1. Study of magnetic properties of a new vanadate Cu 13 Fe 4 V 10 O 44 Janusz Typek Institute of Physics, West Pomeranian University of Technology, Szczecin, Poland

2. Outline Why new vanadate Cu 13 Fe 4 V 10 O 44 Sample preparation and chemistry Measuring methods: dc magnetometry and EPR Results of dc magnetization measurements Results of EPR measurements Conclusions about magnetic structure

3. Why to study Cu 13 Fe 4 V 10 O 44 ? Similar compounds from the same system of vanadates have important catalytic properties Defect structure and grain surface play an important role in catalysis Knowledge of magnetic defects and ions may lead to better understanding of the mechanism of the catalytic processes

4. Sample preparation 13 CuO + 5 V 2 O 5 + 2 Fe 2 O 3 → Cu 13 Fe 4 V 10 O 44 A. Blonska-Tabero, J. Therm. Anal. Calorim. 110 (2012) 161

5. Structure – possible types Lyonsite,  -Cu 3 Fe 4 (VO 4 ) 6, a new iron-copper vanadate mineral six isolated VO 4 tetrahedra FeO 6 octahedra square-planar CuO 4 groups Howardewansite Mineral NaCuFe 2 (VO 4 ) 3 In figure Mn 3 Fe 4 (VO 4 ) 6 VO 4, FeO 6, MnO 5, MnO 4 polyhedra

6. EPR and dc magnetometry Magnetic resonance spectrometer X-band, Bruker E 500 (1997) Magnetic Property Measurements System MPMS XL-7, Quantum Design (2011) Dynamics τ~10 -10 sStatic τ~1 s

7. dc magnetization: susceptibility study

8. dc magnetization: reciprocal susceptibility

9. dc magnetization: Curie-Weiss law Fe 3+, 3d 5, high-spin S=5/2, L=0, J=5/2,, for g=2  μ=5.9 μ B

10. dc magnetization: high-temperature range energy non-magnetic magnetic

11. dc magnetization in an external field T [K]g J C H [μ B /f.u.·Oe] 21.15(2)3.00(3)·10 -5 52.01(3)2.00(5)·10 -5 2009.655(6)0 2509.949(2)0 Modified Langevin AFM clusters

12. EPR: spectra and fitting Lorentzian lineshape B r - resonance field ΔB -linewidth I int – integrated intensity

13. EPR: g-factor

14. EPR: linewidth

15. EPR: linewidth vs. resonance field

16. I 0 =5.373·10 10, C 2 =1.13·10 12, T CW =-60.2 K. EPR: integrated intensity AFM clusters

17. General picture of the magnetic state of Cu 13 Fe 4 V 10 O 44

18. THE END Thank you!