Phase Coexistence Region Research Articles

Morphotropic phase boundary evolution with synergistic effect of sintering temperature to improve electrocaloric and energy storage performances of lead-free Ba0.95Ca0.05Sn0.09Ti0.91O3 (BCST) ceramic

The designing of lead-free ferroelectric ceramics for application in environment-friendly efficient electrocaloric cooling and energy storage devices is still challenging and need to be considered. A major challenge, however, is how to simultaneously achieve higher polarization and low hysteresis loss at low applied electric field. In this perspective, we comprehensively investigated sol-gel derived Ba0.95Ca0.05Sn0.09Ti0.91O3 (BCST) ceramics by varying the sintering temperature to explore its electrocaloric and energy storage capabilities. The excellent ∆T ∼ 1.03 K, ∆S ∼ 1.32 J/kg.K and high electrocaloric responsivity ΔT/ΔE ∼ 0.34 K.mm/kV at very low applied electric field of 30 kV/cm are obtained for pristine BCST sample sintered at 1400 °C. Additionally, we observed Wrec ∼ 136.18 mJ/cm3 and giant energy conversion efficiency η ∼ 94.29 % under very low applied electric field of 30 kV/cm for the same BCST sample. Our results reveal that control of sintering temperature contributes to a favorable and stable microstructure, including R-O-T phase coexistence and substitutional heterogeneity-induced nano-polar regions (PNRs) which strengthens the Polarization and supports the thin hysteresis loop. Thus all these factors simultaneously contributing to make BCST ceramic as a potential material for applications in advanced electrocaloric cooling and energy storage capacitors.

Fabrication of 3YSZ with single tetragonal phase by ultrafast high-temperature sintering

3 mol% yttria-stabilized zirconia (3YSZ) has been widely used as structural ceramics because of the high toughness of the tetragonal phase. However, since the conventional 3YSZ is sintered in the temperature range of the tetragonal-cubic phase coexistence region for several hours, Y3+ distributed inhomogeneously, and Y3+-rich regions undergo phase transformation into thermodynamically stable cubic phase. As a result, these 3YSZ usually exhibit tetragonal and cubic dual phases. Thus, suppressing the Y3+ redistribution during sintering is a key to prevent the phase transformation. Here, a fully dense 3YSZ with single tetragonal phase was successfully sintered by shorting sintering time using the ultrafast high-temperature sintering (UHS) method. The crystal structure, microstructure, and Y3+ distribution were investigated by XRD, SEM and STEM-EDS. We show that compared with the conventionally sintered 3YSZ, UHS effectively suppress Y3+ redistribution. The present results indicate UHS will be powerful to sinter ceramics in a non-equilibrium state.

Phase coexistence induced surface roughness in V2O3/Ni magnetic heterostructures

We present an investigation of the microstructure changes in V2O3 as it goes through its inherent structural phase transition. Using V2O3 films with a well-defined crystal structure deposited by reactive magnetron sputtering on r-plane Al2O3 substrates, we study the phase coexistence region and its impact on the surface roughness of the films and the magnetic properties of overlying Ni magnetic layers in V2O3/Ni hybrid magnetic heterostructures. The simultaneous presence of two phases in V2O3 during its structural phase transition was identified with high resolution x-ray diffraction and led to an increase in surface roughness observed using x-ray reflectivity. The roughness reaches its maximum at the midpoint of the transition. In V2O3/Ni hybrid heterostructures, we find a concomitant increase in the coercivity of the magnetic layer correlated with the increased roughness of the V2O3 surface. The chemical homogeneity of the V2O3 is confirmed through transmission electron microscopy analysis. High-angle annular dark field imaging and electron energy loss spectroscopy reveal an atomically flat interface between Al2O3 and V2O3, as well as a sharp interface between V2O3 and Ni.

Theoretical insights into surface-phase transition and ion competition during alkali ion intercalation on the Cu4Se4 nanosheet.

The development of stable and efficient electrode materials is imperative and also indispensable for further commercialization of sodium/potassium-ion batteries (SIBs/PIBs) and new detrimental issues such as proton intercalation arise when utilizing aqueous electrolytes. Herein the electrochemical performance of the Cu4Se4 nanosheet was determined for both organic and aqueous SIBs and PIBs. By means of density functional theory calculation, Na+, K+ and H+ intercalations onto both sides of the Cu4Se4 nanosheet were revealed. The Cu4Se4 nanosheet well maintains its metallic electronic conductivity and the changes in lateral lattice parameters are within 4.66% during the whole Na+/K+ intercalation process for both SIBS and PIBs. The theoretical maximum Na/K storage capacity of 188.07 mA h g-1 can be achieved by stabilized second-layer adsorption of Na+/K+. The migration barriers of Na and K atoms on the Cu4Se4 nanosheet are 0.270 and 0.173 eV, respectively. It was discovered that Na/K- intercalation in the first layer is accompanied by a first-order surface phase transition, resulting in an intercalation voltage plateau of 0.659/0.756 V, respectively. The region of the two-surface phase coexistence for PIBs, is shifted toward a lower coverage when compared with that for SIBs. The partially protonated Cu4Se4 nanosheet (HxCu4Se4, x ≤ 10/9) was revealed to be structurally and thermodynamically stable. While the partially protonated Cu4Se4 nanosheet is favorable in acidic electrolytes (pH = 0) when protons and Na/K ions compete, we showed that Na+/K+ intercalated products may be preferred over H+ at low coverages in alkali electrolyte (pH = 14). However, the proton intercalation substantially decreases the battery capacity in aqueous SIBs and PIBs. Our work not only identifies the promising performance of Cu4Se4 nanosheets as an electrode material of SIBs and PIBs, but also provides a computational method for aqueous metal-ion batteries.

Compositional induced structural phase transitions in (1 − x)(K0.5Na0.5)NbO3–x(Ba0.5Sr0.5)TiO3 ferroelectric solid solutions

Ferroelectric materials exhibiting switchable and spontaneous polarization have strong potential to be utilized in various novel electronic devices. Solid solutions of different perovskite structures induce the coexistence of various phases and enhance the physical functionalities around the phase coexistence region. The construction of phase diagrams is important as they describe the material properties, which are linked to the underpinning physics determining the system. Here we present the phase diagram of (K0.5Na0.5NbO3)–(Ba0.5Sr0.5TiO3) (KNN-BST) system as a function of composition and their associated physical properties. Lead-free (1 − x)KNN–xBST (0 ≤ x ≤ 0.3) solid solution ceramics were synthesized by conventional solid-state reaction technique. The X-ray diffraction and Raman spectroscopic studies indicate composition-dependent structural phase transitions from an orthorhombic phase for x = 0 to orthorhombic + tetragonal dual-phase (for 0.025 ≤ x ≤ 0.15), then a tetragonal + cubic dual-phase (x = 0.2) and finally a cubic single phase for x ≥ 0.25 at room temperature (RT). Among these, the orthorhombic + tetragonal dual-phase system shows an enhanced value of the dielectric constant at room temperature. The phase transition temperatures, orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), decrease with the increase in BST concentrations. The ferroelectric studies show a decrease of both 2Pr and EC values with a rise in BST concentration and x = 0.025 showed a maximum piezoelectric coefficient.

Effect of γ-Oryzanol on the LE-LC Phase Coexistence Region of DPPC Langmuir Monolayer.

We have studied the effect of relative composition of γ-Oryzanol (γ-Or) on the liquid expanded-liquid condensed phase coexistence region in the mixed Langmuir monolayer of γ-Or and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) molecules at air-water interface. The surface manometry studies at a fixed temperature show that the mixture of γ-Or and DPPC forms a stable monolayer at air-water interface. As the relative composition of γ-Or increases the range of area per molecule over which the coexistence of liquid expanded (LE)-liquid condensed (LC) phases exists reduces. Although the LE-LC phase coexistence corresponds to the first-order phase transition, the slope of the surface pressure-area per molecule isotherm is non-zero. Earlier studies have attributed the non-zero slope in LE-LC phase coexistence region to the influence of the strain between the ordered LC phase and disordered LE phase. The effect of strain on the coexistence of LE-LC phases can be studied in terms of molecular density-strain coupling. Our analysis of the liquid condensed-liquid expanded coexistence region in the isotherms of mixed monolayers of DPPC and γ-Or shows that with the increase in the mole fraction of sterol in the mixed monolayer the molecular lateral density-strain coupling increases. However, at 0.6 mole fraction of γ-Or in the mixed monolayer the coupling decreases. This is corroborated by the observation of minimum Gibb's free energy of the mixed monolayer at this relative composition of γ-Or indicating better packing of molecules.

Composition-driven structural phase transition in ferroelectric PbZrxTi1-xO3 across the morphotropic phase boundary

Materials with coexisting ferroelectric, piezoelectric, and pyroelectric properties have taken a great scientific attraction owing to their potential technological applications. In this work, employing X-ray diffraction and Raman scattering measurements combined with a photoluminescence investigation at room temperature, we report a composition-driven structural phase transition in the ferroelectric PbZrxTi1-xO3 (PZT) system by tuning the Zr content close to the morphotropic phase boundary (MPB) in the range of 0.44≤x≤0.58. The Ti-rich compound (x = 0.44) crystallizes in a tetragonal structure while the Zr-rich compound (x = 0.58) belongs to the rhombohedral symmetry. The system exhibits a phase coexistence region composed of these tetragonal and rhombohedral phases in the vicinity of MPB for compositions with x = 0.50, 0.52, and 0.53. We reveal strong and systematic evolution of the Raman shift, Raman strength, and damping constants for the Raman active phonon modes associated with the aforementioned structural transition and the increased local disorder of Ti4+ or Zr4+ cations as a function of x. We further uncover a resonance Raman phenomenon with 633 nm (1.96 eV) excitation, enhancing the Raman strength and damping constants of certain low-lying transverse optical (TO) phonon modes in the Raman spectra. The photoluminescence emission spectrum shows evidence of in-gap energy levels that could be ascribed to self-trapped excitons, explaining the origin of the resonance Raman effect in PZT ceramics.

Improved piezoelectric properties through manganese-doping in phase coexistence region in lead strontium zirconate titanate (PSZT) thin films

In the quaternary system PbTiO3-PbZrO3-SrTiO3-SrZrO3, compositions that lie close to the antiferroelectric tetragonal and ferroelectric rhombohedral (AFET-FER) phase boundary have potential applications in micro-actuators. However, in thin films, this phase boundary is reported to shift significantly to the zirconium-rich region. Hence, it is necessary to seek alternative approaches to stabilize the tetragonal AFE phase in such compositions. Therefore, this study explores the effect of B-site Mn3+-doping on their structure. Dielectric, ferroelectric, and piezoelectric characteristics of such thin films have been compared with those with increasing Zr/Ti ratios to understand the efficacy of this approach. Transverse piezoelectric coefficient, e31,f, and bipolar strain are found to be higher in Mn3+-doped thin films. Furthermore, large strains and e31,f in thin films have been correlated with structural modifications revealed by systematic Raman spectroscopic investigations.

Unusual crystal structure evolution, multiple phase boundaries and phase coexistence in (1 - x)Ba(Cu1/3Nb2/3)O3-(x)PbTiO3 perovskite solid solution.

Exploring the functionalities of materials requires a profound understanding of the crystal structure. In this paper, room temperature crystal structures of a new solid solution (1 - x)Ba(Cu1/3Nb2/3)O3-(x)PbTiO3 have been investigated in the entire compositional span and different crystallographic phases and phase coexistence regions have been discovered. The confirmation of the symmetry of these crystal structures has been done with the help of Rietveld analysis of the high-resolution XRD data. Despite both the end components, Ba(Cu1/3Nb2/3)O3 and PbTiO3, having tetragonal (P4mm) symmetry, new cubic and monoclinic phases have been discovered for the intermediate compositions with multiple phase boundaries. The composition region 0.05 ≤ x ≤ 0.55 exhibits a cubic crystal structure and increasing PbTiO3 concentration to 0.62 results in a unique coexistence of two tetragonal phases with different tetragonalities. This transformation is mediated by coexisting cubic and tetragonal phases, for 0.59 and 0.60. The crystal structure of the solid solution later transforms into coexisting monoclinic and tetragonal phases for a wider compositional span i.e., 0.65 ≤ x ≤ 0.85. This composition region is very fascinating, as two phenomenologically different monoclinic structures have been observed in it. Finally, a tetragonal phase at x = 1 is achieved through the mediation of two coexisting tetragonal phases, for the region 0.85 < x ≤ 0.975. The evolution of different crystallographic structures and the coexisting phases are critically comprehended using the variations in the lattice parameters and unit cell volume. The presence of multiple phase boundaries spread across a wide range of compositions makes this solid solution very intriguing and a viable choice for exploring different properties with compositional tuning.

Crystalline restacking of 2D-materials from their nanosheets suspensions.

We report here the highly ordered restacking of the layered phosphatoantimonic dielectric materials H3(1-x)M3xSb3P2O14, (where M = Li, Na, K, Rb, Cs and 0 ≤ x ≤ 1), from their nanosheets dispersed in colloidal suspension, induced by a simple pH change using alkaline bases. H3Sb3P2O14 aqueous suspensions are some of the rare examples of colloidal suspensions based on 2D materials exhibiting a lamellar liquid crystalline phase. Because the lamellar period can reach several hundred nanometers, the suspensions show vivid structural colors and because these colors are sensitive to various chemicals, the suspensions can be used as sensors. The structures of the lamellar liquid crystalline phase and the restacked phase have been studied by X-ray scattering (small and wide angle), which has followed the dependence of the lamellar/restacked phase equilibrium on the cation exchange rate, x. The X-ray diffraction pattern of the restacked phase is almost identical to that of the M3Sb3P2O14 crystalline phase, showing that the restacking is highly accurate and avoids the turbostratic disorder of the nanosheets classically observed in nanosheet stacking of other 2D materials. Strikingly, the restacking process exhibits features highly reminiscent of a first-order phase transition, with the existence of a phase coexistence region where both ∼1 nm (interlayer spacing of the restacked phase) and ∼120 nm lamellar periods can be observed simultaneously. Furthermore, this first-order phase transition is well described theoretically by incorporating a Lennard-Jones-type lamellar interaction potential into an entropy-based statistical physics model of the lamellar phase of nanosheets. Our work shows that the precise cation exchange produced at room temperature by a classical neutralization reaction using alkaline bases leads to a crystal-like restacking of the exfoliated free Sb3P2O143- nanosheets from suspension, avoiding the turbostratic disorder typical of van der Waals 2D materials, which is detrimental to the controlled deposition of nanosheets into complex integrated electronic, spintronic, photonic or quantum structures.

Polarity Modulation Induced High Electrostrain Performance with Near-Zero Hysteresis in a (Sr0.7Bi0.2□0.1)TiO3-Based System

High-precision piezo actuators necessitate dielectrics with high electrostrain performance with low hysteresis. Polarity-modulated (Sr0.7Bi0.2□0.1)TiO3-based ceramics exhibit extraordinarily discrete multiphase coexistence regions: (i) the relaxor phase coexistence (RPC) region with local weakly polar tetragonal (T) and pseudocubic (Pc) short-range polar nanodomains and (ii) the ferroelectric phase coexistence (FPC) region with T long-range domains and Pc nanodomains. The RPC composition features a specially high and pure electrostrain performance with near-zero hysteresis (S ∼ 0.185%, Q33 ∼ 0.038 m4·C-2), which is double those of conventional Pb(Mg1/3Nb2/3)O3-based ceramics. Particular interest is paid to the RPC and FPC with multiscale characterization to unravel local structure-performance relationships. Guided by piezoelectric force microscopy, scanning transmission electron microscopy, and phase-field simulations, the RPC composition with multiphase low-angle weakly polar nanodomains shows local structural heterogeneity and contributes to a flat local free energy profile and thus to nanodomain switching and superior electrostrain performance, in contrast to the FPC composition with a macroscopic domain that shows stark hysteresis. This work provides a paradigm to design high-precision actuator materials with large electrostrain and ultralow hysteresis, extending our knowledge of multiphase coexistence species in ferroelectrics.

Mott domain walls: A (strongly) non-Fermi liquid state of matter

Most Mott systems display a low-temperature phase coexistence region around the metal-insulator transition. The domain walls separating the respective phases have very recently been observed both in simulations and in experiments, displaying unusual properties. First, they often cover a significant volume fraction, thus cannot be neglected. Second, they neither resemble a typical metal nor a standard insulator, displaying unfamiliar temperature dependence of (local) transport properties. Here we take a closer look at such domain wall matter by examining an appropriate unstable solution of the Hubbard model. We show that transport in this regime is dominated by the emergence of "resilient quasiparticles" displaying strong non-Fermi liquid features, reflecting the quantum-critical fluctuations in the vicinity of the Mott point.

Hysteresis dynamics of rare earth nickelates: unusual scaling exponent and asymmetric spinodal decomposition

Understanding the dynamics of phase-transitions, interpretations of their experimental observations and their agreement with theoretical predictions continue to be a long-standing research interest. Here, we present detailed phase-transition dynamics of rare earth nickelates associated with its first-order metal–insulator transition. The thermal hysteresis shows absence of training effect and defies the Preisach model. A large phase-coexistence in insulating state during cooling suggests kinetically arrested glassy dynamics of the phase-transition. Experimentally derived hysteresis scaling exponent is much larger than the mean-field predicted universal value of 2/3. In the phase-coexistence region, the quench and hold measurement depicts higher stability of the metallic state compare to that of the insulating one; highlighting the manifestation of phase-coexistence via asymmetric spinodal decomposition. All these observations for nickelates are in stark contrast to the phase-transition dynamics of canonically similar vanadates but are closer to those of glasses, alloys. A substantial disagreement between the experiment and theory emphasizes the necessity to incorporate system-dependent details for the accurate interpretation of the experimental results.

Isothermal phase diagram of CaO–SiO2–Nb2O5-5wt% Fe2O3–TiO2 system at 1200 °C

The lack of thermodynamic data such as the phase diagram of CaO–SiO2–Nb2O5–Fe2O3–TiO2 system has seriously hampered the comprehensive utilization of niobium, titanium and other resources in the Bayan Obo tailing. In this study, phase equilibria of the CaO–SiO2–Nb2O5–Fe2O3–TiO2 system at 1200 °C were investigated using high temperature equilibrium experiment for the first time, and the CaTiO3–Ca10Nb2Si6O27–Ca2SiO4–Ca2Nb2O7 solid phase coexistence region was determined. Afterwards, based on the high temperature equilibrium experiments, the liquidus surfaces of the liquid + CaTiO3 and liquid + SiO2 equilibrium coexistence regions in CaO–SiO2–Nb2O5-5wt% Fe2O3–TiO2 system at 1200 °C were calculated using mathematical methods of interpolation and fitting. Finally, the 1200 °C isothermal phase diagrams of CaO–SiO2–Nb2O5-5wt%Fe2O3–TiO2 system were plotted. The results of the study can provide theoretical guidance for the enrichment and extraction processes of niobium and titanium resources in the Bayan Obo tailing.

Evolution of the statistical disintegration of finite nuclei toward high energy

We develop a statistical approach for the description of complex nuclei formation from dynamically produced baryons in high energy heavy-ion reactions. We consider a finite highly-excited expanding nuclear system formed after central nucleus-nucleus collisions. This system is sub-divided into primary equilibrated nucleon clusters. The final nuclei are produced after the decay of these excited clusters. By the successful comparison with the FOPI experimental data we prove the possibility of such a local equilibrium in nuclear matter with the temperature corresponding to the phase coexistence region. The regularities obtained in this new nuclei production mechanism are shown.

(Invited) Potentiometric Entropy and Operando Calorimetric Measurements to Assess the Performance of Heterogeneous Lithium Ion Battery Electrodes

This talk presents new efforts to use potentiometric entropy and operando isothermal calorimetric measurements to gain insight into the charging mechanisms as well as the thermodynamics and ion transport in lithium ion battery electrodes. Electrodes consisted of particles of different sizes - from a few nanometers to a few microns - synthesized by solid state or sol gel methods and using different conducting polymer binders. Promising battery materials such as lithium sodium vanadium fluorophosphate LixNa1.5-xVOPO4F0.5, tungsten vanadium oxide (W0.2V0.8)3O7, and titanium niobium oxide Ti2Nb2O9 were considered. The effect of particle size and binder on the specific capacity, polarization, thermodynamic behavior, and lithium transport were investigated. Particular attention was paid to various phenomena occurring during charging/discharging including solid solution intercalation, phase transition, and two phase coexistence region. Finally, the heat generation rates associated with (i) Joule heating cause be polarization, (ii) heat of mixing due to ion concentration gradient, and (iii) reversible entropy changes observed at different C-rates were identified and discussed.

Sintering Aid‐Assisted Growth of 0.95(K0.5Na0.5)NbO3–0.05(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 Single Crystals by the Solid‐State Crystal Growth Method and Their Characterization

In this work, 0.95(K0.5Na0.5)NbO3–0.05(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 (KNN–BNZS) lead‐free piezoelectric single crystals are grown by the solid‐state crystal growth (SSCG) method and their phase transitions and properties characterized. Addition of an appropriate amount of Li2CO3 and Bi2O3 sintering aids considerably promotes single‐crystal growth. Chemical composition of the single crystal is similar to the nominal composition with a slight deficiency in Na and K as evaluated by electron probe microanalysis (EPMA). X‐Ray diffraction (XRD), electrical property measurements, and temperature‐controlled Raman scattering reveal that the phase transition near room temperature is from a rhombohedral to an orthorhombic or tetragonal phase. Wide temperature range Raman scattering and dielectric properties consistently indicate transitions associated with the phase transformations or boundaries of a phase coexistence region and further details. Nontrivial frequency dependence of dielectric properties is successfully parameterized by capacitance relaxations described by Debye and Cole–Cole responses with special constant phase elements with fixed exponents of 0.5 (Warburg elements). High‐frequency dielectric constants and additional dielectric relaxations and dc relaxations are deconvoluted. The modeling parameters indicate the phase transition temperatures (or boundaries of the phase coexistence region) unambiguously. Polarization–electric field and bipolar strain–electric field hysteresis loops show that the single crystal is a classic lossy ferroelectric material.

Viscoelastic response of fluid trapped between two dissimilar van der Waals surfaces

Employing grand canonical Monte-Carlo and molecular dynamics simulations, the viscoelastic response of trapped fluid under molecularly thin confinement by walls having different wall–fluid interaction strengths, is investigated. With increase in slit asymmetry, given by the ratio of interaction strengths of the wall having strong wall–fluid interaction to that of the wall with weak wall–fluid interaction, a crossover in effective density of the fluid film, from rarer (R) to denser (D) than the bulk density is observed. Upon increasing asymmetry further, the dense fluid (F) layers undergo bond-orientational (S) ordering. The variation of viscoelastic relaxation time with scaled asymmetry shows a universal behavior, independent of slit width, with two distinct regimes. Below a critical value of asymmetry, the viscoelastic relaxation time is a slowly varying function of asymmetry, comparable with the structural relaxation time. Beyond the critical asymmetry, on the other hand, viscoelastic response time shows a sharp increase upon increasing asymmetry, deviating markedly from the structural relaxation time. Interestingly the critical asymmetry value is found to correlate with R to D crossover. The microscopic origin of the two-regime universal behavior of viscoelastic response time is found to stem from the fact that below critical asymmetry, the overall viscoelastic behaviour of the slit is dominated by that of the fast relaxing layer close to the weakly attracting surface, while above the critical asymmetry, the relaxation behaviour is guided by the dense fluid layer adjacent to the strongly attracting wall. In vicinity of fluid to ordering transition, the loss and storage moduli merge for low frequencies as in gel-like mechanical behaviour. The storage modulus takes over the loss modulus in the phase co-existence region even before the long ranged order sets in. Our findings bear important implications for fluid transport in hetero-structured geometry in nanotechnology.

Effects of polymer nonideality on depletion-induced phase behaviour of colloidal disks and rods

Colloidal dispersions composed of either platelets or rods exhibit liquid crystalline phase behaviour that is strongly influenced by the addition of nonadsorbing polymers. In this work we examined how polymer segment–segment interactions affect this phase behaviour as compared to using either penetrable hard spheres (PHS) or ideal (‘ghost’) chains as depletants. We find that the simplified polymer description predicts the same phase diagram topologies as the more involved polymer descriptions. Therefore the PHS description is still adequate for qualitative predictions. For sufficiently large polymer sizes we find however that the precise polymer description significantly alters the locations of the phase coexistence regions. Especially the stability region of isotropic–isotropic coexistence is affected by the polymer interactions. To illustrate the quantitative effects some examples are presented.

Metal-Insulator phase transition in thin films of vanadium dioxide doped with indium

The electrical conductivity of thin polycrystalline films V(1-x)InxO2 has been studied in a wide temperature range covering the regions of existence of both the metallic and insulator phases. It is shown that with increasing indium concentration, the temperature of the metal-insulator phase transition decreases, and the width of the temperature region of phase coexistence monotonically increases. To explain the temperature dependence of the electrical conductivity of the insulator phase V(1-x)InxO2, a model of hopping conductivity is applied, taking into account the effect of thermal vibrations of atoms on the resonance integral. Calculated the values of the parameter ε depend on the degree of doping of VO2. Keywords: phase transition, vanadium oxides, thin films, polaron, electrical conductivity.