Issue 30, 2022

Ultrasonic study of 1-X adamantane (X = F, Cl, Br) compounds at high pressure and at order–disorder transitions

Abstract

We present an ultrasonic study of the elastic properties of 1-X adamantane (X = F, Cl, Br) during order–disorder and order–quasi-order transitions at various temperatures (77–305 K) and high pressures (up to 1 GPa). On the basis of our ultrasonic experiments, we studied for the first time the high-temperature (HT) Fm3m, medium-temperature (MT) P42/nmc, and low-temperature (LT) P421c phases of 1-fluoroadamantane at high pressures. The elastic properties of these phases at pressures up to 1 GPa at T = 293 and 77 K, as well as at isobaric heating from 77 to 293 K, have been determined. The boundaries of the HT → MT → LT phase transitions have been evaluated, which makes it possible to extend the phase diagram of 1-fluoroadamantane to higher pressures. We have confirmed that the MT → LT transition is a second-order phase transition because it is not accompanied by volume jumps but is manifested in anomalies of the elastic properties and ultrasound transmission both in high-pressure experiments and under isobaric heating. The comparison of the elastic properties of 1-X adamantanes (X = H, F, Cl, Br) has indicated a monotonic dependence at low pressures: the bulk modulus is the highest for adamantane and decreases with an increase of the atomic number of the halogen substitute (from fluorine to bromine).

Graphical abstract: Ultrasonic study of 1-X adamantane (X = F, Cl, Br) compounds at high pressure and at order–disorder transitions

Article information

Article type
Paper
Submitted
15 Jun 2022
Accepted
14 Jul 2022
First published
14 Jul 2022

Phys. Chem. Chem. Phys., 2022,24, 18022-18027

Ultrasonic study of 1-X adamantane (X = F, Cl, Br) compounds at high pressure and at order–disorder transitions

E. L. Gromnitskaya, I. V. Danilov and V. V. Brazhkin, Phys. Chem. Chem. Phys., 2022, 24, 18022 DOI: 10.1039/D2CP02720H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements