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Norimichi Kojima - One of the best experts on this subject based on the ideXlab platform.

  • crystal structure and structural Transition caused by Charge Transfer phase Transition for iron mixed valence complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2004
    Co-Authors: Miho Itoi, Norimichi Kojima, A Taira, Masaya Enomoto, Nobuyuki Matsushita, Yoshihiko Kobayashi, Kichizo Asai, Kazuko Koyama, Tomohito Nakano, Yoshiya Uwatoko
    Abstract:

    Abstract (n-C3H7)4N[FeIIFeIII(dto)3] shows a new type of first order phase Transition called Charge-Transfer phase Transition around 120 K, where the Charge Transfer between FeII and FeIII occurs reversibly. Recently, we have succeeded in obtaining single crystals of the title complex and determined the crystal structure at room temperature. Crystal data: space group P63, a=10.0618(5) A , c=16.0424(7) A , V=1406.54(12) A 3 , Z=2. Moreover, we have investigated the structural Transition caused by the Charge-Transfer phase Transition by means of powder X-ray diffraction measurement. When the temperature is decreased, the a-axis, which corresponds to the hexagonal ring size in two-dimensional honeycomb network structure of [FeIIFeIII(dto)3]∞, contracts by 0.1 A at the Charge-Transfer Transition temperature (TCT), while the c-axis, perpendicular to the honeycomb network layer, elongates by 0.1 A at TCT. Consequently, when the temperature is decreased, the unit cell volume decreases without noticeable anomaly around TCT, which is responsible for the quite small vibrational contribution to the entropy change, compared with usual spin crossover Transition. Thus, the Charge-Transfer phase Transition around 120 K for (n-C3H7)4N[FeIIFeIII(dto)3] is regarded as spin entropy driven phase Transition.

  • Charge Transfer phase Transition and ferromagnetism in a mixed valence iron complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2001
    Co-Authors: Norimichi Kojima, W Aoki, Miho Itoi, Makoto Seto, Yasuhiro Kobayashi, Yu Maeda
    Abstract:

    Abstract We have investigated the physical properties of ( n -C 3 H 7 ) 4 N[Fe II Fe III (dto) 3 ] (dto=C 2 O 2 S 2 ) by means of 57 Fe Mossbauer spectroscopy and magnetic susceptibility measurement. From the analysis of 57 Fe Mossbauer spectra and magnetic susceptibility, we have discovered a new type of first order phase Transition around 120 K, where the Charge Transfer Transition between Fe II and Fe III occurs reversibly. In the higher temperature phase, the Fe III ( S =1/2) and Fe II ( S =2) sites are coordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the Fe III ( S =5/2) and Fe II ( S =0) sites are coordinated by six O atoms and six S atoms, respectively. Moreover, we have found the ferromagnetic phase Transition at 6.5 K. The ferromagnetic order is presumably induced by the Charge Transfer interaction between the Fe III ( S =5/2) and Fe II ( S =0) sites.

  • reversible Charge Transfer phase Transition in n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Synthetic Metals, 2001
    Co-Authors: Norimichi Kojima, W Aoki, Makoto Seto, Yasuhiro Kobayashi, Yu Maeda
    Abstract:

    We have investigated the physical properties of [(n-C 3 H 7 ) 4 N][Fe II Fe III (dto) 3 ](dto = C 2 O 2 S 2 ) by means of 57 Fe Mossbauer spectroscopy, ESR, and magnetic susceptibility. From the analysis of 57 Fe Mossbauer spectra, we have discovered a new type of first order phase Transition for the title complex at about 120 K, where the Charge Transfer Transition between Fe II and Fe III occurs reversibly. Moreover, we have found the ferromagnetic phase Transition at 6 K.

Yu Maeda - One of the best experts on this subject based on the ideXlab platform.

  • Charge Transfer phase Transition and ferromagnetism in a mixed valence iron complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2001
    Co-Authors: Norimichi Kojima, W Aoki, Miho Itoi, Makoto Seto, Yasuhiro Kobayashi, Yu Maeda
    Abstract:

    Abstract We have investigated the physical properties of ( n -C 3 H 7 ) 4 N[Fe II Fe III (dto) 3 ] (dto=C 2 O 2 S 2 ) by means of 57 Fe Mossbauer spectroscopy and magnetic susceptibility measurement. From the analysis of 57 Fe Mossbauer spectra and magnetic susceptibility, we have discovered a new type of first order phase Transition around 120 K, where the Charge Transfer Transition between Fe II and Fe III occurs reversibly. In the higher temperature phase, the Fe III ( S =1/2) and Fe II ( S =2) sites are coordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the Fe III ( S =5/2) and Fe II ( S =0) sites are coordinated by six O atoms and six S atoms, respectively. Moreover, we have found the ferromagnetic phase Transition at 6.5 K. The ferromagnetic order is presumably induced by the Charge Transfer interaction between the Fe III ( S =5/2) and Fe II ( S =0) sites.

  • reversible Charge Transfer phase Transition in n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Synthetic Metals, 2001
    Co-Authors: Norimichi Kojima, W Aoki, Makoto Seto, Yasuhiro Kobayashi, Yu Maeda
    Abstract:

    We have investigated the physical properties of [(n-C 3 H 7 ) 4 N][Fe II Fe III (dto) 3 ](dto = C 2 O 2 S 2 ) by means of 57 Fe Mossbauer spectroscopy, ESR, and magnetic susceptibility. From the analysis of 57 Fe Mossbauer spectra, we have discovered a new type of first order phase Transition for the title complex at about 120 K, where the Charge Transfer Transition between Fe II and Fe III occurs reversibly. Moreover, we have found the ferromagnetic phase Transition at 6 K.

Alberto E Regazzoni - One of the best experts on this subject based on the ideXlab platform.

  • surface complexation at the tio2 anatase aqueous solution interface chemisorption of catechol
    Journal of Colloid and Interface Science, 1996
    Co-Authors: Raul Rodriguez, Miguel A Blesa, Alberto E Regazzoni
    Abstract:

    Abstract Catechol adsorbs at the TiO2(anatase)/aqueous solution interface forming inner-sphere surface complexes. The UV–visible differential reflectance spectrum of surface titanium–catecholate complexes presents a band centered at 420 nm which corresponds to the ligand to metal Charge Transfer Transition within the surface complexes. At pH values below pKa1, the surface excess of catechol is almost insensitive toward pH and presents a Langmuirian dependence with the concentration of uncomplexed catechol. The ratio Γmax:NS(NSbeing the measured density of available OH surface groups) indicates a prevailing 1 to 2 ligand exchange adsorption stoichiometry. In the range pH ≥ pKa1, the catechol surface excess decreases markedly with increasing pH. Formation of 1 to 1 surface complexes produces an excess of negative surface Charge that is revealed by the shift of the iep to lower pH values. The reported data, which are supplemented with information on the charging behavior of TiO2suspended in indifferent electrolyte solutions, are interpreted in terms of the multi-site surface complexation model. In this model, two types of surface OH groups are considered: ≡TiOH1/3−and ≡OH1/3+. Although both surface groups undergo protonation–deprotonation reactions, only ≡TiOH1/3−are prone to chemisorption.

  • surface complexation at the tio2 anatase aqueous solution interface chemisorption of catechol
    Journal of Colloid and Interface Science, 1996
    Co-Authors: Raul Rodriguez, Miguel A Blesa, Alberto E Regazzoni
    Abstract:

    Catechol adsorbs at the TiO(2) (anatase)/aqueous solution interface forming inner-sphere surface complexes. The UV-visible differential reflectance spectrum of surface titanium-catecholate complexes presents a band centered at 420 nm which corresponds to the ligand to metal Charge Transfer Transition within the surface complexes. At pH values below pK(a1), the surface excess of catechol is almost insensitive toward pH and presents a Langmuirian dependence with the concentration of uncomplexed catechol. The ratio Gamma(max):N(S) (N(S) being the measured density of available OH surface groups) indicates a prevailing 1 to 2 ligand exchange adsorption stoichiometry. In the range pH >/= pK(a1), the catechol surface excess decreases markedly with increasing pH. Formation of 1 to 1 surface complexes produces an excess of negative surface Charge that is revealed by the shift of the iep to lower pH values. The reported data, which are supplemented with information on the charging behavior of TiO(2) suspended in indifferent electrolyte solutions, are interpreted in terms of the multi-site surface complexation model. In this model, two types of surface OH groups are considered: identical withTiOH(1/3-) and identical withOH(1/3+). Although both surface groups undergo protonation-deprotonation reactions, only identical withTiOH(1/3-) are prone to chemisorption.

Miho Itoi - One of the best experts on this subject based on the ideXlab platform.

  • crystal structure and structural Transition caused by Charge Transfer phase Transition for iron mixed valence complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2004
    Co-Authors: Miho Itoi, Norimichi Kojima, A Taira, Masaya Enomoto, Nobuyuki Matsushita, Yoshihiko Kobayashi, Kichizo Asai, Kazuko Koyama, Tomohito Nakano, Yoshiya Uwatoko
    Abstract:

    Abstract (n-C3H7)4N[FeIIFeIII(dto)3] shows a new type of first order phase Transition called Charge-Transfer phase Transition around 120 K, where the Charge Transfer between FeII and FeIII occurs reversibly. Recently, we have succeeded in obtaining single crystals of the title complex and determined the crystal structure at room temperature. Crystal data: space group P63, a=10.0618(5) A , c=16.0424(7) A , V=1406.54(12) A 3 , Z=2. Moreover, we have investigated the structural Transition caused by the Charge-Transfer phase Transition by means of powder X-ray diffraction measurement. When the temperature is decreased, the a-axis, which corresponds to the hexagonal ring size in two-dimensional honeycomb network structure of [FeIIFeIII(dto)3]∞, contracts by 0.1 A at the Charge-Transfer Transition temperature (TCT), while the c-axis, perpendicular to the honeycomb network layer, elongates by 0.1 A at TCT. Consequently, when the temperature is decreased, the unit cell volume decreases without noticeable anomaly around TCT, which is responsible for the quite small vibrational contribution to the entropy change, compared with usual spin crossover Transition. Thus, the Charge-Transfer phase Transition around 120 K for (n-C3H7)4N[FeIIFeIII(dto)3] is regarded as spin entropy driven phase Transition.

  • Charge Transfer phase Transition and ferromagnetism in a mixed valence iron complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2001
    Co-Authors: Norimichi Kojima, W Aoki, Miho Itoi, Makoto Seto, Yasuhiro Kobayashi, Yu Maeda
    Abstract:

    Abstract We have investigated the physical properties of ( n -C 3 H 7 ) 4 N[Fe II Fe III (dto) 3 ] (dto=C 2 O 2 S 2 ) by means of 57 Fe Mossbauer spectroscopy and magnetic susceptibility measurement. From the analysis of 57 Fe Mossbauer spectra and magnetic susceptibility, we have discovered a new type of first order phase Transition around 120 K, where the Charge Transfer Transition between Fe II and Fe III occurs reversibly. In the higher temperature phase, the Fe III ( S =1/2) and Fe II ( S =2) sites are coordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the Fe III ( S =5/2) and Fe II ( S =0) sites are coordinated by six O atoms and six S atoms, respectively. Moreover, we have found the ferromagnetic phase Transition at 6.5 K. The ferromagnetic order is presumably induced by the Charge Transfer interaction between the Fe III ( S =5/2) and Fe II ( S =0) sites.

Yoshiya Uwatoko - One of the best experts on this subject based on the ideXlab platform.

  • crystal structure and structural Transition caused by Charge Transfer phase Transition for iron mixed valence complex n c3h7 4n feiifeiii dto 3 dto c2o2s2
    Solid State Communications, 2004
    Co-Authors: Miho Itoi, Norimichi Kojima, A Taira, Masaya Enomoto, Nobuyuki Matsushita, Yoshihiko Kobayashi, Kichizo Asai, Kazuko Koyama, Tomohito Nakano, Yoshiya Uwatoko
    Abstract:

    Abstract (n-C3H7)4N[FeIIFeIII(dto)3] shows a new type of first order phase Transition called Charge-Transfer phase Transition around 120 K, where the Charge Transfer between FeII and FeIII occurs reversibly. Recently, we have succeeded in obtaining single crystals of the title complex and determined the crystal structure at room temperature. Crystal data: space group P63, a=10.0618(5) A , c=16.0424(7) A , V=1406.54(12) A 3 , Z=2. Moreover, we have investigated the structural Transition caused by the Charge-Transfer phase Transition by means of powder X-ray diffraction measurement. When the temperature is decreased, the a-axis, which corresponds to the hexagonal ring size in two-dimensional honeycomb network structure of [FeIIFeIII(dto)3]∞, contracts by 0.1 A at the Charge-Transfer Transition temperature (TCT), while the c-axis, perpendicular to the honeycomb network layer, elongates by 0.1 A at TCT. Consequently, when the temperature is decreased, the unit cell volume decreases without noticeable anomaly around TCT, which is responsible for the quite small vibrational contribution to the entropy change, compared with usual spin crossover Transition. Thus, the Charge-Transfer phase Transition around 120 K for (n-C3H7)4N[FeIIFeIII(dto)3] is regarded as spin entropy driven phase Transition.