Semiconductor metal oxide compounds based gas sensors: A literature review

Abstract

This paper gives a statistical view about important contributions and advances on semiconductor metal oxide (SMO) compounds based gas sensors developed to detect the air pollutants such as liquefied petroleum gas (LPG), H₂S, NH₃, CO₂, acetone, ethanol, other volatile compounds and hazardous gases. Moreover, it is revealed that the alloy/composite made up of SMO gas sensors show better gas response than their counterpart single component gas sensors, i.e., they are found to enhance the 4S characteristics namely speed, sensitivity, selectivity and stability. Improvement of such types of sensors used for detection of various air pollutants, which are reported in last two decades, is highlighted herein.

Keywords

gas sensor / semiconductor metal oxide (SMO) / sensitivity / air pollutant / gas response

References

[1] Kuwabara M, Ide T. CO gas sensitivity in porous semiconducting barium–titanate ceramics. American Ceramic Society Bulletin, 1987, 66(9): 1401–1405

[2] Chiu C M, Chang Y H. The structure, electrical and sensing properties for CO of the La_0.8Sr_0.2Co_1-xNi_xO_3-δ system. Materials Science and Engineering A, 1999, 266(1–2): 93–98

[3] Patil D R. Everyman’s Science, 2011, XLVI(3): 155

[4] Azad A M, Akbar S A, Mhaisalkar S G, . Solid-state gas sensors: a review. Journal of the Electrochemical Society, 1992, 139(12): 3690–3704

[5] Moseley P T. Material and Mechanism in Semiconducting Gas Sensor, Sensor Technology, System and Application. IOP Publishing, 1990

[6] Joseph B, Gopchandran K G, Manoj P K, . Optical and electrical properties of zinc oxide films prepared by spray pyrolysis. Bulletin of Materials Science, 1999, 22(5): 921–926

[7] Dayan N J, Sainkar S R, Karekar R N, . Formulation and characterization of ZnO:Sb thick-film gas sensors. Thin Solid Films, 1998, 325(1–2): 254–258

[8] Krishnan B, Nampoori V P N. Screen printed nanosized ZnO thick film. Bulletin of Materials Science, 2005, 28(3): 239–242

[9] Licari J J, Enlow L R. Hybrid Microcircuit Technology Handbook. 2nd ed. Park Ridge, NJ, USA: Noyes Publications, 1998

[10] Patil A V, Dighavkar C G, Borse R Y. NO₂ gas sensing properties of screen printed ZnO thick films. Sensors & Transducers Journal, 2009, 101(2): 96–103

[11] Moseley P T, Williams D E, Norris J O W, . Electrical conductivity and gas sensitivity of some transition metal tantalates. Sensors and Actuators, 1988, 14(1): 79–91

[12] Moseley P T, Williams D E. A selective ammonia sensor. Sensors and Actuators B: Chemical, 1990, 1(1–6): 113–115

[13] Moseley P T. Materials selection for semiconductor gas sensors. Sensors and Actuators B: Chemical, 1992, 6(1–3): 149–156

[14] Matsuura S. New developments and applications of gas sensors in Japan. Sensors and Actuators B: Chemical, 1993, 13(1–3): 7–11

[15] Bernasik A, Radecka M, Rekas M, . Electrical properties of Cr-doped and Nb-doped TiO₂ thin films. Applied Surface Science, 1993, 65–66: 240–245

[16] Tang H, Prasad K, Sanjines R, . TiO₂ anatase thin films as gas sensors. Sensors and Actuators B: Chemical, 1995, 26(1–3): 71–75

[17] Mizsei J. How can sensitive and selective semiconductor gas sensors be made? Sensors and Actuators B: Chemical, 1995, 23(2–3): 173–176

[18] Ferroni M, Guidi V, Martinelli G, . Characterization of a nanosized TiO₂ gas sensor. Nanostructured Materials, 1996, 7(7): 709–718

[19] Lin H M, Keng C H, Tung C Y. Gas-sensing properties of nanocrystalline TiO₂. Nanostructured Materials, 1997, 9(1–8): 747–750

[20] Zakrzewska K, Radecka M, Rekas M. Effect of Nb, Cr, Sn additions on gas sensing properties of TiO₂ thin films. Thin Solid Films, 1997, 310(1–2): 161–166

[21] Sharma R K, Bhatnagar M C, Sharma G L. Mechanism of highly sensitive and fast response Cr doped TiO₂ oxygen gas sensor. Sensors and Actuators B: Chemical, 1997, 45(3): 209–215

[22] Sharma R K, Bhatnagar M C. Improvement of the oxygen gas sensitivity in doped TiO₂ thick films. Sensors and Actuators B: Chemical, 1999, 56(3): 215–219

[23] Jayaraman V, Gnanasekar K I, Prabhu E, . Preparation and characterisation of Cr_2-xTi_xO_{3<?A3B2 h=-0.2h?>+<?A3B2 h=-0.2h?>δ} and its sensor properties. Sensors and Actuators B: Chemical, 1999, 55(2–3): 175–179

[24] Carotta M C, Ferroni M, Gnani D, . Nanostructured pure and Nb-doped TiO₂ as thick film gas sensors for environmental monitoring. Sensors and Actuators B: Chemical, 1999, 58(1–3): 310–317

[25] Yamada Y, Seno Y, Masuoka Y, . NO₂ sensing characteristics of Nb doped TiO₂ thin films and their electronic properties. Sensors and Actuators B: Chemical, 2000, 66(1–3): 164–166

[26] Ferroni M, Carotta M C, Guidi V, . Structural characterization of Nb–TiO₂ nanosized thick-films for gas sensing application. Sensors and Actuators B: Chemical, 2000, 68(1–3): 140–145

[27] Gao L, Li Q, Song Z, . Preparation of nano-scale titania thick film and its oxygen sensitivity. Sensors and Actuators B: Chemical, 2000, 71(3): 179–183

[28] Rothschild A, Edelman F, Komem Y, . Sensing behavior of TiO₂ thin films exposed to air at low temperatures. Sensors and Actuators B: Chemical, 2000, 67(3): 282–289

[29] Sberveglieri G, Comini E, Faglia G, . Titanium dioxide thin films prepared for alcohol microsensor applications. Sensors and Actuators B: Chemical, 2000, 66(1–3): 139–141

[30] Wang Y D, Chen Z X, Li Y F, . Electrical and gas-sensing properties of WO3 semiconductor material. Solid-State Electronics, 2001, 45(5): 639–644

[31] Savage N O, Akbar S A, Dutta P K. Titanium dioxide based high temperature carbon monoxide selective sensor. Sensors and Actuators B: Chemical, 2001, 72(3): 239–248

[32] Savage N O, Chwieroth B, Ginwalla A, . Composite n–p semiconducting titanium oxides as gas sensors. Sensors and Actuators B: Chemical, 2001, 79(1): 17–27

[33] Jiao Z, Chen F, Su R, . Study on the characteristics of Ag doped CuO–BaTiO₃ CO₂ sensors. Sensors, 2002, 2(9): 366–373

[34] Guidi V, Butturi M A, Carotta M C, . Gas sensing through thick film technology. Sensors and Actuators B: Chemical, 2002, 84(1): 72–77

[35] Li Y, Wlodarski W, Galatsis K, . Gas sensing properties of p-type semiconducting Cr-doped TiO₂ thin films. Sensors and Actuators B: Chemical, 2002, 83(1–3): 160–163

[36] Karunagaran B, Kumar R T R, Mangalaraj D, . Influence of thermal annealing on the composition and structural parameters of DC magnetron sputtered titanium dioxide thin films. Crystal Research and Technology, 2002, 37(12): 1285–1292

[37] Arbiol J, Cerda J, Dezanneau G, . Effects of Nb doping on the TiO₂ anatase-to-rutile phase transition. Journal of Applied Physics, 2002, 92(2): 853–861

[38] Ruiz A M, Sakai G, Cornet A, . Cr-doped TiO₂ gas sensor for exhaust NO₂ monitoring. Sensors and Actuators B: Chemical, 2003, 93(1–3): 509–518

[39] Shaw G A, Parkin I P, Williams D E. Atmospheric pressure chemical vapour deposition of Cr_2-xTi_xO₃ (CTO) thin films (≤ 3 mμm) on to gas sensing substrates. Journal of Materials Chemistry, 2003, 13(12): 2957–2962

[40] Fergus J W. Doping and defect association in oxides for use in oxygen sensors. Journal of Materials Science, 2003, 38(21): 4259–4270

[41] Li W, Ni C, Lin H, . Size dependence of thermal stability of TiO₂ nanoparticles. Journal of Applied Physics, 2004, 96(11): 6663–6668

[42] Baraton M I, Merhari L. Surface chemistry of TiO₂ nanoparticles: influence on electrical and gas sensing properties. Journal of the European Ceramic Society, 2004, 24(6): 1399–1404

[43] Tamaki J, Miyaji A, Makinodan J, . Effect of micro-gap electrode on detection of dilute NO₂ using WO₃ thin film microsensors. Sensors and Actuators B: Chemical, 2005, 108(1–2): 202–206

[44] Obida M Z, Afify H H, Abou-Helal M O, . Egyptian Journal of Solids, 2005, 28(1): 35

[45] San Andres E, Lique M T, Prado A D, . Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2005, 23(6): 1523

[46] Patil S A, Patil L A. Surface modified TTO thick film resistors for NH₃ gas sensing. Sensors & Transducers Journal, 2006, 71(9): 721–728

[47] Patil D R, Patil L A, Jain G H, . Surface activated ZnO thick film resistors for LPG gas sensing. Sensors & Transducers Journal, 2006, 74(12): 874–883

[48] Kagata M, Abe Y. CARTS USA, 2006, 3

[49] Jain G H, Patil L A. Gas sensing properties of Cu and Cr activated BST thick films. Bulletin of Materials Science, 2006, 29(4): 403–411

[50] Chaudhari G N, Bambole D R, Bodade A B, . Characterization of nanosized TiO₂ based H₂S gas sensor. Journal of Materials Science, 2006, 41(15): 4860–4864

[51] Wagh M S, Jain G H, Patil D R, . Modified zinc oxide thick film resistors as NH₃ gas sensor. Sensors and Actuators B: Chemical, 2006, 115(1): 128–133

[52] Viricelle J P, Pijolat C, Riviere B, . Compatibility of screen-printing technology with micro-hotplate for gas sensor and solid oxide micro fuel cell development. Sensors and Actuators B: Chemical, 2006, 118(1–2): 263–268

[53] Maso N, Beltran H, Cordoncillo E, . Synthesis and electrical properties of Nb-doped BaTiO₃. Journal of Materials Chemistry, 2006, 16(30): 3114–3119

[54] Khadayate R S, Sali J V, Patil P P. Acetone vapor sensing properties of screen printed WO₃ thick films. Talanta, 2007, 72(3): 1077–1081

[55] Khadayate R S, Waghulde R B, Wankhede M G, . Ethanol vapour sensing properties of screen printed WO₃ thick films. Bulletin of Materials Science, 2007, 30(2): 129–133

[56] Jain G H, Patil L A, Patil P P, . Studies on gas sensing performance of pure and modified barium strontium titanate thick film resistors. Bulletin of Materials Science, 2007, 30(1): 9–17

[57] Al-Homoudi I A, Thakur J S, Naik R, . Anatase TiO₂ films based CO gas sensor: Film thickness, substrate and temperature effects. Applied Surface Science, 2007, 253(21): 8607–8614

[58] Alessandri I, Comini E, Bontempi E, . Cr-inserted TiO₂ thin films for chemical gas sensors. Sensors and Actuators B: Chemical, 2007, 128(1): 312–319

[59] Kadu A V, Gedam N N, Chaudhari G N. Detection of hydrogen sulphide gas sensor based nanostructured Ba₂CrMoO₆ thick films. Sensors & Transducers Journal, 2007, 85(11): 1728–1738

[60] Fang X, Oh J T. Microstructure and electrical properties of Nb₂O₅ doped titanium dioxide. Materials Science and Engineering B, 2007, 136(1): 15–19

[61] Sonawane N B, Patil D R, Patil L A. CuO-modified WO₃ sensor for the detection of a ppm level H₂S gas at room temperature. Sensors & Transducers Journal, 2008, 93(6): 82–91

[62] Joshi A, Gangal S A, Padma N, . BARC Newsletters, 2008, 297: 236

[63] Baviskar H M, Deo V V, Patil D R, . Study of room temperature H₂S gas sensing behavior of CuO-modified BSST thick film resistors. Sensors & Transducers Journal, 2008, 92(5): 24–31

[64] More A M, Gunjakar J L, Lokhande C D. Liquefied petroleum gas (LPG) sensor properties of interconnected web-like structured sprayed TiO₂ films. Sensors and Actuators B: Chemical, 2008, 129(2): 671–677

[65] Dighavkar C G, Patil A V, Borse R Y, . Effect of firing temperature on electrical and structural characteristics of screen printed TiO₂ thick films. Optoelectronics and Advanced Materials – Rapid Communication, 2009, 3(10): 1013–1017

[66] Patil A V, Dighavkar C G, Sonawane S K, . Effect of firing temperature on electrical and structural characteristics of screen printed ZnO thick films. Optoelectronics and Advanced Materials – Rapid Communication, 2009, 3(9): 879–883

[67] Dighavkar C G, Patil A V, Patil S J, . Ammonia gas sensing performance of Cr₂O₃-loaded TiO₂ thick film resistors. Solid State Science and Technology, 2009, 17(2): 197–207

[68] Dighavkar C G, Patil A V, Patil S J, . Effect on H₂S gas sensing performance of Nb₂O₅ addition to TiO₂ thick films. Sensors & Transducers Journal, 2009, 109(10): 117–125

[69] Patil A V, Dighavkar C G, Sonawane S K, . Formulation and characterization of Cr₂O₃ doped ZnO thick films as H₂S gas sensor. Sensors & Transducers Journal, 2009, 108(9): 189–197

[70] Kumar V, Srivastava S K, Jain K. Cobalt doped SnO₂ thick film gas sensors: conductance and gas response characteristics for LPG and CNG gas. Sensors & Transducers Journal, 2009, 101(2): 60–72

[71] Patil A V, Dighavkar C G, Borse R Y. NO₂ gas sensing properties of screen printed ZnO thick films. Sensors & Transducers Journal, 2009, 101(2): 96–103

[72] Dighavkar C G, Patil A V, Patil S J, . Invertis Journal of Science & Technology, 2010, 3(3): 184

[73] Patil A V, Dighavkar C G, Sonawane S K, . Study of microstructural parameters of screen printed ZnO thick film sensors. Sensors & Transducers Journal, 2010, 117(6): 62–70

[74] Khadayate R S, Patil P P. Invertis Journal of Science & Technology, 2010, 3(3): 194

[75] Abadi M H S, Hamidon M N, Shaari A H, . Characterization of mixed xWO₃(1-x)Y₂O₃ nanoparticle thick film for gas sensing application. Sensors, 2010, 10(5): 5074–5089

[76] Khadayate R S, Patil P P. CO gas sensing properties of screen printed SnO₂ thick films. Journal of Optoelectronics and Advanced Materials, 2010, 12(6): 1338–1342

[77] Dighavkar C G, Patil A V, Patil S J, . Effect on ethanol gas sensing performance of cu addition to TiO₂ thick films. Sensors & Transducers Journal, 2010, 116(5): 28–37

[78] Dighavkar C, Patil A, Patil S, . Al-doped TiO₂ thick film resistors as H₂S gas sensor. Sensors & Transducers Journal, 2010, 9(Special Issue): 39–47

[79] Gaikwad V B, Patil R L, Deore M K, . Gas sensing properties of pure and Cr activated WO₃ thick film resistors. Sensors & Transducers Journal, 2010, 120(9): 38–52

[80] Patil A V, Dighavkar C G, Sonawane S K, . Formulation and characterization of Cu doped ZnO thick films as LPG gas sensor. Sensors & Transducers Journal, 2010, 9(Special Issue): 11–20

[81] Deore M K, Gaikwad V B, Pawar N K, . Preparation and study the electrical, structural and gas sensing properties of ZnO thick film resistor. Sensors & Transducers Journal, 2010, 119(8): 117–128

[82] Patil G E, Kajale D D, Shinde S D, . Effect of annealing temperature on gas sensing performance of SnO₂ thin films prepared by spray pyrolysis. Sensors & Transducers Journal, 2010, 9(Special Issue): 96–108

[83] Wang C, Yin L, Zhang L, . Metal oxide gas sensors: sensitivity and influencing factors. Sensors, 2010, 10(3): 2088–2106

[84] Patil A V, Dighavkar C G, Sonawane S K, . Influence of Nb₂O₅ doping on ZnO thick film gas sensors. Journal of Optoelectronics and Advanced Materials, 2010, 12(6): 1255–1261

[85] Chaudhari R M, Gaikwad V B, Hire P D, . Studies of gas sensing performance of barium zirconate (BaZrO₃). Sensors & Transducers Journal, 2011, 127(4): 76–87

[86] Chavan D N, Gaikwad V B, Patil G E, . CdO doped indium oxide thick film as a low temperature H₂S gas sensor. Sensors & Transducers Journal, 2011, 129(6): 122–134

[87] Shelke P N, Jadkar S R, Khollam Y B, . Journal of Nano- and Electronic Physics, 2011, 3(1): 859

[88] Rao M C, Hussain O M. Research Journal of Chemical Sciences, 2011, 1(7): 76

[89] Ahire D V, Shinde S D, Patil G E, . Preparation of MoO₃ thin films by spray pyrolysis and ITS gas sensing performance. International Journal on Smart Sensing and Intelligent Systems, 2012, 5(3): 592–605

[90] Deshmukh S B, Bari R H, Patil G E, . Preparation and characterization of zirconia based thick film resistor as an ammonia gas sensor. International Journal on Smart Sensing and Intelligent Systems, 2012, 5(3): 540–558

[91] Dunnill C W, Noimark S, Parkin I P. Silver loaded WO_3-x/TiO₂ composite multifunctional thin films. Thin Solid Films, 2012, 520(17): 5516–5520

[92] Pawar N K, Kajale D D, Patil G E, . Nanostructured Fe₂O₃ thick film as an ethanol sensor. International Journal on Smart Sensing and Intelligent Systems, 2012, 5(2): 441–457

[93] Iftimie N, Crisan M, Braileanu A, . On the sensing gas properties of titanium dioxide films. Journal of Optoelectronics and Advanced Materials, 2008, 10(9): 2363–2366

[94] Sahay P P, Nath R K. Al-doped zinc oxide thin films for liquid petroleum gas (LPG) sensors. Sensors and Actuators B: Chemical, 2008, 133(1): 222–227

[95] Satyanarayana L, Reddy K M, Manorama S V. Synthesis of nanocrystalline Ni_1-xCo_xMn_xFe_2-xO₄: a material for liquefied petroleum gas sensing. Sensors and Actuators B: Chemical, 2003, 89(1–2): 62–67

[96] Patil D R, Patil L A. Cr₂O₃-modified ZnO thick film resistors as LPG sensors. Talanta, 2009, 77(4): 1409–1414

[97] Chaudhari G N. LPG-sensing properties of perovskite BiFe_0.6Mn_0.4O₃ nanomaterials. Journal of Optoelectronics and Advanced Materials, 2007, 9(7): 2270–2274

[98] Mitra P, Mondal S. Hydrogen and LPG sensing properties of SnO₂ films obtained by direct oxidation of SILAR deposited SnS. Bulletin of the Polish Academy of Sciences-Technical Sciences, 2008, 56(3): 295–300

[99] Garje A D, Aiyer R C. Effect of decomposition temperature on electrical and gas sensing properties of nano SnO₂ based thick film resistors. Sensors Letters, 2006, 4(4): 380–387

[100] Jain K, Pant R P, Lakshmikumar S T. Effect of Ni doping on thick film SnO₂ gas sensor. Sensors and Actuators B: Chemical, 2006, 113(2): 823–829

[101] Srivastava A, Jain K, Rashmi, . Study of structural and microstructural properties of SnO₂ powder for LPG and CNG gas sensors. Materials Chemistry and Physics, 2006, 97(1): 85–90

[102] Shrivastava A, Rashmi, Jain K. Study on ZnO-doped tin oxide thick film gas sensors. Materials Chemistry and Physics, 2007, 105(2–3): 385–390

[103] Inamdar A D, Aiyer R C. Asian Journal of Physics, 2005, 9(1): 1

[104] Niranjan R S, Mulla I S, Vijayamohanan K. National Seminar on Physics and Technology of Sensors (NSPTS), Pune, India, 2004

[105] Tudorache F, Rezlescu E, Popa P D, . Study of some simple ferrites as reducing gas sensors. Journal of Optoelectronics and Advanced Materials, 2008, 10(7): 1889–1893

[106] Raju A R, Rao C N. Gas-sensing characteristics of ZnO and copper-impregnated ZnO. Sensors and Actuators B: Chemical, 1991, 3(4): 305–310

[107] Jain G H, Patil L A, Wagh M S, . Surface modified BaTiO₃ thick film resistors as H₂S gas sensors. Sensors and Actuators B: Chemical, 2006, 117(1): 159–165

[108] Kersen U. Gas sensing properties of nanocrystalline metal oxide powders produced by thermal decomposition and mechanochemical processing. Dissertation for the Doctoral Degree. Otaniemi, Espoo, Finland: Helsinki University of Technology, 2003

[109] Rumyantseva M, Labeau M, Delabouglise G, . Copper and nickel doping effect on interaction of SnO₂ films with H₂S. Journal of Materials Chemistry, 1997, 7(9): 1785–1790

[110] Saraladevi G, Rao S M V J. Journal of the Electrochemical Society, 1995, 142: 8

[111] Tamaki J, Maekawa T, Miura N, . CuO–SnO₂ element for highly sensitive and selective detection of H₂S. Sensors and Actuators B: Chemical, 1992, 9(3): 197–203

[112] Patil L A, Patil D R. Heterocontact type CuO-modified SnO₂ sensor for the detection of a ppm level H₂S gas at room temperature. Sensors and Actuators B: Chemical, 2006, 120(1): 316–323

[113] Chowdhuri A, Gupta V, Sreenivas K, . Response speed of SnO₂-based H₂S gas sensors with CuO nanoparticles. Applied Physics Letters, 2004, 84(7): 1180–1182

[114] Wu Y, Tong M, He X, . Thin film sensors of SnO₂–CuO–SnO₂ sandwich structure to H₂S. Sensors and Actuators B: Chemical, 2001, 79(2–3): 187–191

[115] Katti V R, Debnath A K, Muthe K P, . Mechanism of drifts in H₂S sensing properties of SnO₂:CuO composite thin film sensors prepared by thermal evaporation. Sensors and Actuators B: Chemical, 2003, 96(1–2): 245–252

[116] Patil L A, Pathan I G. Journal of Nano- and Electronic Physics, 2011, 3(1): 433

[117] Xu C N, Miura N, Ishida Y, . Selective detection of NH₃ over NO in combustion exhausts by using Au and MoO₃ doubly promoted WO₃ element. Sensors and Actuators B: Chemical, 2000, 65(1–3): 163–165

[118] Patil D R, Patil L A. Preparation and study of NH₃ gas sensing behavior of Fe₂O₃ doped ZnO thick film resistors. Sensors & Transducers Journal, 2006, 70(8): 661–670

[119] Ishihara T, Kometani K, Mizuhara Y, . Mixed oxide capacitor of CuO-BaTiO₃ as a new type CO₂ gas sensor. Journal of the American Ceramic Society, 1992, 75(3): 613–618

[120] Miura N, Yan Y, Sato M, . Solid-state potentiometric CO₂ sensors using anion conductor and metal carbonate. Sensors and Actuators B: Chemical, 1995, 24(1–3): 260–265

[121] Imanaka N, Murata T, Kawasato T, . CO₂ detection with lithium solid electrolyte sensors. Sensors & Transducers B, 1993, 13(1–3): 476–479

[122] Telipan G, Ignat M, Vlad A, . Lanthanum complex for gas sensing. Journal of Optoelectronics and Advanced Materials, 2008, 10(12): 3409–3412

[123] Chaudhari G N, Pawar M J. Ethanol sensing performances of modified CoFe₂O₄ nanocrystals prepared by polymerizable complex route. Journal of Optoelectronics and Advanced Materials, 2008, 10(10): 2574–2577

[124] Patil D R, Patil L A, Amalnerkar D P. Ethanol gas sensing properties of Al₂O₃-doped ZnO thick film resistors. Bulletin of Materials Science, 2007, 30(6): 553–559

[125] Ivanov P T. Design, fabrication and characterization of thick film gas sensors. Dissertation for the Doctoral Degree. Tarragona, Spain: Rovira i Virgili University, 2004

Acknowledgements

The authors are thankful to Principal S. G. Patil Arts, Commerce & Science College Sakri and the Principal L. V. H. College, Panchavati, Nashik for providing laboratory facilities and moral support. NGD is thankful to INSA and DST, New Delhi for awarding DST INSPIRE Faculty award [IFA-13 PH-61].

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg