Soft Chemical Method Developed Rare-earth-doped Barium Titanate-based Dielectric Ceramics And Structural Properties

Barium-titanate (BaTiO₃) is the primary material for high dielectric constant ceramic capacitors and multi-layer ceramic capacitors manufacture due to its excellent electronic performance, such as ferroelectric, piezoelectric, high dielectric constant and positive temperature coefficient effect, etc. Barium-titanate ceramics, which have been developed in several decades years, are one of the most important functional ceramics and used as the basic raw materials in the composition of ceramic capacitors. The research of preparation and properties of barium-titanate has been a focal point in the field of inorganic solid chemistry since the excellent dielectric properties of barium-titanate were discovered in 1940s. However, the research of barium-titanate was began only in recent years in our country and there is a lot of work to do.Routes of synthesis BaTiO₃, technical characteristics, research status and recent progress had been presented in this paper firstly. Low temperature wet chemical routes offer an exciting possibility for the synthesis of high purity, homogeneous, ultrafine powders which meet the need of electric components in factual application. Sol-gel method, which can prepare multicomposition barium-titanate powders, was the one of the prospective routes for manufacturing barium-titanate powders. We also summarized recent progress of the doping of microelement in BaTiO₃ based ceramics, and found BSTO and BZTO which have high dielectric constant and good dielectric temperature dependence. So in this paper, Gd-doping barium-titanate powders and ceramics were prepared by sol-gel method. The powders and ceramics were characterized by XRD and SEM. The dielectric properties of the ceramics were determined. In general, the main work is as follows:A, The preparation of BaTiO₃: nanometer-sized barium-titanate powers had been synthesized by sol-gel process from Ba(CH₃COO)₂ and titanium alkoxied and were characterized by XRD. The influence of aging time, calcined temperature had been studied. The results were: when aging time was 24 hours and calcined temperature was 900°C/2h, the properties of the powers were good.