Solid state metathesis read Solid state metathesis reactions can en two salts lIc MoCl(s)+5/2Na S(s)-,MoS, (s)+5NaCI(s)+1/2S( are chosen, a highly exot hermic reaction MoCI, +5/2 Nas- Mos, nAcL+ 1/2s The enthalpy of this reaction is DH=213 kcal/mol started (by grinding spark. ete )the heat generated d by the reaction itself leads to a rapid increase in temperature The maximum temperature attained is-1700K. The reaction is completed in 48 The percent yield is typically 80%6 of theoretical. Washing with CH, OH re Reaction reaches 1050 C and is over in 300 ms B with H-O removes Nacl Washing with chloroform removes remaining s SSM(Solid State Metathesis) olid State Metathesis Reactions to Ill-V Group AB+CD→AC+BD Metal, B:halogen C: alkali metals, D: S, P, As, Sb) En. MC1+2LiS-MS, +4LiCl (M=Ti, Zr, Hf and V)(>400PC) CldANHn SigN, +12HCI MCI+Li Fe OoMFe O+2LiCl(400-500PC) N→+ZN+ LicH1/6N Snl4+2Ii2E→SnEa+4l(E=O,S,Se(500°O PbCl2+Ii2E→PbE+2 LiCI(E=0,Se,Te)(50°C LnCl,+Li N-LnN+3LiCl (Ln=Y, La, Pr, Nd, Sm, Eu, Gd, Tb MCL(8+(x/)Li3N(S)MN(s)+xLiCI+(x-3)/6N,(g) MCI(s)+xNaN(s),MN(8)+xNaCl(s)+(3x-1)/2N(g) Disadvantages of SSM Sintering Overview he product is impure, often contains the impurities such as including is a process specifically for powdered materials, Since the actual reaction temperature is far higher than the uct licl compressed powder is heated to a temperature close to but not with the product I is used on laboratory at particles may bond by solid state bonding, but not melt. research, and ca sed for large scale production. GThe method to All+NayAs--AlAs +Nal+Al +As (1)1000oC/8h (2)wash As CGaNor inn can not be obtained in the similar system of GaCl,or InCl, and Li,N under similar condition, which prod corresponding metals Ga or In and release nitrogen gas. a Surface area reduction e Powder process9 Solid State Metathesis Reactions Can Be Very Exothermic MoCl5 (s)+5/2Na2S(s)®MoS2 (s)+5NaCl(s)+1/2S(s) Reaction reaches 1050ºC and is over in 300 ms Solid State Metathesis Reactions ß A metathesis reaction between two salts merely involves an exchange of anions, although in the context we will use there can also be a redox component. If the appropriate starting materials are chosen, a highly exothermic reaction can be devised. ß MoCl 5 +5/2 Na2 S → MoS2 + 5NaCl + 1/2S ß The enthalpy of this reaction is DHrxn = -213 kcal/mol ß Due to the highly exothermic nature of this reaction, once it is started (by grinding, spark, etc.) the heat generated by the reaction itself leads to a rapid increase in temperature ß The maximum temperature attained is ~ 1700 K. ß The reaction is completed in < 4 s. ß The percent yield is typically 80% of theoretical. ß Washing with CH3OH removes remaining MoCl 5 ß Washing with H2O removes NaCl ß Washing with chloroform removes remaining S SSM (Solid State Metathesis) AB + CD ® AC + BD (A:metal, B:halogen; C: alkali metals, D: S, P, As, Sb) Examples： MCl4+2Li2S®MS2+4LiCl (M=Ti, Zr, Hf and V) (>400°C) 3SiCl4+4NH3®Si3N4+12HCl MCl2+Li2Fe2O4®MFe 2O4+2LiCl (400-500°C) ZrCl4+4/3Li3N®ZrN+4LiCl+1/6N2 SnI4+2Li2E®SnE2+4LiI (E=O, S, Se)(500°C) PbCl2+Li2E®PbE+2LiCl (E=O, Se, Te) (500°C) PbCl2+Li2O®Pb2O2Cl+LiCl+[Pb] (500°C) LnCl3+Li3N®LnN+3LiCl (Ln=Y,La,Pr,Nd,Sm,Eu,Gd,Tb) MClx (s)+(x/3)Li3N(s)®MN(s)+xLiCl+(x-3)/6N2 (g) MClx (s)+xNaN3 (s)®MN(s)+xNaCl(s)+(3x-1)/2N2 (g) Solid State Metathesis Reactions to III-V Group Reactants Condition Products Reactants Condition Products AlI3+Na3P Bomb ignition Amorphous GaI3+Na3S b Bomb ignition GaAs+Sb 990°C/42h AlP <600°C/12h GaAs +Sb(trace) AlI3+Na3As Bomb ignition Amorphous GaF3+Na3Sb Bomb ignition GaAs+Sb 220°C/12h AlAs+Al+As InI3 +Na3P Bomb ignition InP+In+InI 2+ trace P 550°C/17h AlSb+trace As <600°C/12h, InP+In+InI2 AlI3+Na3Sb Bomb ignition AlSb+Al+Sb >600°C/12h InP 550°C/12h AlSb+ trace Al+Sb InF3+Na3P Bomb ignition InP+In+trace impurities >600°C/18h AlSb+ Al+Sb InI3 +Na3As Bomb ignition InAs+In+InI2 GaF3+Na3P Bomb ignition GaP+P(red)+ Ga(trace) <600°C/12h InAs+In+InI2 GaCl3+Na3P Bomb ignition GaP+P(red)+ Ga(trace) >600°C/12h InAs+In GaI3 +Na 3P Bomb ignition GaP+P(red)+ Ga(trace) InF3+Na3As Bomb ignition InAs+In+trace impurities >220°C/8h GaP +Ga(trace) InI3 +Na3Sb Bomb ignition InAs+In+Sb GaI3 +Na 3As Bomb ignition GaAs +Ga(trace) 550 °C/12h InAs+Sb <570°C/12h GaAs +As(trace) 950°C/8h GaAs The product is impure, often contains the impurities such as metals. Since the actual reaction temperature is far higher than the melting point of LiCl, the by-product LiCl is sintered together with the product. Up to now, SSM is used on laboratory research, and can not used for large scale production. The method to remove the impurities: GaN or InN can not be obtained in the similar system of GaCl3 or InCl3 and Li3N under similar condition, which produce corresponding metals Ga or In and release nitrogen gas. Disadvantages of SSM AlAs C/8h (2)wash o (1)1000 AlAs NaI Al As ignite As 3 Na 3 AlI ¾¾¾¾¾¾¾¾¾® ¾¾¾¾¾¾® + ¾¾¾ ¾® + + + Sintering Overview Sintering is a process specifically for powdered materials, including metals, ceramics, and plastics. In this process, the compressed powder is heated to a temperature close to but not at melting, in a controlled-atmosphere furnace. This is done so that particles may bond by solid state bonding, but not melt. Surface area reduction Powder process