About

Erica L. Corral is a Professor of Materials Science and Engineering as well as Aerospace and Mechanical Engineering at the University of Arizona. She holds the title of University Distinguished Scholar in Materials Science and Engineering. Her professional profile is associated with the UA Materials Science & Engineering site and the Department of Aerospace & Mechanical Engineering. Her research focuses on materials science within the context of aerospace and mechanical engineering, contributing to the academic and research community through her faculty role and scholarly activities.

Research topics

• Chemistry
• Metallurgy
• Materials science
• Geology
• Engineering physics
• Mathematics
• Physics
• Thermodynamics
• Crystallography
• Composite material

Selected publications

• Thermodynamic assessment within the Zr–B–C–O quaternary system

  Journal of the American Ceramic Society · 2022 · 6 citations

  Senior authorCorresponding
  • Thermodynamics
  • Materials science
  • Chemistry

  Abstract Thermodynamic modeling of Zr–B–C–O quaternary system is conducted within the CALPHAD framework by employing data obtained from first‐principle calculations and literature. The lower order binary B–O is assessed in this work by estimating the thermodynamic properties of stable solid phases of B 2 O 3 and B 6 O and by estimating the gas and liquid phases. First‐principle calculations, in conjunction with special quasirandom structure were used to predict enthalpies of mixing for the ternary solid‐solution phase of FCC‐Zr(C, O). The calculated results were used to optimize the model parameters pertaining to the cubic phase, which is described by a two‐sublattice model. The modeled Zr–C–O ternary phase diagrams calculated at 1923 and 2273 K under ambient pressure and 4 Pa, respectively, are in agreement with experimental phase diagrams.

  PublisherDOI

• Instantaneous nanowelding of ultra‐high temperature ceramics for hypersonics

  Journal of the American Ceramic Society · 2021 · 8 citations

  Senior authorCorresponding
  • Materials science
  • Metallurgy
  • Engineering physics

  Abstract Ultra‐high temperature ceramics (UHTCs) are a group of advanced ceramic materials that possess excellent high temperature capabilities, which make them especially suitable for extreme environment engineering applications. As an effective assembling method, joining is frequently required for fabricating sophisticated structures for such applications due to the excessive challenges and costs in producing near‐net shapes. Here, we introduce a promising new joining technique to effectively join UHTCs called Instantaneous Nanowelding , which uses direct electric current assisted rapid Joule heating to instantaneously bond hafnium diboride (HfB 2 ) to zirconium diboride (ZrB 2 ) in 1 s down to atomic scale. Our approach is analogous to high temperature spot welding, and the entire process is complete in 10 min, and the instant diffusion occurs in 1 s. Seamless HfB 2 /ZrB 2 interfaces are formed at 1750 for a duration of 1 s. A series of characterizations are done at the interfaces using techniques including SEM, WDS, EBSD, and S/TEM to observe Zr x Hf 1− x B 2 solid solution formation. Highly coherent transition with perfect lattice alignment at atomic scale from ZrB 2 to HfB 2 is observed using S/TEM, meaning that the two materials are brought to atomic contact.

  PublisherDOI

• An Ablation Model for Ultra High Temperature Ceramics

  2019-03-19

  article1st authorCorresponding
  Publisher

• Modifying Grain Boundary Ionic/Electronic Transport in Nano-Sr- and Mg- Doped LaGaO_3-δ by Sintering Variations

  Journal of The Electrochemical Society · 2019-01-01 · 18 citations

  articleOpen access

  Perovskite La0.9Sr0.1Ga0.9Mg0.1O3-δ (LSGM) is one of the fastest known oxide ion conductors, with reported enhanced p-type electronic transference numbers at grain boundaries, attributed to space charge effects. As this material is applied as a solid oxide fuel/electrolysis cell electrolyte, it is of interest to learn how its mixed conductivity may be tailored. Field assisted sintering technique/spark plasma sintering (FAST/SPS) and conventional sintering without field or pressure were employed to prepare pellets with various grain sizes, in order to systematically assess the influence of processing route on the mixed conductivity. AC-impedance spectroscopy and the brick layer model were applied to determine local conductivities as a function of temperature, oxygen partial pressure, and dc bias. With increasing sintering temperature and grain size, the following trends were observed: larger electrical grain boundary (GB) widths, higher GB potentials, lower specific GB conductivity, greater dc-bias dependence of GB conductivity, higher pO2-dependence of GB conductivity indicating higher electronic transference numbers, and lower pre-exponential factor for specific GB conductivity. These results suggest an increasing GB space charge effect with increasing sintering temperature/grain size, which coincided with increasing compositional uniformity by TEM and EDS. The results confirm that sintering route is an important variable for tailoring mixed conduction.

  PublisherDOI

• Tailoring Mixed Ionic/Electronic Conductivity with Grain Boundaries: (La,Sr)(Ga,Mg)O_3-X Case Study

  ECS Meeting Abstracts · 2019-09-01

  article

  Modified point defect chemistry at grain boundaries can be leveraged to turn a predominantly ionic conductor or a predominantly electronic conductor into a mixed conductor, by changing the grain boundary density [1,2]. There are reports indicating that introducing some electronic conductivity into the ionically conducting electrolyte of a solid oxide electrolysis cell could help to alleviate the problem of delamination at or near the electrolyte-oxygen electrode interface [3]. For this reason, we revisited the possible role of grain boundaries in tailoring mixed conduction in the fast oxide-ion conductor La 0.9 Sr 0.1 Ga 0.9 Mg 0.1 O 3-x (LSGM). LSGM is a candidate electrolyte as it exhibits good thermo-chemo-mechanical compatibility with adjacent perovskite-structured electrodes. Previous work has indicated enhanced p-type electronic transference numbers at the grain boundaries of LSGM compared to the bulk, attributed to space charge effects on the basis of the observed non-linear current-voltage behavior of the grain boundaries at sufficiently high voltages [4]. However, the interplay of processing route, grain size, and dopant concentration in tailoring the extent of this effect had not been investigated. In this work [5] we fabricated dense LSGM pellets with non-dilute doping levels typical of electrolytes, with a range of average grain sizes from ~100 nm to ~6 μm, using field- and pressure- assisted sintering with various post-annealing steps as well as conventional sintering. The electrical transport behavior of grain cores and grain boundaries (GBs) was subsequently studied by impedance spectroscopy as a function of temperature, oxygen partial pressure, and dc bias. The brick layer model and the nano-grain composite model were applied to determine specific GB conductivities and electrical widths from the impedance data. Structure and composition were evaluated by X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning transmission microscopy, and energy dispersive X-ray spectroscopy. With increasing sintering temperature (and grain size), the following trends were observed: increasing pO 2 -dependence of the GB conductivity indicating higher local electronic transference numbers, higher apparent GB potentials, lower specific GB conductivity, lower pre-exponential factor for specific GB conductivity, increasing electrical GB widths, and greater dc bias dependence of GB conductivity. On the other hand, as expected, grain core electrical behavior was independent of processing route, grain size, and pO 2 . The results are suggestive of an increasing grain boundary space charge effect with increasing sintering temperature (and grain size), as has been observed for other ionic conductors where grain size and sintering temperature/time were coupled. Additionally, in all cases, the GB electronic transference numbers in these highly doped samples appeared to be smaller than those reported for lightly doped LSGM. Microscopy and EDS revealed that while grain boundaries appeared to be well-crystalline and “clean” in all samples, there was increasing microstructural and compositional homogeneity in samples that were sintered at progressively higher temperatures. The significance of the nanoscale compositional and microstructural fluctuations in the small-grained samples is not yet clear, as the apparent phase purity and density of all the samples was very similar macroscopically. Nonetheless, it seems possible that such inhomogeneity (pores and Sr- rich and Mg-rich areas not limited to GB regions) might limit the space charge contribution at GBs, and that some of the pores could have arisen from residual volatile impurities trapped during the pressure-assisted sintering. Overall, the results confirm that 1) grain boundaries can be sites of mixed conduction in an otherwise predominantly ionically conducting electrolyte and 2) processing route (thermal, pressure, and electrical history) is an important variable for tailoring the magnitude of the local ionic and electronic conductivities and transference numbers. [1] Y.M. Chiang et al., Applied Physics Letters , 69 (2), 185-187 (1996). [2] A.M. Saranya et al., Advanced Energy Materials , 5 (11), 1500377 (2015). [3] A.V. Virkar et al., International Journal of Hydrogen Energy , 40, 5561-5577 (2015). [4] C.T. Chen et al., Physical chemistry chemical physics , 14, 9047-9049 (2012). [5] T. Chen et al., “Modifying grain boundary ionic/electronic transport in nano-Sr- and Mg- doped LaGaO 3-δ by sintering variations,” (under review)

  PublisherDOI

• Thermochemical model on the carbothermal reduction of oxides during spark plasma sintering of zirconium diboride

  Journal of the American Ceramic Society · 2018-06-30 · 11 citations

  articleSenior authorCorresponding

  Abstract Carbon was used to reduce oxides in spark plasma sintered ZrB 2 ultra‐high temperature ceramics. A thermodynamic model was used to evaluate the reducing reactions to remove B 2 O 3 and ZrO 2 from the powder. Powder oxygen content was measured and carbon additions of 0.5 and 0.75 wt% were used. A C–ZrO 2 pseudo binary diagram, ZrO 2 –B 2 O 3 –C pseudo ternaries, and Zr–C–O potential phase diagrams were generated to show how the reactions can be related to an open system experiment in the tube furnace. Scanning transmission electron microscopy identified impurity phases composed of amorphous Zr–B–O with lamellar BN and a Zr–C–O ternary model was calculated under SPS sintering conditions at 1900°C and 6 Pa to understand how oxides can be retained in the microstructure.

  PublisherDOI

• Ionic and Electronic Transport in Nanocrystalline La_0.9Sr_0.1Ga_0.9Mg_0.1O_3-Δ

  ECS Meeting Abstracts · 2018-04-13

  article

  A major limitation for the development of reversible solid oxide cells (R-SOCs) is the delamination between the oxygen electrode and electrolyte in electrolysis mode. Previously, Virkar reported that higher electronic conductivity within the predominantly ionically conducting electrolyte led to a lower tendency for the formation of high internal pressure [1] . Therefore an electrolyte having a small amount of electronic conduction may be beneficial for relieving the delamination between the oxygen electrode and electrolyte in R-SOCs. Strontium- and magnesium-doped lanthanum gallate (LSGM) has been widely investigated as an electrolyte for medium-low temperature (400-650 ºC) R-SOCs due to its high ionic conductivity and compatibility with some perovskite electrodes. Compared to well-established yttria stabilized zirconia electrolytes, which have ionic transference numbers close to 1 across a wide range of oxygen partial pressures, LSGM can exhibit non-negligible p-type electronic conductivity under oxidizing conditions [2, 3] . Furthermore, limited studies have demonstrated enhanced electronic transference numbers at grain boundaries compared to the bulk, attributed to space charge effects [3, 4] . Therefore, it is of interest to understand the impact of nanostructuring and grain boundaries on the ionic and electronic transport properties of LSGM for relieving the delamination issue in R-SOCs. In this work, two methods - field assisted sintering technique/spark plasma sintering (FAST/SPS) and traditional pressureless sintering were employed to prepare dense La 0.9 Sr 0.1 Ga 0.9 Mg 0.1 O 3-δ (LSGM9191) pellets from nanopowders synthesized by the Pechini method. Post-sintering anneals were applied to the FAST/SPS pellets to oxidize them and control grain size. Microstructure was evaluated by scanning and transmission electron microscopy with EELS/EDS line scans at grain boundaries, and transport properties were measured by 2-point ac-impedance spectroscopy over the temperature range using porous Pt/Ag electrodes. Equivalent circuit fitting with application of microstructural models was applied to evaluate local conductivities. The impact of grain size on grain core (gc), grain boundary (gb) and total conductivity were studied. Grain size did not affect the gc conductivity, and the gb and total conductivity increased with grain growth. Specific gb conductivity decreased with increasing grain size. Additionally, the dependence of the conductivities on oxygen partial pressure (pO2) and applied dc bias was measured to assess any electronic contribution to the conductivity. We found that the gb conductivities of LSGM9191 pellets prepared by FAST/SPS with different grain sizes (ranging from ~100nm to 800 nm) did not exhibit pO 2 dependence, showing different behavior than some previous research [5] . The dependence of gb conductivity on dc bias (both in N 2 or 21% O 2 ) was also smaller than previous reports [6, 7] . Therefore, the electronic conductivity and space charge effect was limited, which might be caused by the high dopant content in the present work compared to previous studies and/or by impurities/ amorphous material/ organic residue trapped at the GBs as a result of the FAST/SPS process. However, the gb conductivity of a LSGM9191 pellet prepared by pressureless sintering did show a small pO 2 dependence, indicating some p-type conductivity, albeit lower than in previous reports. The results suggest that factors such as grain size, doping level, grain boundary chemistry, and processing routes could be modified to tailor mixed conduction in LSGM for R-SOC applications. Acknowledgements Support from WPI-I 2 CNER to NHP and a JSPS Fellowship (201702103) to TC are gratefully acknowledged. Reference [1] Anil V. Virkar, Mechanism of oxygen electrode delamination in solid oxide electrolyzer cells, International of Hydrogen Energy, 35 (2010) 9527-9543 [2] V.V. Kharton et al ., Electron-hole transport in (La 0.9 Sr 0.1 ) 0.98 Ga 0.8 Mg 0.2 O 3- δ electrolyte: effects of ceramic microstructure, Electrochimica Acta 48 (2003) 1817-1828 [3] H.J. Park et al ., Space Charge Effects on the Interfacial Conduction in Sr-Doped Lanthanum Gallates: A Quantitative Analysis . Phys. Chem. C 2007, 111, 14903-14910 [4] N.H. Perry, Local electrical and dielectric properties of nanocrystalline solid oxide fuel cell electrolytes, Northwestern University, Ph.D. thesis, 2009 [5] H.J. Park et al. , Mixed conduction behavior in nanostructured lanthanum gallate, Electrochemistry Communications 11(2009) 962-964 [6] C.T. Chen et al. , Current–voltage characteristics of grain boundaries in polycrystalline Sr-doped LaGaO 3 Phys. Chem. Chem. Phys., 2012, 14, 9047–9049 [7] Raghvendra • R. K. Singh • P. Singh, Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate, Appl. Phys. A (2014) 116:1793–1800

  PublisherDOI

• A New Core Facility For Electron And Ion Microscopy At The University Of Arizona

  Microscopy and Microanalysis · 2017-07-01

  articleOpen access
  PublisherOA PDFDOI

• Fabrication and Implementation of a New Ceramic Material in an Adaptive Optics System

  2017-01-01 · 1 citations

  article

  A CNC machine optical polishing protocol for ZrB2 ceramics has been established. The first optic is a deformable mirror facesheet. Light-weight athermal systems with optical and structural components fabricated from the same material will follow.

  PublisherDOI

• Processing high strength low oxide and metal impurity ZrB2 ceramics using boron carbide and spark plasma sintering

  2016-01-01

  article1st authorCorresponding
  Publisher

Recent grants

• CAREER: Discovering New Oxidation Mechanisms at the Interfaces of Multilayered Ultra-High Temperature Ceramics for Application at High-Temperature

  NSF · $620k · 2010–2019

Frequent coauthors

• Luke S. Walker

  University of Arizona

  27 shared

• Ronald E. Loehman

  Radiology Associates of Albuquerque

  26 shared

• Amit Shyam

  Naval Research Laboratory Materials Science and Technology Division

  12 shared

• Enrique V. Barrera

  Rice University

  12 shared

• Edgar Lara‐Curzio

  Oak Ridge National Laboratory

  12 shared

• David Pham

  University of Arizona

  11 shared

• Nicola H. Perry

  University of Illinois Urbana-Champaign

  10 shared

• V. G. Hadjiev

  University of Houston

  8 shared

Awards & honors

• University Distinguished Scholar in Materials Science and En…