Squeezing lanthanide nitrides leads to previously undiscovered phase transitions
Squeezing lanthanide nitrides leads to previously undiscovered phase transitions lead image
Lanthanide pnictides, with their unique electronic and magnetic properties, have attracted interest due to potential applications in magnetic refrigeration and spintronics. However, lanthanide nitrides, close relatives of the pnictides that share many of their interesting properties, remain somewhat unexplored.
Ehrenreich-Petersen et al. report results from diamond anvil experiments on lanthanide nitrides and present the equations of state for 11 lanthanide nitrides, completing the series and opening the door to improving theoretical modeling work on crystal structures containing lanthanides.
“It is our hope that this complete series of experiments can motivate benchmark studies. The experimental data on an entire family of compounds allow theorists a possibility to systematically compare their theoretical modeling against our actual observations,” said author Martin Bremholm.
Early experimental and theoretical studies of lanthanide nitrides assumed a simpler structural transition. This study challenges these simplifications and shows that less ionic and directional bonding would lead to distortion towards a lower symmetry.
Air-sensitive tiny samples of lanthanides nitrides were loaded into diamond anvil cells with applied pressures as high as 114 GPa. Using X-ray diffraction to study the structural changes as a function of pressure, the authors found that the bulk modulus and onset pressure of the phase transition increased linearly with the lanthanide number. For the studied pressure range, four different samples exhibited phase transitions never before seen in those lanthanide nitrides.
The authors hope that this broadened understanding of the series and theoretical modeling can someday be useful in tech applications, for example, enabling a more reliable way of screening structure databases for materials with technologically interesting properties.
Source: “Experimental equation of state of 11 lanthanide nitrides (NdN to LuN) and pressure induced phase transitions in NdN, SmN, EuN and GdN,” by Emma Ehrenreich-Petersen, Morten B. Nielsen, and Martin Bremholm, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/5.0021591 .
