Ta2N,θ一TaN,andε一TaN X-ray analysis of the solid product was per- were obtained outside the reaction zone in the formed with an X-ray powder diffractometer form of powder.The mole percentage of TaC1, equipped with a proportional counter using Ni converted to the nitrides obねined inside the 五1tered Cu radiation.The sample chamber of the diflractometer was maintained under a dry Table l Reaction products of gaseous TaCl5 nitrogen atmosphere,if necessary,to prevent with ammonia at various temperatures contamination of the sample by atmospheric Temp./。C Products moisture during the irradiation。 The sensitivity of the quartz helix used for 200 TaCl5・5NH3 250~350 TaC15・5NH5>Ta3N51NH4Cl thermogravimetry(TG)was approximately94 400 TaCI5・5NH8〉Ta3N51NH4Cl mm/9.The sample(o、29)was heated at a 500 TaC15・5NH3,Ta3N5;NH4CI rate of2.5。C/min and the flow・rate of ammonia 550~600 Ta3N5>TaC15・5NH3;NHもCl was maintained at50cm3/min. 650}950 Ta3N51NH4Cl Throughout this work,the TaC1、and the 1000 Ta3N5>Ta4N51NH4Cl reαction products were handled in an argon 1100~1300 Ta4N5>Ta2N,θ一TaN,ε一TaNl NH4C1,HCl atmosphere to prevent contamination by atmo・ 1400 Ta2N,θ一TaN,ε一TaN>Ta4N51NH4Cl,HC1 6.78 DENKI KAGAKU reaction zone was8%at1100℃,14彩at1200℃, higher than the calculated value,53.92鰯,based 26%at1300。C,and92%at1400℃.Also,HCl on the reaction,3(Taα、・5NH3)十5NH、→Ta3 was formed in addition to NH、Cl above1100℃. N5十15NH4C1. The percentage of HCl formed to the total Therefore,the TaCl5・5NH, (1.O g) in a 「 amount of chlorine introduced as TaCl,was quartz boat(70mm length,15mm width,7mm 10% at 1100。C,21%at 1200。C,46% at1300。C, depth)was p}aced in a stra1ght reaction tube and 96彩 at 1400。C. (28mmガ.4、,1000mm length).Ammonia was The presence of the following tantalum ni- introduced into the reaction tube at a How-rate trides have been reported:Ta、N、(tetragona12)・ of 100cm3/min。 The sample part was then ロ ロ 3):αo=10.22g A,60=3.875A3)or monoclinic: Placed in the centre of an electric furnace (300 α。廻6。廻10.3A,β=90。3)),Ta、N,(tetragona1: mm heating length)maintained at a specified α・=6,83。A,6。=4.272A)3),Ta,N。(hexagona1; temperature for l h.The products obtained α。=5,17、A,6。=10.307A)3),θ一TaN(hexagonaL inside and outside the boat were examined by ロ ロ α。=2.936A,6。=2.885A)4),ε一TaN(hexagonal: X-ray amlysis and chemical analysis. The α・=5.186A,6。=2.913A)4),Ta、N(hexagona1; results are shown in Table2. α。=3.0445A,6。=4.9141A)5),andδ一TaN(cu- Table2 Exper三mental results for TaC15・5NH3 bic)4).It was found that the above tantalum 0n heating in an ammonia stream nitrides except Ta5N6andδ一TaN were formed Products Unreac. by the reaction of gaseous TaCI,with ammonia. Heating ted temp,/℃ TaCl5・5 3,2 Reaction process of gaseous tanta・ In the boat Outside the boat NH3 鰯 lum pentachloride with ammonia 250 Ta3N5(8) NH4Cl 92 To elucidate the reaction process of gaseous 300 Ta3N5(69) NH‘Cl 31 TaCls with ammonia,the behavior of the TaC1,・ 350 Ta3N5(81)r NH4Cl 19 5NH、and the Ta、N、,which ha(1been formed 400 Ta3N5(89) TaCl5・5NH3(く1);NH4Cl 10 during the reaction process, on heating in an 450 Ta3N5(96) TaC15・5NH3(<1)l NH‘Cl 3 500 Ta3N5(99)・ TaaN5(<1),TaCI5・5NH3 ammOnia Stream Were eXamined. (く1);NH4C1 3.2.1BehaviorofTaCI5・5NH30nheat- Note The value in( )is mole percentage of TaC15・ ing in an ammonia stream The TG curve 5M{3converted to the product of TaC15・5NH3in an ammonia stream is shown These resu豆ts and the results obtained by in Fig.2.TaC1,・5NH310st weight above235℃。 TG,mentioned above,sHowed that TaC15・5NH、 It was observed that NH、Ci deposited outside reacted with ammonia to form Ta3N5and NH、 the heating zone