Structural and spectroscopic characterization of double perovskites La2Co4/3M2/3O6 (M= V, Nb or Ta) and La4/3B2/3Co4/3Ta2/3O6

V.C. FUERTES; M.C. BLANCO; D.G. FRANCO; J.M. DE PAOLI; F.P. DE LA CRUZ; N.E. MASSA; R.E. CARBONIO

Denver, Colorado, USA

Congreso; American Physical Society March Meeting; 2007

American Physical Society

Structural and spectroscopic characterization of double perovskites La2Co4=3M2=3O6 (M= V, Nb or Ta) and La4=3Bi2=3Co4=3Ta2=3O6 V.C. FUERTES, M.C. BLANCO, D.G.FRANCO, INFIQC, UNC, C¶ordoba, Argentina, J.M. DE PAOLI,CNEA-CAB, Bariloche, Argentina, F.P. DE LA CRUZ, N.E. MASSA,LANAIS EFO-EQUINOR, UNLP, CP 962, 1900 La Plata, Argentina, R.E. CARBONIO, INFIQC, UNC, C¶ordoba, Argentina | We report the synthesis of the title compounds and the re¯nement of their structures using Rietveld analysis of powder XRD data. All belong tothe monoclinic space group P21/n. While the crystallographic formula can be written as La2(Co)2a(Co1=3M2=3)2bO6 for M= Nb or Ta, indicating the highest possible order for the cations, we ¯nd La2(Co2=3V1=3)2a(Co2=3V1=3)2bO6for V replacement indicating the high-est disorder con¯guration. The cell volume for La2Co4=3M2=3O6 decreases as the ionic radius of the M5+ cation decreases. These compounds were previously shown to be ferrimagnetic with Curie temperatures in the range 60-70 K. Since the incorporation of cations with thesp hybridized lone pair can potentially induce ferroelectric properties,we also synthesized La4=3Bi2=3Co4=3Ta2=3O6 where we found a partialcations disorder. Crystal and magnetic structures re¯ned with powder neutrons di®raction measurements as well as the infrared spectroscopiccharacterization, now in progress, will be presented.2Co4=3M2=3O6 (M= V, Nb or Ta) and La4=3Bi2=3Co4=3Ta2=3O6 V.C. FUERTES, M.C. BLANCO, D.G.FRANCO, INFIQC, UNC, C¶ordoba, Argentina, J.M. DE PAOLI,CNEA-CAB, Bariloche, Argentina, F.P. DE LA CRUZ, N.E. MASSA,LANAIS EFO-EQUINOR, UNLP, CP 962, 1900 La Plata, Argentina, R.E. CARBONIO, INFIQC, UNC, C¶ordoba, Argentina | We report the synthesis of the title compounds and the re¯nement of their structures using Rietveld analysis of powder XRD data. All belong tothe monoclinic space group P21/n. While the crystallographic formula can be written as La2(Co)2a(Co1=3M2=3)2bO6 for M= Nb or Ta, indicating the highest possible order for the cations, we ¯nd La2(Co2=3V1=3)2a(Co2=3V1=3)2bO6for V replacement indicating the high-est disorder con¯guration. The cell volume for La2Co4=3M2=3O6 decreases as the ionic radius of the M5+ cation decreases. These compounds were previously shown to be ferrimagnetic with Curie temperatures in the range 60-70 K. Since the incorporation of cations with thesp hybridized lone pair can potentially induce ferroelectric properties,we also synthesized La4=3Bi2=3Co4=3Ta2=3O6 where we found a partialcations disorder. Crystal and magnetic structures re¯ned with powder neutrons di®raction measurements as well as the infrared spectroscopiccharacterization, now in progress, will be presented.4=3Bi2=3Co4=3Ta2=3O6 V.C. FUERTES, M.C. BLANCO, D.G.FRANCO, INFIQC, UNC, C¶ordoba, Argentina, J.M. DE PAOLI,CNEA-CAB, Bariloche, Argentina, F.P. DE LA CRUZ, N.E. MASSA,LANAIS EFO-EQUINOR, UNLP, CP 962, 1900 La Plata, Argentina, R.E. CARBONIO, INFIQC, UNC, C¶ordoba, Argentina | We report the synthesis of the title compounds and the re¯nement of their structures using Rietveld analysis of powder XRD data. All belong tothe monoclinic space group P21/n. While the crystallographic formula can be written as La2(Co)2a(Co1=3M2=3)2bO6 for M= Nb or Ta, indicating the highest possible order for the cations, we ¯nd La2(Co2=3V1=3)2a(Co2=3V1=3)2bO6for V replacement indicating the high-est disorder con¯guration. The cell volume for La2Co4=3M2=3O6 decreases as the ionic radius of the M5+ cation decreases. These compounds were previously shown to be ferrimagnetic with Curie temperatures in the range 60-70 K. Since the incorporation of cations with thesp hybridized lone pair can potentially induce ferroelectric properties,we also synthesized La4=3Bi2=3Co4=3Ta2=3O6 where we found a partialcations disorder. Crystal and magnetic structures re¯ned with powder neutrons di®raction measurements as well as the infrared spectroscopiccharacterization, now in progress, will be presented.