Meet the Faculty
PhD, New Mexico State University, Las Cruces, NM, Physics, 2010
MSc, New Mexico State University, Las Cruces, NM, Physics, 2008
MSc, University of Jordan, Amman, Jordan, Physics, 2001
BS, Mu’tah University, Mu’tah, Jordan, Physics, 1998
2010-2011 Postdoctoral Associate, Yale University, Department of Geology and Geophysics, New Haven, Connecticut, USA
2006-2010 Research Assistant, New Mexico State University, Department of Physics, Las Cruces, New Mexico, USA
2005-2006 Teaching Assistant, New Mexico State University, Department of Physics, Las Cruces, New Mexico, USA
2001-2005 Full-time Lecturer, Al-Hussein Bin Talal University, Department of Physics, Ma’an, Jordan
1998-2001 Physics Teacher: Ministry of Education, Ajloun, Jordan
Areas of Interest:
Teaching: Classical Mechnics Research: geophysics, materials physics • Using the laser-heated diamond-anvil cell (LHDAC) to study the behavior of materials under extreme conditions • Using density-functional theory based ab-initio computations in high pressure physics in conjunction with experiments • Using Electron Back Scattered Diffraction (EBSD) to study the solidification textures in directionally solidified alloys and their deformation mechanism
Research Interests/Professional Service:
- Journal reviewer for American Mineralogist
- Journal reviewer for Physics and Chemistry of Minerals
Studying the behavior of materials under the extreme conditions of high pressures and high temperatures has been performed since the early 1900s. Often, materials under high pressure show very different physical properties than at ambient conditions. A well-known example is the transformation of graphite to diamond at high pressures, where graphite, a soft material, transforms to diamond, the hardest material known to mankind. Therefore, generally, the expectation is that a material becomes harder by making it denser, either within a single phase, or across volume-reducing phase transition. Thus, high pressure is also used to synthesize mechanically stronger materials such as cubic silicon nitride c-Si3N4. Thus, investigating the high pressure and/or –temperature behavior of materials may lead to the synthesis of new materials with enhanced material properties as well as a test of phase stability under extreme conditions.
Dr. Al-Khatatbeh has investigated the high-pressure and high-temperature behavior of the transition-metal dioxides (TiO2, ZrO2, and HfO2) using both diamond anvil cell (DAC) experiments and first-principles density-functional theory (DFT) computations. He has investigated each dioxide under varying high-pressure and temperature conditions and have used DFT computations to corroborate the experimental phase sequence. The main concerns are the equation of state (EOS) determination, phase stability, phase transitions, volume decrease across high-pressure phase transitions, as well as estimates of mechanical strength.
In his previous studies, Dr. Al-Khatatbeh concluded that phases synthesized at high pressure do not universally result in improved mechanical characteristics and the relationship between hardness and incompressibility is not necessarily. For example, previously, the high-density, quenchable OII phases of both ZrO2 and HfO2 were expected to be superhard due to their high bulk moduli. Unfortunately, this isn’t the case: the hardness of these materials is ~10 GPa, or 1/4th the value to be considered superhard. The low mechanical strength of the OII phase is mainly the result of an increased shortest Zr/Hf-O bondlength and coordination number and negates the effects of the low specific volume. Instead, Dr. Al-Khatatbeh has confirmed that the shear modulus is a better estimator for the mechanical hardness than the bulk modulus.
For these dioxides, Dr. Al-Khatatbeh is also investigating how grain size affects the stability field of the various phases under pressure, the EOS’s and mechanical strength. Using the full-width-half maximum (FWHM) analyses of the diffracted peaks, he studies the effect of pressure and//or temperature on the grain size, micro-strain, and stress of the nano-grained dioxide.
Currently, at Simon’s Rock, Dr. Al-Khatatbeh is working with Mike Bergman, faculty in physics, on an NSF-grant funded research project on the Earth’s inner core to study the solidification texture.
- Y. Al-Khatatbeh, K. K. M. Lee, and B. Kiefer, Compressibility of nanocrystalline TiO2 anatase, Physical Review B (under review)
- Y. Al-Khatatbeh, K. K. M. Lee, and B. Kiefer, Phase diagram up to 105 GPa and mechanical strength of HfO2, Physical Review B 82, 144106 (2010)
- Y. Al-Khatatbeh, K. K. M. Lee, and B. Kiefer, Phase relations and hardness trends of ZrO2 phases at high pressure, Physical Review B 81, 214102 (2010)
- Y. Al-Khatatbeh, K. K. M. Lee, and B. Kiefer, High-pressure behavior of TiO2 as determined by experiment and theory, Physical Review B 79, 134114 (2009)
- Department of Physics Merit-Based award, New Mexico State University, Las Cruces, New Mexico, May 2009
- Graduate Assistantship award, Graduate School, New Mexico State University, Las Cruces, New Mexico, May 2008