Zircon to scheelite phase transition induced by pressure and magnetism in TbCrO4
Abstract
The scheelite form of the TbCrO4 oxide has been obtained by treating TbCrO4 -zircon at 4 GPa and 823 K. X-ray and neutron diffraction data reveal that the high-pressure polymorph of TbCrO4 crystallizes with tetragonal symmetry space group I41/a and lattice parameters a=5.03674(10)Å and c=11.3734(4)Å . Although bisdisphenoids [TbO8] and tetrahedra [CrO4] are present in both scheelite and zircon polymorphs, the remarkable changes observed in both polyhedra appear to support the reconstructive model for the zircon-scheelite first-order phase transition. Specific heat and neutron diffraction measurements confirm the antiferromagnetic ordering previously proposed from magnetic susceptibility measurements, in which both Tb3+ and Cr5+ sublattices are involved. The magnetic structure has been determined and can be described on the basis of the coincidence between the chemical and magnetic cells, k=(0,0,0) , where the magnetic moments of the Tb3+ and Cr5+ cations are antiferromagnetically aligned along the c axis of the structure, with TN=29K . Their values at 2 K are 8.97(3)μB and 1.089(9)μB , respectively.
- Publication:
-
Physical Review B
- Pub Date:
- May 2010
- DOI:
- 10.1103/PhysRevB.81.174419
- Bibcode:
- 2010PhRvB..81q4419C
- Keywords:
-
- 75.25.-j;
- 62.50.-p;
- 61.66.Fn;
- 75.30.Cr;
- High-pressure effects in solids and liquids;
- Inorganic compounds;
- Saturation moments and magnetic susceptibilities