Alexandra Navrotsky

Alexandra Navrotsky
Arizona State University | ASU · School of Molecular Sciences

Professor

About

1,166
Publications
167,612
Reads
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43,072
Citations
Citations since 2016
184 Research Items
18169 Citations
201620172018201920202021202205001,0001,5002,0002,5003,000
201620172018201920202021202205001,0001,5002,0002,5003,000
201620172018201920202021202205001,0001,5002,0002,5003,000
201620172018201920202021202205001,0001,5002,0002,5003,000
Introduction
Thermochemistry of inorganic materials, calorimetry,

Publications

Publications (1,166)
Article
Full-text available
Three crystalline SiC fibers were studied: Tyranno, Hi‐Nicalon, and Sylramic. Thermodynamic stability of the SiC fibers was determined by high temperature oxide melt solution calorimetry. Results shed light on the thermodynamic penalty or benefit associated with microstructural modification of the ceramic fibers, and how energetics correlate to mec...
Technical Report
This project aimed to gain detailed and fundamental understanding of the stability of glass waste forms to be used for safe and reliable encapsulation of nuclear waste. The focus was to understand thermodynamic and structural properties involved in crystallization and phase separation in melt-derived waste form glasses and glass-ceramics by studyin...
Article
Full-text available
The nano-scale, cubic silver(I) oxide (Ag2O.nH2O) with different particles sizes and surface areas were synthesized by a wet chemical technique. The prepared crystallite size ranges were from (33.3±0.3 to 39.4±0.4 nm). Interface areas were estimated by comparing the surface areas measured by N2 adsorption to the crystallite sizes refined from X-ray...
Article
Significance The new experimental thermodynamic studies of bulk, nanophase, and monoclinic high-pressure forms of greigite (Fe 3 S 4 ) confirm its stability in the Fe–S system and explain its common occurrence in sediments, magnetotactic bacteria, and other ambient temperature environments under anoxic conditions. The data disprove the commonly hel...
Article
The defect-fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via solid state synthesis route. The resulting stoichiometry of the oxides are Y2+xTi2-2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase, however for these with predominant fluorite phase, a small amount of addi...
Article
The process of CO2 and H2O adsorption on the surface of nano-oxide semiconductors is important in the overall performance of artificial photosynthesis and other applications. In this study, we explored the thermodynamics of CO2 and H2O adsorption on TiO2 as a function of surface chemistry. We applied gas adsorption calorimetry to investigate the en...
Article
The stability of functional materials in water-containing environments is critical for their industrial applications. A wide variety of metal–organic frameworks (MOFs) synthesized in the past decade have strikingly different apparent stabilities in contact with liquid or gaseous H2O, ranging from rapid hydrolysis to persistence over days to months....
Article
An aerodynamic conical nozzle levitator (CNL) has been used to measure the melting temperatures of refractory ceramics. The well‐established method of cooling traces has been adapted to allow measurements for air‐sensitive samples using a controlled atmosphere, where the oxygen partial pressure can be adjusted and monitored in real time. In this pa...
Chapter
Geologic and planetary processes are punctuated by sudden cataclysmic events, and planetary evolution is irrevocably changed by impacts and intense seismic and magmatic/volcanic activity. Such events often are associated with or generate high temperature, high pressure, and low oxygen fugacity. Their traces in the accessible geologic record are not...
Article
A combination of surface area analyzer and microcalorimetry was employed to investigate the in-situ water uptake energetics and the mechanism of proton incorporation in yttrium-doped barium zirconate in the temperature range 200 to 400 oC. The BaZr1-xYxO3 solid solutions are made with variable yttrium content, (x = 10, 20 and 30 mol %) by a control...
Article
The modeling of a loss-of-coolant-accident scenario involving nuclear fuels with FeCrAl cladding materials in consideration to replace a Zircaloy requires knowledge of the thermodynamics of oxidized structures. At temperatures higher than 1500 °C, oxidation of FeCrAl alloys forms (Fe,Cr,Al)3O4 spinels. In situ high-energy X-ray diffraction in a con...
Article
Cesium lead iodide bromide (CsPbI2Br) has attracted significant research attention as one of emerging inorganic cesium lead halide materials for photovoltaic applications. However, thermodynamic properties that govern its intrinsic stability remain unclear. Using room temperature solution calorimetry and differential scanning calorimetry, we herein...
Article
Ce bastnäsite is the single largest mineral source for light rare earth elements. In view of the growing industrial importance of rare-earth minerals, it is critical to develop more efficient methods for separating the valuable rare-earth-containing minerals from the surrounding gangue. In this work, we employ a combination of periodic density func...
Article
Commonly used methods to assess crystallinity, micro‐/mesoporosity, Brønsted acid site density and distribution (in micro‐ vs. mesopores), and catalytic activity suggest nearly invariant structure and function for aluminosilicate zeolite MFI 2D nanosheets before and after superheated steam treatment. Yet, pronounced reaction rate decrease for benzy...
Article
Some like it hot: A two-dimensional zeolite undergoes pronounced steam-induced coarsening which can only be detected by electron microscopy. For a reaction involving bulky molecules, this coarsening remarkably alters external surface catalytic activity, while preserving microporous catalysis unaltered, demonstrating a new method to fine-tune select...
Article
Hydration of surface ions gives rise to structural heterogeneity and variable exchange kinetics of water at complex mineral-water interfaces. Here, we employ ab initio molecular dynamics (AIMD) simulations and water adsorption calorimetry to examine the aqueous interfaces of xenotime, a phosphate mineral that contains predominantly Y³⁺ and heavy ra...
Article
Metal organic frameworks are a class of porous compounds with potential applications in molecular sieving, gas sequestration, and catalysis. One family of MOFs, zeolitic imidizolate frameworks (ZIFs), is of particular interest for carbon dioxide sequestration. We have previously reported the heat capacity of the sodalite topology of the zinc 2-meth...
Article
Heat capacities and enthalpies of formation of BaGd2O4 were determined by high temperature differential scanning calorimetry and high temperature oxide melt solution calorimetry, respectively. Thermodynamic stability of BaLn2O4 compounds increases with decreasing Ln3+ ionic radius. Previously reported data on BaNd2O4 and BaSm2O4 corroborate this tr...
Article
It has been previously reported in the literature that the vacancy concentration in a solid can be estimated using the linear term derived from low temperature heat capacity measurements. This paper investigates how such a model performs in both random and partially clustered vacancy systems. The heat capacity measurements were used to investigate...
Article
The thermodynamic stability of a series of nitrogen - doped reduced graphene oxides prepared by ammonolysis of graphene oxide has been investigated by high temperature oxidation calorimetry. In terms of enthalpy and depending on the concentration of nitrogen, the nitrogen - doped reduced graphene oxides can be up to 73 kJ·mol⁻¹ more stable than gra...
Article
Differential scanning calorimetry has been employed to analyze the jerky behavior of exothermic, structural reorganization processes of the highly disordered radiation-damaged uranium or thorium containing minerals pyrochlore and allanite. The thermal signals occur as thermal spikes forming crackling noise spectra. The energy of the thermal spikes...
Article
The recent finding of local weberite-like ordered domains in disordered and radiation damaged pyrochlore oxides has sparked interest in studying the structure, stability, and order-disorder in compounds that form in the weberite structure. In order to understand the relationships among the energetics, structure, and disordering, weberites of the fo...
Article
Full-text available
The onset of thermally induced, heterogeneous structural reorganization of highly radiation-damaged allanite-(Ce) begins at temperatures below 700 K. Three strongly disordered allanite samples (S74 20414: ~ 0.55 wt% ThO2, 22.1 wt% REE oxides, and maximum radiation dose 3.5 × 1018 α-decay/g; LB-1: ~1.18 wt% ThO2, 19.4 wt% REE oxides, and maximum rad...
Article
The interaction of water, carbon dioxide and methane with faujasite zeolite Y has been probed by gas absorption calorimetry. The energetics of water sorption reveals guest-induced framework flexibility with transition from a less hydrated form to a more hydrated phase. The differential enthalpy of absorption directly measures strengths of guest-hos...
Article
Thermodynamics of Complex Solids - Volume 34 Issue 19 - Alexandra Navrotsky, Kristina Lilova, Di Wu, Mark Asta
Article
While finding sustainable renewable energy sources is of high priority, it is equally important to develop solutions for energy storage. Advances in lithium ion batteries (LIB) indeed represent a great step in this direction. However, lithium is scarce and expensive, Batteries based on more earth-abundant elements such as sodium are attractive repl...
Article
Full-text available
The thermodynamics of the ZrO2 ‐ SrO system is of interest for the optimization of synthesis and applications of functional materials and high temperature structural ceramics. Earlier data on phase relationships and thermodynamic properties of the system are unfortunately scattered and inconsistent. In this work, the compounds Srn+1ZrnO3n+1 (n = 3,...
Article
Full-text available
The structure and thermochemistry of K2CO3–MgCO3 glass - Volume 34 Issue 19 - Martin C. Wilding, Brian L. Phillips, Mark Wilson, Geetu Sharma, Alexandra Navrotsky, Paul A. Bingham, Richard Brooker, John B. Parise
Article
Cesium lead iodide (CsPbI3) perovskite has shown great potential as a light absorbing material for solar cell ap-plications. Despite intense research leading to increasing power conversion efficiency, a major problem concern-ing CsPbI3 lies in the long-term stability and intercon-version between different CsPbI3 polymorphs, a subject barely studied...
Article
Design and synthesis of thermodynamically metastable yet kinetically achievable materials possessing various desired functional and physical properties have recently drawn tremendous scientific-attention. In addition to conventional heat treatments and wet chemistry approaches, energy deposition into materials can induce unique nonequilibrium phase...
Article
Full-text available
Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and...
Article
Full-text available
Lithium−aluminum layered double hydroxide chloride (LDH) has been recently demonstrated to be a promising sorbent material for selective lithium extraction and recovery from geothermal brine. In this research, LDH samples synthesized from two different starting materials (alumina and gibbsite) and with two post-drying conditions (ambient-dried and...
Article
Enthalpies of formation of the solid solutions of ZrxY0.5−x/2Ta0.5−x/2O2 (0 ≤ x ≤ 0.2 and 0.65 ≤ x ≤ 1) - Volume 34 Issue 19 - Maren Lepple, Kristina Lilova, Carlos G. Levi, Alexandra Navrotsky
Article
Full-text available
Thermodynamics of BaNd2O4 and phase diagram of the BaO–Nd2O3 system - Volume 34 Issue 19 - Weiping Gong, Alexandra Navrotsky
Article
Recently, the causative agents of Maternal Autoantibody-Related (MAR) autism, pathological autoantibodies and their epitopic targets (e.g. lactate dehydrogenase B [LDH B] peptide), have been identified. Herein, we report on the development of Systems for Nanoparticle-based Autoantibody Reception and Entrapment (SNAREs), which we hypothesized could...
Article
The trend toward dimension reduction in electronic devices has driven the research and development of low dielectric constant materials to solve resistance capacitance delays and power consumption issues. Amorphous porous hydrogenated silicon oxycarbides form a class of materials that have even lower dielectric constants than other silicon oxycarbi...
Article
Monazite- (REPO4; RE = La to Gd) and xenotime- (REPO4; RE = Dy to Lu & Y) type materials have been proposed as host matrices for the immobilization of actinides. Aqueous alteration of monazite and xenotime minerals could result in the formation of rhabdophane (REPO4 · 0.667 H2O; RE = La to Dy) and churchite (REPO4 · 2 H2O; RE = Gd to Lu & Y) phases...
Article
High temperature oxide melt solution calorimetry has been used to determine that the slight destabilization caused by the additional surface generated by the mesoporosity introduced in USY zeolite through surfactant‐templating (ca. 2 kJ mol−1 SiO2) is significantly lower than the energetic stabilization resulting from surfactant–silica interactions...
Article
With the aim of understanding the thermochemistry of the introduction of mesoporosity in zeolites by using surfactants, high temperature oxide melt solution calorimetry was used to determine the change in the enthalpy of formation of USY zeolite before and after the introduction of mesoporosity. Our results confirm that this process only slightly d...
Article
Full-text available
Thermodynamics of ZnxMn3−xO4 and Mg1−zCuzCr2O4 spinel solid solutions - Volume 34 Issue 19 - Kristina Lilova, Geetu Sharma, Shmuel Hayun, Daniel P. Shoemaker, Alexandra Navrotsky
Article
Energetics of hydration on uranium oxide and peroxide surfaces - Volume 34 Issue 19 - Xiaofeng Guo, Di Wu, Sergey V. Ushakov, Tatiana Shvareva, Hongwu Xu, Alexandra Navrotsky
Article
The present study introduces a facile single-source precursor preparative access to bamboo-like multiwalled carbon nanotubes (MWCNTs) highly dispersed within a mesoporous silica-rich matrix. The metal-free single-source precursor was synthesized via a one-pot sol-gel process using tetramethyl orthosilicate (TMOS) and 4,4′-dihydroxybiphenyl (DHBP) a...
Article
Ultra‐high temperature ceramics (UHTCs) represent an emerging class of materials capable of providing mechanical stability and heat dissipation upon operation in extreme environments, e.g., extreme heat fluxes, chemically reactive plasma conditions. In the last few decades, remarkable research efforts and progress were done concerning the physical...
Article
In the comment on “In Situ Determination of the HfO2‐Ta2O5‐Temperature Phase Diagram up to 3000 °C”, Fedorov praises the outstanding work performed by McCormack et al. Fedorov proposes that although the sketched monotectic phase field satisfies Gibbs phase rule and the lever rule, the curvature between T‐Ta2O5 and L+T‐ Ta2O5 was incorrect, in that...
Article
Zeolitic imidazolate frameworks (ZIFs) are composed of metal atoms connected with imidazole-like linkers, and these frameworks have potential for applications in molecular sieving, gas sequestration, and catalysis. In addition, these materials form true polymorphs with the same chemical composition but different topologies. In this paper, we presen...
Article
Nanoparticles are widely present in the natural environment. Their surface reactivity, redox ability, and adsorption properties are related to geochemical processes. To explore the thermodynamics of interaction between nano oxides and small gas molecules, we applied gas adsorption calorimetry to investigate the energetics of ethanol and carbon diox...
Article
UeSi intermetallic compounds have drawn great attention due to their potential application as nuclear fuels. However, the thermodynamic properties and phase equilibria of this binary system from ambient to high temperature conditions are not fully understood. Via high temperature oxidative drop calorimetry and detailed characterization of the initi...
Article
The prediction of topological preferences and polymorph stability remains a challenge for the design of metal-organic frameworks (MOFs) exhibiting a rich topological landscape, such as zeolitic imidazolate frameworks (ZIFs). Here, we have used mechanochemical screening and calorimetry to test the ability of dispersion-corrected periodic density fun...
Article
Full-text available
Rare metal-organic framework (MOF) minerals stepanovite and zhemchuzhnikovite can exhibit properties comparable to known oxalate MOF proton conductors, including high proton conductivity over a range of relative humidities at 25 oC, and retention of the framework structure upon thermal dehydration. They also have high thermodynamic stability, with...
Article
Full-text available
Thermodynamic properties of refractory materials, such as standard enthalpy of formation, heat content, and enthalpy of reaction, can be measured by high temperature calorimetry. In such experiments, a small sample pellet is dropped from room temperature into a calorimeter operating at high temperature (often 700 °C) with or without a molten salt s...
Article
We demonstrate the use of ball milling mechanochemistry for rapid, simple, and materials-efficient synthesis of the organic mineral paceite CaCu(OAc) 4 ·6H 2 O (where OAc ⁻ is the acetate ion), composed of coordination polymer chains containing alternating Ca ²⁺ and Cu ²⁺ ions, as well as its cadmium-based analogue CaCd(OAc) 4 ·6H 2 O. While the sy...
Article
The fluorite phase in CeO2 − CaO − ZrO2 is important in nuclear energy and fuel cell applications yet one lacks quantitative evaluation of its composition range and thermodynamic properties. Using experimental thermodynamic data from binary systems ZrO2 − CeO2 CaO − CeO2 and CaO − ZrO2, the present work fitted the enthalpies of mixing to regular so...
Article
Surface water can affect the properties of metal oxide nanoparticles. Investigations on several systems revealed that nanoparticles have different thermodynamic properties than their bulk counterparts due to adsorbed water on their surfaces. Some thermodynamically metastable phases of bulk metal oxides become stable when reduced to the nanoscale, p...
Article
Lithium borate (LB) glasses and crystals with x = Li/(Li+B) = mole fraction of Li2O of 0.2 to 0.5 have been synthesized by the quenching method. The thermodynamics of these materials were analyzed by high temperature oxide melt solution calorimetry. The formation enthalpies from oxides of glasses range from ‐33.6 to ‐67.3 kJ/mol and those of crysta...
Article
Full-text available
The impact of composition on the tunnel features of hollandite materials for the purpose of radioactive cesium (Cs) immobilization was evaluated. The barium (Ba) to cesium (Cs) ratio was varied in the tunnel sites referred to as the A-site of the hollandite structure. Zinc (Zn) was substituted for titanium (Ti) on the B-site to achieve the targeted...
Article
The previously unknown experimental HfO2‐Ta2O5‐temperature phase diagram has been elucidated up to 3000 ˚C using a quadrupole lamp furnace and conical nozzle levitator system equipped with a CO2 laser, in conjunction with synchrotron X‐ray diffraction. These in‐situ techniques allowed the determination of: (i) liquidus, solidus and invariant transf...
Article
Full-text available
In the fast-evolving field of halide perovskite semiconductors, the 2D perovskites (A')2(A) n-1M n X3n+1 [where A = Cs+, CH3NH3+, HC(NH2)2+; A' = ammonium cation acting as spacer; M = Ge2+, Sn2+, Pb2+; and X = Cl-, Br-, I-] have recently made a critical entry. The n value defines the thickness of the 2D layers, which controls the optical and elect...
Article
La1−xNdxPO4 monazite-type ceramics were synthesized by precipitation and sintering. The obtained crystalline powders and pellets were structurally characterized by X-ray diffraction, electron microscopy, and infrared and Raman spectroscopy. The determined unit cell constants agree with published values for the pure end-members ranging from LaPO4 to...
Article
Full-text available
Hollandite materials, as a class of crystalline nuclear waste forms, are promising candidates for the immobilization of radioactive elements, such as Cs, Ba, as well as a variety of lanthanide and transition metal fission products. In this study, three Ga‐doped titanate hollandite‐type phases, Ba1.33Ga2.67Ti5.33O16, Ba0.667Cs0.667Ga2Ti6O16 and Cs1....
Article
Full-text available
Rare earth phosphates comprise a large family of compounds proposed as possible nuclear waste disposal forms. We report structural and thermodynamic properties of a series of rare earth rhabdophanes and monazites. The water content of the rhabdophanes, including both adsorbed and structural water, decreases linearly with increase in ionic radius of...