Study of dielectric properties of doped barium titanates

Abstract

In the present research work thc doped BaTiO) were prepaTed by conventional mixed oxide method. The doping elements were Caleium, Strontium, Chromium and Vanadium. The doping level., were 0.1 and 0.025 mole fraction. The samples were sintered at 1300°C. Effect ot doping, concentration and milling procedure on the dlelectric properties of BaTiOJ based ceramics were studied. The dielectric constant and dielectric lo,s were measured in the frequency range of 0.5 kHz to 13 MHz at room temperature. The highest value of the dielectric constant for sample Ba(Ti'915Cr.Il~5l0J wa, found 2729 a~d the lowc,t value for the sampleBa.9Sr.1 (Ti.mY.o,.I) was found 14.57. The value of dielectric constant wa, found higher at low frequency and almost thc samc at 100 KHz, the dielectric con,tant is lower at high frequencies.PureBaTiOJ exhibit, the curie temperature at 65"C.Thesample Ba(TimsCr.015)OJ, Ba,9Sr.1 (Ti915 Cr'n,)O." BU.gCa.lSr.l(TimsCrmslO, and Ba,sCa.lSr I(Ti.mY.fi2j)O.1 exhibits the curie temperature 80°C at fixed frequency 1 MHz. The sample (Tiom,vO.U15)OJexhibits the maximum curie temperature 1I0aC at fixed frequencylMlh. The sample BU,9Sr,[ (Ti,mY.025)O, exhibits the dielectric constant 90"C. The maximum dielcctric lo,s was 2.74 for the sample Ba.sCa.[SLI(Ti.mCr.02j)O, the minimum dielectric los, was 0.034 ror thc sample BU.9Sr.,(Ti.,"-\C'o,5)O.l at 13 MH~. Dielectric measurement also indicates that curie temperature for doped ,ample is larger than the pure undoped EaTIO, sample. From the pre,ent investigation it i, observed that the substitution of dopant having larger ionic radius increases the dielectric constant. Dielectric constant has dependence on the grain ,ize thereby ball milling time. It i<,ob,erved that dielectric con,tant is higher for 24 hours ball milling sample,.