We have investigated the linear compressibility and thermal expansion properties of KMn[Ag(CN) 2 ] 3 using Raman spectroscopy and DFT calculations. Phonon frequencies and mode assignments from polarized Raman measurements and DFT calculations agree with each other satisfactorily. Computed linear compressibilities and thermal expansion coefficients corroborate the reported measured values. Pressure variation of mean partial phonon frequencies of KMn[Ag(CN) 2 ] 3 shows that large amplitude anharmonic displacements of Ag atoms can occur with minimum enthalpy cost even with increasing pressure. This means that Ag layer can be squeezed relatively easily, which manifests as PLC in the basal plane and coupled NLC along trigonal axis due to the rigid Mn-NC-Ag-CN-Mn chain along ⟨101⟩ crystal direction. Elastic constants of KMn[Ag(CN) 2 ] 3 indicate that the crystal is highly anisotropic and becomes unstable with increasing pressure. Directional Gruneisen parameters of KMn[Ag(CN) 2 ] 3 are found to be highly anisotropic. These properties show that NLC/NTE and PLC/PTE in KMn[Ag(CN) 2 ] 3 are driven by elastic and Gruneisen anisotropies combined with anharmonic lattice vibrations of Ag atoms. Partial phonon frequencies of KMn[Ag(CN) 2 ] 3 are found to be higher than those of Ag 3 [Co(CN) 6 ]. The partial frequency of K atom increases rapidly with pressure and becomes comparable to that of Ag around 2 GPa. This shows that K inclusion stiffens the lattice and changes the dynamics, causing the pressure-induced phase transformation of KMn[Ag(CN) 2 ] 3 to occur at a higher pressure rather than at 0.2 GPa as in Ag 3 [Co(CN) 6 ]. The phase transformation can be attributed to the softening of two low-energy optic modes (A 2 and E) and the softening of C 44 shear elastic constant and hence the transverse acoustic mode.

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a b s t r a c tThree model ODS alloys (Fe-0.3Y 2 O 3 , Fe-0.2Ti-0.3Y 2 O 3 and Fe-14Cr-0.2Ti-0.3Y 2 O 3 ) were prepared by ball milling and then hot extrusion to study the effect of Ti and Cr on the size, distribution, crystal structure and composition of the nano-oxide particles. All alloys were characterized by high resolution transmission electron microscopy (HRTEM), atom probe tomography (APT) and synchrotron-X-ray diffraction (S-XRD) to determine the distribution, structure and composition of the oxide nanoparticles samples. The median particle sizes were 9.6 nm, 7.7 nm and 3.7 nm for the Fe-Y 2 O 3 , Fe-Ti-Y 2 O 3 and Fe-Cr-Ti-Y 2 O 3 alloys, respectively, so the presence of Ti resulted in a significant reduction in oxide particle diameter and the addition of Cr gave a further reduction in size. In the Fe-0.3Y 2 O 3 alloy, the particles are found to be bcc Y 2 O 3 , whereas in the other two alloys (Fe-Ti-0.3Y 2 O 3 and Fe-Cr-Ti-Y 2 O 3 ), the oxide particles were found to be structurally consistent with both orthorhombic Y 2 TiO 5 and fcc Y 2 Ti 2 O 7 . Detailed APT studies showed Cr shells around oxide particles of all sizes in the Fe-Cr-Ti-Y 2 O 3 alloy, that a range of cluster compositions are present and that the particle chemistry varies with cluster size. We show that the addition of Cr has a strong effect on both the size and stoichiometry of the particles.

Thin films of Fe1+δSe1−xTex (δ∼0.18 and x∼0.5) have been successfully grown on (100)-oriented single-crystalline SrTiO3 and LaAlO3 substrates by pulsed laser deposition. The crystal structure was characterized by x-ray diffraction and the superconducting properties by electrical resistivity measurements. X-ray diffraction analysis establishes the growth of films with c-axis orientation. Atomic force microscopy showed a smooth surface morphology for the films grown on SrTiO3 substrates. All the films are observed to be superconducting with a transition temperature, Tc of ∼8–14 K, depending on the deposition conditions. The deposition parameters were optimized to obtain good quality films with Tc comparable to that of the target material. The upper critical field shows a positive curvature near Tc unlike the opposite behavior observed in conventional superconductors.

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