Structural and low temperature electrical transport properties of Mo-doped vanadium oxide NTC ceramic thin films
Introduction
There is currently great interest in identifying new oxide thin film ceramic materials with enhanced negative temperature coefficient (NTC) of resistivity. These ceramic materials can be applied in low temperature sensors and thermal imaging tools in military and medical fields, where precise temperature measurement and control are necessary [1], [2]. However, it is essential to develop highly efficient NTC ceramic oxide materials with better performance characteristics than those of the well-known multi-component NTC ceramic oxides (i.e., spinel oxides, skutterudites, half-Hesular alloys, clathrates, and pentatellurides) [3], [4], [5], [6], [7], particularly for low temperature sensor applications.
Recent studies have been focused on tuning single component (i.e., preferably with one dopant) NTC ceramic oxide materials [8], [9], [10], [11], [12], [13], doping the NTC materials with transition metals, and optimizing device design for low temperature operation, because it is difficult to control the porosity and stoichiometry of multi-component NTC ceramics. Single component NTC oxide ceramic thin films offer many advantages over multi-component NTC oxide materials; high sensitivity to temperature changes at the sub-zero level, high signal to noise ratio, simple operation, and low cost. Moreover, single component NTC oxide ceramics are reliable and last long.
Several classes of single component oxide ceramics including silicon [14], silicon-germanium alloys [15], and vanadium oxide compounds [8], [16], [17] are currently under investigation. Among these, special attention has been given to vanadium compounds because of their high NTC of resistance, extreme ruggedness, and the ease with which their electrical and thermal properties can be modified. Vanadium oxide NTC ceramics have efficient electrical/thermal properties and can be used in sensing elements on any type of substrate, semiconductor, or other ceramic material with considerable ease. Hence, vanadium oxide compounds can be used in the development of low temperature sensor devices. Furthermore, the NTC electrical property of vanadium oxide ceramics can be tailored by various factors (e.g., dopant concentration, annealing process) for low temperature sensing applications.
Vanadium oxide compounds undergo metal-insulator transitions accompanied by structural changes at sub-zero temperatures [18], [19]. The transition temperature must be modified to satisfy the specific temperature requirements of the device. Dopants act as extrinsic impurity that allow for precise control over charge carrier densities. To this end, it was reported that doping and dopant concentration can greatly influence the transition temperatures of vanadium oxides [20], [21]. High impurity dopant concentrations are key to reduce the potential of ceramics for a variety of applications. In addition, the transition temperature and corresponding NTC characteristics of vanadium based ceramics depend on the crystal and micro-structures of these oxides. The crystal and micro-structures of vanadium oxide thin film ceramics can be tuned for low temperature applications by adding suitable dopants and/or varying the processing conditions (e.g., ambient gas flow rates and annealing temperatures) [22], [23]. Therefore, process conditions for the fabrication of vanadium oxide compound ceramic thin films with the desired electrical properties for low temperature applications should be carefully chosen.
In the present work, we have shown that the resistivity of vanadium oxide ceramic thin films can be increased by introducing highly concentrated Mo-dopant as an insulating material into the vanadium oxides. To this end, we fabricated single layer pure vanadium oxide (V2O3) and molybdenum doped vanadium oxide (V1−xMoxO2−x/2) thin films on metal substrates using a sol-gel dip coating method. A series of measurements were conducted over a temperature range of 253.15–273.15 K to monitor the electrical transport properties of the oxide films as a function of Mo concentration. This study describes a new avenue to create thin ceramic NTC Mo/vanadium oxide materials for low temperature applications.
Section snippets
Sol-gel synthesis
Commercial vanadium oxytriisopropoxide (C9H21O4V, Sigma-Aldrich) and molybdenum isopropoxide (C15H35MoO5, Sigma-Aldrich) were used as precursors to synthesize pure V2O3 and Mo-doped V2O3. 2-Propanol (anhydrous 99.5% PriOH, Sigma-Aldrich), the main alcohol of vanadium alkoxides, was used as the diluent. Pure V2O3 was synthesized by mixing vanadium oxytriisopropoxide, 2-propanol, and acetyl acetone (used as a chelating agent) in an inert environment. The resulting vanadium solution was stirred
Results and discussion
In general, multi-layer film coating may cause interfacial surface effects [24] and it is very challenging to maintain consistency of deposition parameters for each layer coating [25]. In the present study, we focused mainly on single layer coating on metal substrates to achieve high electrical resistance [20].
Conclusions
In summary, Mo doped V2O3 thin ceramic films were deposited by varying Mo concentration from 5 to 10 mol % by sol-gel dip coating method on metal substrates. From the microstructural and electrical studies, annealing effect and high Mo concentration induced NTC resistivity evolving from semi-metallic nature to insulating behavior have been observed in the low temperature region (over the range of 273.15 to 253.15 K). The increasing concentration of Mo in the V2O3 induces changes in the film
Acknowledgement
One of the authors M.K. gratefully acknowledges the New & Renewable Energy Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP) (No. 20142010102930) for the PDF financial support.
References (55)
- et al.
The effect of manganese substitution to gallium on the physical properties of MgGa2− xMn x O4 spinel type ceramic thermistors
J. Eur. Ceram. Soc.
(2007) - et al.
Investigation of vacuum deposition of Bi2Te3-based thermoelectric materials
Mater. Res. Bull.
(1987) - et al.
Vanadium oxide nanostructures on another oxide: the viewpoint from model catalysts studies
Coord. Chem. Rev.
(2015) - et al.
Pulsed laser deposited nanostructured vanadium oxide thin films characterized as ammonia sensors
Sens. Actuat. B Chem.
(2015) - et al.
The influence of transition metal oxides type M+/M++ on the vanadium–tellurite glasses electrical behavior
Solid State Sci.
(2015) - et al.
An experimental feasibility study of vanadium oxide films on metallic bipolar plates for the cold start enhancement of fuel cell vehicles
Int. J. Hydrogen Energy
(2011) - et al.
Electrical and thermal transport properties of vanadium oxide thin films on metallic bipolar plates for fuel cell applications
Int. J. Hydrogen Energy
(2013) - et al.
IR bolometers made of polycrystalline silicon germanium
Sens. Actuat. A Phys.
(1998) - et al.
Structural electrical and infrared optical properties of vanadium pentoxide (V2O5) thick film thermistors
Sens. Actuat. A Phys.
(1993) - et al.
Systematics in the metal-insulator transition temperatures in vanadium oxides
Solid State Commun.
(2016)
Electrically-driven metal–insulator transition of vanadium dioxide thin films in a metal–oxide-insulator–metal device structure
Mat. Sci. Semicond. Proc.
Synthesis, characterization, and transport properties of single-layer pure and molybdenum-doped vanadium oxide thin films on metallic conductive substrates
Thin Solid Films
Surface and interface stress effects in thin films
Prog. Surf. Sci.
Structural properties and electrical resistivity behaviour of La1− x Kx MnO3 (x= 0.1, 0.125 and 0.15) manganites
Mater. Chem. Phys.
Molybdenum-doped vanadium dioxide coatings on glass produced by the aqueous sol–gel method
Thin Solid Films
Structural and electrochromic properties of molybdenum doped vanadium pentoxide thin films by sol–gel and hydrothermal synthesis
Thin Solid Films
Influence of the annealing in nitrogen atmosphere on the XRD, EDX, SEM and electrical properties of chemical bath deposited CdSe thin films
Mater. Chem. Phys.
Effects of nitrogen content on structure and electrical properties of nitrogen-doped fluorinated diamond-like carbon films
Trans. Nonferr. Metal. Soc.
Inhibition of grain growth by second phase particles: three dimensional Monte Carlo computer simulations
Scr. Metal. Mater.
Preparation and characterization of Fe+3- doped Ni 0.9Co 0.8 Mn1.3- xFexO4 (0≤ x≤ 0.7) negative temperature coefficient ceramic materials
Microelect. Eng.
Structural, electronic and optical features of molybdenum-doped bismuth vanadium oxide
Mat. Sci. Semicond. Proc.
High temperature NTC ceramic resistors (ambient–1000° C)
J. Eur. Ceram. Soc.
S.Ramanathan, Limits on vanadium oxide Mott metal–insulator transition field-effect transistors
Solid-State Electron.
Negative temperature coefficient resistance (NTCR) ceramic thermistors: an industrial perspective
J. Am. Ceram. Soc.
Semiconducting Temperature Sensors and Their Applications
Searching for new thermoelectrics in chemically and structurally complex bismuth chalcogenides
Mater. Res. Soc. Symp. Proc.
Thermoelectric materials, phenomena, and applications: a bird's eye view
MRS Bull.
Cited by (17)
Enhanced dual superconducting and ferromagnetic properties of YBCO film tuned with boron and oxygen partial pressures
2023, Journal of Alloys and CompoundsLow-temperature electrical transport and tunable optical properties of Mo-doped V<inf>2</inf>O<inf>3</inf> thin films
2023, Materials Science and Engineering: BCitation Excerpt :The broadening of bandgap can be seen at higher Mo concentrations (i.e., 8 and 10 mol%) in V2O3, which is mainly due to two factors: (i) decrease of charge carrier concentrations, and (ii) empty state (un-filling) of the electrons near the bottom of the conduction band of V2O3 lattice. When the films are annealed with 20 sccm N2 at 673.15 K, the grain size becomes smaller [12,17] leading to increased density of grain boundary and consequently a higher number of trapped carriers, which makes a few charge carriers available for the conduction band. Such a variation in carrier concentration by the addition of higher concentrated Mo (>7 mol%) leads to a drastic modification in the bandgap and degenerating metal or semiconducting property, which is clearly explained by the Burstein-Moss effect [40].
Self-powered ferroelectric NTC thermistor based on bismuth titanate
2019, Nano EnergyCitation Excerpt :Mostly, high temperature NTC thermistors used in inrush current limiters (electrical power supply industries, and motor drives), as well as exhaust temperature gas sensors/catalytic converters as a pyrometer gauge in internal combustion engines of vehicles [11,12]. There is a great research interest in recognizing alternative novel perovskite materials with improved thermal sensitivity (β) than the spinel, carbon materials [13–15]. Current manufacturing methods for thermistor devices (rigid and flexible) require high-cost instruments and specific atmospheric conditions.
Electrostatic precipitability of TiB2-Fe-Mo-Co ceramic-metal composites
2019, Journal of Alloys and CompoundsElectrical properties and temperature sensitivity of Li/Mg modified Ni<inf>0.7</inf>Zn<inf>0.3</inf>O based ceramics
2018, Journal of Alloys and CompoundsCitation Excerpt :Not only can the values of ρ25 of the semiconducting single oxide be effectively adjusted and controlled by element doping, but also the B values can be modified by suitable ionic substitution. In recent years, the compounds based on the single oxide or the ones with simple crystalline structure have attracted much attention on developing new systems of NTC thermistors [13–22]. Of rock salt crystalline structure as that of NaCl, Zn-Ni-O system materials such as Zn1-xNixO (x ≤ 0.7) ceramics have been reported to show typical NTC characteristic with high B values (between 3998 and 5464 K) [21].
Phase evolutions, microstructure and reaction mechanism during calcification roasting of high chromium vanadium slag
2018, Journal of Alloys and CompoundsCitation Excerpt :Vanadium is one of the most important rare metals, which is growing more and more attractive to the modern technology and industry [1–5].