Multi-fold Enhancement of Seebek and Thermoelectric Efficiency in SnTe under Pressure
SnTe belongs to the family of potential thermoelectric materials similar to PbTe and it is lead free. Pressure tuning is one of the efficient methods to look on the thermoelectric properties of thermoelectric materials to understand the transport behavior, phase changes and stability under extreme conditions. Further, pressure studies are important to understand the changes in the carrier concentration and provide an insight to perform chemical doping in these systems for enhancing the efficiencies. The research team comprising of Jason Baker, Ravhi Kumar, Andrew Cornelius (UNLV), Nenad Velisavljevic (LANL) and Changyong Park, Curtis Kenney-Benson (HPCAT) has investigated the thermal and structural properties of polycrystalline SnTe under HP-HT conditions. A significant enhancement of Seebeck co-efficient and thermoelectric efficiency was observed in the experiments. The results are recently published in ChemPhysChem. https://doi.org/10.1002/cphc.201700994 https://twitter.com/ChemPhysChem/status/924983157828521984
2017 Extreme Crystals Weekend Workshop
The 2017 Extreme Crystals Weekend Workshop just closed with a Q/A on careers in high pressure by invited speakers Christian Mailhiot (SNL), Lisa Danielson (JETS, NASA) and by organized Pamela Burnley (UNLV). About 20 students from all over the Country attended the workshop.
GRADUATION! JASON BAKER graduated with his Ph.D. Physics degree August, 2017 under the supervision of Dr. Andrew Cornelius and Dr. Ravhi Kumar. His dissertation work entitled “Instrumentation and Measurement of Thermoelectric and Structural Properties of Binary Chalcogenides and Half-Heusler Alloys at Extreme Conditions Using a Paris-Edinburgh Press” was supported by HiPSEC. Jason is continuing his research in the Physics and Astronomy Department at UNLV under the supervision of Dr. Andrew Cornelius and Dr. Ravhi Kumar.
26th AIRAPT International Conference on High Pressure Science and Technology
HiPSEC sent a large delegation of participants to the AIRAPT 2017 conference in Beijing, including eight students and five faculty members. The conference included many stimulating sessions on high pressure’s most cutting edge research. John Kearney, a fourth year undergraduate, Dean Smith, a postdoctoral scientist, and Liping Wang, a research faculty member, gave full talks. Graduate students Vahe Mkrtchyan, Howard Yanxon, Christian Childs, and Jasmine Hinton presented posters.
Jasmine Hinton, a second year Master’s Student working with Ashkan Salamat, was honored to receive an Excellent Poster Award at the conclusion of the AIRAPT 2017 Conference in Beijing.
Maranatha Malonzo, an undergraduate student working with Dr. Ravhi Kumar has received an award for $4000 from the Nevada National Science Foundations Experimental Program to Stimulate Competitive Research (NSF EPSCoR) for 2017-2018 Academic Year. Her project to study the pressure distribution in the DAC culets has been selected for funding by Undergraduate Research Opportunity Program (UROP). She will carryout her research project from Sept 1, 2017 through May 31, 2018.
Howard Yanxon, a graduate student working under the supervision of Dr. Ravhi Kumar has been awarded the Donna Weistrop and David B. Shaffer Scholarship. The scholarship was established by an endowment from Donna Weistrop and David B. Shaffer. This award is designated for graduate students in Physics, Astronomy, Chemistry, or Geoscience and worth approximately $1000.
Shock induced Phosphate dehydration and the water budget of Mars
A research team under lead of UNLV Geoscience- and HiPSEC personnel found that shock-induced dehydration of igneous martian phosphate minerals is a possible key for understanding the water budget of Mars in its remote past. Martian meteorites tell us that the most common martian phosphate mineral merrillite contains little to no water. Adcock et al. demonstrated that shock-pressures like those experienced by any Martian meteorite transform the water-bearing phosphate whitlockite into its anhydrous analogue merrillite. If part of the currently anhydrous martian phosphate has been hydrous prior meteorite ejection, Mars has been more water-rich and for longer time than previously assumed. Lead author Chris Adcock has recently obtained his PhD from UNLV and is a frequent user of HiPSEC- and HPCAT facilities. The team conducted shock-recovery experiments at UNLV and examined the recovered samples by micro-diffraction at APS- and ALS-beamlines. more
C. Adcock, O. Tschauner. E. Hausrath, A. Udry, Y. Cai, S.N. Luo, Nature Communications 8, Article number: 14667 (2017). link
Extreme Crystal Workshop
Learn about careers and science in the fields of high pressure physics and chemistry. Get hands-on experience with cutting edge research tools and find out how they are used to make technical advances in fields from planetary science to national security. This two and a half day weekend workshop is aimed at undergraduate physics, chemistry, and geoscience majors interested in pursuing graduate degrees who want to explore options in high pressure science. The workshop will be hosted by the High Pressure Science and Engineering Center at the University of Nevada, Las Vegas. Reimbursement for travel expenses is available.
SSAP 2017 Symposium
HiPSEC students and faculties at the SSAP 2017 Symposium on April 12-13, 2017 in Naperville, IL.
AWARD! UNLV graduate students Daniel Sneed and Jason Baker won poster presentations awards at the SSAP 2017 Symposium.
2016 Quadrennial Physics Congress
HiPSEC members Jason Baker, Pamela Burnley and Jasmine Hinton attended the 2016 Quadrennial Physics Congress (PhysCon) as exhibitors. PhysCon is a meeting for undergraduate physics students sponsored by the American Institute of Physics and Sigma Pi Sigma. We brought our new demonstration DAC and showed students how to use pressure to freeze water at room temperature. We were enthusiastically received and talked to hundreds of students about HiPSEC.
In-situ measurement of thermoelectricity and crystal structure of materials under high-pressure conditions
Thermoelectrics are important in power generation and have drawn vast attention in recent years. They are widely used in devices for clean energy, defense and satellite operations. Application of pressure could tune the thermal properties of thermoelctrics and stabilize new crystallographic phases with high figure of merit. A collaborative UNLV-Los Alamos National Laboratory (LANL) and Advanced Photon Source (APS) scientific team has developed a unique sample cell assembly to study thermoelectric materials at the BM-B beam line of HPCAT at APS employing a Paris-Edinburgh type press. This assembly allows unique capability of in-situ investigation of thermal conductivity, Seebeck co-efficient, resistivity and crystal structure of the samples subjected to high-pressure conditions. The setup could also be used for exploring P-T phase diagrams of variety of materials. Graduate student Jason Baker (UNLV) was extensively involved in the design and development of this technique.
New CO2 laser heating facilities at HPCAT
The development of a new CO2 laser heating system has been initiated by HiPSEC researchers in the Salamat group in collaboration with scientists at HPCAT. Once completed, the system will be compatible across various beamlines in APS Sector 16 and opens up the capability to perform high-pressure high-temperature experiments on wide band gap materials up to several thousand Kelvin, with in situ X-ray diffraction and spectroscopic measurements.
(L-R: Jesse Smith and Eric Rod of HPCAT, Dean Smith, Christian Childs and Ashkan Salamat of HiPSEC)
GRADUATION! VAHE MKRTCHYAN graduated with his M.S. Physics degree August, 2016 under the supervision of Dr. Andrew Cornelius and Dr. Ravhi Kumar. His thesis work entitled “Structural Behavior of NbSexTe2-x Compounds Under High Pressure” was supported by HiPSEC. Vahe is continuing his education in the Ph.D. program in the Physics and Astronomy Department at UNLV under the supervision of Dr. Andrew Cornelius and Dr. Ravhi Kumar.
GRADUATION! DANIEL SNEED graduated with his M.S. Physics degree August, 2016 under the supervision of Dr. Michael Pravica. His thesis work entitled “Forcing Cesium into Higher Oxidation States via Useful Hard X-ray Induced Chemistry at Extreme Conditions” was supported by HiPSEC. Daniel is continuing his education in the Ph.D. program in the Physics and Astronomy Department at UNLV under the supervision of Dr. Ashkan Salamat.
Extreme Crystals Weekend Undergraduate workshop
On the weekend of April 9 – 10, 2016 HiPSEC held its first annual Extreme Crystals Weekend Workshop for undergraduate students. Twenty students from around the country came to Las Vegas to learn about high pressure physics, chemistry and geoscience. The workshop included demonstrations of diamond anvil cells, laser heating, large volume high pressure apparatus, shock experiments, x-ray and electron diffraction and Raman spectroscopy. The workshop also featured talks and discussions about careers in high pressure science and information about working at the National Labs and NASA as well as in academic environments. The workshop was a lot of fun for everyone involved. HiPSEC members enjoyed the participant’s energy and enthusiasm, the students enjoyed seeing the wide variety of science and instrumentation on display, and with the exception of a brief period of violent rainstorms and flash flooding, everyone enjoyed the mild spring temperatures.
GRADUATION! QUINLAN SMITH graduated with his M.S. Physics degree May, 2016 under the supervision of Dr. Michael Pravica. His thesis work entitled “Impedance Spectroscopy Studies of Yttria Stabilized Zirconia (3.8% mol YSZ) Under Extreme Pressures and Temperatures” was supported by HiPSEC. Quinlan took a job as a Laboratory Assistant at the Oak Ridge National Laboratory.
GRADUATION! ANDREW ALVARADO graduated with his M.S. Physics degree May, 2016 under the supervision of Dr. Changfeng Chen. His thesis work entitled “High Pressure Properties of Several Narrow Bandgap Semiconductors from First-Principles Calculations” was supported by HiPSEC. Andrew is continuing his education in the Ph.D. Material Science program at UCLA.
GRADUATION! CHRIS HIGGINS graduated with his M.S. Physics degree May, 2016 under the supervision of Dr. Changfeng Chen. His thesis work entitled “Ab Initio Structure Determination and Property Characterization of High-Pressure Ca-O Compounds and Li2(OH)Br Crystals” was supported by HiPSEC. Chris is continuing his education in the Ph.D. program in the Physics and Astronomy Department at UNLV under the supervision of Dr. Ashkan Salamat.
PUBLISHED! Equation of state for technetium from X-ray diffraction and first-principle calculations.
Technetium is the lightest radioelement, meaning that every isotope is radioactive and because of this has but the smallest natural abundance. It is however a major fission product from nuclear fission reactions and produced on the kilogram scale at nuclear reactors around the world. To date, no structural studies have investigated the high pressure behavior of this metal likely due to the implicit challenges with working with radioactive material. Utilizing HPCAT experimental facilities at the Advanced Photon Source, ANL, Ph.D. student Daniel Mast obtained the first x-ray diffraction experiments up to 67GPa. An experimental equation of state for technetium was derived compared to a theoretical compression curve. (Mast et al, Journal of Physics and Chemistry of Solids, 95 (2016) 6-11, http://dx.doi.org/10.1016/j.jpcs.2016.03.007)
SSAP 2016 SYMPOSIUM Several HiPSEC members, including 10 students, attended the meeting in Bethesda, Maryland.