Thermochemical Properties of High Pressure Neodymium Monoxide
Yifeng Han1, Benjamin L Brugman1, Logan J Leinbach2
1Navrotsky Eyring Center for Materials of the Universe, School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States.
Abstract:
Neodymium monoxide (NdO) is a metastable rare earth oxide material with a unique electronic structure, which has potential applications across various fields such as semiconductors, energy, catalysis, laser technology, and advanced communications. Despite its promising attributes, the thermodynamic properties of NdO remain unexplored. In this study, high pressure, high temperature phases of neodymium monoxide (NdO, with a rocksalt structure) and body-centered cubic (bcc) Nd metal were synthesized at 5 GPa and 1473 K. X-ray photoelectron spectroscopy (XPS) measurements indicate that the Nd 3d peak shifts to higher energy in NdO relative to Nd2O3, suggesting the possibility of complex electronic states in NdO. Formation enthalpies for the reaction 1/3Nd2O3 + 1/3bcc Nd = NdO obtained from high temperature solution calorimetry in molten sodium molybdate and for the reaction dhcp Nd (metal) = bcc Nd (metal) from differential scanning calorimetry are 25.98 ± 8.65 and 5.2 kJ/mol, respectively. Utilizing these enthalpy values, we calculated the pressure-temperature boundary for the reaction 1/3 bcc Nd + 1/3Nd2O3 = NdO, which has a negative P-T slope of -1.68× 10-4 GPa/K. These insights reveal the high pressure behavior of NdO and neodymium metal, underscoring their potential utility in technological applications.
More Related Videos
Related Concept Videos
Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
Thermochemical Equations
Phase Transitions
Hess's Law
Thermodynamic Potentials
States of Matter and Phase Changes


