EosFit7-GUI: a new graphical user interface for equation of state calculations, analyses and teaching

Abstract

EosFit7-GUI is a full graphical user interface designed to simplify the analysis of thermal expansion and equations of state (EoSs). The software allows users to easily perform least-squares fitting of EoS parameters to diffraction data collected as a function of varying pressure, temperature or both. It has been especially designed to allow rapid graphical evaluation of both parametric data and the EoS fitted to the data, making it useful both for data analysis and for teaching.

Strain engineered pyrochlore at high pressure

“…This maximum pressure was chosen because plotting out to too high of a pressure can include effects from structural distortions due to the creation of the high-pressure cotunnite phase 44 , as well as increased non-hydrostaticity of the silicone oil pressure-transmitting medium 45 . Data are fit with a third-order Birch-Murnaghan equation of state using EosFit7-GUI 46, 47 to determine the bulk moduli (B 0 ) of the samples. The pressure-derivative of bulk modulus (Bʹ) is held constant at 8 for all samples so a direct comparison of B 0 could be conducted.…”

Structural Behavior of ZnCr2S4 Spinel under Pressure

“…Refinements were performed using the GSAS+EXPGUI software packages 42,43 . The P-V data were fitted with a Birch-Murnaghan equation of state (B-M EoS) 44 using the EosFit program 45 .…”

“…In order to look for subtle structural changes which may reflect the aforementioned electronic change, we have employed the Eulerian strain f E as a function of the normalized pressure F (F-f E ) plots 45 for the ZnCr 2 S 4 , ZnCr 2 Se 4 , and HgCr 2 S 4 compounds. This approach has served well before for identifying subtle structural anomalies in the vicinity of electronic transitions 72,73 ; the F-f E parameters should exhibit a linear correlation, with potential divergence from a linear trend implying (subtle) structural changes.…”

High Pressure Properties of a Ba-Cu-Zn-P Clathrate-I

“…Furthermore, EOSfit7-GUI was used to fit the experimental pressure/volume data of the clathrate to a third-order Birch-Murnaghan equation of state model and determine the bulk modulus of the clathrate at different pressures. In this model, the following formulas are used to calculate the bulk modulus, K , where f E is the finite Eulerian strain: $K_{PT}=K_{0T}{\left(1+2f_E\right)}^{5/2}\left(1+(3K_{0T}^{\text{'}}-5)f_E+\frac{27}{2}(K_{0T}^{\text{'}}-4)f_E^2\right)$ [13,14,15,16,23]. …”