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Electrical conductivity of platinum metal — nonplatium metal double oxides
Mat. Res. Bul. Vol. 13, pp. 229-235, 1978. P e r g a m o n P r e s s , Inc. Printed in the United States.
On the 70th birthday of Academician N. M. Zhavoronkov
ELECTRICAL CONDUCTIVITY OF PLATINUM METAL - NONPLATIUM METAL DOUBLE OXIDES V. B. L a z a r e v and I. S. Shaplygin Kurnakov Institute of General and Inorganic C h e m i s t r y Leninsky Avenue 31, Moscow 117071, USSR
(Received J a n u a r y 3, 1978; Communicated by R. Roy)
ABSTRACT The authors have determined an e l e c t r i c a l conductivity type for 145 platinum metal-nonplatinum metal double oxides such as Ln2M207 pyrocblores, AMO3 perovskites, ARh204 spinels, Rh MO4 rutiles, MxPd304 and MxPt304 bronzes, etc. It was shown that conductivity type is a c e r t a i n function of the d - e l e c t r o n configuration of platinum metal ion in the double oxide, n a m e l y the double oxide with d 4 o r d 5 electron configuration for platinum m e t a l ion exhibits m e t a l l i c conductivity while the oxide with d 6 or d 8 electron configuration for the ion is a semiconductor.
The systematical investigation of electrical properties of platinum metal (PM) - nonplatinummetal (NM) - oxygen ternary compounds has shown the same conductivity type of the platinum metal simple oxide as the corresponding PM-N~ double oxide for any nonplatinummetal (1,2). Nevertheless, platinum metal mixed oxides were known which had none stable platinum metal simple oxide as a precursor. ~or example, we did not know stable Ru203 for LaRuO 3 mixed oxide since the only stable oxide form for ruthenium is ruthenium dioxide RuO$ . In Table I we give 145 platinum metal mixed oxides for which experimental data about conductivity type are known. Analysis of the data from electrical and optical measurements results in the conclusions: i) if platinum metal ion electron configuration in any double oxide is d ~ or d s theoternary compound exhibits metallic conductivity; ii) for d 6 or d" electron configuration double oxide is a semiconductor (I). Arthur Sleight (3) for the first time has prepared a new pyrochlore Bi2Pt20~ for which semlconducting behavior was expected since Pt(IY) is 5d ~ and there would be a filled t2~ band. Electrical measurements on a pellet of Bi2Pt207 confirmed-the idea (a room temperature resistivity of 8 ohm-cm with the activation energy of 0.15 eV). 229
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TABLE I Platinum metal mixed oxides for which electrical properties are determined
I group A - LiPt 304, LiRh02' NaRh02' KRh02' Li2RuO 3 'Li21rO 3' Li 20 sO 3 'Na 20 sO 3 'Na21r03 'Na 2P t 03 ,Na 2Pd304, K2Pd02 , K2RuO 3" B - CuRh204,OUoo5Pt304,AgRhO2,CuRh02" I! group A - BeRh204, MgRh20 4, CaRh204, SrRh204' BaRb204' Ca2Ru04' Ca2IrO4,CaPd304,BaPd304,MgPd304,Ca0sO3,SrOs03' BaOsO3,CaRuO3,BaRuO3,CaIrO3,SrIrO3,BaIrO3,Ca4Pt06 , SrRuO 3 • B - CdPd304,CdRh204, ZnRh204,CdOs03" If|group A - Ln2RU2OT,Ln2Ir2OT,Ln2OS2OT'Ln2Pt207 (Ln - all lanthanides except promethium), Sm2Pd2OT,Sm2Rh207 , Sc2Rh207,LnRhO3,LaRu03 • B - RhBO3,InRhO3,T12RU2OT,T12Ir2OT,T12Pt2OT'T12Rh207' |V group A B V group A B ~Igroup A B ~[group A ~gro~p B
T120s207 • No compounds Pb2Ru206,Pb2Ir206,Pb2Os206,Pb2Pt206+x (for x=O;0.3 and 0,7), PbRh204,PbPd0 2. RhVO4,RhNbO4,RhTa04 • RhSbO4,Bi2PdO4,BiRhO3,Bi2Rh206,Bi2Ru207'Bi2Ir207 '
Bi2Os207,Bi2Pt207- Rh2Mo06,Rh2WO6,RhOr03 • - Rh2TeO 6. -~LRh204,NnRhO 3. - CoRh204,NiRh204,Co2RuO4,Nioo8Pt304,O°o.6Rt304"
In the present study we consider in de~ail crystal chemistry and electrical properties of double oxides containing platinum and nonplatinum metals for different nonplatinummetals in the oxides. I. All six platinum metals give a number of compounds with alkaline metals (with a different stoichiometrie). For the first time monoclinic Li2RuO 3 was prepared by Dulac (4); later it was repared and studied in detail by the authors of this paper 2,5). Orthorhombic Li21r03, Na21r03 and Na2Pt03 were described
~
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in ref.6; however only Li2IrO ~ is really orthorhombic while two others have monoclinic structure after McDaniel (7) and it was confirmed in our article (5). Orthorhombic Na2Pd304 (8), K2Pd02 (9), hexagonal LiRhO 2 (10) and cubic LiPt304 (11) have been described too and all the phases were also prepared and nvestigated by us. Both isostructural hexagonal NaRh02, KRh02 space group R3m, ~ - N a F e 0 2 structure type) and orthorhombic Li2OsO~ and Na2Os0~ (Li2IrO 3 type) together with orthorhombic K~Ru03 ~ (K2SnO q structure type) were synthesized by the authors o~ the paper ~5). Li2MO 3 (M= Ru, Os, Ir), NaoOsO~, Na2IrOq and K2RuO 3 have a room temperature resistivity o~ below 2.1x16 2 ohm,cm and exhibit metallic conductivity. Other abovementioned phases are semiconductors with ~ 2 9 8 K >7xI0~ ohm-cm. We were the first to prepare the new compounds Rb2Pd02, Cs2Pd02, RbRh02 and CsRh02; they are hygroscopic, nonisostructural with Na, K analogs and have semiconducting properties.
~
For IB Group five phases with_platinum metals are known: tetragonal spinel CuRb204 (s.g. I45d) (12), hexagonal CuRhO 2 (10) and AgRhO 2 (13) with delafosslte structure, cubic Cuo.sPt304 (NaxPt304 type) (14) and orthorhombic CuPtxOg (15). The former four compounds are semiconductors, electri~aI properties of CuPt306 prepared by Olaf Muller and Rustum Roy were not studiea. k
2. Ternary compounds PM-NM-oxv~en wish NM of II Group a r e nown zor each PM and they have different structure types (see Table I). There are cubic compounds (spinels BeRh204, MgRh204, ZnRh204 and CdRh~O 4 or phases CaPd304, MgPd304, CdPd30÷ with NaxPt304 structure), orthorhombic CaRh2Oa, ~ u O ~ and MOsOx for M=Oa, St, compounds with hexagonal layer-structGre (BaIr05, BaRuO 3 , BaOsOa), dlmorphic SrIrO 3 and Ca4PtO 6 and so on in systems PM-NM--oxygen. According t o the rules formulated in ref.1 for all these compounds containing Ru(IY), Ir(IY) and Os(IY) namely where PM ion has d~ or d ~ electron configuration metallic conductivity must occur while Pd(II,IY), Pt(II,IY), Rh(III) compounds (i.e. with d @ and d$ PM ions) have to be semiconductors. The rules hold true for all compounds of Table I from known experimental data and in the future we will not point out the conductivity type for each of the represented groups of compounds. We believe that the reader will do the simple procedure himself according to the formal oxidation state of PM in each double oxide; we shall comment some "unusual" cases only. Existance of two polymorphous modifications doesn't affect electrical properties and the concept is confirmed by SrIrO 3 (16) or Ca~PtO 6 (17). Por Zn2PtO 4 (13), Cd2PtO 4 (19), H~Pt306 and C dPt306 which were prepared by Olaf Muller and Rustum Roy for the first time electrical properties were not investigated; it concerns also Zn2PdO 4 prepared by Paul Hagenmuller with colleagues in 1976 (20) i and we did not include all these phases in Table I. Ii
x)
Recently Prof. Hagenmuller has reported a rather high c o n of Zn~Pd O~but conductivity type for the compound was not determined. (Private communication). ductivity
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3. The p~rrochlores Ln2RuoO 7 (13 compounds) and Ln2Ir207 (12 compounds)were prepared NyBertaut et al for the Zirsttime (21,22) and magnetic properties of Ln2Ru207 were also investigated (23,24), however electrical measurements of these two families were not carried out up to now (with the exception of some compounds). We have determined the electrical properties of Lu2Ru207 and Lu2Ir207 together with the same measurements for 13 pyrochlores Ln20s~O 7 (25). Electrical properties of other ruthenates and irridate~ ~re given in ref.2. Sleight (26) and Hoekstra and Gallagher (27) have prepared Ln~Pt~O 7 pyrochlores in 1968 however electrical behavior of th~ eleSen compounds for Ln= Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, Lu (all of these were synthesized under high pressure ~ 4 0 kbars) was determined by us in 1975 only. We have found semiconducting behavior for the compounds. In ref.2 we have described properties of MoRho07 (M=Sm, Sc, TI), Sm~l~07 and TloPto07 which were synthesizer under hlgh^pressu~e ~40-60 kbaSs)"a6d at high temperature (8001200~C) (together with G.L.Aparnikov). Tha results are given in Table 2. Here we give unit cell parameter and resistivity for high pressure ~yrochlores T12Ru207, T120s207 and T12Ir207. Experimental data from Table 2 don't confirm the conclusion of ref.28 about semiconducting behavior of T12Ruz0 7 and T12Rh207 although a room temperature resistivity in (28) for TloRh~0~ coicides with our data ( ~ ~ for TI~Rh~0~ is 6xSG4~ ~hm-cm in ref.28). The absen~°~f any aSso~p~ion bands in infrared spectra of T12M207 for M= Ru, Ir, Os, Rh also proves that T12Ru207 and TI2Rh207 are metallic. Por semiconducting T12Pt207 we have found four absorption bands at 680, TABLE 2 Unit cell parameters and electrical properties of some M2M207 pyrochlores ,i
Compound
a,A
~298KOhm-cm
Sm2Pd207 TI2Pt207 Sc2Rh207 Sm2Rh207 T12Rh207 T120s207 T12Ir207 TI2Ru207
10.307 10.133 9.800 10.302 10.155 10.306 10.218 10.210
6.6~I01 4.1xi0 -I 2o7x10 -2 5.8x10 -3 8.0xi0 -4 4.0xi0 -4 4.8xi0 -3 3.3xi0 -4
Conductivity type Semiconducting Semiconducting ~etallic Metallic Metallic Metallic Metallic Metallic
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CONDUCTIVITY
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OXIDES
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TABLE 3 Some properties of other pyrochlores with iridium and ruthenium j
After ref.3 Compound
Bi21r207 Bi2Ru207 Nd2Ru207 Eu2Ir207 Eu2Ru207
a, A 10.315 10.292 10.330 10.290 10.255
2298K' ohm-cm 8.2xi0 -3 4.7xi0 -3 4.2xi0 -3 6.0xi0 "3 7.7xi0 -3
j
.
After ref.31 a, A 10.3269 10.2993 10.3419 10.3025 10.2503
~ 298K' ohm-cm
.
.
.
.
.
.
.
Other data ~ 298K' ohm-cm
2xi0 -3 7xi0-3(32) 7xi0 -4 2~4xI0-3(32) . . . . 1.5x10 -2 -6xi0 ° --
560, 450 and 360 cm -I in IR spectrum and the result coincides with spectral data of Hoekstra and Siegel (29). To be noted that an existance of dis~inc~ absorbtion maxima in IR spectrum of a compound is the result of it's semiconducting properties (see for example, ref.30). Therefore for instance the spectral data for M2Pt207 from (27) give another experimental proof of semiconduc~ing properties of the compounds which also follows from our electrical measurements. We emphasize espesially that IR spectroscopic data and corresponding electrical measurements allow to determine metallic or semiconducting properties of transition metal mixed oxides. We have found that for all LnRRu207, Ln20s207 and. Ln.2Ir270 pyrochlore families conductivity type did not depena on lanthanide atomic number. All these compounds in the whole interval (i.e. from Pr to Lu) are metallic. IR spectra of these compounds have no absorption bands in the region 2000-200 cm -I. We should like to note an anionic sublattice dependence on unit cell parameters as well as on dissolved admixtures, that are first of all superstoichiometric M203and NO or a simple nonplatlnum oxide. We have found tha~ ~nit ce~l parameters for Nd2Ru207, Eu2Ru207 and Eu2Ir207 are very close to published values: 1 0 . 3 3 1 A and I0.29A respectively according to (21,22) and I0.293A for Eu2Ir207 after (33). Eor other compounds from Table 3 we have r~ce~v@d unit cell parameters coinciding~with data from ref.31, however Eu2Ru207 resistivity is less 10 factor from our measurements than the value given in ref.31.
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V . B . LAZAREV, et al.
Vol. 13, No. 3
Shannon (29) has found semiconductlng properties for InRhO . We have measured electrical properties of single crystals RhBO 3 and polycristalline perovskites L r~h03, where Ln is yttrium and all lalthanides but promethium (3). There are no compounds in the systems TiO2-ND2, ZrO2-MO 2 ( ~ Ru, Os, Ir, Pt), TiO2-Rh203, Zr02-Pd0 and ZrO2-Rh20 B. There are only narrow fields of-solid solutions in these-systems. We have found a new compound PdTi0~+ x in system PdO-TiO 2 under high pressure and the phase is a-s~miconductor. Doubl~ oxides containing lead are characterised for each of platinum metals (35-38). There are only 22 double oxides of PM-NM-oxygen type for elements of Y-YIII Groups of Periodic Table up to now. Pour compounds Rh~O 4 (M= V, Nb, Ta, Sb) with futile structure were prepared earlier but we have reprepared them and studied electrical and spectral properties thls year (39) together with earlier prepared Bi2PdO 4 (40). Resistivity and conductivity type for double oxides of PM-NM-oxygen ternary system where N M - metal of Y-YIII Groups we have determined just now and found that all the compounds are semiconductors except for metallic Bi2Ru 0 , Bi21r20 , Bi20s 07 and Co2Ru04. Finishing the comments of ~a~le I we s~ould li~e to emphasize that formal oxidation state of manganese c h a ~ e s ~oichiomet~iq and crystalline structure of a compound for ~m"Rh~O 4 and ~u~Rh=O~ but a difference between resistivity values ~s small and bo~h compounds are semiconductors. We have the opposite case namely a change of conductivity type from semiconducting for SmRhmO3to metallic for Sm2RE207 i.e. it is connected with the change of PM electron configuration from d 6 to d ~. We are glad to have the examples because the fact is the best illustration for another confirmation of possibility to predict a conductivity type in double oxides of ternary system PM-NM-oxygen on the basis of the fundamental rules which were formulated in 1974 for the first time (I). References 1. I.S.Shapl~gin and V.B.Lazarev, Doklady of Acad.Sci.of USER, 218, 629 (1974) (in Russian), N.~.Zhavoronkov, V.B.Lazarev a-~ I.S.Shaplygin. Proc.X Meeting on chemlstry~ technology and analyses of noble metals, Novosiblrsk, 1976. 2. V.B.Lazarev and I.S.Shaplygin, Zh.Neorg.Khim.(Russlan), 23, 295 (1978) (in press). 3" A.W.Sleight, ~at.Res.Bull., ~, 1177 (1974)~ J.-P.Dulac, C,~.Acad.Sci., ~ , 223 (1970). V.B.Lazarevand I.S.Shaplygln, Zh.Neorg.Khim.(Russian) 23, 1222 (1978) (in press). 6. J.J.Sheer, A.E.van Arkel and R.D.Heyding, Can.J.Chem., 33, 683 (1955). 7. C.L.McDaniel, J.Solid State Chem., ~, 139 (1974). 8. M.Wilhelm and R.Hoppe, Z.anorg.allgem.Chem., ~ , 60 (1974). 9. H.Sabrowski, W.Br~nger and D.Schmitz, Z.Naturo~sch., 29b, 10,(1974). 10. P.Bertaut and J.-P.Dulac, J.Phys.Chem.Solids, 21, 118
(1961),
11. D.Bergner and R.Kohlhaas, Z.anorg.allgem.Chem., (1973).
401, 15
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CONDUCTIVITY OF DOUBLE OXIDES
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12. P.Bertaut, F.Porrat and J.-P.Dulac, C.r.Acad.Sci., 249, 726 (1959). 13. R.D.Shannon, D.B.Rogers and C.T.Prewitt, Inorg.Chem., 10, 713 (1971). 14. V.B.Lazarev and I.S.Shaplygin, Doklady Acad.Sci.of USSR, ~, 894 (1977) (in Russian). 15. 01&f Muller and RustumRoy, J.Less-Common Mat., 19, 809 (1969). 16. J.M.Longo, J.A.Kafalas and R.J.Arnott, J.Solid State Chem., ~:
174(1971).
17. S.Shaplygin and V.B.Lazarev, Mat.Res.Bull., 10, 903(1975). 18. Olaf Muller and Rustum Roy, Mat.Res.Bull., ~, ~ (1969). 19. 01af ~luller and Rustum Roy, J.Less-Common Mat., 20, 161 (1970). 20. G.Demazeau, l.Omeran, M.Pouchard and Paul Hagenmuller, Mat. Res.Bull., 11, 1449 (1976). 21. P.Bertaut~ r.Porrat and M.O.Montmory, C.r.Acad.Sci., 256, 829 (1959). 22. M.C.Montmory and ?.Bertaut, C.r.Acad.Sci., 252, 4171 (1961). 23. J.Rosset and D.K.Ray, J.Chem.Phys., 37, 1017 ~1962). 24. R.Aleonard, P.Bertaut, M.C.Montmory and R.Pauthenet, J.Appl. Phys., Suppl.to 33. 1205 (1962). 25. I.S.Shaplygin and V.B.Lazarev, Mat.Res.Bull., 8, 761 (1973). 26. A.W.Sleight, Mat.Res.Bull., i, 699(1968). 27. H.R.Hoekstra and P.Gallagher, Inorg.Chem., L 2453 (1968). 28. A.W.Sleight and J.L.Gillson, Mat.Res.Bull.,-6, 781 (1971). 29. H.R.Hoekstra and S.Siegel, Inorg.Ohem., ~, 171 (1968). 30. C.A.Wer% and R.M.Thomson, Physics of Solids. McGrow-Hill Book Co., N-Y., 1964, Chapter 10. 31. R.J.Bouchard and J.L.Gillson, ~t.Res.Bull., 6. 669 (1971). 32. P.L.van Loan, J.Camad.Oeram.Soc., 40, 49 (197T). 33. S.J.Schneider, J.L.Waring and R.E.Tressler, J.Res.NBS, 69A,
245
(1965).
_
.
_
34. ~ . S h a n n o n , Inorg.Chem., ~, 1474 (1967). 35. J.M.Longo, P.M.Raccah and John B.Goodenough, Mat.Res.Bull., 36. ~' 191(1969). .P.Badaud and J.0maly, C.r.Acad.Scl., c274, 178 (1972). 37. I.S.Shaplygin, A.V.Bromberg and V.A.Sokol~Zh.Neorg.Kh~m. (Russian), 15, 8305 (1970~. 38. I.S.Shaplygi'Hand V.B.Lazarev, Zh.Neorg.Khim.(Russian), 18, 525 (1973). _ . 39. Y~.s.Shaplygin, l.I.Procychev and V.B.Lazarev, za~.aeorg. Khlm.(Russian), 23, 946 (1978) (in press). 40. V.B.Lazarev and I.S.Shaplygin, Zh.Neorg.Khim.(Russlan), 19, 2388 (1974).
On the 70th birthday of Academician N. M. Zhavoronkov
ELECTRICAL CONDUCTIVITY OF PLATINUM METAL - NONPLATIUM METAL DOUBLE OXIDES V. B. L a z a r e v and I. S. Shaplygin Kurnakov Institute of General and Inorganic C h e m i s t r y Leninsky Avenue 31, Moscow 117071, USSR
(Received J a n u a r y 3, 1978; Communicated by R. Roy)
ABSTRACT The authors have determined an e l e c t r i c a l conductivity type for 145 platinum metal-nonplatinum metal double oxides such as Ln2M207 pyrocblores, AMO3 perovskites, ARh204 spinels, Rh MO4 rutiles, MxPd304 and MxPt304 bronzes, etc. It was shown that conductivity type is a c e r t a i n function of the d - e l e c t r o n configuration of platinum metal ion in the double oxide, n a m e l y the double oxide with d 4 o r d 5 electron configuration for platinum m e t a l ion exhibits m e t a l l i c conductivity while the oxide with d 6 or d 8 electron configuration for the ion is a semiconductor.
The systematical investigation of electrical properties of platinum metal (PM) - nonplatinummetal (NM) - oxygen ternary compounds has shown the same conductivity type of the platinum metal simple oxide as the corresponding PM-N~ double oxide for any nonplatinummetal (1,2). Nevertheless, platinum metal mixed oxides were known which had none stable platinum metal simple oxide as a precursor. ~or example, we did not know stable Ru203 for LaRuO 3 mixed oxide since the only stable oxide form for ruthenium is ruthenium dioxide RuO$ . In Table I we give 145 platinum metal mixed oxides for which experimental data about conductivity type are known. Analysis of the data from electrical and optical measurements results in the conclusions: i) if platinum metal ion electron configuration in any double oxide is d ~ or d s theoternary compound exhibits metallic conductivity; ii) for d 6 or d" electron configuration double oxide is a semiconductor (I). Arthur Sleight (3) for the first time has prepared a new pyrochlore Bi2Pt20~ for which semlconducting behavior was expected since Pt(IY) is 5d ~ and there would be a filled t2~ band. Electrical measurements on a pellet of Bi2Pt207 confirmed-the idea (a room temperature resistivity of 8 ohm-cm with the activation energy of 0.15 eV). 229
230
V . B . LAZAREV, et al.
Vol. 13, No. 8
TABLE I Platinum metal mixed oxides for which electrical properties are determined
I group A - LiPt 304, LiRh02' NaRh02' KRh02' Li2RuO 3 'Li21rO 3' Li 20 sO 3 'Na 20 sO 3 'Na21r03 'Na 2P t 03 ,Na 2Pd304, K2Pd02 , K2RuO 3" B - CuRh204,OUoo5Pt304,AgRhO2,CuRh02" I! group A - BeRh204, MgRh20 4, CaRh204, SrRh204' BaRb204' Ca2Ru04' Ca2IrO4,CaPd304,BaPd304,MgPd304,Ca0sO3,SrOs03' BaOsO3,CaRuO3,BaRuO3,CaIrO3,SrIrO3,BaIrO3,Ca4Pt06 , SrRuO 3 • B - CdPd304,CdRh204, ZnRh204,CdOs03" If|group A - Ln2RU2OT,Ln2Ir2OT,Ln2OS2OT'Ln2Pt207 (Ln - all lanthanides except promethium), Sm2Pd2OT,Sm2Rh207 , Sc2Rh207,LnRhO3,LaRu03 • B - RhBO3,InRhO3,T12RU2OT,T12Ir2OT,T12Pt2OT'T12Rh207' |V group A B V group A B ~Igroup A B ~[group A ~gro~p B
T120s207 • No compounds Pb2Ru206,Pb2Ir206,Pb2Os206,Pb2Pt206+x (for x=O;0.3 and 0,7), PbRh204,PbPd0 2. RhVO4,RhNbO4,RhTa04 • RhSbO4,Bi2PdO4,BiRhO3,Bi2Rh206,Bi2Ru207'Bi2Ir207 '
Bi2Os207,Bi2Pt207- Rh2Mo06,Rh2WO6,RhOr03 • - Rh2TeO 6. -~LRh204,NnRhO 3. - CoRh204,NiRh204,Co2RuO4,Nioo8Pt304,O°o.6Rt304"
In the present study we consider in de~ail crystal chemistry and electrical properties of double oxides containing platinum and nonplatinum metals for different nonplatinummetals in the oxides. I. All six platinum metals give a number of compounds with alkaline metals (with a different stoichiometrie). For the first time monoclinic Li2RuO 3 was prepared by Dulac (4); later it was repared and studied in detail by the authors of this paper 2,5). Orthorhombic Li21r03, Na21r03 and Na2Pt03 were described
~
Vol. 13, No. 3
CONDUCTMTY OF DOUBLE OXIDES
231
in ref.6; however only Li2IrO ~ is really orthorhombic while two others have monoclinic structure after McDaniel (7) and it was confirmed in our article (5). Orthorhombic Na2Pd304 (8), K2Pd02 (9), hexagonal LiRhO 2 (10) and cubic LiPt304 (11) have been described too and all the phases were also prepared and nvestigated by us. Both isostructural hexagonal NaRh02, KRh02 space group R3m, ~ - N a F e 0 2 structure type) and orthorhombic Li2OsO~ and Na2Os0~ (Li2IrO 3 type) together with orthorhombic K~Ru03 ~ (K2SnO q structure type) were synthesized by the authors o~ the paper ~5). Li2MO 3 (M= Ru, Os, Ir), NaoOsO~, Na2IrOq and K2RuO 3 have a room temperature resistivity o~ below 2.1x16 2 ohm,cm and exhibit metallic conductivity. Other abovementioned phases are semiconductors with ~ 2 9 8 K >7xI0~ ohm-cm. We were the first to prepare the new compounds Rb2Pd02, Cs2Pd02, RbRh02 and CsRh02; they are hygroscopic, nonisostructural with Na, K analogs and have semiconducting properties.
~
For IB Group five phases with_platinum metals are known: tetragonal spinel CuRb204 (s.g. I45d) (12), hexagonal CuRhO 2 (10) and AgRhO 2 (13) with delafosslte structure, cubic Cuo.sPt304 (NaxPt304 type) (14) and orthorhombic CuPtxOg (15). The former four compounds are semiconductors, electri~aI properties of CuPt306 prepared by Olaf Muller and Rustum Roy were not studiea. k
2. Ternary compounds PM-NM-oxv~en wish NM of II Group a r e nown zor each PM and they have different structure types (see Table I). There are cubic compounds (spinels BeRh204, MgRh204, ZnRh204 and CdRh~O 4 or phases CaPd304, MgPd304, CdPd30÷ with NaxPt304 structure), orthorhombic CaRh2Oa, ~ u O ~ and MOsOx for M=Oa, St, compounds with hexagonal layer-structGre (BaIr05, BaRuO 3 , BaOsOa), dlmorphic SrIrO 3 and Ca4PtO 6 and so on in systems PM-NM--oxygen. According t o the rules formulated in ref.1 for all these compounds containing Ru(IY), Ir(IY) and Os(IY) namely where PM ion has d~ or d ~ electron configuration metallic conductivity must occur while Pd(II,IY), Pt(II,IY), Rh(III) compounds (i.e. with d @ and d$ PM ions) have to be semiconductors. The rules hold true for all compounds of Table I from known experimental data and in the future we will not point out the conductivity type for each of the represented groups of compounds. We believe that the reader will do the simple procedure himself according to the formal oxidation state of PM in each double oxide; we shall comment some "unusual" cases only. Existance of two polymorphous modifications doesn't affect electrical properties and the concept is confirmed by SrIrO 3 (16) or Ca~PtO 6 (17). Por Zn2PtO 4 (13), Cd2PtO 4 (19), H~Pt306 and C dPt306 which were prepared by Olaf Muller and Rustum Roy for the first time electrical properties were not investigated; it concerns also Zn2PdO 4 prepared by Paul Hagenmuller with colleagues in 1976 (20) i and we did not include all these phases in Table I. Ii
x)
Recently Prof. Hagenmuller has reported a rather high c o n of Zn~Pd O~but conductivity type for the compound was not determined. (Private communication). ductivity
232
V . B . LAZAREV, et al.
Vol. 13, No. 3
3. The p~rrochlores Ln2RuoO 7 (13 compounds) and Ln2Ir207 (12 compounds)were prepared NyBertaut et al for the Zirsttime (21,22) and magnetic properties of Ln2Ru207 were also investigated (23,24), however electrical measurements of these two families were not carried out up to now (with the exception of some compounds). We have determined the electrical properties of Lu2Ru207 and Lu2Ir207 together with the same measurements for 13 pyrochlores Ln20s~O 7 (25). Electrical properties of other ruthenates and irridate~ ~re given in ref.2. Sleight (26) and Hoekstra and Gallagher (27) have prepared Ln~Pt~O 7 pyrochlores in 1968 however electrical behavior of th~ eleSen compounds for Ln= Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, Lu (all of these were synthesized under high pressure ~ 4 0 kbars) was determined by us in 1975 only. We have found semiconducting behavior for the compounds. In ref.2 we have described properties of MoRho07 (M=Sm, Sc, TI), Sm~l~07 and TloPto07 which were synthesizer under hlgh^pressu~e ~40-60 kbaSs)"a6d at high temperature (8001200~C) (together with G.L.Aparnikov). Tha results are given in Table 2. Here we give unit cell parameter and resistivity for high pressure ~yrochlores T12Ru207, T120s207 and T12Ir207. Experimental data from Table 2 don't confirm the conclusion of ref.28 about semiconducting behavior of T12Ruz0 7 and T12Rh207 although a room temperature resistivity in (28) for TloRh~0~ coicides with our data ( ~ ~ for TI~Rh~0~ is 6xSG4~ ~hm-cm in ref.28). The absen~°~f any aSso~p~ion bands in infrared spectra of T12M207 for M= Ru, Ir, Os, Rh also proves that T12Ru207 and TI2Rh207 are metallic. Por semiconducting T12Pt207 we have found four absorption bands at 680, TABLE 2 Unit cell parameters and electrical properties of some M2M207 pyrochlores ,i
Compound
a,A
~298KOhm-cm
Sm2Pd207 TI2Pt207 Sc2Rh207 Sm2Rh207 T12Rh207 T120s207 T12Ir207 TI2Ru207
10.307 10.133 9.800 10.302 10.155 10.306 10.218 10.210
6.6~I01 4.1xi0 -I 2o7x10 -2 5.8x10 -3 8.0xi0 -4 4.0xi0 -4 4.8xi0 -3 3.3xi0 -4
Conductivity type Semiconducting Semiconducting ~etallic Metallic Metallic Metallic Metallic Metallic
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CONDUCTIVITY
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OXIDES
233
TABLE 3 Some properties of other pyrochlores with iridium and ruthenium j
After ref.3 Compound
Bi21r207 Bi2Ru207 Nd2Ru207 Eu2Ir207 Eu2Ru207
a, A 10.315 10.292 10.330 10.290 10.255
2298K' ohm-cm 8.2xi0 -3 4.7xi0 -3 4.2xi0 -3 6.0xi0 "3 7.7xi0 -3
j
.
After ref.31 a, A 10.3269 10.2993 10.3419 10.3025 10.2503
~ 298K' ohm-cm
.
.
.
.
.
.
.
Other data ~ 298K' ohm-cm
2xi0 -3 7xi0-3(32) 7xi0 -4 2~4xI0-3(32) . . . . 1.5x10 -2 -6xi0 ° --
560, 450 and 360 cm -I in IR spectrum and the result coincides with spectral data of Hoekstra and Siegel (29). To be noted that an existance of dis~inc~ absorbtion maxima in IR spectrum of a compound is the result of it's semiconducting properties (see for example, ref.30). Therefore for instance the spectral data for M2Pt207 from (27) give another experimental proof of semiconduc~ing properties of the compounds which also follows from our electrical measurements. We emphasize espesially that IR spectroscopic data and corresponding electrical measurements allow to determine metallic or semiconducting properties of transition metal mixed oxides. We have found that for all LnRRu207, Ln20s207 and. Ln.2Ir270 pyrochlore families conductivity type did not depena on lanthanide atomic number. All these compounds in the whole interval (i.e. from Pr to Lu) are metallic. IR spectra of these compounds have no absorption bands in the region 2000-200 cm -I. We should like to note an anionic sublattice dependence on unit cell parameters as well as on dissolved admixtures, that are first of all superstoichiometric M203and NO or a simple nonplatlnum oxide. We have found tha~ ~nit ce~l parameters for Nd2Ru207, Eu2Ru207 and Eu2Ir207 are very close to published values: 1 0 . 3 3 1 A and I0.29A respectively according to (21,22) and I0.293A for Eu2Ir207 after (33). Eor other compounds from Table 3 we have r~ce~v@d unit cell parameters coinciding~with data from ref.31, however Eu2Ru207 resistivity is less 10 factor from our measurements than the value given in ref.31.
234
V . B . LAZAREV, et al.
Vol. 13, No. 3
Shannon (29) has found semiconductlng properties for InRhO . We have measured electrical properties of single crystals RhBO 3 and polycristalline perovskites L r~h03, where Ln is yttrium and all lalthanides but promethium (3). There are no compounds in the systems TiO2-ND2, ZrO2-MO 2 ( ~ Ru, Os, Ir, Pt), TiO2-Rh203, Zr02-Pd0 and ZrO2-Rh20 B. There are only narrow fields of-solid solutions in these-systems. We have found a new compound PdTi0~+ x in system PdO-TiO 2 under high pressure and the phase is a-s~miconductor. Doubl~ oxides containing lead are characterised for each of platinum metals (35-38). There are only 22 double oxides of PM-NM-oxygen type for elements of Y-YIII Groups of Periodic Table up to now. Pour compounds Rh~O 4 (M= V, Nb, Ta, Sb) with futile structure were prepared earlier but we have reprepared them and studied electrical and spectral properties thls year (39) together with earlier prepared Bi2PdO 4 (40). Resistivity and conductivity type for double oxides of PM-NM-oxygen ternary system where N M - metal of Y-YIII Groups we have determined just now and found that all the compounds are semiconductors except for metallic Bi2Ru 0 , Bi21r20 , Bi20s 07 and Co2Ru04. Finishing the comments of ~a~le I we s~ould li~e to emphasize that formal oxidation state of manganese c h a ~ e s ~oichiomet~iq and crystalline structure of a compound for ~m"Rh~O 4 and ~u~Rh=O~ but a difference between resistivity values ~s small and bo~h compounds are semiconductors. We have the opposite case namely a change of conductivity type from semiconducting for SmRhmO3to metallic for Sm2RE207 i.e. it is connected with the change of PM electron configuration from d 6 to d ~. We are glad to have the examples because the fact is the best illustration for another confirmation of possibility to predict a conductivity type in double oxides of ternary system PM-NM-oxygen on the basis of the fundamental rules which were formulated in 1974 for the first time (I). References 1. I.S.Shapl~gin and V.B.Lazarev, Doklady of Acad.Sci.of USER, 218, 629 (1974) (in Russian), N.~.Zhavoronkov, V.B.Lazarev a-~ I.S.Shaplygin. Proc.X Meeting on chemlstry~ technology and analyses of noble metals, Novosiblrsk, 1976. 2. V.B.Lazarev and I.S.Shaplygin, Zh.Neorg.Khim.(Russlan), 23, 295 (1978) (in press). 3" A.W.Sleight, ~at.Res.Bull., ~, 1177 (1974)~ J.-P.Dulac, C,~.Acad.Sci., ~ , 223 (1970). V.B.Lazarevand I.S.Shaplygln, Zh.Neorg.Khim.(Russian) 23, 1222 (1978) (in press). 6. J.J.Sheer, A.E.van Arkel and R.D.Heyding, Can.J.Chem., 33, 683 (1955). 7. C.L.McDaniel, J.Solid State Chem., ~, 139 (1974). 8. M.Wilhelm and R.Hoppe, Z.anorg.allgem.Chem., ~ , 60 (1974). 9. H.Sabrowski, W.Br~nger and D.Schmitz, Z.Naturo~sch., 29b, 10,(1974). 10. P.Bertaut and J.-P.Dulac, J.Phys.Chem.Solids, 21, 118
(1961),
11. D.Bergner and R.Kohlhaas, Z.anorg.allgem.Chem., (1973).
401, 15
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CONDUCTIVITY OF DOUBLE OXIDES
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12. P.Bertaut, F.Porrat and J.-P.Dulac, C.r.Acad.Sci., 249, 726 (1959). 13. R.D.Shannon, D.B.Rogers and C.T.Prewitt, Inorg.Chem., 10, 713 (1971). 14. V.B.Lazarev and I.S.Shaplygin, Doklady Acad.Sci.of USSR, ~, 894 (1977) (in Russian). 15. 01&f Muller and RustumRoy, J.Less-Common Mat., 19, 809 (1969). 16. J.M.Longo, J.A.Kafalas and R.J.Arnott, J.Solid State Chem., ~:
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17. S.Shaplygin and V.B.Lazarev, Mat.Res.Bull., 10, 903(1975). 18. Olaf Muller and Rustum Roy, Mat.Res.Bull., ~, ~ (1969). 19. 01af ~luller and Rustum Roy, J.Less-Common Mat., 20, 161 (1970). 20. G.Demazeau, l.Omeran, M.Pouchard and Paul Hagenmuller, Mat. Res.Bull., 11, 1449 (1976). 21. P.Bertaut~ r.Porrat and M.O.Montmory, C.r.Acad.Sci., 256, 829 (1959). 22. M.C.Montmory and ?.Bertaut, C.r.Acad.Sci., 252, 4171 (1961). 23. J.Rosset and D.K.Ray, J.Chem.Phys., 37, 1017 ~1962). 24. R.Aleonard, P.Bertaut, M.C.Montmory and R.Pauthenet, J.Appl. Phys., Suppl.to 33. 1205 (1962). 25. I.S.Shaplygin and V.B.Lazarev, Mat.Res.Bull., 8, 761 (1973). 26. A.W.Sleight, Mat.Res.Bull., i, 699(1968). 27. H.R.Hoekstra and P.Gallagher, Inorg.Chem., L 2453 (1968). 28. A.W.Sleight and J.L.Gillson, Mat.Res.Bull.,-6, 781 (1971). 29. H.R.Hoekstra and S.Siegel, Inorg.Ohem., ~, 171 (1968). 30. C.A.Wer% and R.M.Thomson, Physics of Solids. McGrow-Hill Book Co., N-Y., 1964, Chapter 10. 31. R.J.Bouchard and J.L.Gillson, ~t.Res.Bull., 6. 669 (1971). 32. P.L.van Loan, J.Camad.Oeram.Soc., 40, 49 (197T). 33. S.J.Schneider, J.L.Waring and R.E.Tressler, J.Res.NBS, 69A,
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_
.
_
34. ~ . S h a n n o n , Inorg.Chem., ~, 1474 (1967). 35. J.M.Longo, P.M.Raccah and John B.Goodenough, Mat.Res.Bull., 36. ~' 191(1969). .P.Badaud and J.0maly, C.r.Acad.Scl., c274, 178 (1972). 37. I.S.Shaplygin, A.V.Bromberg and V.A.Sokol~Zh.Neorg.Kh~m. (Russian), 15, 8305 (1970~. 38. I.S.Shaplygi'Hand V.B.Lazarev, Zh.Neorg.Khim.(Russian), 18, 525 (1973). _ . 39. Y~.s.Shaplygin, l.I.Procychev and V.B.Lazarev, za~.aeorg. Khlm.(Russian), 23, 946 (1978) (in press). 40. V.B.Lazarev and I.S.Shaplygin, Zh.Neorg.Khim.(Russlan), 19, 2388 (1974).