Super-stable permittivity and low dielectric loss of(1-x)Na_(0.5)Bi_(0.5+y)TiO_(3-x)NaTaO_(3)ceramics within an ultra-wide temperature range

This work designs a new system(1-x)Na_(0.5)Bi_(0.5+y)TiO_(3-x)NaTaO_(3)with a nonstoichiometric bismuth ratio,which is used as dielectrics of ceramics capacitors.Phase structure evolution of(1-x)Na_(0.5)Bi_(0.5+y)TiO_(3-x)NaTaO_(3)is characterized using XRD,Raman and TEM.Dielectric and resistant properties of(1-x)Na_(0.5)Bi_(0.5+y)TiO_(3-x)NaTaO_(3)are investigated with increasing concentration of NaTaO_(3).With these in-vestigations,the structure and defect chemistry of(1-x)Na_(0.5)Bi_(0.5+y)TiO_(3-x)NaTaO_(3)are rationalized and their respective impact on capacitor properties are elucidated.The optimized composition 0.8Na_(0.5)Bi_(0.51)TiO_(3)-0.2NaTaO_(3)possesses an ultra-wide operating temperature range(-92e398C),in which both stable permittivity and low dielectric loss is obtained.Furthermore,the fabrication of multilayer ceramics capacitors(MLCC)based on 0.8Na_(0.5)Bi_(0.51)TiO_(3)-0.2NaTaO_(3)dielectrics is investigated.With the addition of sintering aids,0.8Na_(0.5)Bi_(0.51)TiO_(3)-0.2NaTaO_(3)could be co-fired with Ag at 910℃in air,and the low temperature co-fired ceramic(LTCC)capacitors maintain good temperature stability of permittivity and low dielectric loss in-100-352℃.Therefore,our work provides a new route for pre-paring ultra-wide operating temperature capacitors at low manufacturing costs.

Phase diagram and dielectric properties of Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3) ceramics

xPb(In_(1/2)Nb_(1/2))O_(3)–yPb(Mg_(1/3)Nb_(2/3))O_(3)–zPbTiO_(3)(xPIN–yPMN–zPT)ternary ceramics with morphotropic phase boundary(MPB)composition were synthesized by columbite precursor method.xPIN–yPMN–zPT phase diagram was investigated by x-ray diffraction and dielectric measurements.According to the results of dielectric measurements,the Curie temperatures(Tc)and rhombohedral to tetragonal phase transition temperature(T_(r-t))were found to be in the range of 173–212℃and 114–155℃,respectively,indicating that the _(Tr-t) was increased with adding PIN component.In the MPB region,the highest T_(r-t)=155℃was found in 0.32PIN–0.38PMN–0.30PT ceramic,that greatly expanded temperature usage range.

SINTERING BEHAVIOR AND MICROWAVE DIELECTRIC PROPERTIES OF NOVEL LOW TEMPERATURE FIRING Bi_(3)FeMo_(2)O_(12)CERAMIC

In the present work,a novel low temperature-ring Bi_(3)FeMo_(2)O_(12) ceramic was synthesized via the solid-state reaction method.The monoclinic Bi_(3)FeMo_(2)O_(12) phase can be formed at a low temperature 670℃.A relative density above 96%can be obtained when sintering temperature is above 800℃.The Bi_(3)FeMo_(2)O_(12) ceramic sintered at 845℃ for 2 h shows high microwave dielectric performance with a permittivity-27.2,a Qf value of 14,500GHz and a temperature coefficient of-80 ppm/℃.It might be a candidate for low temperature co-fired ceramics technology.