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The magnetoelectric composites with the composition Y [Li 0.5 Ni 0.75− x /2 Zn x /2 Fe 2 O 4 ] + (1 − Y )[Ba 0.5 Sr 0.5 TiO 3 ] where x = 0.1, 0.2. 0.3 and Y = 0.1, 0.2, 0.3 were prepared by standard double sintering ceramic technique. The XRD patterns confirmed the coexistence of piezomagnetic and piezoelectric phases. Both dielectric constant ( ɛ ′) and loss tangent (tan δ ) decrease with increase in frequency exhibiting normal dielectric behaviour. The linearity in the log σ ac vs. log ω 2 plots confirmed the small polaron hopping type of conduction mechanism in the composites studied. Flat curves in the ME output vs. dc magnetic field are obtained which may be due to the presence of strontium in the composites. ME output showed direct relation with the resistivity of the composites.

Nanocrystalline CdSe and Al:CdSe semiconductor thin films have been successfully synthesized onto amorphous and FTO glass substrates by spray pyrolysis technique. Aqueous solutions containing precursors of Cd and Se have been used to obtain good quality films. The optimized films have been characterized for their structural, morphological, wettability and optical properties. X-ray diffraction (XRD) studies show that the films are polycrystalline in nature with hexagonal crystal structure. Scanning electron microscopy (SEM) studies show that the film surface is smooth, uniform and compact in nature. Water wettability study reveals that the films are hydrophilic behavior. The formation of CdSe and Al:CdSe thin film were confirmed with the help of FTIR spectroscopy. UV–vis spectrophotometric measurement showed a direct allowed band gap lying in the range 1.673–1.87 eV. Output characteristics were studied by using cell configuration n- CdSe/Al:CdSe |1 M (NaOH + Na 2 + S)|C. An efficient solar cell having a power conversion efficiency of 0.38% at illumination 25 mW cm −2 was fabricated.

Non-stiochiometric ternary chalcogenides Zn 1− x Fe x S ( x = 0.005, 0.013, 0.05, 0.231, and 0.43) bulk powders were prepared by coprecipitation of ZnS and FeS by adding Na 2 S to aqueous solutions containing FeSO 4 and ZnSO 4 . Pellets of resulting material were sintered at 1123 K in vacuum-sealed quartz ampoules maintained at 10 −2 torr for a total of 165 h. Direct optical bandgaps were found to decrease with increase in Fe content viz. 2.1 eV E g x > 0.005. A subsidiary peak attributed to photoionization transitions of Fe ions appeared at lower energy values (around 2.7 eV) whose intensity increased with increase in Fe content. Room temperature photoluminescence emission studies (PLE) of the pellets were obtained with λ exc = 225 nm, revealed UV region peaks centered at energies above that of bandgap ( E g ), and correspond to free exciton emission. While those of energies below that of E g are attributed to defects due to vacancies and interstitials. The PLE peaks in visible region (viz. 491, 518, and 596 nm) are attributed to transitions involving impurity levels. Peak at 617 nm is expected to be due to transitions associated with Fe 2+ levels localized at 2.1 eV below the (Zn, Fe)S conduction edge. The various bypassing processes leading to the deactivating behavior of Fe 2+ as evident from decreasing luminescence peak intensity with increasing ‘ x ’, have been explained qualitatively.

Bi 2 S 3 thin films were prepared on amorphous glass substrates by successive ionic layer adsorption and reaction (SILAR) method at room temperature using bismuth nitrate and thioacetamide as the cationic and anionic precursors in aqueous medium. The X-ray diffraction study reveals that as-deposited films of Bi 2 S 3 are amorphous in nature, it becomes polycrystalline after annealing at 573 K. The decrease in activation energy from 0.65 to 0.36 eV and optical band gap energy, E g , from 2.35 to 1.86 eV are observed as film thickness varies from 67 to 150 nm. Such changes are attributed to the quantum size effect in semiconducting films.

In the present work ternary chalcogenide p-type semiconductor Zn 1− x Fe x S has been prepared by co-precipitation method for x =0.18 and 0.4 concentrations of Fe. The precipitate was repeatedly sintered at 800 °C in sealed quartz ampoules for a total of 165 h The material was then characterized by X-ray diffraction, X-ray fluorescence (XRF), EDAX, EPMA, diffuse reflectance spectroscopy, thermoelectric, electrochemical and capacitance measurement techniques. Compositional analysis techniques, viz. XRF, EDAX and EPMA reflected the composition of the solutions from which precipitation was carried out while X-ray reveals a sphalerite crystal structure. Capacitance measurements indicate that the relaxation effects are enhanced with increasing Fe substitution. Thermoelectric measurements indicate p-type conductivity in agreement with the results obtained by electrochemical analysis. The flat band potential V fb has values 2.94 V ( x =0.18) and 2.66 V ( x =0.4) as obtained by Mott–Schottky plot. Similarly the optical band gap was found to decrease with increase in Fe concentration.

Antimony trisulphide thin films have been prepared by a spray pyrolysis technique using various concentrations of complexing agent (tartaric acid) in the spray solution. These films are characterized for structural, electrical and optical properties. The results of XRD studies reveal that the films are polycrystalline. The crystallinity and direction of growth is found to be a function of the concentration of complexing agent. It is found that resistivity varies with the concentration of complexing agent. The resistivity of the films is 106–107 Ω cm−1. The band gap energy also varies with the concentration of the complexing agent from 1.92 to 2.13 eV.

The thin films of cadmium indium selenide (CdIn 2 Se 4 ) have been deposited onto amorphous glass substrates using simple and low cost spray pyrolysis technique. The aqueous solutions containing precursors of Cd, In and Se have been used to obtain good quality deposits at different substrate temperatures. The preparative parameters, such as substrate temperature and concentration of precursor solution have been optimized and are found to be 280 °C and 0.0125 M, respectively. The films have been characterized by X-ray diffraction (XRD), optical absorption and energy dispersive analysis by X-rays (EDAX) techniques. The spray-deposited CdIn 2 Se 4 films are polycrystalline with cubic crystal structure. The optical absorption studies reveal that the transition is direct with band gap energy E g =1.92 eV. The EDAX studies reveal that the films obtained at substrate temperature 280 °C are nearly stoichiometric.

Electrodeposition and characterization of EuSe thin films onto different substrates such as stainless steel (SS), Ti, Cu, fluorine-doped tin oxide (F-SnO2) covered glasses is described. The films have been prepared in potentiostatic mode using aqueous acidic electrolyte containing Eu and Se precursors at 70 °C bath temperature and pH 4. The disodium salt of ethylenediaminetetraacetic acid (Na2-EDTA) is used as a complexant. The results of polarization studies reveal that the deposition potential for EuSe thin films is different for different substrates. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse analysis by X-rays (EDAX) and optical absorption techniques. The electrodeposited EuSe films are polycrystalline. The SEM investigation revealed that the deposit surface is rough when deposited on copper, titanium and SS, however, it is relatively smooth and fine-grained on F-SnO2 glass substrate. The surface patterns are spherical for titanium and F-SnO2 substrates, while for SS and copper, they are cauliflower- and leaf-like, respectively. The optical absorption studies revealed that the transition is direct and band gap energy Eg is 1.75 eV.

Thin chalcogenide films of antimony have been attracting a great deal of attention because of their some special applications in optoelectronic devices and solar cells. The Sb2S3 and Sb2Se3 thin films have been prepared by a spray pyrolysis technique at their optimized conditions of substrate temperature and solution concentrations from the aqueous and non-aqueous media. The studies reveal that the films prepared from aqueous medium are amorphous and those obtained from non-aqueous medium are polycrystalline; especially the Sb2Se3 prepared from non-aqueous become polycrystalline after annealing. The optical absorption studies show the values of optical gap to be 1.1 and 1.28 eV, respectively, for Sb2S3 and Sb2Se3 for the aqueous medium while the same materials have direct band gap energies of 1.8 and 2.14 eV, respectively, when prepared from non-aqueous medium. When heated in nitrogen atmosphere for 2 h at optimized annealing temperature, the films of Sb2S3 and Sb2Se3 remain amorphous but those obtained from non-aqueous medium show enhancement in the crystallinity. The electrical resistivity for both films studied in the temperature range 300–500 K shows that the resistively is of the order of 106–107 Ω cm. The Sb2S3 and Sb2Se3, irrespective of preparation medium, are found to be n- and p-type, respectively. Both the materials are found to be photoactive when used in photoelectrochemical solar cells.

Europium metal thin films have been electrodeposited potentiostatically onto the fluorine-doped tin-oxide (FTO) covered glass substrates from an aqueous acidic bath, complexed with a citric acid. Bath pH value of 2–2.5 and citric acid as complexing agent play an important role in bringing down the deposition potential and thus making the deposition process possible. The effects of preparative parameters such as deposition potential and bath temperature are studied. The films are exposed to atmospheric oxygen for their conversion into europium oxide and are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. The XRD studies reveal that the material formed on FTO covered glass substrates is europium oxide and polycrystalline one. The grain size for the deposited material is about 300 A. The SEM studies show that total substrate surface is covered by the film with small grains.

Antimony doped SnO2 films have been prepared by spray pyrolysis. The films deposited at an optimised substrate temperature of 520°C were found to have a resistivity as low as 0.4×10−4 Ω cm. Doping concentration of Sb in the spraying solution was varied from 0.5 to 5%, keeping the spray rate constant. The sheet resistance was as low as 6 Ω cm−2. About 80% average transmission in the visible region was obtained for 1% Sb doped films. The refractive index increased from 1.62 to 2.64 with increasing the Sb content from 0 to 5%. Van-der-Pauw’s four probe technique of conductivity measurement was used to measure electrical conductivity (σ), Hall coefficient (RH), carrier concentration (n) and Hall mobility (μH) of the Sb:SnO2 films. The films deposited using 1% Sb doping showed the best properties.

Semiconducting Bi2S3 thin films were prepared on stainless steel and fluorine-doped tin oxide (FTO) coated glass substrates from non-aqueous media using the electrodeposition technique. It has been found that bismuth nitrate and thiourea in the volumetric proportions as 8:2 and their equimolar solutions of 0.05 M concentration form good quality films of Bi2S3. The characterization of the prepared films was carried out using the X-ray diffraction and optical absorption techniques. These studies reveal that, as deposited films are polycrystalline having an optical band edge (direct) 1.8 eV.

Sb 2 S 3 thin films have been prepared by spraying the mixture of non-aqueous equimolar solutions of antimony trichloride [SbCl 3 ] and thiourea [CS(NH 2 ) 2 ] in acetic acid (glacial) onto fluorine doped tin oxide (FTO) coated glass substrates. The cell configuration n -Sb 2 S 3 /0.5M (KCl + KI) + 0.01M I 2 /C is used for studying the current–voltage ( I – V ) characteristics in dark and light, photovoltaic output, spectral response, photoresponse and photovoltaic rise and decay characteristics. The studies reveal that the Sb 2 S 3 thin films are n -type in conductivity. Using the Butler model, the optical band gap and minority carrier diffusion length ( L P ) are found to be 1.73 eV and 0.033 μm, respectively. The junction quality factor in dark ( n d ) and light ( n l ), series and shunt resistance ( R s and R sh ), fill factor ( FF ) and efficiency ( η ) for the cell have been estimated. The measured FF and η of the cell are 59.5 and 0.30%, respectively. Annealing and etching are found to improve the photoelectrochemical performance of the PEC cell.

Thin films of Sb 2 S 3 deposited by spray pyrolysis technique are characterized electrochemically and photoelectrochemically in a polyiodide electrolyte. The effect of substrates on the working of n -Sb 2 S 3 thin film/polyiodide/C photoelectrochemical (PEC) solar cells has been investigated. The role of substrates like titanium, stainless steel and fluorine doped tin oxide (FTO)-pre-deposited glass slides on the Mott–Schottky plots is investigated at various (1 kHz and 100 Hz) frequencies and the reasons for the dispersion observed have been explained. Band edges of spray deposited Sb 2 S 3 are located. Performance of the PEC cell is found to be improved on annealing and photoelectrochemical etching.

Bi2S3 thin films have been prepared without complexing agent and with different concentrations of ethylene diamine tetra acetic acid (EDTA) as complexing agent by a spray pyrolysis technique. The effect of concentrations of complexing agent on the properties of Bi2S3 thin films is studied by characterizing the films by X-ray diffraction, scanning electron microscopy (SEM), optical absorption and dark electrical resistivity measurement techniques. These studies reveal that all films are polycrystalline. The band gap energy for as deposited films is observed to be 1.72 eV. However, the band gap energy is observed to be 2.0 eV for different concentrations of complexing agent. The electrical resistivity of the films with complexing agent is higher than that of the films prepared without complexing agent. The electrical resistivity also depends upon the concentration of the complexing agent.

n -Sb 2 S 3 thin films were deposited using spray pyrolysis technique from non-aqueous medium. The semiconductor-septum (SC-SEP) storage cell is fabricated with the configuration | C | 0.5 M Polyiodide | n -Sb 2 S 3 | Ti || 0.1 M Fe(CN) 6 4− /Fe(CN) 6 3− | C |. The charging and discharging modes are studied and discussed. It was found that the storage of chemical energy in the semiconductor-septum cell is possible by using Sb 2 S 3 electrode.

Thin films of cadmium oxide are prepared on a glass substrate by a spray pyrolysis technique from an aqueous solution of cadmium acetate. The X-ray diffraction studies shows that the films are polycrystalline. The room temperature resistivity is of the order of 10 −2 Ω cm. From optical absorption data the bandgap energy of CdO is estimated to be 2.5 eV. Thermoelectric power measurement is carried out to understand the conduction mechanism.

Semiconducting p-Sb 2 Se 3 thin films have been spray deposited using two Se sources viz. SeO 2 and (CSe(NH 2 ) 2 ) at their optimised preparative parameters of deposition. The film thickness is of the order of 0.5 μm. X-ray diffraction studies reveal that the as-deposited films prepared using SeO 2 as a Se source are amorphous while those prepared using (CSe(NH 2 ) 2 ) are polycrystalline with orthorhombic crystal structure. Optical gap of the amorphous film is found to be 1.28 eV, while that of the polycrystalline film has 1.26 eV. Polycrystalline films have dark resistivity in the order of 10 7 Ω cm whereas amorphous films have in the order of 10 5 –10 6 Ω cm. Thermoelectric power (TEP) measurement studies reveal that both the films show p-type conductivity with the Seebeck coefficient to be 45 μV/°C and 1.82 mV/°C for the polycrystalline and amorphous Sb 2 Se 3 thin films, respectively.

Thin films of Sb2Se3 have been electrodeposited from an aqueous acidic bath at room temperature using selenium dioxide as a selenium ion source. The electrodeposition potentials for different bath compositions and concentrations of solution are estimated from the polarization curves. It has been found that SbCl3 and SeO2 in the volumetric proportion as 9 : 1 and their equimolar solutions of 0.0075 M form a good quality films. The films are annealed in a nitrogen atmosphere at 200°C for 1 h. The films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical absorption techniques. The XRD patterns of the films show that the as-deposited and annealed films are polycrystalline. The optical band gap energy for direct transition in Sb2Se3 thin films is found to be 1.55 eV.

Semiconducting thin films of sulphides of antimony and bismuth have been prepared onto glass substrates from non-aqueous medium using a spray pyrolysis technique. Transient photoconductivity measurement of the films in the microwave frequency is performed using the time resolved microwave conductivity (TRMC) method. From TRMC measurements the decay time of electrons is estimated to be 26 ns for Sb 2 S 3 and 50, 61 and 52 ns for Bi 2 S 3 thin films deposited at 220, 270 and 320°C temperatures, respectively.

Powders of Sb 2 S 3 are obtained by a bulk preparation technique using aqueous solutions of antimony trichloride and thioacetamide for two different complexing agents, namely, oxalic acid and tartaric acid. The concentration of solution is kept constant at 0.1 M and only the concentration of complexing agent is varied. The effect of concentration of the complexing agents on the properties of precipitated powder is studied. The powders precipitated using oxalic acid are grey, whereas the powders precipitated using tartaric acid are orange in colour. X-ray diffraction studies reveal that the powders are polycrystalline in nature. Crystallinity using the former acid is relatively higher than that with the latter. It has been observed that the crystallinity goes on decreasing as the concentration of complexing agents increases. Infrared spectroscopy studies indicate the presence of carbon and absorbed water in the powders complexed with oxalic acid. Optical absorption studies show that the direct bandgap energy of the precipitated powders prepared using oxalic acid varies from 1.59 to 1.98 eV and it is found to be higher (1.98 eV) for powder prepared using 0.25 M oxalic acid, while for powders prepared using tartaric acid, it varies from 1.92 to 2.02 eV and is found to be higher (2.02 eV) for the powder prepared using 0.75 M tartaric acid. Electrical resistivity study reveals that the room-temperature electrical resistivity of the powders prepared using oxalic acid is relatively lower (10 4 –10 6 Ω cm) than that of tartaric-acid-complexed powders (10 5 –10 7 Ω cm).

Bi2S3 thin films are deposited by a spray pyrolysis technique using oxalic acid as a complexing agent. The films are characterized for their structural, optical and electrical properties. The results are compared with the properties of Bi2S3 thin films produced by the same technique without using the complexing agent. The XRD studies reveal that the growth of the film in a particular direction can be obtained just by controlling the quantity of the complexing agent. The resistivity of complexed films is more than that of as-deposited films. Thermoelectric power (TEP) measurement shows that the carrier concentration and mobility decrease with increasing quantity of oxalic acid. Optical absorption study reveals that the band gap energy, irrespective of the quantity of oxalic acid added to the material, is 1.75 eV.

Thin films of Bi 2 Se 3 have been prepared from an aqueous acidic bath at room temperature using selenium dioxide as a selenium ion source by a simple, inexpensive electrodeposition technique. The electrodeposition potentials for different bath compositions and concentrations are estimated from polarization curves. It has been found that Bi(NO 3 ) 3 and SeO 2 in the volumetric proportion as 7:3 and their equimolar solutions of 0.025 M form good quality films. The films are annealed in a nitrogen atmosphere at 200 °C for 2 h. The films are characterized by scanning electron microscopy, X-ray diffraction and optical absorption techniques. Studies reveal that as-deposited and annealed thin films are continuous and polycrystalline in nature. The optical band gap has been found to be 0.55 eV for the above-mentioned composition and concentration of the film.

Sb2S3 semiconducting thin films and precipitated powders have been prepared by a spray pyrolysis technique and bulk precipitation method, respectively. The concentration of solution is kept constant at 0.1 M and only the concentration of complexing agent (tartaric acid) is varied from 0.25 M to 1 M. The thickness of the film measured by weight difference method is found to be relatively higher for the film deposited with 0.5 M tartaric acid. The film thickness is of the order of 0.1 μm. As-deposited films are found to be uniform, dark grey and well adherent to the glass substrates. In contrast, the precipitated powders are orange in colour. X-ray diffraction studies reveal that the precipitated powders are polycrystalline whereas films are amorphous in nature. Also it has been found that the crystallinity of the precipitated powder is higher for 0.25 M concentration and decreases for the further concentrations of complexing agent. The direct bandgap of the thin films is found to be 2.7 eV irrespective of concentration of complexing agent, whereas the direct bandgap of the precipitated powder varies from 1.92 to 2.02 eV and is found to be higher (2.02 eV) for the powder prepared using 0.75 M tartaric acid. Electrical resistivity study reveals that at 0.5 M tartaric acid, the R.T. resistivity of the thin film is relatively lower (∼ 106 Ωcm) than that of precipitated powder (∼ 10su8–109 Ωcm).

Bi2O3 thin films have been prepared by spray pyrolysis method onto the glass substrates at optimised substrate temperature of 450 °C. The spray rate was maintained to be constant during the deposition. These films have been converted into Bi2S3 thin films by a chemical method. The Bi2O3 thin films when dipped into a solution of sodium sulphide [Na2S] are found to be converted into Bi2S3 thin films. The structural, optical and electrical properties of both the Bi2O3 and Bi2S3 thin films are reported.

Semiconducting Sb2S3 thin films were prepared on glass substrate from non-aqueous medium using the spray pyrolysis technique. The films were deposited at the optimized substrate temperature and solution concentration. The films were characterized by means of X-ray diffraction, scanning electron microscopy, optical absorption and dark resistivity techniques. These studies revealed that as-deposited films are polycrystalline in nature with an optical band gap (direct) of 1.8 eV and electrical conductivity in the order of 10−6-10−7 ohm−1 cm