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Abstract The environmental conical nozzle levitator (E‐CNL) with dual‐wavelength lasers is an extreme environment materials characterization system that was designed to investigate ultra‐high‐temperature materials: refractory metals, oxides, carbides, and borides above 3000 K in a controlled atmosphere. This article details the characterizations using this system to establish its high‐temperature capabilities and to outline ongoing work on materials under extreme conditions. The system has been used to measure the melting point of several oxide materials (TiO₂, Tm = 2091 ± 3 K; Al₂O₃, Tm = 2310 3 K; ZrO₂, Tm = 2984 31 K; and HfO₂, Tm = 3199 ± 45 K) and several air‐sensitive refractory metals (Ni, Tm = 1740 K; Ti, Tm = 1983 K; Nb, Tm = 2701 K; and Ta, Tm = 3368 K—note: mean ± standard deviation) during levitation which matched literature values within 0.17–2.43 % demonstrating high accuracy and precision. This containerless measurement approach is critical for probing properties without container‐derived contamination, and dual‐wavelength laser heating is essential to heat both relatively poor electrical conductors (some refractory metals and carbides) and insulators (oxides). The highest temperature achieved utilizing both lasers in these experiments was ∼4250 ± 34 K on a 76.6 mg, molten HfO₂sample using a normal spectral emissivity of 0.91. Stable levitation was demonstrated on spherical samples (yttria‐stabilized zirconia) while adjusting levitation gas composition from pure oxygen to pure argon, verifying atmospheric control up to 3173 K on solid or molten samples. These successes demonstrate the viability of in situ high‐temperature environmentally controlled studies potentially up to 4000 K on all classes of ultra‐high‐temperature materials in one system. These measurements highlight the E‐CNL system will be essential for the development of next‐generation ultra‐high‐temperature materials for hypersonic platforms, nuclear fission and fusion, and space exploration. 

To enhance the solubility of orally administered pharmaceuticals, liquid capsules or amorphous tablets are often preferred over crystalline drug products. However, little is known regarding the variation in bonding mechanisms between pharmaceutical molecules in their different disordered forms. In this study, liquid and melt-quenched glassy carbamazepine have been studied using high energy X-ray diffraction and modeled using Empirical Potential Structure Refinement. The results show significant structural differences between the liquid and glassy states. The liquid shows a wide range of structures; from isolated molecules, to aromatic ring correlations and NH-O hydrogen bonding. Upon quenching from the liquid to the glass the number of hydrogen bonds per molecule increases by ~50% at the expense of a ~30% decrease in the close contact (non-bonded) carbon-carbon interactions between aromatic rings. During the cooling process, there is an increase in both singly and doubly hydrogen-bonded adjacent molecules. Although hydrogen-bonded dimers found in the crystalline states persist in the glassy state, the absence of a crystalline lattice also allows small, hydrogen-bonded NH-O trimers and tetramers to form. This proposed model for the structure of glassy carbamazepine is consistent with the results from vibrational spectroscopy and nuclear magnetic resonance. 

Abstract Structure and thermodynamics of pure cubic ZrO₂and HfO₂were studied computationally and experimentally from their tetragonal to cubic transition temperatures (2311 and 2530 °C) to their melting points (2710 and 2800 °C). Computations were performed using automatedab initiomolecular dynamics techniques. High temperature synchrotron X-ray diffraction on laser heated aerodynamically levitated samples provided experimental data on volume change during tetragonal-to-cubic phase transformation (0.55 ± 0.09% for ZrO₂and 0.87 ± 0.08% for HfO₂), density and thermal expansion. Fusion enthalpies were measured using drop and catch calorimetry on laser heated levitated samples as 55 ± 7 kJ/mol for ZrO₂and 61 ± 10 kJ/mol for HfO₂, compared with 54 ± 2 and 52 ± 2 kJ/mol from computation. Volumetric thermal expansion for cubic ZrO₂and HfO₂are similar and reach (4 ± 1)·10⁻⁵/K from experiment and (5 ± 1)·10⁻⁵/K from computation. An agreement with experiment renders confidence in values obtained exclusively from computation: namely heat capacity of cubic HfO₂and ZrO₂, volume change on melting, and thermal expansion of the liquid to 3127 °C. Computed oxygen diffusion coefficients indicate that above 2400 °C pure ZrO₂is an excellent oxygen conductor, perhaps even better than YSZ. 

Abstract 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 CO₂laser, in conjunction with synchrotron X‐ray diffraction. These in‐situ techniques allowed the determination of the following: (a) liquidus, solidus, and invariant transformation temperatures as a function of composition from thermal arrest experiments, (b) determination of equilibrium phases through testing of reversibility via in‐situ X‐ray diffraction, and (c) molar volume measurements as a function of temperature for equilibrium phases. From these, an experimental HfO₂–Ta₂O₅‐temperature phase diagram has been constructed which is consistent with the Gibbs Phase Rule.