Read me file for data from One Site, Two Cations, Three Environments: s2 and s0 Electronic Configurations Generate Pb-Free Relaxor Behavior in a Perovskite Oxide

The piezoelectric devices widespread in society use noncentrosymmetric Pb-based oxides because of their outstanding functional properties. The highest figures of merit reported are for perovskites based on the parent Pb(Mg1/3Nb2/3)O3 (PMN), which is a relaxor: a centrosymmetric material with local symmetry breaking that enables functional properties, which resemble those of a noncentrosymmetric material. We present the Pb-free relaxor (K1/2Bi1/2)(Mg1/3Nb2/3)O3 (KBMN), where the thermal and (di)electric behavior emerges from the discrete structural roles of the s0 K+ and s2 Bi3+ cations occupying the same A site in the perovskite structure, as revealed by diffraction methods. This opens a distinctive route to Pb-free piezoelectrics based on relaxor parents, which we demonstrate in a solid solution of KBMN with the Pb-free ferroelectric (K1/2Bi1/2)TiO3, where the structure and function evolve together, revealing a morphotropic phase boundary, as seen in PMN-derived systems. The detailed multiple-length-scale understanding of the functional behavior of KBMN suggests that precise chemical manipulation of the more diverse local displacements in the Pb-free relaxor will enhance performance.


Dielectric data

Real and imaginary components of the dielectric permittivity for (1-x)KBMN-xKBT for x = 0, 0.25, 0.5, 0.7, 0.8, 0.9, and 1.0. The data as a function of frequency from 20 Hz to 2 MHz at room temperature and the data as a function of temperature from room temperature to 650°C for four frequencies (1 kHz, 10 kHz, 100 kHz, and 1 MHz) are both included. In addition to variable frequency and variable temperature data, the variable temperature data from 109 to 486 K for KBMN (x = 0) is included.


Diffraction data

For KBMN (x = 0) synchrotron X-ray diffraction data as a function of 2-theta, neutron diffraction data as a function the time-of-flight, and variable temperature Mo Kalpha X-ray diffraction data as a function of 2-theta is included. For x = 0.25, 0.5, and 1.0 Co Kalpha X-ray diffraction data as a function of 2-theta is included. For x = 0.7, 0.8, and 0.9 synchrotron X-ray diffraction data is included.


Heat Capacity data


The heat capacity as a function of temperature from 1.8 - 967 K for KBMN (x = 0) is included. The transformation of these data is included as well, where the observed heat capacity is interpolated to match the temperature step size of the calculated model, the difference of these two, and their integration (anomalous entropy) are included.


PE-SE-IE-TSDC data

For KBMN (x = 0) the polarization as a function of electric field (PE) at room temperature at 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, and 150 kV/cm is shown and the strain as a function of electric field (SE) is given at 140 kV/cm. The current as a function of applied field (IE) at room temperature is included for the same experiment as the polarization experiment at the same applied fields. The PE for KBMN (x = 0) is given at 200 K for 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 kV/cm. The thermally stimulated depolarization current (TSDC) from 125 - 220 K is given as well was its integration of the current with the surface area to yield the polarization. The PE and IE data at room temperature for 10, 20, 30, 40, 50, 60, 70, and 80 kV/cm and the SE at 80 kV/cm for x = 0.7, 0.8, 0.9, and 1.0 are given.