A bismuth ferrite and barium titanate solid solution compound can achieve good piezoelectric properties with a high Curie temperature when fabricated with low-temperature sintering followed by a water-quenching process, with no complicated grain alignment processes performed. By adding the super-tetragonal bismuth gallium oxide to the compound, the piezoelectric properties are as good as those of lead zirconate titanate ceramics.

Using neutron pair distribution function analysis over the temperature range from 1000 to 15 K, we demonstrate the existence of local polarization and the formation of medium-range, polar nanoregions (PNRs) with local rhombohedral order in a prototypical relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3. We estimate the volume fraction of the PNRs as a function of temperature and show that this fraction steadily increases from 0% to a maximum of approximately 30% as the temperature decreases from 650 to 15 K. Below T approximately 200 K the volume fraction of the PNRs becomes significant, and PNRs freeze into the spin-glass-like state.

The mean-square relative displacements (MSRD) of atomic pair motions in crystals are studied as a function of pair distance and temperature using the atomic pair distribution function (PDF). The effects of the lattice vibrations on the PDF peak widths are modelled using both a multi-parameter Born von-Karman (BvK) force model and a single-parameter Debye model. These results are compared to experimentally determined PDFs. We find that the near-neighbor atomic motions are strongly correlated, and that the extent of this correlation depends both on the interatomic interactions and crystal structure. These results suggest that proper account of the lattice vibrational effects on the PDF peak width is important in extracting information on static disorder in a disordered system such as an alloy. Good agreement is obtained between the BvK model calculations of PDF peak widths and the experimentally determined peak widths. The Debye model successfully explains the average, though not detailed, natures of the MSRD of atomic pair motion with just one parameter. Also the temperature dependence of the Debye model largely agrees with the BvK model predictions. Therefore, the Debye model provides a simple description of the effects of lattice vibrations on the PDF peak widths.

High real-space resolution atomic pair distribution functions (PDF)s from the alloy series Ga1−xInxAs have been obtained using high-energy x-ray diffraction. The first peak in the PDF is resolved as a doublet due to the presence of two nearest neighbor bond lengths, Ga-As and In-As, as previously observed using XAFS. The widths of nearest, and higher, neighbor pairs are analyzed by separating the strain broadening from the thermal motion. The strain broadening is five times larger for distant atomic neighbors as compared to nearest neighbors. The results are in agreement with model calculations.The average atomic arrangement of crystalline semiconductor alloys is usually obtained from the position and intensities of the Bragg peaks in a diffraction experiment [1], and the actual nearest neighbor and sometimes next nearest neighbor distances for various pairs of atoms by XAFS measurements [2]. In this Letter we show how high energy x-ray diffraction and the resulting highresolution atomic pair distribution functions (PDF)s can be used for studying the internal strain in Ga 1−x In x As alloys. We show that the first peak in the PDFs can be resolved as a doublet and, hence, the mean position and also the widths of the Ga-As and In-As bond length distributions determined. The detailed structure in the PDF can be followed out to very large distances and the widths of the various peaks obtained. We use the concentration dependence of the peak widths to separate the strain broadening from the thermal broadening. At large distances the strain broadening is shown to be about five times larger than for nearest neighbor pairs. Using a simple valence force field model, we get good agreement with the experimental results.

The atomic motions in crystals are correlated. In this paper we demonstrate that information about the correlated motion of atoms, and consequently about the bonding within the crystal, can be obtained by analyzing the peak width of the atomic pair distribution function (PDF). We have measured the PDFs of Ni and InAs using synchrotron X-ray diffraction. The analysis of the Ni data allowed us to determine the Debye temperature which is in good agreement with values found in the literature. In contrast to the isotropic metallic bonding in Ni resulting in a relatively weak correlation between the motion of neighboring atoms, we found a very strong correlation in InAs as one might expect from the covalent bond between In and As. The results are compared with theoretical predictions by Chung and Thorpe (Phys. Rev. B 1977, 55, 1545).