prof. dr. E.W. Gorter his contributions to structural chemistry in - PowerPoint PPT Presentation

prof. dr. E.W. Gorter his contributions to structural chemistry in relation to physical properties Jacob van Dijk (CHG) Kees Plug (CHG) 1

Compliments by W.G.Burgers (1961) 2

Evert Willem Gorter 1912 (Leiden) -1972 (Leiden) 3

Gorter (left) with J. van Ormondt 4

Ferrites • Early history – Verwey was first to exploit this research line 1935 – Van Arkel published article with Verwey as early as 1936 – Snoek did write first booklet about ferrites 1947 • Why did ferrites receive so much attention? – availability cheap raw materials – electrical isolator – flexibility of composition & magnetic properties – novelty 5

Spinel Mg Al 2 O 4 6

Dilution of M(II)Fe 2 O 4 with Zn 7

Predicted Néel anomaly Li 0,5 Fe 2,5-a Cr a 0 4 Néel theory 8

Super-exchange “model Gorter” Spin ordering BaFe 12 O 19 9

Letter E.W.Gorter 10

Gorter: Thesis and Inaugural Address 11

Gorter’s approach Chemical Composition Crystal Structure Physical Properties 12

Gorter with his “blokje” 13

Gorter blokje 14

Close packed layers A B C A B C 15

CCP = Cubic Close Packed FCC = Face Centered Cubic B A C A 16

Gorter blokje of NaCl + NiAs 17

Gorter blokje of CdCl 2 + Cd(OH) 2 18

Gorter blokje of TiO 2 Rutile + Anatase 19

Gorter blokje of spinel 20

Gorter’s representation of CaFe 2 O 4 Face shared octahedra Ca-ion in 9-coordination 21

Hyde’s representation of CaTi 2 O 4 Face shared octahedra 22

Conclusions – Gorter was eminent scientist/group leader at Philips directly after the war • Ferroxcube / Ferroxdure • Confirmation Neel theory • Model for super exchange in hexagonal ferrites – Gorter’s time as professor at Leiden • Too short to form a real school • Unique way to represent, understand and inter-relate crystal structures • Methodology to predict crystal structures 23

We like to thank the following persons who helped us during the preparation Family man: Philips employee: • Eline Schepers (daughter) • Frans Kools • Freek Schepers (grandson) • George Blasse • Nol Broese van Groenou Professor Leiden: • Coen Rooijmans • Daan IJdo (co-worker) • Guus Schippers (assistant) • Jan Reedijk (em prof Leiden) 24