Samples with overall composition HoxSr1−xCoO3−δ within the range 0.05 ≤ x ≤ 0.9 were prepared by a solid-state technique at 1100 °C in air. Single-phase HoxSr1−xCoO3−δ oxides were obtained within the range 0.05 ≤ x ≤ 0.30. Solid solutions of Ho0.05Sr0.95CoO3−δ and Ho0.1Sr0.9CoO3−δ were indexed in the cubic structure (Pm3m sp. gr.) with the unit cell parameters a = 3.846 Å and a = 3.842 Å, respectively. Further introduction of holmium leads to a change of crystal structure from cubic to a tetragonal 2ap × 2ap × 4ap superstructure. All samples with x > 0.3 were multiphase, containing a saturated solid solution with approximate composition Ho0.3Sr0.7CoO3−δ with Ho2O3 and CoO. The change of oxygen nonstoichiometry was measured by thermogravimetric analysis within the temperature range 25 ≤ T (°C) ≤ 1100. The absolute value of oxygen nonstoichiometry was calculated from the results of chromatometric titration. Thermal expansion coefficients of Ho1−xSrxCoO3−δ were measured by dilatometry within the temperature range 25 ≤ T (°C) ≤ 1100 in air.

The analysis of nanoindentation force data are based on Sneddon’s solution for a linear elastic half space with a rigid axisymmetric indenter. Berkovich indenters commonly used in indentation experiments are normally modeled as cones. The idea of effective tip shape was presented to better explain the behavior of the unloading curve and pressure distribution under the tip in real experiments. We examine the concept of effective tip in three dimensions by importing real indenter metrology by atomic force microscope directly into finite element analysis and simulate fused silica indentation experiments. We show that fitting the elastic reloading curves overestimates the elastic modulus of fused silica. This is explained by studying the pressure distribution at maximum depth under the effective tip. While the effective tip describes the problem geometrically, it is believed that neglecting the deformed zone in the indented material is responsible for over estimating the modulus value.

We report a systematic investigation of the thermoelectric properties of n-type Ga-doped ZnO synthesized using different ball milling conditions. Samples fabricated by the high-energy ball milling resulted in a highly dense layered structure with randomly distributed voids. These samples measured the lowest room temperature thermal conductivity, i.e., 27 W/mK due to increased phonon scattering. Furthermore, the Ga:ZnO system showed a metal–semiconductor transition above 300 K with transition temperature decreasing with increasing doping level. Measurement of the activation energy revealed the presence of one donor level around 3.9–7.8 meV and a deeper donor level around 15.4–18.1 meV below the conduction band for the Ga-doped samples. For Ga-doped ZnO, Seebeck coefficient of −185 μV/K (at 1000 K) was achieved, which is ∼30–45% higher than the values previously reported for Zn:Ga system. Jonker plot analysis was used to analyze the scope of Ga:ZnO bulk system.