Advertisement

Processing of Barium Zinc Tantalate (BZT) Microwave Dielectric Ceramics for RF Window Application in Fusion Reactor

  • Swathi Manivannan
  • Dibakar DasEmail author
Living reference work entry

Abstract

The ever-increasing energy demand by the human civilization and rapid depletion of conventional fossil fuel has triggered the scientists and engineers to look for alternative source of energy. Fusion energy, where four hydrogen nuclei combine to produce one helium nucleus with subsequent release of enormous amount of energy, could very well meet the future energy demand. Radio-frequency (RF) power is used as one of the noninductive methods to maintain the fusion plasma current under steady-state condition. RF window, used in the transmission line, acts as a vacuum barrier and transmits the microwave (MW) power to the plasma and hence a very critical component in the transmission line. Microwave dielectric ceramics, with high-quality factor/low loss, high dielectric constant, good temperature stability, high dielectric strength, high thermal conductivity, high mechanical strength, and ability to braze to the base metal, are most preferred materials for RF window application. High-purity dense alumina ceramics is the most common material for such application as of now. But the lower dielectric constant of Al2O3 ceramic poses a serious problem in thermal management of the window sections, and hence an alternate material is preferred. Barium zinc tantalate Ba(Zn1/3Ta2/3)O3 (BZT) is a well-known microwave dielectric ceramics with excellent properties such as high dielectric constant (εr), low loss (tanδ), very low temperature coefficient of resonance frequency (τf), and high-quality factor in the microwave frequency range and hence could be a potential candidate for MW window application. But, the major drawback in processing BZT ceramics at high temperatures is the volatilization of low-melting Zn from the BZT composition rendering the final product containing lot of defects including the presence of other phases. This chapter deals with the processing of BZT ceramics with properties suitable for RF window application. The effect of processing conditions and sintering techniques on development of mechanically robust BZT ceramics with highest density (close to the theoretical density), high dielectric constant, low loss (high-quality factor, Q), very low and stable temperature coefficient of resonance frequency, and high thermal conductivity has been discussed in detail.

Keywords

RF window Dielectric ceramics BZT Microwave sintering Brazing 

List of Abbreviations

BKZT

Ba1-xKx(Zn(1-x)/3Ta(2 + x)/3)O3

BLZT

Ba1-xLax(Zn(1 + x)/3Ta(2-x)/3)O3

BLZTG

Ba1-xLax(Zn(1 + x-2y)/3Ta(2-x-y)/3Gay)O3

BMN

Ba (Mg1/3Nb2/3)O3

BMT

Ba(Mg1/3Ta2/3)O3

BZN

Ba(Zn1/3Nb2/3)O3

BZT

Barium zinc tantalate (Ba(Zn1/3Ta2/3)O3

BZT–SGT

0.95BaZn1/3Ta2/3O3–0.05SrGa1/2Ta1/2O3

DRs

Dielectric resonators

EM

Electromagnetic

FWHM

Full width at half maxima

LHCD

Lower hybrid current drive

MLCC

Multilayer ceramic capacitors

MW

Microwave

POP

Plaster of paris

RF

Radio-frequency

SEE

Secondary electron emission

SEM

Scanning electron microscope

TD

Theoretical density

UHV

Ultrahigh vacuum

XRD

X-ray diffraction

References

  1. 1.
    Wootton AJ, Wiley JC, Edmonds PH, Ross DW (1997) Compact tokamak reactors. Nucl Fusion 37(7):927CrossRefGoogle Scholar
  2. 2.
    Goldston RJ (1984) Energy confinement scaling in Tokamaks: some implications of recent experiments with Ohmic and strong auxiliary heating. Plasma Phys Control Fusion 26(1A):87–103CrossRefGoogle Scholar
  3. 3.
    Sharma PK, Rao SL, Ramella KK, Bora D (2008) Design, fabrication and testing of UHV compatible high power RF devices for lower hybrid current drive system on SST-1 tokamak. Fusion Eng Des 83(4):601–605CrossRefGoogle Scholar
  4. 4.
    Cummings KA, Risbud SH (2000) Dielectric materials for window applications. J Phys Chem Solids 61(4):551–560CrossRefGoogle Scholar
  5. 5.
    Saito Y, Michizono S, Anami S, Kobayashi S (1993) Surface flashover on alumina rf windows for high-power use. IEEE Trans Electr Insul 28(4):566–573CrossRefGoogle Scholar
  6. 6.
    Pimenta JS, Buschinelli AJA, do Nascimento RM, Martinelli AE, Remmel J (2013) Brazing of zirconia to titanium using Ag-Cu and Au-Ni filler alloys. Soldag Insp (Sao Paulo) 18(4):349–357CrossRefGoogle Scholar
  7. 7.
    Pisharody M, Barnes P, Chojnacki E, Durand R, Hays T, Kaplan R, Kirchgessner J, Reilly J et al (1996) High power window tests on a 500 MHz planar waveguide window for the CESR upgrade. Proc Part Accel Conf 3:1720–1722CrossRefGoogle Scholar
  8. 8.
    Kesari V, Singh A, Seshadri R, Kamath S (2016) Boron Nitride and Sapphire windows for 95-GHz Gaussian RF beam. IEEE Trans Electron Devices 63(8):1–5CrossRefGoogle Scholar
  9. 9.
    Neubauer M, Rimmer RA (1991) High power co-axial srf coupler. WE5PFP044. Proceedings of PAC09, Vancouver, BC, Canada, pp 2095–2097Google Scholar
  10. 10.
    Matsumoto H, Tamura H, Wakino K (1991) Ba(Mg,Ta)O3 -BaSnO3 high-Q dielectric resonator. Jpn J Appl Phys 30(9B):2347–2349CrossRefGoogle Scholar
  11. 11.
    Nomura S, Toyama K, Kaneta K (1982) Ba(Mg1/3 Ta2/3)O3 ceramics with temperature-stable high dielectric constant and low microwave loss. Jpn J Appl Phys 21(10):624–626CrossRefGoogle Scholar
  12. 12.
    Nomura S, Kaneta K (1984) Ba(Mn1/3 Ta2/3)O3 ceramic with ultra-low loss at microwave frequency. Jpn J Appl Phys 23(4R):507–508CrossRefGoogle Scholar
  13. 13.
    Chen MY, Chia CT, Lin IN, Lin LJ, Ahn CW, Nahm S (2006) Microwave properties of Ba(Mg1/3Ta2/3) O3, Ba(Mg1/3Nb2/3)O3and Ba(Co1/3Nb2/3)O3 ceramics revealed by Raman scattering. J Eur Ceram Soc 26(10–11):1965–1968CrossRefGoogle Scholar
  14. 14.
    Desu SB, O’Bryan HM (1985) Microwave loss quality of BaZn1/3Ta2/3O3 ceramics. J Solid State Chem 68(10):546–551Google Scholar
  15. 15.
    Moulson AJ, Herbert JM (1990) Dielectrics and insulators. In: Electroceramics. Chapman and Hall, London, pp 300–310Google Scholar
  16. 16.
    Tamura H, Konoike T, Sakabe Y, Wakino K (2006) Improved high-Q dielectric resonator with complex perovskite structure. J Am Ceram Soc 67(4):59–61CrossRefGoogle Scholar
  17. 17.
    Roulland F, Allainmat G, Pollet M, Marinel S (2005) Low temperature sintering of the binary complex perovskite oxides xBa(Zn1/3Ta2/3)O3+(1-x)Ba (Mg1/3Ta2/3)O3. J Eur Ceram Soc 25(12):2763–2768CrossRefGoogle Scholar
  18. 18.
    Yang J-I, Nahm S, Choi C-H, Lee H-J, Kim J-C, Park H-M (2002) Effect of Ga2O3 on microstructure and microwave dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics. Jpn J Appl Phys 41(Part 1, No. 2A):702–706CrossRefGoogle Scholar
  19. 19.
    Jeong Y-H, Kim M-H, Nahm S, Lee W-S, Yoo M-J, Kang N-K, Lee H-J (2005) Effect of Ta2O5 on microstructure and microwave dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramic. Jpn J Appl Phys 44(2):956–960CrossRefGoogle Scholar
  20. 20.
    Varma MR, Kataria ND (2007) Effect of dopants on the low temperature microwave dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics. J Mater Sci Mater Electron 18(4):441–446CrossRefGoogle Scholar
  21. 21.
    Lee CJ, Pezzotti G, Kang SH, Kim DJ, Hong KS (2006) Quantitative analysis of lattice distortion in Ba(Zn1/3Ta2/3)O3 microwave dielectric ceramics with added B2O3 using Raman spectroscopy. J Eur Ceram Soc 26(8):1385–1391CrossRefGoogle Scholar
  22. 22.
    Kim JS, Kim JW, Cheon CI, Kim YS, Nahm S, Byun JD (2001) Effect of chemical element doping and sintering atmosphere on the microwave dielectric properties of barium zinc tantalates. J Eur Ceram Soc 21(15):2599–2604CrossRefGoogle Scholar
  23. 23.
    Varma MR, Biju S, Sebastian MT (2006) Preparation of phase pure Ba(Zn1/3Ta2/3) O3 nanopowders for microwave dielectric resonator applications. J Eur Ceram Soc 26(10–11):1903–1907CrossRefGoogle Scholar
  24. 24.
    Manivannan S, Joseph A, Sharma PK, Raju KCJ, Das D (2017) Effect of colloidal processing on densification and dielectric properties of Ba(Zn1/3Ta2/3)O3 ceramics. Ceram Int 43(15):12658–12666CrossRefGoogle Scholar
  25. 25.
    Yang J-I, Nahm S, Yoon S-J, Park H-M, Lee H-J (2004) Structural variation and microwave dielectric properties of ZrO2 added Ba(Zn1/3Ta2/3)O3 ceramics. Jpn J Appl Phys 43(1):211–214CrossRefGoogle Scholar
  26. 26.
    Bieringer M, Moussa SM, Noailles LD, Burrows A, Kiely CJ, Rosseinsky MJ, Ibberson RM (2003) Cation ordering, domain growth, and zinc loss in the microwave dielectric oxide Ba3ZnTa2O9 - δ. Chem Mater 15(2):586–597CrossRefGoogle Scholar
  27. 27.
    Tamura H, Sagala DA, Wakino K (1986) Lattice vibrations of Ba(Zn1/3Ta2/3)O3 crystal with ordered perovskite structure. Jpn J Appl Phys 25(Part 1, No. 6):787–791CrossRefGoogle Scholar
  28. 28.
    Surendran KP, Sebastian MT, Mohanan P, Moreira RL, Dias A (2005) Effect of nonstoichiometry on the structure and microwave dielectric properties of Ba(Mg0.33Ta0.67)O3. Chem Mater 17(1):142–151CrossRefGoogle Scholar
  29. 29.
    Wada K, Kakimoto K, Ohsato H (2004) Anisotropic microwave dielectric properties of textured Ba4Sm9.33Ti18O54 ceramics. Key Eng Mater 269:207–210CrossRefGoogle Scholar
  30. 30.
    Dick GJ, Santiago DG, Wang RT (1994) Temperature compensated sapphire resonator for ultra-stable oscillator capability at temperatures above 77 kelvin. Proc IEEE 48th Annu Symp Freq Control 42:421–432Google Scholar
  31. 31.
    Alford NM, Breeze J, Penn SJ, Poole M (2000) Layered Al2O3-TiO2 composite dielectric resonators with tuneable temperature coefficient for microwave applications. IEE Proc Sci Meas Technol 147(6):269–273CrossRefGoogle Scholar
  32. 32.
    Lee C-C, Chou C-C, Tsai D-S (1997) Effect of La/K A-site substitutions on the ordering of Ba(Zn1/3Ta2/3)O3. J Am Ceram Soc 80(11):2885–2890CrossRefGoogle Scholar
  33. 33.
    Kageyama K (1992) Crystal structure and microwave dielectric properties of Ba(Znl/3Ta2/3)03-(Sr,Ba)(Gal/2Tal/2)03 ceramics. J Am Ceram Soc 75(7):1767–1771CrossRefGoogle Scholar
  34. 34.
    Reaney IM, Wise PL, Qazi I, Miller CA, Price TJ, Cannell DS, Iddles DM, Rosseinsky MJ, Moussa SM, Bieringer M, Noailles LD, Ibberson RM (2003) Ordering and quality factor in 0.95BaZn1/3Ta2/3O3–0.05SrGa1/2Ta1/2O3 production resonators. J Eur Ceram Soc 23:3021–3034CrossRefGoogle Scholar
  35. 35.
    Koga E, Yamagishi Y, Moriwake H, Kakimoto K, Ohsato H (2006) Large Q factor variation within dense, highly ordered Ba(Zn1/3Ta2/3)O3 system. J Eur Ceram Soc 26(10–11):1961–1964CrossRefGoogle Scholar
  36. 36.
    Tolmer V, Desgardin G (1997) Low-temperature sintering and influence of the process on the dielectric properties of Ba(Zn1/3Ta2/3)O3. J Am Ceram Soc 80(8):1981–1991CrossRefGoogle Scholar
  37. 37.
    Lee C-C, Chou C-C, Tsai D-S (1998) Variation in the ordering of Ba(Zn1/3Ta2/3)O3 with A-site substitutions. Ferroelectrics 206(1):293–305CrossRefGoogle Scholar
  38. 38.
    Galasso F, Pyle J (1963) Ordering in compounds of the A(B’0.33Ta0.67)O3 type. Inorg Chem 2(3):482–484CrossRefGoogle Scholar
  39. 39.
    Marinel S, Roulland F, d’Astorg S, Chaouchi A (2007) Effects of the sintering atmosphere on the BaZn1/3Ta2/3O3 based Cu multilayer ceramic capacitors. J Eur Ceram Soc 27(13–15):3605–3608CrossRefGoogle Scholar
  40. 40.
    Nomura S, Uchino K (1983) Recent applications of PMN-based electrostrictors. Ferroelectrics 50(1):197–202CrossRefGoogle Scholar
  41. 41.
    John AF (1999) Ceramic brazing. Mater World 7(11):686–688Google Scholar
  42. 42.
    Pimenta JS, Buschinelli AJA, do Nascimento RM, Martinelli AE, Remmel J (2010) Joining of zirconia mechanically metallized with titanium. Cerâmica 56:212–221CrossRefGoogle Scholar
  43. 43.
    Twentyman ME, Popper P (1975) High-temperature metallizing. J Mater Sci 10(5):791–798CrossRefGoogle Scholar
  44. 44.
    Jacobson DM, Humpston G (2005) Principles of brazing. ASM International, Materials ParkGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.School of Engineering Sciences and Technology (SEST)University of HyderabadHyderabadIndia

Section editors and affiliations

  • Tetsuji NODA

There are no affiliations available

Personalised recommendations