Thermal evolution of stillwellite, CeBSiO5, a natural prototype for a family of NLO-active materials

Research subject. Reedmergnerite and stillwellite-(Ce) were obtained from the rocks of the Dara-i-Pioz alkaline massif located on the southern slope of the Alai Range in Tajikistan, which is characterized by the presence of rare mineral species including borosilicates and lithium minerals. Aim. To investigate the thermal behavior of reedmergnerite and stillwellite-(Ce) using high-temperature X-ray diffraction, including the determination of phase transition temperatures and expansion/compression of the unit cell parameters, as well as the calculation of thermal expansion coefficients. Materials and methods. Chemical analysis was performed using a TESCAN MIRA 3 microscope (EDS mode) and a JEOL JXA-8230 electron probe microanalyzer (WDS mode). High-temperature powder X-ray diffraction data were collected using a D8 ADVANCE Bruker diffractometer with an HTK16 heating chamber, covering temperatures from 30°C to 750°C in ambient air. Results. The thermal expansion coefficients of reedmergnerite and stillwellite-(Ce) were determined. Heating reedmergnerite resulted in slight changes in the unit cell parameters, with the parameter c experiencing the smallest change and the parameter a showing the greatest increase. The unit cell volume increased by 1.8% when heated to 750°C and returned to its initial value upon cooling. When stillwellite-(Ce) is heated in the temperature range of 400–450°C, a phase transition occurs, which is confirmed by previously recorded temperature values. The conducted heating and subsequent cooling experiments revealed that the volume and unit cell parameters of stillwellite-(Ce) did not fully revert to their original values. Conclusions. The coefficients of thermal expansion tensor (αij) of rhodmerdgnertite and stillwellite-(Ce) were investigated as a function of temperature using high-temperature in-situ experiments. The phases exhibited relatively low values of thermal expansion parameters compared to the general data for feldspars and borosilicates obtained from literature. These findings contribute to the understanding of the thermoelastic behavior of this group of minerals and their potential applications in various fields.

show abstract

Non-ambient crystal chemistry of stillwellite-like BaBPO<SUB>5</SUB> from single crystal XRD data

Krzhizhanovskaya,

Gorelova,

Kopylova

et al. 2024

Zapiski Vserossijskogo mineralogičeskogo obŝestva

View full text Add to dashboard Cite

Stillwellite-(Ce) and some its synthetic analogues tend to undergo phase transition from polar (ferroelectric) to nonpolar (paraelectric) modification on heating. However, the reasons for the transition and phase stability remain the subject of scientific debate. Here we present detail studies (scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and single-crystal X-ray diffraction (SCXRD)) of hydrothermally grown BaBPO5 isostructural with stillwellite-(Ce). Its thermal behavior was studied by an in situ low- (from –173 to +25 °C) and high-temperature (HT; 25–800 °C) SCXRD. Fully ordered crystal structure of BaBPO5 (at T = 25 °C: trigonal, P3221, a = 7.1166(1) Å, c = 7.0011(1) Å, V = 307.07(1) Å3, R1 = 1.42 %) does not exhibit any change of symmetry upon cooling / heating unlike natural stillwellite-(Ce). Thermal expansion of BaBPO5 is almost isotropic (αmin = 8.4, αmax = 8.7⋅10-6 °C-1) despite the chain nature of borophosphate anion. The comparative crystal chemical analysis of HT behavior of cationic polyhedra in the stillwellite-family members is presented.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Thermal evolution of stillwellite, CeBSiO5, a natural prototype for a family of NLO-active materials

Cited by 3 publications

References 55 publications

The structural origin and boundaries of thermal transitions in stillwellite-type LnBSiO5

The structural origin and boundaries of thermal transitions in stillwellite-type LnBSiO5

Reedmergnerite and stillwellite-(Ce) from the Dara-i-Pioz alkaline massif: insights into high-temperature behavior of borosilicates

Non-ambient crystal chemistry of stillwellite-like BaBPO<SUB>5</SUB> from single crystal XRD data

Contact Info

Product

Resources

About