Cation ordering in the 1322 perovskite CaCu3Fe2Nb2O12 has been investigated by synchrotron X-ray diffraction structure analysis, high-resolution electron microscopy, and magnetic measurements. All of the samples have full 1:3 ordering of Ca and Cu cations at the perovskite A-sites, but the Fe and Nb cations at the B sites show different degrees of orderingRead more
Blog
T. P. Croft, C. Lester, M. S. Senn, A. Bombardi, and S. M. Hayden, Phys. Rev. B 89 (2014), 224513 We report hard (14 keV) x-ray diffraction measurements on three compositions (x=0.11,0.12,0.13) of the high-temperature superconductor La 2−x Sr x CuO 4 . All samples show charge density wave (CDW) order with onset temperatures in the range 51–80Read more
Wei-tin Chen, Masaichiro Mizumaki, Hayato Seki,Mark S. Senn, Takashi Saito, Daisuke Kan, J. Paul Attfield & Yuichi Shimakawa, Nature Communications 5 (2014), 3909. Strong correlation between spins and conduction electrons is key in spintronic materials and devices. A few ferro- or ferrimagnetic transition metal oxides such as La1−xSrxMnO3, Fe3O4, CrO2 and Sr2FeMoO6 have spin-polarized conductionRead more
Angel M. Arevalo-Lopez, Mark S. Senn, Lauren Skedd and J. Paul Attfield, Zeitschrift für anorganische und allgemeine Chemie, 640 (2014), 1164–1167. The new phase 3C1:2-Ba3NaRu2O9 was synthesized by heating the hexagonal perovskite 6H-Ba3NaRu2O9 at 900 °C under a pressure of 9 GPa. 3C1:2-Ba3NaRu2O9 adopts the 1:2 B site-ordered cubic perovskite type structure [space group Pm1,Read more
Takashi Saito, Ryuta Yamada Clemens Ritter Mark S. Senn, J. Paul Attfield, and Yuichi Shimakawa, Inorg. Chem., 53 (2014), 1578–1584. A-site-ordered perovskite Ce1/2Cu3Ti4O12 crystallizes in two different forms, one with random and the other with ordered Ce/vacancy distribution at the A site of the prototype AA′ 3 B 4O12 structure. Both phases form a G-typeRead more
Angel M. Arevalo-Lopez, Bing Liang, Mark S. Senn, Claire Murray, Chiu Tang and J. Paul Attfield, J. Mater. Chem. C, 2 (2014), 9364-9367. New CaCrO3d superstructure phases (d ¼ 0.33, 0.4, and 0.5) have been discovered through ‘soft’ low temperature reduction of the perovskite CaCrO3 made at ‘hard’ high pressure–temperature conditions. Their structures form aRead more
Nonmagnetic spin-singlet dimer formation and coupling to the lattice in the 6H perovskite Ba3CaRu2O9
Mark S Senn, Angel M Arevalo-Lopez, Takashi Saito, Yuichi Shimakawa and J Paul Attfield, Journal of Physics: Condensed Matter, 25 (2013),6. Non-conservation of magnetic neutron scattering from the six-layer hexagonal perovskite Ba3CaRu2O9 on cooling reveals that (Ru5+)2 dimers form nonmagnetic spin-singlet ground states. This is in contrast to Ba3BRu2O9 (B=Co or Ni) analogues which displayRead more
MS Senn, JP Wright, JP Attfield, Journal of the Korean Physical Society 62 (2013), 1372-1375 Magnetite (Fe3O4) is the original magnetic material and the parent of ferrite magnets, with modern applications ranging from spintronics to MRI contrast agents. At ambient temperatures magnetite has a cubic spinel-type crystal structure, but it undergoes a complex structural distortionRead more
Takenori Tohyama, Mark S. Senn, Takashi Saito, Wei-tin Chen, Chiu C. Tang, J. Paul Attfield, and Yuichi Shimakawa. Chem. Mater.,25 (2013), 178–183 A-site-ordered perovskites La1–xNaxMn3Ti4O12 with (x = 0, 0.5, 1) were synthesized under high-pressure and high-temperature conditions, and their crystal structures and magnetic properties were investigated. Ti/Mn occupancies at the B site were alsoRead more
Hard-soft synthesis of SrCrO3-δ superstructure phases. Angel M. Arévalo-López, Jennifer A. Rodgers, Mark S. Senn, Falak Sher, James Farnham, William Gibbs, and J. Paul Attfield. Angew. Chem. Int. Ed. 124 (2012) 10949 “Soft” reactions, which alter local chemistry and structure while retaining the basic lattice arrangement, are important for synthesizing solids with novel properties. ForRead more