The phase transition of Li₃PO₄ solid electrolyte for secondary batteries in vacuum has been studied by using real-time synchrotron X-ray scattering. According to the vacuum heating results, the crystal β-Li₃PO₄ phase was stable only from room temperature to 400°C. The crystal γ-Li₃PO₄ phase appeared at 410°C and the crystal β-Li₃PO₄ phase completely disappeared at 430°C. The transition from the β-Li₃PO₄ to the γ-Li₃PO₄ phases occurred primarily at 410°C, which is 40°C lower than the transition temperature of 450°C in air. The decrease in the phase transition temperature in vacuum, compared to that in air, is attributed to a relatively high concentration of oxygen vacancies. As the isothermal annealing time at 390°C was increased to 8 hours, the β-Li₃PO₄ phase was completely transitioned into the γ-Li₃PO₄ phase. Our study revealed the detailed transition behavior from the β-Li₃PO₄ to the γ-Li₃PO₄ phases during real-time annealing in vacuum.

X-ray photon correlation spectroscopy (XPCS) provides access to nanoscale dynamics, yet practical approaches for interpreting its data remain limited. This tutorial presents a systematic framework for XPCS data analysis, illustrated using measurements performed at the NSLS-II CHX beamline. The fundamental concepts of speckle pattern and the intensity autocorrelation function are introduced, followed by ferroelectric case studies demonstrating how polarization switching and phase transition dynamics can be extracted from XPCS measurements. The influence of the probed q-range experimental conditions such as X-ray transmittance is examined for data interpretation. These elements are consolidated into practical guidelines for the reliable analysis of XPCS data.

Rietveld refinement has become an essential tool for the quantitative analysis of crystal structures in polycrystalline systems using X-ray diffraction data. This tutorial paper focuses on the background, case studies, and practical implementation of Rietveld refinement using the open-source software PROFEX. Key structural parameters, such as lattice constants and phase fractions, can be quantitatively extracted through full-pattern fitting. Case studies involving compositional variation, electric fields, temperature changes, and battery cycling demonstrate the broad applicability of Rietveld refinement in materials science, energy storage, and catalysis. A step-by-step procedure for performing Rietveld refinement is presented using Bi_1/2Na_1/2TiO₃ perovskite ceramic as an example, providing guidance on software installation, preparing crystal structure information files, performing Rietveld refinement, evaluating results using R-factor and χ² values, and summarizing the results. This tutorial aims to improve understanding and accessibility of Rietveld refinement for researchers seeking to investigate structure-property relationships in complex material systems.

Citations

• Bandgap tuning in anion-mixed perovskite oxysulfide BaZrO3-xSx
  Munir Ahmad, Seongboo Park, Hwan Min Kim, Muhammad Sheeraz, Chang Won Ahn, Ill Won Kim, Soobeom Shin, Hu Young Jeong, Furqanul Hassan Naqvi, Jae-Hyeon Ko, Jieun Kim, Young-Han Shin, Tae Heon Kim
  Current Applied Physics.2026; 89: 100.     CrossRef

In functional materials, in situ experimental techniques as a function of external stimulus (e.g., electric field, magnetic field, light, etc.) or changes in ambient environments (e.g., temperature, humidity, pressure, etc.) are highly essential for analyzing how the physical properties of target materials are activated/evolved by the given stimulation. In particular, in situ electric-field-dependent X-ray diffraction (XRD) measurements have been extensively utilized for understanding the underlying mechanisms of the emerging electromechanical responses to external electric field in various ferroelectric, piezoelectric, and electrostrictive materials. This tutorial article briefly introduces basic principles/key concepts of in situ electric-field-dependent XRD analysis using a lab-scale XRD machine. We anticipate that the in situ XRD method provides a practical tool to systematically identify/monitor a structural modification of various electromechanical materials driven by applying an external electric field.

Lead zirconate titanate/poly-vinylidene fluoride (PZT/PVDF) piezoelectric devices were fabricated by incorporating carbon nanotubes (CNTs), for use as flexible energy harvesting devices. CNTs were added to maximize the formation of the β phase of PVDF to enhance the piezoelectricity of the devices. The phase transition of PVDF induced by the addition of CNTs was confirmed by analyzing the X-ray diffraction patterns, scanning electron microscopy images, and atomic force microscopy images. The enhanced output efficiency of the PZT/PVDF piezoelectric devices was confirmed by measuring the output current and voltage of the fabricated devices. The maximum output current and voltage of the PZT/PVDF piezoelectric devices was 200 nA and 350 mV, respectively, upon incorporation of 0.06 wt% CNTs.

We investigated the dielectric relaxation properties 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics with CuO addition. With increasing CuO addition, the lattice parameter was increased by substitution of small amount Cu2+ ion in B-site of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics. Also the grain size and the maximum dielectric constant of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics was decreased with increasing amounts of CuO addition. Moreover, the diffused phase transition properties (γ) of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics was increased by compositional fluctuation with increasing of CuO amount, changed from 1.45 at 1 wt% CuO addition to 1.94 at 7 wt% CuO addition.

Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at 108±2℃ on heating and paraelectric phase to ferroelectric phase at 78±2℃ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.