Low-temperature structural phase transitions of TbB4 and ErB4 studied by high resolution X-ray diffraction and profile analysis
Heiba, zein Elabidin; Schäfer, W.; Jansen, E.; Will, G.;
Abstract
The isostructural rare earth tetraborides TbB4 and ErB4 of tetragonal space group P4/mbm undergo structural phase transitions to orthorhombic symmetry around T = 80 K and T = 15 K, respectively. The lattice distortions have been investigated by individual peak profile analysis performed on high-precision X-ray data. The experimental and analytical processing is outlined. The deviations from a tetragonal cell at 4.2 K are 2 × 10-2 Å for TbB4 and 3 × 10-3 Å for ErB4. The relative volume change between 300 and 4.2 K is less than 10-3 in the TbB4 lattice and 2.3 × 10-3 in ErB4. The tetragonal to orthorhombic distortions are discussed in the context of the antiferromagnetic phase transitions of TbB4 at TN = 43 K and of ErB4 at TN = 13 K. The relationship between the structural and magnetic phase transitions differs for the two compounds. In TbB4, the structural transition, which occurs at a definitely higher temperature than the magnetic ordering, is assumed to be driven by a strong electron-lattice coupling or by an electronic quadrupole-quadrupole interaction. In ErB4, the structural distortion is attributed to magnetostrictive effects occurring simultaneously with the magnetic ordering process. © 1986.
Other data
Title | Low-temperature structural phase transitions of TbB<inf>4</inf> and ErB<inf>4</inf> studied by high resolution X-ray diffraction and profile analysis | Authors | Heiba, zein Elabidin ; Schäfer, W.; Jansen, E.; Will, G. | Keywords | borides;Phase transition;profile analysis;rare earth tetraborides;X-ray diffraction | Issue Date | 1-Jan-1986 | Journal | Journal of Physics and Chemistry of Solids | Volume | 47 | Issue | 7 | Start page | 651 | End page | 658 | ISSN | 00223697 | DOI | 10.1016/0022-3697(86)90078-8 | Scopus ID | 2-s2.0-0022583327 |
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