Composite ceramics based on the spinel Mg2TiO4 were prepared by a conventional mixed‐oxide route. To achieve the temperature stabilization of the dielectric constant, each of the composites was added with 7 mol% CaTiO3. The effect of the substitution of isovalent Co for Mg on the microstructure and the microwave dielectric properties of the composite ceramics was also investigated. A maximum Q×f value of around 150–160 THz was obtained for the undoped Mg2TiO4, whereas a reduced Q×f value was observed for an increase in the Co concentration in the system (1−x)Mg2TiO4−xCo2TiO4. Upon doping with 7 mol% CaTiO3, the Q×f value passed through a maximum with increasing Co concentration. Adding ZnO–B2O3 to the composite system based on Co‐doped Mg2TiO4 resulted in a reduction of the sintering temperature by 150°–200°C without any significant degradation in the Q×f value.

The dependence of ionic transport properties on the structure and composition of perovskites Li0.5 - x Na x La0.5TiO3 (0 ≤ x ≤ 0.5) has been analyzed by means of ND, XRD, NMR, and impedance spectroscopy. Local lithium mobility is shown to decrease progressively by 2 orders of magnitude along the series; however, long-range dc conductivity decreases sharply at x = 0.2 more than 6 orders of magnitude. The decrease of dc conductivity from values typical of fast ionic conductors, 10-3 S/cm at room temperature, to values of insulators, 10-10 S/cm, is discussed in terms of a three-dimensional percolation model for lithium diffusion. As deduced from XRD and ND data, the number of vacant sites in conduction pathways is controlled by the amount of Na and La in the perovskite.

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Dielectric resonator aided sensitivity-enhancing electron paramagnetic resonance was successfully applied to small single crystals of the previously reported metal-organicin a conventional X-band EPR spectrometer at 7 K sample temperature to reveal the nature of mononuclear Cu 2+ ion defect species. We found that these paramagnetic defects are not related to an impurity phase or extraframework species of the parent metal-organic framework material but are formed within the framework. Novel angular resolved single crystal continuous wave electron paramagnetic resonance supported by powder measurements and single crystal X-ray diffraction on this metal-organic framework compound identified defective copper paddle wheel units with one missing Cu 2+ ion as the observed mononuclear paramagnetic species in this compound. The sensitivity enhancement by an estimated factor of 8.6 for the single crystal electron paramagnetic resonance spectroscopy is required to efficiently record the Cu 2+ ion signals in single crystals of typical sizes of 200 × 50 × 50 µm 3 at X-band frequencies. The results demonstrate that conventional electron paramagnetic resonance spectrometers operating at X-band frequencies and equipped with dielectric resonators can successfully be used to perform single crystal studies of these porous, low density materials with very small volume samples at low temperatures.

Ferroelectric PbTiO3 nanoparticles were synthesized to be used as inorganic components of new composite materials based on a liquid crystalline elastomer (LCE) matrix. The preparation and characterization of the composite materials, with a relatively high concentration of PbTiO3 nanoparticles, in the form of thin films is described. The composite films retain the thermomechanical response typical of standard LCEs and the nanoparticles are distributed in the film in anisotropic structures indicating the presence of a coupling between the LCE ordered matrix and the nanomaterials. The nematoelastic coupling and the supercritical nature of the paranematic−nematic transition of the LSCE-based composites was verified also in the presence of ferroelectric nanoparticles.