TRANSITION METAL CHEMISTRY Volume 26, Numbers 4-5, 384-387, DOI: 10.1023/A:1011055306645 Synthesis, crystal structure and magnetic property of a binuclear iron(III) citrate complex Xiang Hao, Yongge Wei and Shiwei Zhang
Dimer model, antiferromagnetic interaction.
Za dva Fe3+ S=5/2 pricakujemo peff 8.37 BM. Pravilno, ko iz enega pricakovanega 5.9 BM, izracunamo C, pomnozimo z dva, preracunamo peff. Oni so izmerili 8.2 at RT. Low T susceptibility (below 5 K), susceptibility rises sharply due to paramagnetic impurities such as the monomeric Fe3+.
Susceptibility so fitali iz reference: Polyhedron in reference there. Ne da se mi iskati.
Potem nekaj pisejo kdaj je lahko FM interakcija med Fe .. ce so "face-shared octahedral dimers".

Solid State Sciences 6 (2004) 853–858 The first ferric carboxylate with a three-dimensional hydrid open-framework (MIL-82): its synthesis, structure, magnetic behavior and study of its dehydration by Mössbauer spectroscopy Morgane Sanselme, Jean-Marc Greneche, Myriam Riou-Cavellec, Gérard Férey, francozi
Struktura: ferric carboxylate with a 3D open structure that has been synthesized up to now. Its structure is built up from chains of octahedra connected by carboxylate ligands; it displays small channels filled by water molecules
Zanimive magnetne lastnosti, o katerih so malo napisali. Pri 5 K AFM, metamagnetism, Pri visjih temperaturah X(T) = konstant!? Zakaj ni paramagnet? Mogoce koristno pisanje o "According to Goodenough’s overlap orbital theory [16], Fe3+ –O–Fe3+ superexchange interactions are antiferromagnetic for 180 deg superexchange angle. The low TN is indicative of weak couplings due to the small superexchange angle (Fe(1)–O(2) –Fe(1): 126.59(7) deg and justifies the metamagnetic transition observed for applied magnetic field above 0.5 T (Fig. 9). Referenca 16 je: J.B. Goodenough, Magnetism and the Chemical Bond, Interscience, New York, 1963.

Solid State Sciences 4 (2002) 1419–1424 A new three-dimensional iron fluoride pyromellitate K(H3O)[Fe2F2(C10O8H2)]·3.5H2O Morgane Sanselme, Myriam Riou-Cavellec, Gérard Férey, francozi
Struktura: The 3D structure is built up from chains of [FeO4F2] octahedra sharing trans fluorine vertices. These chains are connected by 1,2,4,5-benzenetetracarboxylate anions leading to a 3D open structure: K+ , H3O+ and water molecules are located in a complex way within the channels
Magnetism: H = 0.5 T (BUUU!), X-1 vs T shows AFM with TN = 10 K. Hight temp: C = 4.63 emu K/mol Fe2+. This value is high for Fe2+, but has been observed in other iron(II) compounds. Theta = -74 K. Tudi ti pisejo o Goodenough: "Within the chains, Fe(1)–F(2)–Fe(3) and Fe(1)–F(1)–Fe(2) superexchange angles are respectively 118.5 deg and 119.7 deg. Strong antiferromagnetic 180 deg superexchange interactions should be observed according to the Goodenough’s rules [8]: whatever the correlation or delocalization mechanism, d6–d6 180 deg -type interactions are antiferromagnetic. However, the weak values of the superexchange angles (~ 120 deg) induced by bridging carboxylate functions (since O...O distances within CO2- groups are about 2.24(1) A) probably generate a halfway situation. The competing contribution of 90 deg -type superexchange interactions which can be either antiferromagnetic or ferromagnetic (by correlation mechanism for eg–p sigma –p sigma' –eg orbital overlap) is probably responsible for the weakening of the strong antiferromagnetic 180 deg sigma-interaction along a trans-chain."

Solid State Sciences 4 (2002) 1221–1225 A new three-dimensional iron trimesate: [Fe3(H2O)5(C9O6H3)2·3H2O] or MIL-65 Myriam Riou-Cavellec , Gérard Férey, francozi
Structure: Its structure is built up from dimers of iron(II) in octahedral coordination and also isolated [FeO4 (H2O)2 ] octahedra. Both units are connected by 1,3,5-benzenetricarboxylate anions leading to a threedimensional open structure; water molecules are located in channels.
Pravijo, da je paramagneten, kazejo le M(H) pri treh temperaturah. Imajo Fe2+.

Polyhedron 22 (2003) 1921-1192, Binary metal(II)
/pyromellitate coordination polymers, M2(pm) (=/Co, Fe, Mn): synthesis, structures and magnetic properties Hitoshi Kumagai, Karena W. Chapman, Cameron J. Kepert Mohamedally Kurmoo
Structure: The structure consists of 1D chains of edgesharing MO6 octahedra that are connected into layers via O-C-O bridges. The layers are held together by the pyromellitate (pm4-) backbone to give a 3D structure where each ligand participates in an unprecedented 12 coordination M-O bonds to ten metal atoms. Magnetism: Co .. mocno Fm, ZFCFC razcep. Mn in Fe AFM. Vsi so divalentni compounds. Naredili se cp in Moesbouer. Dober clanek po eksperimentih, manj glede razlage. Nic niso fitali, ne povej kaksen AFM je za Mn in Fe vzorca.

Solid State Sciences 4 (2002) 267–270 Ferromagnetism of the hybrid open framework K[M3(BTC)3]·5H2O (M=Fe, Co) or MIL-45 M. Riou-Cavellec , C. Albinet , C. Livage , N. Guillou M. Nogues , J.M. Greneche , G. Férey
MIL-45 or K[M3 (BTC)3]·5H2O (M=Co, Fe) presents a hybrid 3D open structure based on undulating octahedral chains linked by two different trimesate anions. This compound exhibits ferromagnetic behaviour below 10 K for the pure Co phase and 20 K for the mixed-metal (Co, Fe) phase. Ni X(T)-ja. Samo M(H)ji.

Dalton Trans. , 2003, 1148 – 1152 Hydrothermal synthesis and characterization of the ?rst oxalate–bta mixed-ligand three-dimensional frameworks: Li-Juan Zhang, Ji-Qing Xu,* Zhan Shi, Wei Xu and Tie-Gang Wang China,
Both of the complexes have intramolecular antiferromagnetic interactions. Izmerili X(T), maximum v X, AFM, Curies Weiss fit, nic vec.

CHEM. COMMUN., 2002, 2172–2173: [Fe2(C10O8H2)]: An antiferromagnetic 3D iron(II) carboxylate built from ferromagnetic edge-sharing octahedral chains (MIL-62) M. Sanselme, J. M. Greneche, M. Riou-Cavellec* and G. Férey*
Slaba analiza magnetnih lastnosti: The magnetization measurements (between 4.5 and 290 K) used a SQUID magnetometer with applied fields in the range 0–5.5 T. The X-1 (T) curve at low fields (Fig. 2(a)) is typical of antiferromagnetism below TN = 25(1) K; moreover the ZFC–FC and M(H) curves at 4.5 K under 0.01 T (Fig. 2(b)) indicate a non-canted behaviour. Above 150 K, the Curie–Weiss law is verified, with a Curie constant of 7.874 emu Oe-1 K mol-1 and an experimental magnetic moment of 7.94 mB mol-1, in fair agreement with the expected theoretical value of 7.64 mB mol-1 when some L–S coupling for Fe2+ in high spin octahedral coordination is taken into account. Finally, in this chain-like compound, the weak positive value of qp (+7 K) is difficult to rationalize in terms of low-dimensional magnetism since Thetap should be much higher than TN. Clanki

Namigi iz èlankov

Fluoroargentates (F-AG spojine) ... zanimive, ker nekateri superprevodni.

The spin-gap system is a magnetic system having the singlet ground spin liquid state with a finite excitation gap. Glej Dagotto, Science 271, 618 (1996)

From Olivier Kahn, Molecular Magnetism, Diamagnetic contribution: Here is an explanation from Olivier Kahn, Molecular Magnetism: .... Diamagnetism is an underlying property of matter. It is always presented, even when it is masked by the paramegnetism. The diamagnetism is due to the interaction of the magnetic field with the motion of the electron in their orbits. ALL ELECTRONS (even those from inner shells) contribute to diamagnetism! For example classical explanation is at http://www.sjsu.edu/faculty/watkins/diamag.htm. It is connected with a "current" loop (electron around the nuclei) that oppose to the changes of magnetic flux through it. Rough estimation of the diamagnetic susceptibility is X_D= k M 1E-6 cm3/mol. where M is the molecular weight of the compound and k is a factor varying between 0.4 and 0.5. For more accurate values of X_D one can look at the Pascal tables. X_D is almost temperature independent and its contribution to the magnetization (M_D = X_D*H) is linear with field up to 5 T and much more.

A kagome lattice is an arrangement of laths composed of interlaced triangles such that each point where two laths cross has four neighboring points. Although called a lattice, it is more closely related to the trihexagonal tiling than to a mathematical lattice. Its name derives from the Japanese word kagome, meaning the pattern of holes ("me", literally "eyes") in a basket ("kago").

Doktorat o nanoparticles http://students.washington.edu/mbeerman/Research/Section3.htm

bulk MnO ima theta iz Curie-Wies -548 K (RWTyler, Phys Rev 44, 776 (1933)). Ima tudi prehod pri 122 K. (Roth WL Phys Rew 110, str 1333 (1958)

Pri pripravi MnO vzorcev se je tezko znebiti Mn3O4 prispevka. Ta ima nek ferimagneten prehod pod 40 K.

Printaj http://students.washington.edu/mbeerman/Research/progress.htm

http://www.dep.anl.gov/p_undergrad/ugsymp/2005Abstracts(PDF)/Adhikary,Bijoy.pdf dober abstract. Size distribution from AC measurements.

http://ltp.epfl.ch/page17706.html je precej o uporabi nanparticles (alpha-Fe2O3) v medicinske namene

http://ieeexplore.ieee.org/iel5/20/27635/01233183.pdf?tp=&arnumber=1233183&isnumber=27635

ZFC-FC nanoparticles: Blocking temperature increases za vecje delce. Za delce s premerom 5 nm so izmerili 48 K. Delci so bili Fe-oxide: Fe3O4 ali alpha Fe2O3.

Dober clanek, da se naucis kako roentgen uporabis. Lahko dolocis velikost delcev.

Sythesis and Magnetic Properties of Highly Concentrated alpha-Fe2O3 nanoparticles in silica matrix.

Gamma-Fe2O3 (maghemite) je ferrimagnetic. Uporablja se v magnetic recording systems in za catalysis.

alpha Fe2O3 (hematite) je antiferomagnetic. Uporaba v pigmentih, katalitskih reakcijah, anticorrosive agent. Kristalizira v trigonal system. Bulk hematite imam Neel temperature (prehod v AFM) pri okoli 950 K. Pri Morin temperature TM263 K se zgodi Morin transition. Morin transition je "transition specific to alpha Fe2O3 in which there is a change in the direction of the atomic magnetic moments in the AFM state from parallel to perpendicular to the c-axis." Pod TM je bulk alpha Fe2O3 kakor enoosni antiferomagnet. Nad TM so spini malo "canting" in izmerimo weak ferromagnetism.

Ko delamo z nanodelci alpha Fe2O3 se pojavi se blocking temperature. Morin temperature se zniza. Pri delcih pod 8 nm Morin prehod izgine.

Nad blocking temperature imamo nanodelce, ki so single domain in njihov magnetni moment fluctuates due to thermal agitation which lead to superparamagnetic behavior.

Ce pri ZFC-FC FC veja strmo narasca pod blocking temperature, to pomeni, da imamo non-interacting particles. Èe pa dobimo plateau pri FC, pomeni da nanodelci med sabo interagirajo.

Èe ZFC in FC nista enaki celo pri 5 T pomeni, da imamo veliko anisotropy energy.

Blocking temerature je odvisna od velikosti nanodelcev. Ker imamo porazdelitev po velikosti, sta maximum ZFC in razcep ZFC-FC na razliènih mestih. Temperatura, pri kateri se ZFC in ZF zacneta cepiti, je blocking temperature najvecjih delcev. Ce sta zacetek razcepa in maksimum ZFC pri podobnih temperaturah, to pomeni da imamo ozko porazdelitev delcev.

Enaèba (1, Langevin) je le za delce enake velikost. Ker imamo porazdelitev po velikosti, lahko iz clanka, ki ga prilagam, izracunamo tudi sigma (disperzijo po dremeru delcev).

Diverse coordination of two ligands ... Cu
Bojan Kozlevèar