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The Ba0.85Sr0.15Zr0.18Ti0.82O3 (BSZT) thin films were deposited via sol–gel process on LaNiO3-coated silicon substrates. The grain size decreased and the microstructure became dense when substitute Zr for Ti. Dielectric properties were investigated as a function of temperature, frequency and direct current electric field. The temperature dependent dielectric measurements revealed that the thin films have diffuse phase transition characteristics. The tunability of Ba0.8Sr0.2Sn0.10Ti0.90O3 thin films is about 57%, at an applied field of 415 kV/cm and measurement frequency of 1 MHz. It was observed that the leakage current density of Ba0.85Sr0.15Zr0.18Ti0.82O3 is higher than that of BZT thin films. [Copyright &y& Elsevier]

Abstract: The compositionally graded and homogeneous Ba(Zr x Ti1−x )O3 (BZT) thin films were fabricated on LaNiO3 (LNO) buffered Pt/Ti/SiO2/Si and Pt/Ti/SiO2/Si substrates by a sol–gel deposition method, respectively. These films crystallized into a single perovskite phase. The BZT thin films deposited on LaNiO3/Pt/Ti/SiO2/Si substrates had a highly (100) preferred orientation and exhibited a preferred (110) orientation when the thin films were deposited on Pt/Ti/SiO2/Si substrates. The LNO and Ba(Zr0.30Ti0.70) served as seed layer on Pt/Ti/SiO2/Si substrates and analyze the relationship of seed layer, microstructure and dielectric behavior of the thin films. The compositionally graded thin films from BaTiO3 to BaZr0.35Ti0.65O3 were fabricated on LNO/Pt/Ti/SiO2/Si substrates. The tunability behavior of compositionally graded films was analyzed in order to produce optimum effective dielectric properties. The dielectric constant of BaZr x Ti1−x O3 compositionally graded thin films showed weak temperature dependence. This kind of thin films has a potential in a fabrication of a temperature stable tunable device. [Copyright &y& Elsevier]

Abstract: BaTi4O9 (BT4) microwave dielectric ceramics using a copper electrode and containing 10wt% BaO–ZnO–B2O3–SiO2 (BZBS) glass frit were sintered under reducing atmosphere at 950°C and were investigated on the phase evolutions, microstructures and dielectric properties of BT4 with various BaO/SiO2 and ZnO/SiO2 ratios of BZBS glasses. Experimental results show that the BaO/SiO2 ratio contributes to wettability of glass with BaTi4O9 ceramics, and ZnO/SiO2 ratio determines the densification of BaTi4O9 ceramics. The different Ba–Ti–O and Ba–Cu–O phases with various Ba/Ti and Ba/Cu ratios can be attributed to the contents of BaO in glass. Ba4Ti13O30 and Ba2Cu3O5+X may form when BaO contents are too high, and inducing copper diffusion due to the reactions of BaO and Cu, accompanying with degrading of the dielectric characteristics. If the ZnO contents of BZBS glasses were raised, a little bit of ZnSiO3 and Ba2Cu3O5+X phases appear without Cu diffusion due to non-reaction of ZnO and CuO. The high ZnO/SiO2 ratio of glass reveals the lower softening point, indicating that the high ZnO glass could enhance the density and therefore increase the dielectric constant and quality factor. [Copyright &y& Elsevier]

Abstract: Effects of Al and Nb doped (Bi0.5Na0.5)0.94Ba0.06TiO3(abbreviated as BNB6T) ceramics on dielectric, ferroelectric, and strain properties were investigated. The results indicated that the d33 ⁎ value is significantly higher in pure BNB6T ceramics than in Nb doped BNB6T and Al doped BNB6T ceramics, and that S–E curve for the Al doped BNB6T ceramics displayed a typical W-shaped butterfly curve, but pure BNB6T and Nb doped BNB6T ceramics display a V-shaped curve. The P–E loops for pure BNB6T and Nb doped BNB6T ceramics were similar to soft PZT ceramics with slim profiles. According to the results of microstructures analysis, significant strain may originate from the development of the optimum compound domains coexistence (the mixture of microdomain and nanodomain), which provide large saturation polarization and low-energy barrier dipole switching under an applied electric field. All these would provide a new concept for lead-free ceramics to realize high strain response for practical applications in actuator or other piezoelectric devices. [Copyright &y& Elsevier]

Abstract: In this article, various amounts of CaTiO3 (CT) were added into (Na0.52K0.48)NbO3 (NKN) ceramics using conventional oxide-mixing method for improving NKN''s properties. The experimental results show that the (1−x)(Na0.52K0.48)NbO3–xCaTiO3 (x=0∼0.07) solid solution system can be successfully synthesized. Addition of CaTiO3 not only effectively prevents materials from deliquescence, but also improves the density and the electrical properties of the ceramics. The dielectric constant–temperature (ε r −T) curves exhibit that the temperatures of the Curie point (T c ) and the phase transition from tetragonal to orthorhombic (T O−T ) are decreasing monotonously as the amount of CT addition is increased. A morphotropic phase boundary (MPB) can be found in the (1−x)NKN−xCT solid solution system as the doping amount of x=0.03, and the 0.97NKN–0.03CT ceramics, with a high bulk density, 98% theoretical density, and an appropriate grain size of about 1∼2μm, present a superior domain switching ability and the optimum properties: d 33=117pC/N, k p =0.39, P r =21μC/cm2, and T c =333°C. [Copyright &y& Elsevier]