Pressure-induced chemical decomposition of copper orthovanadate (α-Cu3V2O8)
The high pressure stability of α-Cu3V2O8 has been investigated via complementary high pressure synchrotron X-ray diffraction experiments and theoretical density functional theory calculations. The results of both experiment and theory are in close agreement. The main result of this work is that α-Cu3V2O8 undergoes a pressure-induced chemical decomposition into CuO and V2O5 at a modest pressure of ∼1.35 GPa according to the experimental observations, and at ∼2.45 GPa according to the calculations. The decomposition is investigated with enthalpy calculations and one of the main driving factors is the stability of the octhedral oxygen-coordination of the metal atoms in the decompositon product…
GdBO3 and YBO3 crystals under compression
High-pressure X-ray diffraction studies on nanocrystals of the GdBO3 and YBO3 rare-earth orthoborates are herein reported up to 17.4(2) and 13.4(2) GPa respectively. The subsequent determination of the room-temperature pressure-volume equations of state is presented and discussed in the context of contemporary publications which contradict the findings of this work. In particular, the isothermal bulk moduli of GdBO3 and YBO3 are found to be 170(13) and 163(13) GPa respectively, almost 50% smaller than recent findings. Our experimental results provide an accurate revision of the high-pressure compressibility behaviour of GdBO3 and YBO3 which is consistent with the known systematics in isomor…
Simple New Method for the Preparation of La(IO<sub>3</sub>)<sub>3</sub> Nanoparticles
We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route which takes a matter of hours, thereby providing an alternative to the common hydrothermal method which takes days. Nanoparticles of pure &alpha;-La(IO3)3 and pure &delta;-La(IO3)3 were synthesised via the new method depending on the source of iodate ions, thereby demonstrating the versatility of the synthesis route. The crystal structure, nanoparticle size-dispersal and chemical composition were characterised via angle- and energy-dispersive powder X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectrosco…
Pressure-Driven Symmetry-Preserving Phase Transitions in Co(IO3)2
[EN] High-pressure synchrotron X-ray diffraction studies of cobalt iodate, Co(IO3)(2), reveal a counterintuitive pressure-induced expansion along certain crystallographic directions. High-pressure Raman and infrared spectroscopy, combined with density-functional theory calculations, reveal that with increasing pressure, it becomes energetically favorable for certain I-O bonds to increase in length over the full range of pressure studied up to 28 GPa. This phenomenon is driven by the high-pressure behavior of iodate ion lone electron pairs. Two pressure-induced isosymmetric monoclinic-monoclinic phase transitions are observed at around 3.0 and 9.0 GPa, which are characterized by increasing o…
Simple New Method for the Preparation of La(IO3)3 Nanoparticles
We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route, which takes a matter of hours, thereby providing an alternative to the common hydrothermal method, which takes days. Nanoparticles of pure &alpha
A review on the advancements in the characterization of the high-pressure properties of iodates
The goal of this work is to report a systematic and balanced review of the progress made in recent years on the high-pressure behavior of iodates, a group of materials with multiple technological applications and peculiar behaviors under external compression. This review article presents results obtained from multiple characterization techniques which include: X-ray diffraction, Raman and infrared spectroscopy, optical-absorption, resistivity, and second-harmonic generation measurements. The discussion of the results from experiments will be combined with density-functional theory calculations which have been shown to be a very useful tool for the interpretation of experimental data. Throug…
Prediction of pressure-induced superconductivity in the novel ternary system ScCaH2n (n = 1–6)
Hydrogen-rich systems are currently thought to constitute the most promising potential high-temperature superconductor materials. Here, the high-pressure structure and superconductivity of the ternary hydrogen-rich system ScCaH2n (n = 1–6) are systematically investigated by using the prediction method of particle swarm optimization structure combined with first-principles calculations. As n increases, the electron local function (ELF) indicates that the hydrogen atoms in this system exhibit different behaviors corresponding to single H atoms, H2 molecules, graphene-like layers and, ultimately, H clathrate cages. The electron phonon coupling (EPC) calculation shows that the superconducting t…
Experimental and theoretical study of dense YBO3 and the influence of non-hydrostaticity.
[EN] YBO3 is used in photonics applications as a host for red phosphors due to its desirable chemical stability, high quantum efficiency and luminescence intensity. Despite its fundamental thermodynamic nature, the isothermal bulk modulus of YBO3 has remained a contentious issue due to a lack of comprehensive experimental and theoretical data and its vibrational modes are far from being understood. Here, we present an experimental-theoretical structural and vibrational study of YBO3. From structural data obtained from synchrotron X-ray diffraction data and ab initio calculations, we have determined the YBO3 bulk modulus, isothermal compressibility tensor and pressure-volume (P-V) equation o…