Related Experiment Video
Updated: Jan 28, 2026

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography
Published on: April 24, 2018
High-Temperature Isostructural Phase Transition in Ce2(MoO4)3: A Rare Phenomenon Investigated through X‑ray
Zeyna Dos Santos Viegas1, Alan Silva de Menezes1, Cleânio Luz-Lima2
1Departamento de Física, Centro de Ciências Exatas e Tecnologia, Universidade Federal do Maranhão, CEP 65080-800 São Luís, MA, Brazil.
Abstract:
The rare-earth compound cerium-(III) molybdate (Ce2(MoO4)3) has gained attention due to its diverse industrial applications, such as photocatalysis, corrosion inhibition, self-repair of protective layers, as well as antiviral and antibacterial properties. However, its response to extreme temperature conditions remains insufficiently explored. This study employs ambient powder X-ray diffraction (PXRD), UV-vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy techniques to confirm the successful hydrothermal synthesis of a crystalline sample of the Ce2(MoO4)3 compound. Subsequently, in situ temperature-dependent (13-973 K) XRD and Raman scattering (293-998 K) studies were conducted. Rietveld analysis of diffraction patterns reveals a stable low-temperature phase (13-303 K) and anomalies in the high-temperature evolution (T > 583 K) of lattice parameters and the sample's microstrain and crystallite size. In the high-temperature (T > 848 K) Raman spectra of Ce2(MoO4)3, an additional band emerges at 452 cm-1; the observed anomalies are attributed to an isostructural phase transition (IPT). This type of phase transition is among the rarest phenomena reported in the literature. Our findings enhance the understanding of the physical properties of Scheelite-type compounds and emphasize the importance of investigating these uncommon phenomena. This knowledge can potentially drive the development of novel materials and expand their applications in materials science.
Related Concept Videos
Phase Transitions
Phase Transitions: Vaporization and Condensation
Phase Transitions: Sublimation and Deposition
Phase Transitions: Melting and Freezing
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
X-ray Diffraction of Biological Samples
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal...

