Synthesis and Properties of the BaPrWO Double Perovskite.

We report details on the synthesis and properties of barium praseodymium tungstate, BaPrWO, a double perovskite that has not been synthesized before. Room-temperature (RT) powder X-ray diffraction identified the most probable space group (SG) as monoclinic 2/, but it was only slightly distorted from the cubic structure. X-ray photoelectron spectroscopy confirmed that the initial (postsynthesis) material contained praseodymium in both 3+ and 4+ charge states.

Correction to "Synthesis Attempt and Structural Studies of Novel ACeWO Double Perovskites (A = Ba, Ca) in and outside of Ambient Conditions".

[This corrects the article DOI: 10.1021/acsomega.2c00669.

Synthesis Attempt and Structural Studies of Novel ACeWO Double Perovskites (A = Ba, Ca) in and outside of Ambient Conditions.

This comprehensive work showcases two novel, rock-salt-type minerals in the form of amphoteric cerium-tungstate double perovskite and ilmenite powders created via a high-temperature solid-state reaction in inert gases. The presented studies have fundamental meaning and will mainly focus on a detailed synthesis description of undoped structures, researching their possible polymorphism in various conditions and hinting at some nontrivial physicochemical properties like charge transfer for upcoming optical studies after eventual doping with selectively chosen rare-earth ions. The formerly mentioned, targeted ABB'X group of compounds contains mainly divalent alkali cations in the form of A = Ba, Ca sharing, here, oxygen-arranged clusters (X = O) with purposely selected central ions from f-block B = Ce and d-block B' = W since together they often possess some exotic properties that could be tuned and implemented into futuristic equipment like sensors or energy converters.

Site-occupancy scheme in disordered CaRE(BO): a dependence on rare-earth (RE) ionic radius.

The structures of polycrystalline CaRE(BO) (RE = La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Y; space group Pnma) orthoborates were determined using powder X-ray diffraction. Trends in the unit-cell dimensions and yet unreported trends in other structural properties (interatomic distances and the fractional occupation of three Ca/RE sites) for these compounds are demonstrated as a function of RE ionic radius. The unit-cell volume and a unit-cell parameter present a linear dependence, while the b and c unit-cell parameters change in a nonlinear manner.

Variation of cation distribution with temperature and its consequences on thermal expansion for CaEu(BO).

The structure of calcium europium orthoborate, CaEu(BO), was determined using high-resolution powder X-ray diffraction data collected at the ID22 beamline (ESRF) under ambient conditions, as well as at high temperature. Rietveld refinement allowed determination of the lattice constants and structural details, including the Ca/Eu ratios at the three cationic sites and their evolution with temperature. Clear thermal expansion anisotropy was found, and slope changes of lattice-constant dependencies on temperature were observed at 923 K.

High-Pressure Low-Temperature Optical Studies of BaWO:Ce,Na Crystals.

We report detailed optical studies of BaWO:Ce and BaWO:Ce,Na single crystals. The material does not emit any luminescence at ambient pressure under near-UV (325 nm) excitation. Efficient green light is emitted only at high pressure (HP) and low temperature (LT).

Equation of State and Amorphization of CaR(VO) (R = La, Nd, Gd): A Combined High-Pressure X-ray Diffraction and Raman Spectroscopy Study.

CaR(VO) (R = rare earth) multicomponent oxides of a whitlockite-related structure are under consideration for applications in optoelectronics. In this work, the Czochralski-grown CaR(VO) crystals were investigated as a function of pressure by powder X-ray diffraction and single-crystal Raman spectroscopy. The diffraction experiments were performed at the ALBA synchrotron under pressures ranging up to 9.