We report on the synthesis of TbMnO 3 nanoparticles by chemical co-precipitation route and their ... more We report on the synthesis of TbMnO 3 nanoparticles by chemical co-precipitation route and their structural, chemical bonding, magnetic and dielectric properties. It is shown that the interesting multiferroic properties of this system as reflected by the concurrent occurrence of magnetic and dielectric transitions are retained in the nanoparticles (size ~40 nm). However, the nanoparticle constitution and properties are seen to depend significantly on the calcination temperature. While the nanoparticles obtained by calcination at 800 °C correspond very well with the reported properties of single phase TbMnO 3 (all the key magnetic and dielectric features near 7, 27 and 41 K, albeit with reduced dielectric constant) the nanoparticles obtained by calcination at 900 °C develop a Tb deficient skin which softens the transitions, reducing the dielectric constant further.
The magnetic properties of alkali-metal peroxychromate K2NaCrO8 are governed by the S = 1/2 penta... more The magnetic properties of alkali-metal peroxychromate K2NaCrO8 are governed by the S = 1/2 pentavalent chromium cation, Cr 5+ . Specific heat, magnetocalorimetry, ac magnetic susceptibility, torque magnetometry, and inelastic neutron scattering data have been acquired over a wide range of temperature, down to 60 mK, and magnetic field, up to 18 T. The magnetic interactions are quasitwo-dimensional prior to long-range ordering, where TN = 1.66 K in H = 0. In the T → 0 limit, the magnetic field tuned antiferromagnetic-ferromagnetic phase transition suggests a critical field Hc = 7.270 T and a critical exponent α = 0.481 ± 0.004. The neutron data indicate the magnetic interactions may extend over intra-planar nearest-neighbors and inter-planar next-nearest-neighbor spins.
We report on the synthesis of TbMnO 3 nanoparticles by chemical co-precipitation route and their ... more We report on the synthesis of TbMnO 3 nanoparticles by chemical co-precipitation route and their structural, chemical bonding, magnetic and dielectric properties. It is shown that the interesting multiferroic properties of this system as reflected by the concurrent occurrence of magnetic and dielectric transitions are retained in the nanoparticles (size ~40 nm). However, the nanoparticle constitution and properties are seen to depend significantly on the calcination temperature. While the nanoparticles obtained by calcination at 800 °C correspond very well with the reported properties of single phase TbMnO 3 (all the key magnetic and dielectric features near 7, 27 and 41 K, albeit with reduced dielectric constant) the nanoparticles obtained by calcination at 900 °C develop a Tb deficient skin which softens the transitions, reducing the dielectric constant further.
The magnetic properties of alkali-metal peroxychromate K2NaCrO8 are governed by the S = 1/2 penta... more The magnetic properties of alkali-metal peroxychromate K2NaCrO8 are governed by the S = 1/2 pentavalent chromium cation, Cr 5+ . Specific heat, magnetocalorimetry, ac magnetic susceptibility, torque magnetometry, and inelastic neutron scattering data have been acquired over a wide range of temperature, down to 60 mK, and magnetic field, up to 18 T. The magnetic interactions are quasitwo-dimensional prior to long-range ordering, where TN = 1.66 K in H = 0. In the T → 0 limit, the magnetic field tuned antiferromagnetic-ferromagnetic phase transition suggests a critical field Hc = 7.270 T and a critical exponent α = 0.481 ± 0.004. The neutron data indicate the magnetic interactions may extend over intra-planar nearest-neighbors and inter-planar next-nearest-neighbor spins.
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Papers by S. Cheong