High permittivity and low dielectric loss analysis of lead free Sr_1−xLa_x(Ti_0.5Fe_0.5)O₃

Abstract

The structural and electrical properties of lead free Sr_1−xLa_x(Ti_0.5Fe_0.5)O₃ (SLTFO) prepared by standard solid state reaction technique were studied. The X-ray diffraction analysis confirmed the formation of a single-phase cubic perovskite structure. The compositional dependence of lattice constant, density and microstructural studies show that they vary significantly with La³⁺ content. When measured at 10 kHz, all the compositions of SLTFO at room temperature exhibit a high permittivity (about 10⁴) and low dielectric loss (about 10⁻³). SLTFO also display minimum dielectric loss within the lower and higher limits of frequency, indicating that the samples are of good quality. It is concluded from the calculated ac conductivity that the conduction is due to mixed polarons hopping. The complex impedance plot exhibits a tendency of forming a single semicircular arc for all compositions, which implies a dominance of grain boundary resistance on the impedance. Impedance parameters were determined by fitting the experimental data with Cole-Cole empirical formula. The results of the present experiment indicate that the lead free SLTFO materials with higher permittivity and lower dielectric loss have possible practical applications.

Keywords

dielectric properties / solid state reaction / Sr titanate / X-ray diffraction

References

[1] FanH, KimH E. Effect of lead content on the structure and electrical properties of Pb((Zn_1/3Nb_2/3)_0.5(Zr_0.47Ti_0.53)_0.5)O₃ ceramics [J]. Journal of American Ceramic Society, 2001, 84: 636-638

[2] RaiR, SharmaS, SoniN C, ChoudharyR N P. Investigation of structural and dielectric properties of (La, Fe)-doped PZT ceramics [J]. Physica B, 2006, 382: 252-256

[3] RaiR, MishraS, SinghN K. Effect of Fe and Mn doping at B-site of PLZT ceramics on dielectric properties [J]. Journal of Alloys and Compounds, 2009, 487: 494-498

[4] PanJ S, ZhangX W. Dielectric and ferroelectric properties of Pb(Ni_1/3Nb_2/3)O₃-Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ ternary ceramics [J]. Material Science Engineering B, 2006, 127: 6-11

[5] ShiJ, YangW. Piezoelectric and dielectric properties of CeO₂-doped (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ lead-free ceramics [J]. Journal of Alloys and Compounds, 2009, 472: 267-270

[6] WuJ, XiaoD, WuB, WuW, ZhuJ, YangZ, WangJ. Sintering temperature-induced electrical properties of (Ba_0.90Ca_0.10) (Ti_0.85Zr_0.15)O₃ lead-free ceramics [J]. Materials Research Bulletin, 2012, 47: 1281-1284

[7] RamirezA P, SubramanianM A, GardelM, BlumbergG, LiD, VogtT, ShapiroS M. Giant dielectric constant response in a copper-titanate [J]. Solid State Communication, 2000, 115: 217-220

[8] WuJ, NanC W, LinC W, DengY. Giant dielectric permittivity observed in Li and Ti doped NiO [J]. Physical Review Letter, 2002, 89: 217601-4

[9] RodewaldS, FleigJ, MaierJ. Microcontact impedance spectroscopy at single grain boundaries in Fe-doped SrTiO₃ polycrystals [J]. Journal of American Ceramic Society, 2001, 84: 521-530

[10] WangH C, WangC L, SuW B, LiuJ, SunY, PengH, MeiL M. Doping effect of La and Dy on the thermoelectric properties of SrTiO₃ [J]. Journal of American Ceramic Society, 2011, 94: 838-842

[11] XuS, QuY, YangD. Structure, dielectric and electric properties of (Ba_0.68−xSr_0.308Bi_0.006Na_0.006Mg_x)(Ti_0.99Sn_0.01)O₃ ceramics [J]. Journal of Alloys and Compounds, 2011, 509: 2753-2757

[12] SinghP, GautamC R, SinghS, KumarD, ParkashO. Synthesis, structure and electrical conduction behaviour of the system Sr_1−xNd_xTi_1−xMn_xO₃ (x<0.50) [C]. International Symposium of Research Students on Materials Science and Engineering (ISRS), Chennai, India, 20041-9

[13] LiY, QuY. Dielectric properties and substitution mechanism of samarium-doped Ba_0.68Sr_0.32TiO₃ ceramics [J]. Materials Research Bulletin, 2009, 44: 82-85

[14] GautamC R, DwivediR K, KumarD, ParkashO. Synthesis and electrical conduction behaviour of strontium yttrium titanium cobalt oxide (Sr_1−xY_xTi_1−xCo_xO₃, 0.01≤x≤0.10) [J]. Materials Letters, 2001, 50: 254-258

[15] MendelsonM I. Average grain size in polycrystalline ceramics [J]. Journal of American Ceramic Society, 1969, 52: 443-446

[16] NelsonJ B, RileyD P. An experimental investigation of extrapolation methods in the dimensions of crystals derivation of accurate unit-cell [J]. Processing Physical Society, London, 1945, 57: 160-177

[17] VegardL. The constitution of mixed crystals and the space occupied by atoms [J]. Zeitschrift fur Physik, 1921, 5: 17-26

[18] AbdeenA M, HemedaO M, AssemE E, El-SehlyM M. Structural, electrical and transport phenomena of Co ferrite substituted by Cd [J]. Journal of Magnetism and Magnetic Materials, 2002, 238: 75-83

[19] HaqueM M, HuqM, HakimM A. Densification, magnetic and dielectric behaviour of Cu-substituted Mg-Zn ferrites [J]. Materials Chemistry and Physics, 2008, 112: 580-586

[20] KumarM, YadavK L. Rapid liquid phase sintered Mn doped BiFeO₃ ceramics with enhanced polarization and weak magnetization [J]. Applied Physics Letter, 2007, 91: 112911-4

[21] SinghN K, KumarP, RaiR. Study of structural, dielectric and electrical behavior of (1−x)Ba(Fe_0.5Nb_0.5)O_3−xSrTiO₃ ceramics [J]. Journal of Alloys and Compounds, 2011, 509: 2957-2963

[22] WangX X, ChoyS H, TangX G, ChanH L W. Dielectric behavior and microstructure of (Bi_1/2Na_1/2)TiO₃-Bi_1/2K_1/2)TiO₃-aTiO₃ lead-free piezoelectric ceramics [J]. Journal of Applied Physics, 2005, 97: 104101-104104

[23] MaxwellJ CElectricity and Magnetism, V-1 [B], 1973LondonOxford University Press

[24] WagnerK W. Zur theorie der unvollkommenen dielektrika [J]. Annalen der Physik (Leipzig), 1913, 40: 817-855

[25] KoopsC G. On the dispersion of resistivity and dielectric constant of some semiconductors at audio frequencies [J]. Physical Review, 1951, 83: 121-124

[26] BuscagliaM T, BuscagliaV, VivianiM, NanniP, HanuskovaM. Influence of foreign ions on the crystal structure of BaTiO₃ [J]. Journal of the European Ceramic Society, 2000, 20: 1997-2007

[27] ParkashO, KumarD, DwivediR K, SrivastavaK K, SinghP, SinghS. Effect of simultaneous substitution of La and Mn on dielectric behavior of barium titanate ceramic [J]. Journal of Materials Science, 2007, 42: 5490-5496

[28] KrogerF A, VinkH J. Relations between the concentrations of imperfections in crystalline solids [J]. Solid State Physics, 1956, 3: 307-435

[29] ChungC C, ChaiY L, ChangY S. Dielectric properties of valence compensated Ca_1−xBi_xTi_1−xCr_xO₃ perovskite prepared using the sol-gel process [J]. Journal of Physics and Chemistry of Solids, 2008, 69: 1877-1882

[30] HuangC L, LinS H, LiuS S, ChenY B. x(Mg_0.7Zn_0.3)_0.95Co_0.05TiO₃-(1-x)(La_0.5Na_0.5)TiO₃ ceramic at microwave frequency with a near zero temperature coefficient of resonant frequency [J]. Journal of Alloys and Compounds, 2010, 489: 541-544

[31] PatilD R, ChouguleB K. Effect of resistivity on magnetoelectric effect in xNiFe₂O₄-(1-x)Ba_0.9Sr_0.1TiO₃ ME composites [J]. Journal of Alloys and Compounds, 2009, 470: 531-535

[32] PandeyL, KatareR, ParkashO, KumarD. Evidence of two ferroelectric PTCR components in valence-compensated ceramic system Ba_1−xLa_x Ti_1−xCo_xO₃ [J]. Bulletin Material Science, 1997, 20: 933-947

[33] RanjanR, KumarR, KumarN, BeheraB, ChoudharyR N P. Impedance and electric modulus analysis of Sm-modified Pb(Zr_0.55Ti_0.45)_1−x/4O₃ ceramics [J]. Journal of Alloys and Compounds, 2011, 509: 6388-6394

[34] AngC, YuZ. Dielectric relaxor and ferroelectric relaxor: Bi-doped paraelectric SrTiO₃ [J]. Journal of Applied Physics, 2002, 91: 1487-1494