SrTiO3 is a model of the perovskite-like compounds for structural transition which inducing the intriguing physical properties around the critical phase transition temperature TAFD (antiferrodistortive, abbrev. as AFD). Here we report that the electrical transport behavior is a new way to quantify Nb concentration for Nb-doped SrTiO3. The lattice parameter (c), phase transition temperature (TAFD), and the carrier concentration (n) of SrTiO3 may be manipulated by niobium doping. TAFD increases with increasing the niobium content in a rate of about 30 K per (wt%, i.e. niobium element’s weight verses total weight) niobium and n in a rate of about 2.5 $$\times$$ × 1020/cm3 per (wt%) niobium.

The emerging two-dimensional (2D) materials such as graphene have opened the door to industrial applications. Here, we consider the oxide perovskite monolayer of SrTiO 3 (STO), LaAlO 3 (LAO) and their heterostructures as the 2D transitional metal system. Results show that a band-gap transition from indirect to direct occurs when the separated monolayer STO (indirect band gap of 3.210 eV), and LAO (indirect band gap of 4.024 eV), form the heterostructures (direct band gap of 2.976 eV). The obtained bandgap for the stable bilayers may effectively be modulated by biaxial strains from −12% to 8%. With 12% compressive biaxial strain, the band gap reduces to be 0.23 eV. The optical properties for the stable bilayers are also tuned by the biaxial strain. When the strain increases from compressive strain to tensile strain, the strongest peak of the imaginary part of dielectric function red shifts to lower energy. In comparing with the monolayer STO and LAO, the elastic property enhances obviously for the stable heterostructure, suggesting the heterostructure can be more stable freestanding or may be applied in device fabrications.

Effects of Sn doping at Ru site on the structural, magnetic, and transport behavior of polycrystalline SrRu 1−x Sn x O 3 (x ≤ 0.1) have been investigated here. Substitution of Sn 4+ for Ru 4+ remains the same crystal symmetry with that of Sn-free SrRuO 3 , while induces the Ru(Sn)O 6 octahedral distortions. Samples with the low doping concentration (x ≤ 0.08) show a metallic behavior at high temperature, while a metal to insulator transition occurs at low temperature. On the other hand, an insulator behavior is detected for sample with x = 0.1, which follows Arrhenius-type process in the temperature range of 80-140 K and Mott's variable range hopping model in the temperature range of 140-300 K. Further, we find that Sn 4+ has a significant effect on the magnetic behavior of Sn doping in SrRuO 3 where ferromagnetic transition temperature and magnetic moment decrease rapidly due to octahedral distortion and site dilution.