Structural phase transition in (1-x)SrTiO3 + (x)SrMg1/3Nb2/3O3 solid solutions

The temperature dependences of the shear modulus and internal friction in ceramic samples of (1-x)SrTiO3 + (x)SrMg1/3Nb2/3O3 solid solutions were studied by the torsional vibration method in the range 80-300 K. It was established that the temperature Ta of the Oh1-D4h18 structural phase transition in these solid solutions increases with increasing x, although the lattice constant also increases. A discussion is presented of the contributions to the Ta(x) dependence due to a change in the volume and changes caused by the presence of a second solid-solution component (the impurity contribution). It is also shown that the defect-induced relaxation revealed earlier in a study of the dielectric properties of these materials manifests itself in internal friction peaks.